Statistical model analysis of local structure of quaternary sphalerite crystals

At the 2004 Ural International Winter School, we introduced the statistical strained tetrahedron
 model and discussed ternary tetrahedron structured crystals. The model allows one to interpret
 x-ray absorption fine structure (EXAFS) data and extract quantitative information on ion s...

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Опубліковано в: :Физика низких температур
Дата:2007
Автори: Robouch, B.V., Kisie, A., Marcelli, A., Sheregii, E.M., Cestelli Guidi, M., Piccinini, M., Polit, J., Cebulski, J., Mycielsk, A., Ivanov-Omski, V.I., Sciesinska, E., Sciesinski, J., Burattini, E.
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Опубліковано: Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України 2007
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Цитувати:Statistical model analysis of local structure of quaternary
 sphalerite crystals / B.V. Robouch, A. Kisiel, A. Marcelli, E.M. Sheregii, M. Cestelli Guidi, M. Piccinini, J. Polit, J. Cebulski, A. Mycielski, V.I. Ivanov-Omskii, E. Sciesinska, J. Sciesinski, and E. Burattini // Физика низких температур. — 2007. — Т. 33, № 2-3. — С. 291-303. — Бібліогр.: 40 назв. — англ.

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Digital Library of Periodicals of National Academy of Sciences of Ukraine
_version_ 1860228352268304384
author Robouch, B.V.
Kisie, A.
Marcelli, A.
Sheregii, E.M.
Cestelli Guidi, M.
Piccinini, M.
Polit, J.
Cebulski, J.
Mycielsk, A.
Ivanov-Omski, V.I.
Sciesinska, E.
Sciesinski, J.
Burattini, E.
author_facet Robouch, B.V.
Kisie, A.
Marcelli, A.
Sheregii, E.M.
Cestelli Guidi, M.
Piccinini, M.
Polit, J.
Cebulski, J.
Mycielsk, A.
Ivanov-Omski, V.I.
Sciesinska, E.
Sciesinski, J.
Burattini, E.
citation_txt Statistical model analysis of local structure of quaternary
 sphalerite crystals / B.V. Robouch, A. Kisiel, A. Marcelli, E.M. Sheregii, M. Cestelli Guidi, M. Piccinini, J. Polit, J. Cebulski, A. Mycielski, V.I. Ivanov-Omskii, E. Sciesinska, J. Sciesinski, and E. Burattini // Физика низких температур. — 2007. — Т. 33, № 2-3. — С. 291-303. — Бібліогр.: 40 назв. — англ.
collection DSpace DC
container_title Физика низких температур
description At the 2004 Ural International Winter School, we introduced the statistical strained tetrahedron
 model and discussed ternary tetrahedron structured crystals. The model allows one to interpret
 x-ray absorption fine structure (EXAFS) data and extract quantitative information on ion site occupation
 preferences and on the size and shape of each elemental constituent of the configuration tetrahedra.
 Here we extend the model to cover quaternary sphalerite crystal structures. We discuss the
 two topologically different quaternary sphalerite systems: the pseudo balanced A₁₋xBxYyZ₁₋y (2:2
 cation:anion ratio), and the unbalanced AxBx 
 C₁₋x₋x 
 Z or AXyYy 
 Z₁₋y₋y (3:1 or 1:3 cation:anion ratios)
 truly quaternary alloy systems. These structural differences cause preference values in pseudo
 quaternaries to vary with the relative contents, but to remain constant in truly quaternary compounds.
 We give equations to determine preference coefficient values from EXAFS or phonon spectra
 and to extract nearest-neighbour inter-ion distances by EXAFS spectroscopy. The procedure is illustrated
 and tested on CdMnSeTe, GaInAsSb, and ZnCdHgTe quaternary alloys.
first_indexed 2025-12-07T18:20:31Z
format Article
fulltext Fizika Nizkikh Temperatur, 2007, v. 33, Nos. 2/3, p. 291–303 Statistical model analysis of local structure of quaternary sphalerite crystals B.V. Robouch1, A. Kisiel2, A. Marcelli1, E.M. Sheregii3, M. Cestelli Guidi1, M. Pic- cinini1,4, J. Polit3, J. Cebulski3, A. Mycielski5, V.I. Ivanov-Omskii6, E. Sciesi~nska7, J. Sciesi~nski7, and E. Burattini8 1INFN-Laboratori Nazionali di Frascati, Via E. Fermi, 40, Frascati I-00044, Italy E-mail: robouch@Lnf.infn.it 2Instytut Fizyki, Universytet Jagiellonski, Reymonta, 4, Krakow 30-059, Poland 3Institute of Physics, University of Rzeszow, Rejtana, 16A, Rzeszow 35-310, Poland 4Dipartimento Scienze Geologiche, Universita Roma Tre, L. go S.L. Murialdo, Rome 00146, Italy 5Instytut Fizyki PAN, Al. Lotnikow, Warszawa 32/46, Poland 6A.F. Ioffe Physical-Technical Institute, St. Petersburg 194021, Russia 7Institute of Nuclear Physics, Krakow, Poland 8University of Verona, Department of Informatics, str. Le Grazie 15, Verona 37134, Italy Received October 4, 2006 At the 2004 Ural International Winter School, we introduced the statistical strained tetrahe- dron model and discussed ternary tetrahedron structured crystals. The model allows one to interpret x-ray absorption fine structure (EXAFS) data and extract quantitative information on ion site occu- pation preferences and on the size and shape of each elemental constituent of the configuration tetra- hedra. Here we extend the model to cover quaternary sphalerite crystal structures. We discuss the two topologically different quaternary sphalerite systems: the pseudo balanced A1–xBxYyZ1–y (2:2 cation:anion ratio), and the unbalanced AxBx′C1–x–x′Z or AXyYy′Z1–y–y′ (3:1 or 1:3 cation:anion ra- tios) truly quaternary alloy systems. These structural differences cause preference values in pseudo quaternaries to vary with the relative contents, but to remain constant in truly quaternary com- pounds. We give equations to determine preference coefficient values from EXAFS or phonon spec- tra and to extract nearest-neighbour inter-ion distances by EXAFS spectroscopy. The procedure is il- lustrated and tested on CdMnSeTe, GaInAsSb, and ZnCdHgTe quaternary alloys. PACS: 61.43. Dq Amorphous semiconductors; metals and alloys. Keywords: sphalerite quaternary A1–xBxYyZ1–y, AxBx′C1–x–x′Z, AXyYy′Z1–y–y′ systems; local crystal structure; statistical model. 1. Introduction In recent years interest in multinary sphalerite structured semiconductors has developed rapidly, moving from binary to ternary, then to quaternary systems, as an extra ion-component leads to an addi- tional degree of freedom in controlling material pa- rameters. Indeed, the substitution of one cation by an- other in the cation sublattice, and the substitution of one anion by another in the anion sublattice, induces a reconstruction of the electronic structure and the phonon spectra as the composition is varied, leading to almost unique property variations. As observed, ion substitution in sphalerite crystals exhibits site occupa- tion preferences (SOPs) linked to the thermodynamic properties of the creation of the quaternary system. We recall here that the elemental structure of a sphalerite (zincblende) binary AZ compound is a regu- © B.V. Robouch, A. Kisiel, A. Marcelli, E.M. Sheregii, M. Cestelli Guidi, M. Piccinini, J. Polit, J.Cebulski, A. Mycielski, V.I. Iva- nov-Omskii, E. Sciesi~nska, J. Sciesi~nski , and E. Burattini, 2007 lar tetrahedron with alternatively at the center an A (or a Z) ion, and at its four vertices the other ion Z (or A). Alloying two binary compounds such as AZ + BZ (or AZ+AY) leads to the formation of different ter- nary A1–xBxZ (or AYyZ1–y) systems with A ions