Analysis of direct transformation from graphite to diamond crystal
The lattice parameters of cubic diamond and rhombohedral graphite under the probable direct transformation synthesis conditions have been obtained by means of linear expansion coefficient and elastic constant. Based on the empirical electron theory in solid and molecules, the valence electron struct...
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Інститут надтвердих матеріалів ім. В.М. Бакуля НАН України
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| Cite this: | Analysis of direct transformation from graphite to diamond crystal / B. Tian, B. Xu, Y. Xu // Сверхтвердые материалы. — 2016. — № 3. — С. 3-10. — Бібліогр.: 26 назв. — англ. |
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| author_facet | Tian, B. Xu, B. Xu, Y. |
| citation_txt | Analysis of direct transformation from graphite to diamond crystal / B. Tian, B. Xu, Y. Xu // Сверхтвердые материалы. — 2016. — № 3. — С. 3-10. — Бібліогр.: 26 назв. — англ. |
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| description | The lattice parameters of cubic diamond and rhombohedral graphite under the probable direct transformation synthesis conditions have been obtained by means of linear expansion coefficient and elastic constant. Based on the empirical electron theory in solid and molecules, the valence electron structures (VESs) of graphite and diamond, the covalent electron densities (CEDs), and the relative electron density differences (REDDs) of the diamond growth interfaces have been calculated. It has been found that the REEDs of graphite/diamond interfaces were awfully large and the CEDs were discontinuous at the first order approximation. Not any meaningful atomic state of graphite structure, which satisfied the bond length difference formula, existed on the detonation synthetic conditions. Accordingly, it was considered that the direct transformation from graphite to diamond could not come true from the perspective of VES. In addition, the mechanism of synthesis diamond by explosive detonation was discussed based on the VESs of graphite and diamond.
Визначено параметри решіток алмазу кубічного габітусу і ромбоедричної графіту в умовах ймовірного прямого перетворення з використанням коефіцієнта лінійного розширення і пружною постійною. На основі емпіричної теорії електронів в твердому тілі і молекулах було розраховано структуру валентних електронів графіту і алмазу, щільність ковалентних електронів і відносні відмінності в щільності електронів в міжфазних межах зростання алмазу. Виявлено, що відносна різниця в щільності електронів в міжфазній межі графіт/алмаз дуже велика, а щільність ковалентних електронів переривчаста при апроксимації першого порядку. В умовах детонаційного синтезу не існує жодного значимого атомного стану структури графіту, яке б відповідало різниці у формулі довжини зв’язку. Відповідно, вважали, що пряме перетворення графіту в алмаз не може статися через структуру валентних електронів. Крім того, на основі структури валентних електронів графіту і алмазу обговорено механізм синтезу алмазу вибуховою детонацією.
Определены параметры решеток алмаза кубического габитуса и ромбоэдрического графита в условиях вероятного прямого превращения с использованием коэффициента линейного расширения и упругой постоянной. На основе эмпирической теории электронов в твердом теле и молекулах были рассчитаны структура валентных электронов графита и алмаза, плотность ковалентных электронов и относительные различия в плотности электронов в межфазных границах роста алмаза. Обнаружено, что относительная разница в плотности электронов в межфазной границе графит/алмаз очень большая, а плотность ковалентных электронов прерывистая при аппроксимации первого порядка. В условиях детонационного синтеза не существует ни одного значимого атомного состояния структуры графита, которое бы соответствовало разнице в формуле длины связи. Соответственно, полагали, что прямое превращение графита в алмаз не может произойти из-за структуры валентных электронов. Кроме того, на основе структуры валентных электронов графита и алмаза обсужден механизм синтеза алмаза взрывной детонацией.
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ISSN 0203-3119. Сверхтвердые материалы, 2016, № 3 3
Получение, структура, свойства
UDC 546.26-162:548.735
B. Tian*, B. Xu, Y. Xu
School of Materials Science & Engineering,
Shandong Jianzhu University, Jinan, China
*btin198@163.com
Analysis of direct transformation from graphite
to diamond crystal
The lattice parameters of cubic diamond and rhombohedral graphite
under the probable direct transformation synthesis conditions have been obtained by
means of linear expansion coefficient and elastic constant. Based on the empirical
electron theory in solid and molecules, the valence electron structures (VESs) of
graphite and diamond, the covalent electron densities (CEDs), and the relative electron
density differences (REDDs) of the diamond growth interfaces have been calculated. It
has been found that the REEDs of graphite/diamond interfaces were awfully large and
the CEDs were discontinuous at the first order approximation. Not any meaningful
atomic state of graphite structure, which satisfied the bond length difference formula,
existed on the detonation synthetic conditions. Accordingly, it was considered that the
direct transformation from graphite to diamond could not come true from the
perspective of VES. In addition, the mechanism of synthesis diamond by explosive
detonation was discussed based on the VESs of graphite and diamond.
Keywords: graphite, diamond, direct transformation, HPHT, VES.
INTRODUCTION
Since the diamond particles were synthesized by G.E. in 1954, the
transformation mechanism of graphite to diamond crystals at high pressure and
high temperature (HPHT) has been the focus of researchers. But there have been
no clear explanation so far. The solid direct transformation theory believed that the
graphite structure could be transformed into diamond structure directly without
decomposition [1–3]. There are two kinds of graphite: hexagonal and
rhombohedral. Gou et al. believed that only rhombohedral graphite could be
directly transformed into diamond. Except synthesis at HPHT, graphite can directly
transform into diamond by explosive detonation, but the detonation synthesis
mechanism remains unclear too. Therefore, the study on whether the carbon source
for diamond growth comes from graphite structure direct transformation under the
probable direct transformation synthesis conditions will make clear the direct
transformation mechanism further.
© B. TIAN, B. XU, Y. XU, 2016
www.ism.kiev.ua/stm 4
The empirical electron theory (EET), which is established on the basis of
Pauling’s valence bond theory and the energy band theory, has been successfully
applied to many research areas. Based on the lattice parameters and its crystal
structure, the valence electron structures (VESs) of solid or molecular system can
be confirmed by means of the bond-length-difference (BLD) method, and the cova-
lent electron density (CED) of a certain crystal plane can also be calculated [4, 5].
The carbon source for diamond crystal growth definitely comes from the
transformation of carbon source phase (CSP), and the smaller the value of the
relative electron density differences (REDDs) of interfaces between diamond
naked planes and corresponding CSP planes, the more similar the VESs of the two
adjacent planes, the lower the driving force for C atoms transforming from CSP
into diamond growth planes. The calculation of VESs is established on the crystal
lattice parameters [6]. Because the direct transformation from graphite to diamond
occurred at HPHT, the calculation of VESs at HPHT can not be carried out
according to the lattice parameters, which are determined at normal temperature
and pressure. However, in this paper, the lattice parameters of graphite and
diamond at HPHT were confirmed by the use of a linear expansion coefficient and
elastic constant. Then, the VESs of graphite, diamond and the REEDs of
graphite/diamond interfaces were calculated, and the possibility of the direct
transformation from graphite to diamond in different synthetic conditions, by
means of the REEDs analysis of graphite/diamond interfaces, the diamond growth
direct transformation mechanism was discussed from the perspective of VES.
Besides, the mechanism of diamond synthesis by explosive detonation was
discussed based on the VESs of graphite and diamond.
CRYSTAL STRUCTURE OF GRAPHITE AND DIAMOND
The BLD method is the basic method to calculate the VESs in EET. The
precondition of calculation is to confirm the unit crystal structure, lattice
parameter, and atomic coordinate.
The rhombohedral graphite with an ABCABC stacking order is more likely to
be transformed into cubic diamond structure [7]. Its space group is D5
3d-R 3m and
the lattice parameters at room temperature (RT) are a0 = 0.24612 nm and c0 =
1.0062 nm. The most common structure of diamond crystals synthesized at HPHT
is cubic. Its space group is OA
7-Fd3m and lattice parameters at RT are a0 = 0.35668
nm.