being progressively substituted by B ions (or Z by Y). Thus one of the sublattices remains homogeneously mono- ion, while the other is modulated by the two compet- ing ions. At the same time the tetrahedron is distorted, becoming strained (see Fig. 1 in [1]), whence the name of strained tetrahedron model introduced to treat these systems. In the following, we use the same nomenclature in- troduced in [1] and used since [2–6] and define cat- ions by A, B, C, anions by X, Y, Z, and the relative contents of site competing ions by x, x′ for cations, and by y, y′ for anions. We thus write AZ for a binary compound, A1–xBxZ or AYyZ1–y for a ternary system, and either A1–xBxYyZ1–y (2:2 cation:anion ratios, re- ferred to as Q22) or A1–x–x′Bx′CxZ or AXyYy′Z1–y–y′ (with respectively (3:1 or 1:3 cation:anion ratios) for quaternary systems. We shall refer to them, respec- tively, as Q31 and Q13 systems. We immediately note that configuration-struc- ture-wise, the quaternary systems are of two different natures: the Q31 and Q13 are quaternaries of the «un- balanced» truly-quaternary (truly-Q) type with re- spectively a 3:1 or 1:3 cation:anion ratio. Here, of the possible fifteen elemental tetrahedron configurations, ion-occupation-wise, three are binary, nine ternary, and three quaternary; indeed, the elementary tetrahe- dron contains respectively two, three, and four differ- ent ions. On the other hand, the Q22 type of quater- nary is balanced, contains only 2:2 cation:anion species, and can be considered pseudo-quaternary (pseudo-Q). Ion-occupation-wise Q22 can have six- teen tetrahedron configurations, of which four are binary, and twelve ternary. None of its sphalerite tet- rahedron configurations can canonically be «quater- nary». Indeed, in a Q22 system, each cation (anion) has only two anions (cations) of the opposite polarity that can occupy the four vertex sites of the sublattice. Implanting into a vertex position of an ion with the same polarity as the central ion corresponds to intro- ducing it into the opposite sublattice, i.e., creating an antisite occupation point defect. Thus we can consider the four ternary constituents (each with its tetrahe- dron configurations) as dissolved in a quaternary me- dium, with a A1–xBxYyZ1–y consisting of A1–xBxY or AYyZ1–y, A1–xBxZ or BYyZ1–y. The Q31 (Q13) and Q22 systems are usually chem- ically identified as quaternary alloys. However, there is a basic structural difference between the pseudo-Q and the truly-Q systems. Indeed, while a truly-Q has one of its sublattices with a homogeneously mono- ionic population, the complementary sublattice is modulated by the three ion species competing for each site. This leads to a crystal structure with alterna- tively a homogenous ion-shell, followed by a heteroge- neous shell with site-competing ions. On the other hand, in pseudo-Q the sublattices, and hence the suc- cessive ion shells, are all heterogeneous, have succes- sively anions or cations, intracompeting for site occu- pation in that shell. While the denomination is a consequence of the existing configurations, the occur- rence of successive homogeneous\inhomogeneous shell structures conditions basic differences in the properties of the two classes of quaternaries. The topo- logical differences between quaternary sphalerite Q31 (Q13) and Q22 structured systems impose different statistical model approaches and thus the statistical analysis of the pseudo and truly-Q compounds is not a simple generalisation. This explains why, after the Q22 compound analysis [4], an ad hoc statistical strained tetrahedron model for quaternary sphalerite Q31 and Q13 systems is developed in Ref. 7. An understanding of the properties of quaternary alloys requires accurate and systematic structural in- vestigations using different techniques such as neu- tron scattering, extended x-ray absorption fine struc- ture (EXAFS) [8,9] or far infrared (FIR) [10,11] vibrational spectroscopy. In particular the last two methods yield respectively information on the real lo- cal structure and on the collective internal vibrations (phonons) of the investigated systems. As generally reported, ternary tetrahedron coor- dinated A1–xBxZ and AYyZ1–y systems ([12–15] for FIR and [16–28] for EXAFS), as well as balanced quaternaries of type A1–xBxYyZ1–y (such as GaInAsSb [29] for EXAFS, CdMnSeTe [30] for EXAFS and [6,31] for FIR, analyzed in [32], ZnCdSeTe [33] for FIR), and unbalanced quaternary A1–x–x′Bx′ CxZ (such as MnCdHgTe [34], ZnCdHgTe [35,36]), or AXyYy′Z1–y–y′ system FIR spectra all exhibit SOPs; such preferences are linked to the thermodynamic properties of each system. To extract quantitative information on the local structure of tetrahedron configured crystals, we origi- nally developed the statistical strained tetrahedron model to return site preferences as well as sizes and shapes of the elemental tetrahedron configurations from sphalerite and some wurzite EXAFS experimen- tal data for ternary semiconductor alloys [1,2]. Suc- cessively, the model was expanded to treat ternary M3(XX′)1 type intermetallide alloys [3] and then to interpret FIR spectra of ternary sphalerite structure [4,5]. To our knowledge no EXAFS data for truly-Q systems are available in the literature. 292 Fizika Nizkikh Temperatur, 2007, v. 33, Nos. 2/3 B.V. Robouch et al. For wurzite systems, the model returns a valid analysis of EXAFS data provided the electron wave backscattering from ions beyond the next nearest neighbours (NNN) remains negligible with respect to that from nearest neighbours (NN) and from NNN ions; the same restriction applies to both balanced pseudo-Q [6] and unbalanced truly-Q [7] sphalerite structured systems. The basic assumptions or axioms of the statistical model are [1,2]: 1. The elemental tetrahedra are free to have differ- ent sizes and shapes (Fig. 1 in [1,2]). 2. Bernoulli binomial polynomials with preference weight coefficients describe ion-pair and configuration populations. 3. All NNNs and further fills are determined by NN preferences. 4. The total coordination number is conserved when dilution varies (this defines the range of values with physical meaning and imposes bounds on coeffi- cient values). 5. The formation of each ternary or quaternary ele- mental configuration proceeds, respecting mass conser- vation, until complete exhaustion of one of the binary ingredients, or of both simultaneously as in the random case. This axiom is crucial to understand and interpret SOP estimations returned from EXAFS and FIR analy- sis. Then to interpret EXAFS distance data [1]: 6. All nineteen elemental inter-ion ternary dis- tances are tetrahedron constrained. 7. Elemental volumes of the two sublattices, for each of the three strictly ternary configurations, relax pair-by-pair to common values (i.e., three volume re- laxation constraints [VRC] on the distance parame- ters). For FIR spectra, the lines issued from the differ- ent configurations by a given ion ij-dipole have an invariant [4,5]. 6′. Line width shape ij � and 7′. Oscillator strength ij s. We compare the statistical models of balanced and un- balanced quaternary compounds and quantify preferences using both EXAFS and FIR experimental data. We at- tempt to extract NN inter-ion distances from EXAFS data. Finally, we apply the model to balanced quaternary alloys CdMnSeTe, GaInAsSb and the available unbal- anced quaternary ZnCdHgTe phonon spectra [35,36]. To facilitate comprehension of the text, we confine all the equations to the appendix, but refer to the pub- lished articles where they are derived and presented in extensio so that the reader can interpret EXAFS data or FIR vibrational spectra and extract quantitative in- formation on SOP coefficients, or for just EXAFS, the elemental configuration distances between NN and NNN ions. 2. General considerations Sphalerite (zincblende) systems are face centered cubic (fcc) structure with tetrahedron coordinated configurations with an anion (cation) at the center and a cation (anion) at each of the four vertices. De- pending on whether we have at the vertices one, two, or three types of ions (with the extra ion type at the center), the systems are respectively binary, ternary, or quaternary. In all cases, the cations form one of the two crystal sublattices, while the anions constitute the complementary sublattice shifted by a 1/4 of the length of the main diagonal of the elemental cube. A binary AZ compound consists of regular tetrahe- dra T a0( )AZ , is defined by its lattice constant aAZ with inter-ion distances AZ AZ AA4;d a / d/ 0 1 2 03� � � �ZAZ AZd a / / 0 1 22 , and its first and second shells are strict spheres, one of cations, the other of anions; thus, determining aAZ by interferometer spectrome- try, defines the distribution and elemental dimen- sions. A ternary A1–xBxZ (or AYyZ1–y) system is ob- tained by a progressive substitution of A by B ions (or Z by Y) in the configuration tetrahedra { } ,Tk k�0 4, where k stands for the number of substituting ions B (or Y) at the vertices. Still, one of the two sublattices remains strictly homogeneous mono-ionic, while the other is modulated by the two competing ions. Com- petition is conditioned by the preference of the one competing ion to the other; thus the ion distribution departs from pure randomness. At the same time, since competing ions have different radii, the tetrahedron becomes distorted i.e., strained (Fig. 1 in [1]). A quaternary sphalerite structured semiconductor system results from a further substitution of yet ano- ther ion into a ternary alloy. Such an intrusion may or may not keep one of the two sublattices strictly homogeneous mono-ionic. When AxBx′ C1–x–x′Z or AXyYy′Z1–y–y′ are generated, the «unbalanced» Q31 and Q13 have one sublattice mono-ionic homogeneous, while the second is modulated by the three competing ions and hence are truly-Q. Their configuration tetra- hedra are { }, , ; ,Tk j k j k� � �0 4 0 4 , where k and j stand for the number of substituting ions A and B (or X and Y) at the vertices. On the other hand, in a A1–xBxYyZ1–y system with a balanced Q22 with 2:2 cation:anion ratio competition occurs in both sublattices. Indeed, a Q22 system cannot (excluding antisite point defects) have a canonical quaternary configuration and hence is a pseudo-Q [6]. Thus a Q22 A1–xBxYyZ1–y is a mixture of four ternary systems, each with a distinct c-ion (A,B,Y, or Z) at the center; their configuration tetra- hedra are { } ,, ;c k kT � �03 c A,B,Y,Z where k stands for the number of substituting ions Y (or B) at the vertices. Statistical model analysis of local structure of quaternary sphalerite crystals Fizika Nizkikh Temperatur, 2007, v. 33, Nos. 2/3 293 In the absence of SOPs, ion distribution through- out the configuration sites is random. The ion distri- bution in the successive shells with N sites (4 in the NN shell, 12 in the NNN shell) around the central c-ion are described by Bernoulli binomials. In the case of two competing ions (occupation of N sites by mA ions and hence ( )N m� B ions with rela- tive contents x and 1 � x), by { ( ) ( ) }[ ] ,pm x C x xN m N m N m m N� � � �1 0 (1) with C N / m N mm N � �! [ !( )!] the binomial coeffi- cient and { ( )}[ ] , pm xN m N � � � 1 0 ; { ( )}[ ] , mp x Nxm N m N � � � 0 . In the case of three competing ions, as for truly-Q systems (with occupation of N sites by kA ions, jB ions and (N–k–j)C ions, with respective relative con- tents x, x′, and (1–x–x′)) (see for instance [37]) by { ( , )[ ]p x x C x C xkj N k N k j N k j� � � �� � � � � � � � � �( ) } , ; ,1 0 0x x N k j k N j N k (2a) a set of fifteen terms, one for each configuration, with j kk kjp x x � �� �� � � 0 40 4 1 ,, { ( , )} while 0 1� � �( )x x . (2b) Whenever the system presents preferences, the distri- bution is no longer random, and to describe probabili- ties, SOP weight coefficients W are applied to each Bernoulli binomial [1]. Binary weight coefficients are evidently Wbinary � 1. Thus, a ternary with its three truly ternary configurations and two binary requires three { } ,Wk k�1 3 SOP coefficients [1], while the Q22, mixture of four ternary systems, requires 12 (= 4 3) { } , ;c k k cW � �1 3 A,B,Y,Z coefficients (Table 1 and [6]). The truly-Q with { } , ; ,Wkj k j k� � �0 4 0 4 coefficients, with the binary W W W00 04 40 1� � � (Table 4), needs 12 coefficients. Since all probability coefficients are non- negative, the SOP W coefficient values are restricted. Because preferences imply unbalanced populations (with respect to random, W � 1), the excess (or scar- city) of one of the constituent ions competing for sites with respect to stoichiometry determined populations. Actually when the minor constituent is no more avail- able, the excess remains as a binary. Respect to the ran- dom case the resulting nonbinary configuration pro- babilities are depressed each time anyW-coefficient � 1, and the corresponding depression factor CW �1 appears, with the ions in excess going to enhance the correspond- ing binary populations, see Appendix 1. Once the values of the SOP coefficients are known, all coordination numbers (CN), see Appendix 2, and configuration probabilities (Pternary: Pk(x); Ppseudo-Q: cPk(x,y); Ptruly-Q: Pkj(x,y)) as functions of the respec- tive ion relative contents (x, x′, y, y′ as appropriate for each system) are fully determined, see Appendix 3. From these quantities we get the expressions for the evaluation of the elemental configuration inter ij-ion distances ( )i j d , derivable from EXAFS � i j CN and � i j d (see Appendix 4), or from FIR spectra the preference SOP coefficients of the multinary (see Appendix 5). In the following for the sake of clarity, we will use the above-mentioned mnemonic symbolism rather than the traditional Rj and � j EXAFS parameters. We now concentrate on the two quaternary systems Q22 and Q31 or Q13 and outline the consequence on SOPs: Pseudo-Q is a mixture of ternaries, so SOPs drift with contents! On the other hand, truly-Q SOP coefficient values remain invariant as the relative ion contents vary! 3. Pseudo-quaternary A1–xBxYyZ1–y sphalerite structure Tetrahedron coordinated sphalerite structure qua- ternary systems of type A1–xBxYyZ1–y consist exclu- sively of binary and ternary elemental