The direct transformation from graphite to diamond could not come true at any
temperature and any pressure. The conditions of static pressure synthesis without
catalyst are p = 12–13 GPa and T = 3000–4000 K [8]. The conditions of explosive
detonation synthesis are p > 30 GPa and T = 2500–4000 K [9–11]. In this paper,
the calculations are carried out on the three conditions (Con1, Con2, Con3) as
shown in Table 1.
Table 1. Lattice parameters of graphite and diamond under different
synthesis conditions
Lattice parameters, nm
graphite No. p, GPa T, K
a axis c axis
diamond
1 12.5 4000 0.24525 0.80017 0.36169
2 13 3000 0.24504 0.74343 0.35856
3 35 3000 0.24244 0.14569 0.35264
ISSN 0203-3119. Сверхтвердые материалы, 2016, № 3 5
Linear expansion coefficient (LEC) is a material’s inherent attribute, which
shows the impact of temperature on material’s length (or volume). According to
the LEC, the relationship between lattice parameter and temperature can be defined
[12, 13]. Based on the experimental results achieved by Morgan and Reeber [14–
17], the relationships between linear expansion coefficient and temperature of
graphite and diamond were given separately in this paper. For the space limitation,
the detailed calculation process is not listed.
Hooke’s law considers that the stress is proportional to strain in a solid when
the stress is less than proportional limit. The generalized Hooke’s law can be
achieved under the condition of three-dimensional stress and strain state. The
lattice parameter and pressure can be contacted with each other by the coefficients
in generalized Hooke’s law (elastic constant) [18].
By fitting the effects of temperature and pressure on lattice parameter, the
lattice parameter of a crystal at HPHT can be obtained. Table 1 shows the lattice
parameters of graphite and diamond under three synthesis conditions.
VESS AND CEDS OF GRAPHITE, DIAMOND AND REDDS
OF INTERFACES
VESs of graphite and diamond
The VESs of rhombohedral graphite and diamond under the three conditions
shown in Table 1 are calculated by the BLD method based on EET [7]. The results
are listed in Tables 2–6, respectively.
Table 2. VES of graphite on the condition of Con1
Bond I Dnα, nm αnD , nm nα Dn, nm
DA
C–C 3 0.14160 0.14612 1.23382 0.00452
DB
C–C 6 0.24525 0.24977 0.04280 0.00452
DC
C–C 3 0.28319 0.28771 0.01250 0.00452
DD
C–C 1 0.37463 0.37915 0.00064 0.00452
DE
C–C 9 0.40009 0.40461 0.00028 0.00452
DF
C–C 6 0.42440 0.42892 0.00013 0.00452
DG
C–C 6 0.46927 0.47379 0.00003 0.00452
DH
C–C 9 0.49017 0.49469 0.00002 0.00452
C: σ = 6, R6(1) = 0.0763 nm, nc
6 = 4.0000, nc = 4.0000, β = 0.0710 nm, σN = 1
Table 3. VES of graphite on the condition of Con2
Bond I Dnα, nm αnD , nm nα Dn, nm
DA
C–C 3 0.14147 0.14617 1.23196 0.00470
DB
C–C 6 0.24504 0.24974 0.04284 0.00470
DC
C–C 3 0.28295 0.28765 0.01253 0.00470
DD
C–C 1 0.37430 0.37900 0.00065 0.00470
DE
C–C 9 0.37172 0.37642 0.00070 0.00470
DF
C–C 6 0.39773 0.40243 0.00030 0.00470
DG
C–C 6 0.44522 0.44992 0.00007 0.00470
DH
C–C 9 0.46715 0.47185 0.00003 0.00470
C: σ = 6, R6(1) = 0.0763 nm, nc
6 = 4.0000, nc = 4.0000, β = 0.0710 nm, σN = 1
www.ism.kiev.ua/stm 6
Table 4. VES of graphite on the condition of Con3
Bond I Dnα, nm αnD , nm nα Dn, nm
DA
C–C 3 0.13997 0.24727 0.04641 0.10730
DB
C–C 6 0.24244 0.34974 0.00167 0.10730
DC
C–C 3 0.27995 0.38725 0.00050 0.10730
DD
C–C 1 0.15779 0.26509 0.02604 0.10730
DE
C–C 9 0.37033 0.47763 0.00003 0.10730
DF
C–C 6 0.07285 0.18015 0.40918 0.10730
DG
C–C 6 0.25315 0.36045 0.00118 0.10730
DH
C–C 9 0.28927 0.39657 0.00037 0.10730
C: σ = 6, R6(1) = 0.0763 nm, nc
6 = 4.0000, nc = 4.0000, β = 0.0710 nm, σN = 0
According to the calculation results (ΔD = 0.1073 nm >> 0.005 nm) as shown
in Table 4, it can be found that there isn’t any meaningful atomic state of graphite
structure on the condition of explosive detonation (Con 3), so the VES of diamond
under the condition can’t be defined.