tetrahedra, four of the first and four of the latter, each one with three configurations, i.e., a total of sixteen elemental tetra- hedron configurations (Table 1). Counting the di- poles, we have 4 from binary + (4 3 2) from the ter- nary configurations; i.e., potentially a total of up to 28 phonon lines in 4 basic bands (Fig. 1) of closely overlapping lines. However, these configurations can- not contain simultaneously all four constituent atoms in the same elemental tetrahedron; as a consequence we can consider each ternary tetrahedron composition as being diluted in the quaternary compound. Thus, A1–xBxYyZ1–y EXAFS data can be treated by using the strained tetrahedron model which, originally de- veloped to deal with ternary systems, has already ex- hibited excellent agreement with numerous experi- mental data [1,2]. Table 1. The 16 tetrahedron configurations of a quater- nary A1–xBxYyZ1–y system: 4 binary (AY, AZ, BY, BZ) + (4·3) ternary (A1–xBxY, A1–xBxZ, AYyZ1–y, BYyZ1–y) =16. No pure quaternary configuration occurs. j B = \ k A = 0 1 2 3 4 0 CZ 1A3C:Z 2A2C:Z 3A1C:Z AZ 1 1B3C:Z 1A1B2C:Z 2A1B1C:Z 3A1B:Z 2 2B2C:Z 1A2B1C:Z 2A2B:Z 3 3B1C:Z 1A3B:Z 4 BZ 294 Fizika Nizkikh Temperatur, 2007, v. 33, Nos. 2/3 B.V. Robouch et al. To determine ion site occupation preferences of qua- ternary systems, we applied this model to GaInAsSb [29] data available in the literature and to our EXAFS data for CdMnSeTe [30], and we compared the results with those derived from ternary EXAFS data for GaInAs [16] and CdMnTe [17,18]. In both sets, as the ternary is diluted in the quaternary system, different preference values respect to the pure ternary are ob- served. The present analysis of the experimental reflec- tivity FIR phonon spectra of quaternary CdMnSeTe crystals [6] confirms the model predictions and leads to a consistent interpretation of the experimental data for A1–xBxYyZ1–y quaternary systems [6]. From Table 1, the total number of dipole contributions is 4 from bi- nary + (12 2) from the ternary configurations; i.e., we expect up to 28 phonon lines in 4 basic bands (Fig. 1). 4. Truly-quaternary AxBx� C1–x–x� Z or AXyYy� Z1–y–y� sphalerite structured systems Tetrahedron coordinated sphalerite quaternary sys- tems of the type AxBx�C1–x–x�Z or AXyYy�Z1–y–y� con- sist of fifteen elemental tetrahedra, each containing at the center one ion and at the vertices one, two, or three competing ions, i.e., respectively binary, ter- nary, and truly-Q in composition (Table 2). Counting the dipoles, we have 3 from binary + (3 3 2) from the ternary + (3 3) from the quaternary configurations; i.e., up to 30 phonon lines in 3 basic bands (Fig. 2). By tuning the x-ray energy to the K- (or L- or M-) edge of one of the constituent ions «c» ( where c = {A, B, C, or Z} of the AxBx�C1–x–x�Z quaternary) we probe the average (over the sample and over all configura- tions) local structure around the selected atom; one thus may retreive: the relative number of ions of a given type around it, i.e., ion pairs or coordination numbers (CN), <center vertex CN(x,x�)>; inter-ion dis- tance center vertex< d(x,x�)> between the selected c-ion and the NN or NNN vertex-ions around it. Table 2. The 15 tetrahedron configurations of the quater- nary AxB �x C1–x– �x Z or AXyY �y Z1–y– �y system: 3 binary (AZ, BZ, CZ) + (3·3) ternary (A1–xBxZ, C1–xBxZ, AY Zy y1– , BY Zy y1� ) + (1·3) quaternary (1A1B2C:Z, 2A1B1C:Z, 1A2B1C:Z ) = 15 j B = \ k A = 0 1 2 3 4 0 CZ 1A3C:Z 2A2C:Z 3A1C:Z AZ 1 1B3C:Z 1A1B2C:Z 2A1B1C:Z 3A1B:Z 2 2B2C:Z 1A2B1C:Z 2A2B:Z 3 3B1C:Z 1A3B:Z 4 BZ The NN average coordination numbers � � i y x xCN( , ) are a «count» of ij-ion-pair numbers, explicitly the av- erage number of «j» ions around a central «i» ion. For the truly-Q structure with alternate homogeneous mono ion shells around the «competing» ions A, B, C, the NN shells have only Z-ions, i.e., � � �i Z x xCN( , ) 4, while around the Z-ions the expressions of probabili- ties of the «competing» A, B, C ions occupying the four NN sites, are given in the Appendix 2. Using the configuration probabilities { ( , )} , ; ,( )P x xkj k j k� � � �0 4 0 4 (Appendix 3) that duly account for stoichiometry, the expressions for the average NN inter-ion distances � � z d x xvertex ( , ) are given in Appendix 4 [1]. To interpret far infrared reflection\transmission spectra, the Kramers—Kronig transformation is ap- Statistical model analysis of local structure of quaternary sphalerite crystals Fizika Nizkikh Temperatur, 2007, v. 33, Nos. 2/3 295 100 150 200 250 0 4 8 MnSe MnTe CdSe Im30K.dat Sp.fit f100.2 f140 f142.8 f145.5 f148.3 f151 f153.8 f156.6 f159.3 f162.1 f164.8 f167.6 f170.4 f173.1 f175.9 f178.6 f181.4 f184.1 f186.9 f189.7 f192.4 f195.2 f197.9 f200.7 f203.5 f206.2 f209 f211.7 f214.5 f220 0.80.20.10.9Cd Mn Se Te � �( ) 2 Wavenumber –1�, cm CdTe Fig. 1. Deconvolution of the � �2( , )T function obtained by the KK-transform of the reflectivity spectrum of the Cd0.9Mn0.1Se0.2Te0.8 sample measured at T � 30 K (closed circles). Sp-fit is the obtained best fit curve; the 30 pseudo Voigt-shaped lines are labelled «f» followed by their pho- non frequency. Experimental �-resolution = 2 cm–1; �2 uncertainty �0.06; error bars are shown. The four main phonon bands [6] are addresed. 50 100 150 200 0 40 80 Possible ( ) Hg vacancies ZnTe CdTe HgTe KKdata Fit L1 C3 C4 C5 C6 C7 C8 C9 C10 L10 C12 C13 C14 C15 C16 C17 C18 L18 C Wavenumber –1�, cm � ( ) � 2 0.750.130.12Zn Cd Hg Te Fig. 2. Deconvolution of a Zn0.12Cd0.13Hg0.75Te spectrum (using Lorentzian line shapes). Experimental �-resolution = 2 cm–1; �2 uncertainty bars = �0.63; error bars are shown. Note the three main bands, and possibly Hg-vacancy point defects [7]. plied (carrefully as the experimental �-range is fi- nite), to obtain the corresponding complex dielectric constant � �( , , )x x� , whose general expression is [10,11]: � � � � � � �( , , ) { [( ) ]} , x x S / ij j j n j j� � � � �� � � 2 2 1 2 � � � � ��� � � � � �� � � �plasma 2 / i x x i x x[ ( )] ( ) ( , , )� 1 2 (3) where � �� �1( )x x� , and � �� �2( )x x� are respectively, the real and imaginary parts of the dielectric constant; � �( , , )x x� . In the equation, the first term �� is the optic dielectric constant; the second term represents contribu- tions by lattice and defect vibration modes, with � j the frequency of the phonon mode, �j the damping con- stant (or line half-width), and Sj the (dimensionless) oscillator strength (OS) of the spectrum component n lines; the third, the Drude term is related to plasma contribution with �plasma the plasma frequency, and � � 1/� , where � is the scattering time of free carries, apparent in semimetal alloys. The line profiles are assumed to be either Lorentzian, ( ( )yL � � � � s /L L L L� �2 2 2 0 2 2 2 2� � � �[( ) ] [10]), indicated at low temperatures, or whenever � �L G�� or Gaussian ( ( ) exp { [( ) ] }y s /G G G G� � �� � � 0 2� whenever the experimental line profile half width is greater than the natural spectral half width � �G L�� ; or a linear com- bination of both, referred to as pseudo-Voigt line shaped, y y yG LVoigt ( ) ( )� � �� �1 whenever �L � � �G ; with 0 1� �� , pseudo-Voigt covers both extreme and intermediate line shapes, leading to better quality best fits. A detailed comparative study of the spectral fit by Gaussian, Lorentzian, or pseudo-Voigt line shapes can be found in Ref. 40. Each line is associated to an ij-dipole ( ,i j� �A,B, or C Z, Y, or X) of the different configurations: one phonon from each of the binary configurations, two phonons from each of the three ter- nary configurations, and three phonons from each of the quaternary (see Appendix 5). The total number of phonon lines and the corresponding number of mode bands is particular to each system. The oscillator strength of each phonon is determined by the configura- tion probabilities P xk( ) (taking into account the SOPs, see Appendix 3) and the specific oscillator strengths of the binary compounds involved. The explicit expression of the equation for � �2( ) is given in Appendix 5. 5. Discussion and conclusions Experimental data of EXAFS and FIR of quaternary systems are rather scarce. We retrieved and processed EXAFS data of pseudo-Q GaInAsSb [29] (Fig. 3 and Table 3) and our previous data of CdMnSeTe [30] 296 Fizika Nizkikh Temperatur, 2007, v. 33, Nos. 2/3 B.V. Robouch et al. Table 3. Ga1–xInxAsySb1–y [6]: comparison of NN values for GaInAs(as T) [1,17] with those of GaInAs(in Q). GaInAs y Sb 1–y cTk c = As k = 1 AsWk 2 3 1 AsCk 2 3 k = 1 As Gadk 2 3 1 As In dk 2 [�] 3 GaInAs (in Q) y As = 0.05 x Ga = {0.2, 0.5, 0.65, 0.8, 0.95} 1.88 1.54 1.32 0.71 0.46 0.05 2.81 2.45 — 2.66 2.53 � y As = 0.10 x Ga = {0.1, 0.5, 0.9} 1.93 1.59 1.33 0.69 0.41 0 2.84 2.34 — 2.65 2.49 � both together 1.89 1.56 1.33 0.70 0.44 0 2.80 2.44 — 2.65 2.52 � GaInAs (as T) 1.05 0.25 0.58 0.85 0.25 0.58 2.49 2.42 2.48 2.59 2.60 2.61 0 0.5 1.0 0 4 N N < A sG a C N > < A sIn C N > x Ga Fig. 3. Analysis of Ga1–xInxAsySb1–y EXAFS � �CN Ga As K edge( )x data [31]. Experimental points (trian- gles up y � 01. , triangles down y � 02. ); derived curves � As Ga GaCN( )x (solid); � As GaCNln ( )x (dash dotted). Random limits (dotted). (Fig. 4 and Table 4), a system for which also the FIR reflectivity spectra are available [6]. From these the imaginary part of the respective dielectric functions � �2( ) were obtained (Fig. 1), and the data interpreted using the strained tetrahedron model. To our knowl- edge no truly-Q EXAFS data are available in the litera- ture. ZnCdHgTe FIR spectra are available [35,36] and the analysis [7], partially presented here (Fig. 2) is still in progress. Note that using pseudo-Voigt line shapes gives a better fit (Fig. 1), than using Lorentzian (Fig. 2), as observed in Refs. [6,38]. Table 4. Cd1–xMnxSeyTe1–y: comparison of NN values for CdMnTe(as T) [1,18,19] with those of CdMnTe (in Q) [6]. Ternary cTk c k = 1 cWk 2 3 k = 1 cCk 2 3 MnSeTe (in Q) Mn 3.23 3.22 3.23 0 0 0.20 0.40 0.26 0 0 0.40 0.20 CdMnSe (in Q) Se 2.18 0 1.33 0.54 0 0 CdSeTe (in Q) Cd 2.38 0 1.33 0.54 0 0 CdMnTe (in Q) CdMnTe (as T) Te 3.23 0.68 0 1.33 0 0 0.26 0.68 0 0.67 0 0 Quaternary sphalerite crystals have two distinct system structures — pseudo-Q and truly-Q — and re- quire distinct ad hoc theoretical treatments. The topo- logical structure of the ideal, canonical crystal (i.e., with no point defects or impurities) attributes respec- tively 28 and 30 basic phonon frequencies. In a real crystal, due to defects and impurities the number of frequencies further increases (see, for instance, [39,40]). We discussed EXAFS and phonon spectra of pseudo-Q alloys (GaInAsSb [29] (Fig. 3 and Table 3) and our data of CdMnSeTe [30] (Fig. 4 and Table 4)) and the phonon spectra of truly-Q ZnCdHgTe. Three of the four Q22 CdMnSeTe samples investigated by EXAFS, have been re-examined with FIR reflectivity [6], and the main results are summarized below. A pseudo-Q zincblende system responds as a linear superposition of the contributions of binary and ternary elemental tetrahedra of the four ternary components, as shown by the analysis of both EXAFS and FIR phonon spectra. Thus, the strained tetrahedron model, designed to interpret ternary tetrahedron coordinated systems, successfully interprets A1–xBxYyZ1–y systems. Most se- miconductors exhibit SOPs, as experimentally con- firmed yielding quantitative SOP coefficient values reli- ably using different models. The strained tetrahedron model gives a good agreement for both EXAFS data [1,2] and FIR spectra [4,5] of sphalerite ternary A1–xBxZ and AYyZ1–y, and now to the Q22 A1–xBxYyZ1–y systems [6]. It also successfully inter- prets EXAFS data of intermetallic M3(XX�) [3] sys- tems, and within certain limitations may do so for some wurzite crystalline structures [2], returning SOP coeffi- cient values. As a ternary is progressively diluted within the Q22, the evolution of the SOP-coefficients is a valu- able index of the thermodynamic evolution of the sys- tem. Indeed, the heterogeneous presence of competing ions in the NNN shell profoundly modifies the SOPs with respect to the corresponding pure ternary (which has a perfectly homogeneous NNN shell composition), and the system is affected by the site occupation compe- tition in both the cation and the anion sublattices, i.e., all shells, hence, SOPs conditioned by relative concen- trations. Thus in contrast with SOPs of a pure ternary Statistical model analysis of local structure of quaternary sphalerite crystals Fizika Nizkikh Temperatur, 2007, v. 33, Nos. 2/3 297 0 0.1 0.2 0.3 0.5 1.0 0 2 4 < M nS e C N (y S e )> , < M nTe C N (y S e )> y Se Mn Se CN Mn TeCN 0 0.1 0.2 0.3 0.5 1.0 0 2 4 Se Cd CN Se Mn CN < S eM n C N (x M n) > , < S eC d C N (x M n)> x Mn Fig. 4. Analysis of Cd1–xMnxSeyTe1–y EXAFS � CN data [32]. Experimental points: triangles pointing (a) down: Mn Se CN, up: Mn Te CN, (b) left: Se CdCN, right: Se MnCN; de- rived � CN curves, within the sphalerite range (solid), (dotted) beyond the sphalerite range. Random limit (dash dotted). for GaInAs(as T) in which the NNN ions around any cation are all As-anions, in GaxIn1–xAs0.05Sb0.95, GaInAs(in Q) they are almost all Sb-anions. In Q22 and in ternary systems, line shapes and intensities are deter- mined, to a first approximation, by the cation-anion di- pole pair, and are unaffected by the center-vertex posi- tion of the dipole within the tetrahedron configuration. Indeed, observing the normalized variance s2 values of successive best-fit results (Table 3 [6]) confirms our as- sumption that the two phonons emitted by a dipole ZA from the ternary AxB1–xZ and by AZ from the comple- mentary AYyZ1–y, are substantially equivalent. In contrast with Q22, the Q31 and Q13 systems have SOP coefficients invariant with relative contents values. Indeed, a truly-Q system, Q31 or Q13, is char- acterised by three ions competing for site occupation in a shell bounded on both sides by shells with homo- geneous mono-ions of the complementary sublattice. Many semiconductors exhibit SOPs with extreme values. Such a behavior indicates that the ternary fill- ing of one (sometimes two) of the three elemental tet- rahedron configuration(s) is almost negligible. This may be explained by a thermodynamic affinity of cat- ion–anion pair components in ternary or quaternary systems. A wide group of semiconductors is character- ized by missing elementary configurations, a behavior that is still not understood. Noteworthy, Q22 FIR spectra exhibit a trend ver- sus temperature, that could be correlated to the EXAFS analysis of these materials at different temper- atures and in particular to the behavior of the Debye-Waller parameters. Our analysis shows that one of the major conse- quences of the difference among SOPs in truly-Q and pseudo-Q is due to their structural difference. In fact as the relative ion contents vary, in a truly-Q the 12 SOP coefficient values remain constant, while in a pseudo-Q system, i.e., a mixture of ternaries, the 12 SOP values are functions of the relative contents. Work is in progress to determine from available FIR-spectra [7] the values of the twelve SOP-coeffi- cients for the truly-Q ZnCdHgTe similarly to the work performed in the ternary GaAsP [4,5]. Part of this work was supported by EU TARI-pro- ject contract HPRI-CT-1999-00088. 