Table 5. VES of diamond on the condition of Con1
Bond I Dnα, nm αnD , nm nα Dn, nm
DA
C–C 4 0.15662 0.15698 0.86750 0.00036
DB
C–C 12 0.25575 0.25611 0.03484 0.00036
DC
C–C 12 0.29990 0.30026 0.00832 0.00036
DD
C–C 6 0.36169 0.36205 0.00112 0.00036
DE
C–C 12 0.39414 0.39450 0.00039 0.00036
DF
C–C 8 0.44298 0.44334 0.00008 0.00036
C: σ = 6, R6(1) = 0.0763 nm, nc
6 = 4.0000, nc = 4.0000, β = 0.0710 nm, σN = 2
Table 6. VES of diamond on the condition of Con2
Bond I Dnα, nm αnD , nm nα Dn, nm
DA
C–C 4 0.15526 0.15711 0.86392 0.00185
DB
C–C 12 0.25354 0.25539 0.03567 0.00185
DC
C–C 12 0.29730 0.29915 0.00863 0.00185
DD
C–C 6 0.35856 0.36041 0.00118 0.00185
DE
C–C 12 0.39073 0.39258 0.00042 0.00185
DF
C–C 8 0.43914 0.44099 0.00009 0.00185
C: σ = 6, R6(1) = 0.0763 nm, nc
6 = 4.0000, nc = 4.0000, β = 0.0710 nm, σN = 2
ISSN 0203-3119. Сверхтвердые материалы, 2016, № 3 7
CEDs of graphite, diamond, and REDDs of interfaces:
If all covalent electrons in a structure unit are distributed on its all covalent
bonds [5], the number of covalent electrons on one crystal plane should be equal to
that of all covalent bonds on this plane [7]. According to the theory, the CED of a
certain crystal plane can be calculated.
The REDD of an interface can be defined as:
%100
2/)(
(%)
21
21 ×
ρ+ρ
ρ−ρ
=ρΔ .
Then the CEDs of common carbon crystal planes in rhombohedral graphite and
diamond structure and REDDs of rhombohedral graphite/diamond interfaces on the
condition of Con1 and Con2 are calculated and the results are shown in Tables 7–
10, respectively.
Table 7. CED of common planes in graphite on the condition of Con1
and Con2
∑nc S, nm2 ρ, nm–2 Crystal
plane Con1 Con2 Con1 Con2 Con1 Con2
G(001) 7.9992 7.98882 0.05209 0.05200 153.56498 153.63115
G(100) 0.17188 0.17304 0.19624 0.18217 0.87587 0.94988
G(110) 7.4823 7.47708 0.33990 0.31553 22.01324 23.69689
G(113) 1.2467 1.24537 0.06235 0.05866 19.99519 21.23031
Table 8. CED of common planes in diamond on the condition of Con1
and Con2
∑nc S, nm2 ρ, nm–2
Crystal plane
Con1 Con2 Con1 Con2 Con1 Con2
D(100) 0.288 0.294 0.130 0.129 2.1991 2.2929
D(111) 0.418 0.428 0.113 0.111 3.6903 3.8444
D(110) 7.297 7.278 0.185 0.182 39.4430 40.0316
Table 9. REDDs of graphite/diamond interface on the condition
of Con1 (%)
G(001) G(100) G(110) G(113)
D(100) 194.4 86.1 163.7 160.4
D(111) 190.6 123.3 142.6 137.7
D(110) 118.3 191.3 56.7 65.4
Table 10. REDDs of graphite/diamond interface on the condition
of Con2 (%)
G(001) G(100) G(110) G(113)
D(100) 194.1 82.8 164.7 161
D(111) 190.2 120.7 144.2 138.7
D(110) 117.3 190.7 51.3 61.4
D means diamond, G means graphite.
www.ism.kiev.ua/stm 8
DISCUSSION
Liu et al. suggested that the CED between the heterogeneous interfaces should
be continuous. If the REDD value of an interface is less than 10 %, it is approved
that the CED between the heterogeneous interfaces is continuous at the first order
approximation. The smaller the REDDs value of interfaces, the more similar the
VESs of the two adjacent planes, the lower the driving force for one structure
transforming into another [7]. The carbon source for diamond crystal growth defi-
nitely comes from the transformation of CSP, the continuity of CED between dia-
mond naked planes and corresponding graphite planes is just the essential condi-
tion for diamond growth.
In crystallography, the naked crystal planes just are the planes whose growth
rate is faster in the course of crystal growth. In diamond, (100), (110) and (111)
planes are the main crystal growth planes. As shown in Table 9 and Table 10, the
REDDs of all graphite/diamond interfaces calculated in this paper are far more
than 10 %, that is to say, the VESs difference of the adjacent planes between
graphite and diamond are so large that the driving force for graphite direct
transforming into diamond will be great. Through the detail researches on metallic
film surrounding as-grown diamond by Transmission Electron Microscope (TEM),
Raman, and other experimental methods, Xu discovered that there was not
diamond structure in the entire metallic film, and also not graphite structure in the
inner of the metallic film, which was quite similar to diamond. The rich-carbon-
content phase in the metal film/diamond interface was Me3C [19–23]. Li considers
that the carbon sources forming diamond may come from the decomposition of
Me3C type carbides, because three among those of Fe3C/diamond interfaces are
less than 10 % in their calculation from the view point of VES [24] (lattice
parameters used in the calculation are determined at normal temperature and pres-
sure). Then from the perspective of VES, the direct transformation from graphite to
diamond could not come true. During the course of graphite transforming into
diamond, the synthesis success needs some transition mesophases or the
participation of catalyst. The transition mesophase (carbides) may be generated at
first before carbon atoms, which come from graphite structures’ decomposition,
nucleate to the nucleus of diamond crystal, and the nucleating carbon sources of
diamond crystal may come from the decomposition of carbides.
As to the diamond synthesis mechanism by explosive detonation, some
researchers suggested that this transformation process as follows may be
undergone: the explosive molecules were decomposed into various atoms (C, H, O,
N) in detonation zone firstly; and then, the diamond atomic groups were made up
by the excessively aggregated carbon atoms combining with each other; finally, the
atomic groups transformed into stable diamond structure [25]. Other researchers
insisted that because of the supersaturation of the free carbon atoms in detonation
zone, carbon droplets generated and then the carbon droplets crystallized in
diamond crystal [26]. In the two synthesis mechanism explanations above, the
disappearance of graphite structure is acknowledged and diamond structures are
originated from the reconstruction of carbon atoms. According to the calculation as
shown in Table 4, any meaningful atomic state of graphite structure which satisfied
BLD formula does not exist on the detonation synthetic conditions. So from the
perspective of VES graphite structure can’t exist on the detonation synthetic
conditions, which is in accordance with the synthesis mechanism above.
CONCLUSIONS
According to the calculation and analysis from the perspective of VES, it is
shown that the REDDs of the graphite/diamond interfaces are far more than 10 %,
ISSN 0203-3119. Сверхтвердые материалы, 2016, № 3 9
the diamond structure could not come from graphite structure’s direct
transformation. During the course of graphite transforming into diamond, the
synthesis success needs some transition mesophases or the participation of catalyst.
Any meaningful atomic state of graphite structure, which satisfies BLD formula,
does not exist on the detonation synthetic conditions. From the perspective of VES,
it is proved that diamond crystals are originated from the reconstruction of carbon
atoms on the detonation synthetic conditions.
This work was supported by the National Natural Science Foundation of China
under grants Nos. 50972084 and 51101093, and the Natural Science Foundation of
Shandong Province of China under grant No. Y2007F11.