298 Fizika Nizkikh Temperatur, 2007, v. 33, Nos. 2/3 B.V. Robouch et al. Appendix (vademecum of Sphalerite system equations) We here reassume the equations based on the assumptions of the statistical strained tetrahedron model as de- rived in extenso in manuscripts [1–6]. The corresponding parameters are indicated. Appendix 1. SOP W- and C-coefficients [1, 6] All probability coefficients being nonnegative, restricts SOP W-coefficients values. Preferences affect configuration probability C-coefficients as follows System ternary [1] 3 {W k } k=1.3 parameters with {0 �W k � 4/k} k=13. 0 � {C k = min [W k ,1,(4 – kW k )/(4 – k)] } k=1.3 � 1 pseudo quaternary [6] 12 { c W k } k=1.3;c=A,B,Y,Z parameters with {0 � c W k �4/k} k=1.3;c=A,B,Y,Z 0 � { c C k = min [ c W k ,1,(4 – k c W k )/(4 – k)] } k=1.3;c=A,B,Y,Z � 1 truly quaternary and for pure Q – configurations 12 {W kj } k=0.3;j=0.3–k with 0 �{(k+ j)W kj } k=0.3;j=0.3–k � 4, 0 � {kW k,(4–k) } k=1.3 � 4, and 0�W 2.1 �4/3, 0 �W 1.2 � 4/3 , 0 � W 1.1 � 2 0 � C kj = min {W kj , 1, [4 – (k+ j)W kj ]/(4 – k – j)} �1 Statistical model analysis of local structure of quaternary sphalerite crystals Fizika Nizkikh Temperatur, 2007, v. 33, Nos. 2/3 299 Appendix 2. EXAFS – coordination numbers equations defining the average NN coordination numbers Ternary A1–xBxZ (or AYyZ1–y) [1] Parameters 3: {Wk}k=1.3 < A ZCN (x)> = < B ZCN (x)> = 4 < Z BCN(x)> = � k=0.3 � j=1.4–k [( j W kj ) p kj (x)] < Z ACN(x)> = � k=1.4 � j=0.4–k [( k W kj ) p kj (x)] = 4 – < Z BCN(x)> Pseudo quaternary A1–xBxYyZ1–y [6] Parameters 12: {cWk}k=1.3;c=A,B,Y,Z NN dipole <CN(x,y)> Pseudo quaternary A 1–x B x Y y Z 1–y AZ < A ZCN (y)> = � k=0.3 [(4 – k A W k )p k [4](y)] = 4 – < A YCN(y)> < Z ACN (x)> = � k=0.3 [(4 – k Z W k )p k [4](x)] = 4 – < Z BCN(x)> BZ < B ZCN (y)> = � k=0.3 [ (4 – k B W k )p k [4](y)] = 4 – < B YCN(y)> < Z BCN(x)> = � k=1.4 [ k Z W k p k [4](x)] = 4 – < Z ACN(x)> AY < A YCN(y)> = � k=1.4 [ k A W k p k [4](y)] = 4 – < A ZCN(y)> < Y ACN(x)> = � k=0.3 [ (4 – k Y W k ) p k [4](x)] = 4 – < Y BCN(x)> BY < B YCN(y)> = � k=1.4 [ k B W k p k [4](y)] = 4 – < B ZCN(y)> < Y BCN (x)> = � k=1.4 [ k Y W k p k [4](x)] = 4 – < Y ACN(x)> Truly quaternary AxB �x C1–x– �x Z or AXyYy�Z1–y–y� [7] Parameters 12: {Wkj} < A ZCN (x,x�)> = < B ZCN (x,x�)> = < C ZCN (x,x�)> = 4 < Z ACN(x,x�)> = � k=1.4 � j=0.4–k [( k W kj ) p kj (x,x�)] < Z BCN(x,x�)> = � k=0.3 � j=1.4–k [( j W kj ) p kj (x,x�)] < Z CCN(x,x�)> = � k=0.3 � j=0.3–k [ (4 – k – j)W kj p kj (x,x�)] = = 4 – < Z ACN(x,x�)> – < Z BCN(x,x�)> Appendix 3. Tetrahedron configuration probabilities (Pternary : Pk(x); PpseudoQ : Pk(x,y); PtrulyQ : Pkj(x,y)) Ternary A1–xBxZ (or AYyZ1–y) [1] Non binary configurations: 3{Tk}k=1.3.Parameters 3: {Wk}k=1.3 Stoichiometry preference shifts: Wk < 1 enhances binary AZ populations, while Wk > 1 that of binary BZ, i.e. {P k (x) = C k p k [4]} k=1.3 of ternary T k P 0 (x) = { p 0 [4](x) + � k=1.3 [max (0, 1 – W k ) p k [4] (x) ] } of binary AZ configuration T 0 P 4 (x) = { p 4 [4](x) + � k=1.3 [max (0, k(W k – 1)/(4 – k)) p k (x) ] } of binary BZ configuration T 4 300 Fizika Nizkikh Temperatur, 2007, v. 33, Nos. 2/3 B.V. Robouch et al. Pseudo quaternary A1–xBxYyZ1–y [6] Non binary configurations: 12 {cTk}c=A,B,Y,Z;k=1.3. Parameters 12: {cWk}c=A,B,Y,Z;k=1.3 Stoichiometry preference shifts to binary: AZ for ZWk < 1 and for AWk < 1, BZ for ZWk > 1 and BWk < 1, AY for YWk <1 and AWk >1, BY for BWk >1 and YWk >1. Let {cv(x,y)}c=A,B,Y,Z: = x for c = Y or c = Z , and = y for c = A or c = B , and {�c(x,y)}c=A,B,Y,Z;k=1.3) = { (1 – x)/2, x/2, y/2, (1 – y)/2}, with �c=A,B,Y,Z �c(x,y) �1 { c P k (x,y) = � c (x,y) c C k p k [4][ c v(x,y)] } k=1.3 of ternary c T k c P 0 (x,y) = � c (x,y) { p 0 [4](x) + � k=1.3 [max (0, 1 – c W k ) p k [4](x) ] } of binary AZ configuration c T 0 cP 4 (x,y) = � c (x,y) { p 4 [4](x) + � k=1.3 [max (0, k( c W k – 1)/(4 – k)) p k [4](x) ] } of binary BZ configuration c T 4 In the random case, when {Wk�1}k=1.3,{cPk [4](x,y) ���c(x,y)pk[cv(x,y)]}k=0.4 Truly quaternary AxB �x C1–x– �x Z or AXyYy�Z1–y–y� [7] Non binary configurations: 12 {Tkj}. Parameters 12: {Wkj} { P kj (x,x�) = C kj p kj (x,x�)} k=0.4;j=0,(4–k) for non binary P 40 (x,x�) = � k=1.3 � j=0.3–k [max (0,(k+ j)(W kj – 1)/(4 – k – j)) p kj (x,x�)] + � k=1.3 [max (0,k(W k,(4–k) – 1)/(4 – k)) p k,(4–k) (x,x�)] for binary AZ P 04 (x,x�) = � k=0.3 � j=1.3–k [max (0,(k+ j)(W kj – 1)/(4 – k – j)) p kj (x,x�)] + � k=1.3 [max (0,1 – W k,(4–k) ) p k,(4–k) (x,x�)] for binary BZ P 00 (x,x�) = � k=0.3 � j=0.3–k [max (0, 1 – W kj ) p kj (x,x�)] for binary CZ (4) with � k=0.4 � j=0.4–k {P kj (x,x�)}+ P 40 (x,x�)+ P 04 (x,x�)+ P 00 (x,x�) = = � k=0.4 � j=0.4–k {p kj (x,x�)} 1 (5) � k=0.4;j=0.4–k k*p kj (x,x�)} 4x , � k=0.4;j=0.4–k j*p kj (x,x�)} 4x�, � k=0.4;j=0.4–k k*p kj (x,x�)} 4(1 – x – x�) (6) In the random case, when {W kj 1} k=0.4;j=0.4–k , {P kj (x,x�) �p kj (x,x�)} k=0.4;j=0.4–k Appendix 4. EXAFS – average NN inter – ion distances <Z vertexd(x,x�)> (the binary distance values are from the literature) Ternary A1–xBxZ (or AYyZ1–y) [1] NN equations: 2. Parameters 9: 6 distance { AZdk , BZdk}k=1.3 + 3 {Wk}k=1.3 < Z Bd(x)> = � � k=1.4 [ (k C k )BZd k + 4 Max (0,W k – 1) BZd 4 ] p[4] k (x) } /� � k=1.4 [ (k C k ) + 4 Max (0,W k – 1) ] p[4] k (x) } < Z Ad(x)> = � � k=0.3 [(4 – k C k ) AZd k + 4 Max (0,1 – W k ) AZd 0 ] p[4] k (x) } /� � k=0.3 [ (4 – k C k ) + 4 Max (0,1 – W k ) ] p[4] k (x) } Statistical model analysis of local structure of quaternary sphalerite crystals Fizika Nizkikh Temperatur, 2007, v. 33, Nos. 2/3 301 Pseudo quaternary A1–xBxYyZ1–y [6] NN equations: 4. Parameters 36: 24 distances { c cvdk }k=1.3;c=A,B,Y,Z;v=v1,v2 + 12 {cWk}c=A,B,Y,Z;k=1.3 < A Zd (x,y)> = � (1 – x) � k=0.3 { A Zdk (4 – k A C k ) + 4 A AZd0 max (0,1 – A w k ) + 4 A AZd4 max [0, (k A W k – 1)/(4 – k)]} p k [4](y) } / / � (1 – x) � k=0.3 {(4 – k A C k ) + 4 max (0,1 – A W k ) + 4 max [0, (k A W k – 1)/(4 – k)]} p k [4](y) } < B Zd (x,y)> = { x � k=1.4 { B BZdk (4 – k B C k ) + 4 B BZd4max (0,1 – B W k ) + 4 B AZd4 max [0, (k B W k – 1)/(4 – k)] } p k [4](y) }/ / { x � k=1.4 { (4 – k B C k ) + 4 max (0,1 – B W k ) + 4 max [0, (k B W k – 1)/(4 – k)] }p k [4](y) } < Y Ad (x,y)> = � y � k=0.3 { Z AYdk(4 – k Z C k ) + 4 Z AYd0 max (0,1 – Z w k ) + 4 Z AYd4 max [0, (k Z W k – 1)/(4 – k)] } p k [4](x) } / �y � k=0.3 {(4 – k Z C k ) + 4 max (0,1 – Z W k ) + 4 max [0, (k Z W k – 1)/(4 – k)] }p k [4](x) } < Z Bd (x,y)> = { y � k=1.4 { Z BYdk k Z C k + 4 Z BYd4max (0,1 – Z W k ) + 4 Z BYd4 max [0, (k Z W k – 1)/(4 – k)] }p k [4](x) } / { y � k=1.4 { k Z C k + 4 max (0,1 – Z W k ) + 4 max [0, (k Z W k – 1)/(4 – k)] }p k [4](x) } Truly quaternary AxB �x C1–x– �x Z or AXyYy�Z1–y–y� [7] NN equations: 3. Parameters 21: 9 distance { vZdk }k=1.3;v=A,B,C+ 12 {Wkj} < Z Ad(x,x�)> = {� k=1.4 � j=0.4–k [ Z Ad kj k P kj (x,x�) ] + 4 Z A d 40 P 40 (x,x�) }/4x < Z Bd(x,x�)> = {� k=0.3 � j=1.4–k [ Z Bd kj j P kj (x,x�) ] + 4 Z B d 04 P 04 (x,x�) }/4x� < Z Cd(x,x�)> = {� k=0.3 � j=0.3–k [ Z Cd kj (4 – k – j) P kj (x,x�) ] + 4 Z C d 00 P 00 (x,x�) }/4(1 – x – x�) Appendix 5. FIR Recall that by axioms �6 ad �7 : AZ ����� AZ �k � AZ �kj�� BZ ����� BZ �k� BZ �kj�� CZ ����� CZ �k� CZ �kj}, and AZs = {AZsk = AZskj}, BZs = {BZsk = BZskj}, CZs = {CZsk = CZskj} for all k = 0.4 and j = 0.4 Ternary A1–xBxZ (or AYyZ1–y) [1,4,5] Parameters 15: 8 { AZ �k}k=0.3 , { BZ �k}k=1.4} + 3 {Wk}k=1.3 + 2 {AZ �� BZ �} + 2 {AZs,BZs } � � �,x) = {{4 AZs 0 AZ � 0 2 AZ � 0 � / [ �2 � AZ � 0 2)2 + AZ � 0 2 � 2]} P 0 (x) binary AZ � � k=1.3 {k BZs k BZ � k 2 BZ � k � / [ �2 � BZ � k 2)2 + BZ � k � � 2] + (4 – k) AZs k AZ � k 2 AZ � k � /[ �2 � AZ � k 2)2+ AZ � k � � 2]}P k (x) ternary ABZ ��4 BZs 4 BZ � 4 2 BZ � 4 � / [(�2 � BZ � 4 2)2 + BZ � 4 2 � 2]} P 4 (x) } binary BZ Pseudo quaternary A1–xBxYyZ1–y [6,4,5] Parameters 52: 32 { ij c�k} + 12 {cWk}c=A,B,Y,Z;k=1.3 + 4 {AZ �� BZ �� AY �� BY �} + 4 {AZs,BYs,AZs,BYs} � � �,x) = � � � �,x) + � � � �,x) + Y � � �,x) + � � � �,x) each taken as defined in the above table where � � �,x) = � � � �,x) was Z-centred with the binary allowed to have distinct frequencies (whence the extra 4 parameters). 302 Fizika Nizkikh Temperatur, 2007, v. 33, Nos. 2/3 B.V. Robouch et al. Truly quaternary AxB �x C1–x– �xZ or AXyYy�Z1–y–y� Parameters 48: 30 { vZ �kj}+ 12 {Wkj} + 3 {AZ �� BZ �� CZ �} + 3 {AZs,BZs,CZs} � � ��,x,x�) = { k A, k B + {4 AZs 0 AZ� 0 �/ [��2 �AZ� 0 2)2 + AZ� 0 2 �2]} p 00 (x,x�) binary AZ 4,0 ��4 BZs 4 BZ� 4 �/ [(�2 �BZ� 4 2)2 + BZ� 4 2 �2]} p 40 (x,x�) binary BZ 0.4 + {4 CZs 0 CZ� 0 �/ [��2 �CZ� 0 2)2 + CZ� 0 2 �2]} p 04 (x,x�) binary CZ 0,0 � k=1.3 { k ABZC k BZs k BZ� k �/ [��2 �BZ� k 2)2 + BZ� k � �2] ternary ABZ k,0 + (4 – k ABZC k ) AZs k AZ� k �/ [��2 �AZ� k 2)2+ AZ� k � �2] 4 Max (0, ABZW k – 1) BZs 4 BZ� 4 �/ [(�2 �BZ� 4 2)2 + BZ� 4 2 �2] excess in binary BZ 4 Max (0, 1 – ABZW k ) AZs 4 �/ [(�2 �AZ� 4 2)2 + AZ� 4 2 �2]} p k0 (x,x�) excess in binary AZ �� k=1.3 { k BCZC k CZs k CZ� k �/ [��2 �CZ� k 2)2 + CZ� k � �2] + (4 – k BCZC k ) BZs k BZ� k �/ [��2 �BZ� k 2)2+ BZ� k � �2] ternary CBZ k,(4 – k) 4 Max (0, BCZW k – 1) CZs 4 CZ� 4 �/ [(�2 �CZ� 4 2)2 + CZ� 4 2 �2] excess to binary CZ 4 Max (0, 1 – BCZW k ) BZs 4 �/ [(�2 �BZ� 4 2)2 + BZ� 4 2 �2]} p k(4–k) (x,x�) excess to binary BZ � k=1.3 { k CAZC k AZs k AZ� k �/ [��2 �AZ� k 2)2 + AZ� k � �2] + (4 – k CAZC k ) CZs k CZ� k �/ [��2 �CZ� k 2)2+ CZ� k � �2] ternary ACZ 0,k 4 Max (0, CAZW k – 1) AZs 4 AZ� 4 �/ [(�2 �AZ� 4 2)2 + AZ� 4 2 �2] excess to binary AZ 4 Max (0, 1 – CAZW k ) CZs 4 �/ [(�2 �CZ� 4 2)2 + CZ� 4 2 �2]} p 0k (x,x�) excess to binary CZ + { 1 C 11 AZs 11 AZ� 11 �/[��2 �AZ�2 11 )2 + AZ� 11 � �2] quaternary A 1 B 1 C 2 Z 1,1 + 1 C 11 BZs 11 BZ� 11 �/[��2 �BZ�2 11 )2 + BZ� 11 � �2] + 2 C 11 CZs 11 CZ� 11 �/[��2 �CZ�2 11 )2 + CZ� 11 � �2] + Max (0, 1 – W 11 ) 4 CZs 11 CZ� 11 �/[��2 �CZ�2 11 )2 + CZ� 11 � �2] excess to binary CZ + Max (0, W 11 – 1){ 1 BZs 21 BZ� 21 �/[��2 �BZ�2 21 )2 + BZ� 21 � �2] excess to binary BZ + 1 AZs 21 AZ� 21 �/[��2 �AZ�2 21 )2 + AZ� 21 � �2] } }p 11 (x,x�) excess to binary AZ + { 1 C 12 AZs 12 AZ� 12 �/[��2 �AZ�2 12 )2 + AZ� 12 � �2] quaternary A 2 B 1 C 1 Z 1,2 + 2 C 12 BZs 12 BZ� 12 �/[��2 �BZ�2 12 )2 + BZ� 12 � �2] + 1 C 12 CZs 12 CZ� 12 �/[��2 �CZ�2 12 )2 + CZ� 12 � �2] + Max (0, 1 – W 12 ) 4 CZs 12 CZ� 12 �/[��2 �CZ�2 12 )2 + CZ� 12 � �2] excess to binary CZ + Max (0, W 12 – 1){ 1 BZs 21 BZ� 21 �/[��2 �BZ�2 21 )2 + BZ� 21 � �2] excess to binary BZ + 2 AZs 21 AZ� 21 �/[��2 �AZ�2 21 )2 + AZ� 21 � �2] } }p 12 (x,x�) excess to binary AZ + { 2 C 21 AZs 21 AZ� 21 �/[��2 �AZ�2 21 )2 + AZ� 21 � �2] quaternary A 1 B 2 C 1 Z 2,1 + 1 C 21 BZs 21 BZ� 21 �/[��2 �BZ�2 21 )2 + BZ� 21 � �2] + 1 C 21 CZs 21 CZ� 21 �/[��2 �CZ�2 21 )2 + CZ� 21 � �2] + Max (0, 1 – W 21 ) 4 CZs 21 CZ� 21 �/[��2 �CZ�2 21 )2 + CZ� 21 � �2] excess to binary CZ + Max (0, W 21 – 1){ 2 BZs 21 BZ� 21 �/[��2 �BZ�2 21 )2 + BZ� 21 � �2] excess to binary BZ + 1 AZs 21 AZ� 21 �/[��2 �AZ�2 21 )2 + AZ� 21 � �2] } }p 21 (x,x�) excess to binary AZ } 1. B.V. Robouch, A. Kisiel, and J. Konior, J. Alloys Compounds 339, 1 (2002). 2. B.V. Robouch, A. Kisiel, and J. Konior, J. Alloys Compounds 340,13 (2002). 3. B.V. Robouch, E. Burattini, A. Kisiel, A.L. Suvorov, and A.G. Zaluzhnyi, J. Alloys Compounds 359, 73 (2003). 4. B.V. Robouch, E.M. Sheregii, and A. Kisiel, Fiz. Nizk. Temp: 30, 1225 (2004) [Low Temp. Phys. 30, 921 (2004)]. 5. B.V. Robouch, E.M. Sheregii, and A. Kisiel, Phys. Status Solidi C1, 3015 (2004). 6. B.V. Robouch, A. Kisiel, A. Marcelli, M. Cestelli Guidi, M. Piccinini, E. Burattini, and A. Mycielski, J. Alloys Compounds 426, 31 (2006). 7. B.V. Robouch, A. Kisiel, A. Marcelli, E.M. Sheregii, M. Cestelli Guidi, M. Piccinini, J. Polit, J. Cebulski, V.I. Ivanov-Omskii, and E. Burattini, J. Alloys Com- pounds (in submission) (2006). 8. P.A. Lee, P.H. Citrin, P. Eisenberger, and B.M. Kin- caid, Rev. Mod. Phys. 53, 769 (1981). 9. B.K. Teo, EXAFS: Basic Principles and Data Analy- sis, Springer Verlag (1986). 10. F. Stern, Solid State Phys. 15, 299 (1968); Encyclo- pedia of Physics, S. Flugge (ed.), Springer–Verlag, Berlin (1970), XXV/2c Light and Matter 1c, p.190, Eq.VII.4.19. 11. D.W. Taylor, in book: Optical Properties of Mixed Crystals, R.J. Elliot and I.P. Ipatova (eds.), Elsevier Science Publishers B.V. (1988), p. 35. 12. H.W. Verleur and A.S. Barker, Phys. Rev. 149, 715 (1966); H.W. Verleur and A.S. Barker, Phys. Rev. 155, 750 (1967). 13. S.P. Kozyrev, L.K. Vodopyanov, and R. Tribulet, Solid State Commun. 45, 383 (1983). 14. S. Perkowitz, L.S. Kim, and P. Becla, Phys. Rev. 43, 6598 (1991). 15. S. Perkowitz, L.S. Kim, Z.C. Feng, and P. Becla, Phys. Rev. 42, 1455 (1990). 16. J.C. Mikkelsen and J.B. Boyce, Phys. Rev. Lett. 49, 1412 (1982); J.C. Mikkelsen and J.B. Boyce, J. Phys. Rev. B28, 7130 (1983). 17. A. Balzarotti, N. Motta, A. Kisiel, M. Zimnal-Star- nawska, M.T. Czyzyk, and M. Podgorny, Phys. Rev. B31, 7526 (1985); A. Balzarotti, M.T. Czyzyk, A. Ki- siel, N. Motta, M. Podgorny, and M. Zimnal-Star- nawska, Phys. Rev. B30, 2295 (1984). 18. A. Balzarotti, M.T. Czyzyk, A. Kisiel, P. Letardi, N. Motta, M. Podgorny, and M. Zimnal-Starnawska, Festk�rperprobleme 25, 689 (1985). 19. A. Bunker, J. Vac. Sci. Technol. A5, 3003 (1987). 20. A. Marbeuf, D. Ballutaud, R. Triboulet, H. Dexpert, P. Lagarde, and Y. Marfaine, J. Phys. Chem. Solids 50, 975 (1989). 21. R.A. Mayanovic, W.-F. Pong, and B.A. Bunker, Phys. Rev. B42, 11174 (1990). 22. W.-F. Pong, R.A. Mayanovic, B.A. Bunker, J.K. Fur- dyna, and U. Debska, Phys. Rev. B41, 8440 (1990). 23. Z. Wu, K. Lu, Y. Wang, J. Dong, H. Li, Ch. Li, and Zh. Fang, Phys. Rev. B48, 8694 (1993). 24. M. Zimnal-Starnawska, J. Lazewski, and A. Kisiel, Acta Phys. Pol. 86, 763 (1994). 25. R. Iwanowski, K. Lawniczak-Jablonska, I. Winter, and J. Hormes, Solid State Commun. 97, 879 (1996). 26. J. Lazewski, M. Zimnal-Starnawska, A. Kisiel, F. Bo- scherini, S. Pascarelli, and W. Giriat, Phys. Status Solidi B197, 7 (1996). 27. N. Happo, H. Sato, T. Mihara, S. Hosokawa, Y. Ueda, and M. Taniguchi, J. Phys. Condens. Matter 8, 4315 (1996). 28. K.E. Miyano, J.C. Woicik, L.H. Robins, C.E. Boul- din, and D.K. Wickenden, Appl. Phys. Lett. 70, 2108 (1997). 29. Sh.M. Islam and B.A. Bunker, Phys. Lett. A156, 247 (1991). 30. A. Kisiel, J. Lazewski, M. Zimnal-Starnawska, E. Bu- rattini, and A. Mycielski, Acta Phys. Pol. A90, 1032 (1996); A. Kisiel, J. Lazewski, M. Zimnal-Starnawska, E. Burattini, and A. Mycielski, J. Phys. (France) C2, 1197 (1997). 31. N. Romcevic, M. Romcevic, A. Golubovic, Le Van Khoi, A. Mcielski, D. Jovanovic, D. Stojanovic, S. Nikolic, and S. Duric, J. Alloys Compounds 397, 52 (2005). 32. B.V. Robouch and A. Kisiel, Acta Phys. Pol. A94, 497 (1998); B.V. Robouch and A. Kisiel, J. Alloys Com- pounds 286, 80 (1999); B.V. Robouch and A. Kisiel, Synchrotron Radiation Studies of Materials, Proc. 5th Polish National Symp. Synchrotron Radiation Users, Warsaw (1999), J. Gronkowski, M. Lefeld-Sosnowska (eds.), Institute of Experimental Physics, Warsaw Univ., Warsaw (1999), p. 207. 33. Q. Lu, B.A. Bunker, H. Luo, A.J. Kropf, K.M. Kem- ner, and J.K. Furdyna, Phys. Rev. B55, 9910 (1997). 34. E. Oh, R.G. Alonso, I. Miotkowski, and A.K. Ram- das, Phys. Rev. B45, 10934 (1992). 35. J. Polit, R. Hus, E.M. Sheregii, E. Sciesinska, J. Sciesinski, B.V. Robouch, and A. Kisiel, Far Infrared Spectra in the Tetrahedral Quaternary Alloys (Proc. NGS 10) Proc. 10th Intern. Conf. Narrow Gap Semi- conductors and Related Small Energy Phenomena, Physics and Applications, Jpn. Adv. Institute of Sci- ence and Technology and Kanazawa Kokusai May 27–31 (2001), Ishikawa, Japan (IPAP) The Institute of Pure and Applied Physics Conf. Series2 (2001), p. 155. 36. E.M. Sheregii, J. Polit, J. Cebulski, P. Sliz, A. Kisiel, M. Piccinini, A. Marcelli, B.V. Robouch, M. Cestelli Guidi, P. Calvani, and V.I. Ivanov-Omskii, Infrared Phys.&Tech. 49, 13 (2006). 37. B.V. Robouch and A. Kisiel, J. Alloys Compounds 286, 80 (1999). 38. B.V. Robouch, P. Zajdel, A. Kisiel, E.M. Sheregii, A. Marcelli, J. Cebulski M. Cestelli Guidi, M. Pic- cinini, J. Polit, E. Burattini, and A. Mycielski, Solid State. Commun. (in submission (2006). 39. P. Zajdel, A. Kisiel, J. Polit, B.V. Robouch, E.M. Sheregii, J. Warczewski, J. Cebulski, E. Burattini, A. Marcelli, M. Cestelli Guidi, M. Piccinini, and A. Mycielski, J. Alloys Compounds 426, 12 (2006). 40. J. Polit, E.M. Sheregii, B.V. Robouch, A. Marcelli, J. Cebulski, M. Cestelli Guidi, M. Piccinini, A. Kisiel, P. Zajdel, E. Burattini, and A. Mycielski, J. Appl. Phys. 100, 13521 (2006). Statistical model analysis of local structure of quaternary sphalerite crystals Fizika Nizkikh Temperatur, 2007, v. 33, Nos. 2/3 303
id nasplib_isofts_kiev_ua-123456789-127732
institution Digital Library of Periodicals of National Academy of Sciences of Ukraine
issn 0132-6414
language English
last_indexed 2025-12-07T18:20:31Z
publishDate 2007
publisher Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України
record_format dspace
spelling Robouch, B.V.
Kisie, A.
Marcelli, A.
Sheregii, E.M.
Cestelli Guidi, M.
Piccinini, M.
Polit, J.
Cebulski, J.
Mycielsk, A.
Ivanov-Omski, V.I.
Sciesinska, E.
Sciesinski, J.
Burattini, E.
2017-12-27T11:01:11Z
2017-12-27T11:01:11Z
2007
Statistical model analysis of local structure of quaternary&#xd; sphalerite crystals / B.V. Robouch, A. Kisiel, A. Marcelli, E.M. Sheregii, M. Cestelli Guidi, M. Piccinini, J. Polit, J. Cebulski, A. Mycielski, V.I. Ivanov-Omskii, E. Sciesinska, J. Sciesinski, and E. Burattini // Физика низких температур. — 2007. — Т. 33, № 2-3. — С. 291-303. — Бібліогр.: 40 назв. — англ.
0132-6414
PACS: 61.43. Dq
https://nasplib.isofts.kiev.ua/handle/123456789/127732
At the 2004 Ural International Winter School, we introduced the statistical strained tetrahedron&#xd; model and discussed ternary tetrahedron structured crystals. The model allows one to interpret&#xd; x-ray absorption fine structure (EXAFS) data and extract quantitative information on ion site occupation&#xd; preferences and on the size and shape of each elemental constituent of the configuration tetrahedra.&#xd; Here we extend the model to cover quaternary sphalerite crystal structures. We discuss the&#xd; two topologically different quaternary sphalerite systems: the pseudo balanced A₁₋xBxYyZ₁₋y (2:2&#xd; cation:anion ratio), and the unbalanced AxBx &#xd; C₁₋x₋x &#xd; Z or AXyYy &#xd; Z₁₋y₋y (3:1 or 1:3 cation:anion ratios)&#xd; truly quaternary alloy systems. These structural differences cause preference values in pseudo&#xd; quaternaries to vary with the relative contents, but to remain constant in truly quaternary compounds.&#xd; We give equations to determine preference coefficient values from EXAFS or phonon spectra&#xd; and to extract nearest-neighbour inter-ion distances by EXAFS spectroscopy. The procedure is illustrated&#xd; and tested on CdMnSeTe, GaInAsSb, and ZnCdHgTe quaternary alloys.
Part of this work was supported by EU TARI-project&#xd; contract HPRI-CT-1999-00088.
en
Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України
Физика низких температур
Структура и свойства полупроводников с переходными элементами
Statistical model analysis of local structure of quaternary sphalerite crystals
Article
published earlier
spellingShingle Statistical model analysis of local structure of quaternary sphalerite crystals
Robouch, B.V.
Kisie, A.
Marcelli, A.
Sheregii, E.M.
Cestelli Guidi, M.
Piccinini, M.
Polit, J.
Cebulski, J.
Mycielsk, A.
Ivanov-Omski, V.I.
Sciesinska, E.
Sciesinski, J.
Burattini, E.
Структура и свойства полупроводников с переходными элементами
title Statistical model analysis of local structure of quaternary sphalerite crystals
title_full Statistical model analysis of local structure of quaternary sphalerite crystals
title_fullStr Statistical model analysis of local structure of quaternary sphalerite crystals
title_full_unstemmed Statistical model analysis of local structure of quaternary sphalerite crystals
title_short Statistical model analysis of local structure of quaternary sphalerite crystals
title_sort statistical model analysis of local structure of quaternary sphalerite crystals
topic Структура и свойства полупроводников с переходными элементами
topic_facet Структура и свойства полупроводников с переходными элементами
url https://nasplib.isofts.kiev.ua/handle/123456789/127732
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