Визначено параметри решіток алмазу кубічного габітусу і ромбоедрич-
ної графіту в умовах ймовірного прямого перетворення з використанням коефіцієнта
лінійного розширення і пружною постійною. На основі емпіричної теорії електронів в
твердому тілі і молекулах було розраховано структуру валентних електронів графіту і
алмазу, щільність ковалентних електронів і відносні відмінності в щільності електронів в
міжфазних межах зростання алмазу. Виявлено, що відносна різниця в щільності електро-
нів в міжфазній межі графіт/алмаз дуже велика, а щільність ковалентних електронів
переривчаста при апроксимації першого порядку. В умовах детонаційного синтезу не
існує жодного значимого атомного стану структури графіту, яке б відповідало різниці у
формулі довжини зв’язку. Відповідно, вважали, що пряме перетворення графіту в алмаз
не може статися через структуру валентних електронів. Крім того, на основі структу-
ри валентних електронів графіту і алмазу обговорено механізм синтезу алмазу вибуховою
детонацією.
Ключові слова: графіт, алмаз, пряме перетворення, високий тиск–
висока температура, структура валентних електронів.
Определены параметры решеток алмаза кубического габитуса и ром-
боэдрического графита в условиях вероятного прямого превращения с использованием
коэффициента линейного расширения и упругой постоянной. На основе эмпирической
теории электронов в твердом теле и молекулах были рассчитаны структура валентных
электронов графита и алмаза, плотность ковалентных электронов и относительные
различия в плотности электронов в межфазных границах роста алмаза. Обнаружено,
что относительная разница в плотности электронов в межфазной границе гра-
фит/алмаз очень большая, а плотность ковалентных электронов прерывистая при ап-
проксимации первого порядка. В условиях детонационного синтеза не существует ни
одного значимого атомного состояния структуры графита, которое бы соответство-
вало разнице в формуле длины связи. Соответственно, полагали, что прямое превращение
графита в алмаз не может произойти из-за структуры валентных электронов. Кроме
того, на основе структуры валентных электронов графита и алмаза обсужден механизм
синтеза алмаза взрывной детонацией.
Ключевые слова: графит, алмаз, прямое превращение, высокое давле-
ние–высокая температура, структура валентных электронов.
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Received 08.06.15
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| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 0203-3119 |
| language | English |
| last_indexed | 2025-12-07T15:43:22Z |
| publishDate | 2016 |
| publisher | Інститут надтвердих матеріалів ім. В.М. Бакуля НАН України |
| record_format | dspace |
| spelling | Tian, B. Xu, B. Xu, Y. 2018-11-13T19:41:46Z 2018-11-13T19:41:46Z 2016 Analysis of direct transformation from graphite to diamond crystal / B. Tian, B. Xu, Y. Xu // Сверхтвердые материалы. — 2016. — № 3. — С. 3-10. — Бібліогр.: 26 назв. — англ. 0203-3119 https://nasplib.isofts.kiev.ua/handle/123456789/143839 546.26-162:548.735 The lattice parameters of cubic diamond and rhombohedral graphite under the probable direct transformation synthesis conditions have been obtained by means of linear expansion coefficient and elastic constant. Based on the empirical electron theory in solid and molecules, the valence electron structures (VESs) of graphite and diamond, the covalent electron densities (CEDs), and the relative electron density differences (REDDs) of the diamond growth interfaces have been calculated. It has been found that the REEDs of graphite/diamond interfaces were awfully large and the CEDs were discontinuous at the first order approximation. Not any meaningful atomic state of graphite structure, which satisfied the bond length difference formula, existed on the detonation synthetic conditions. Accordingly, it was considered that the direct transformation from graphite to diamond could not come true from the perspective of VES. In addition, the mechanism of synthesis diamond by explosive detonation was discussed based on the VESs of graphite and diamond. Визначено параметри решіток алмазу кубічного габітусу і ромбоедричної графіту в умовах ймовірного прямого перетворення з використанням коефіцієнта лінійного розширення і пружною постійною. На основі емпіричної теорії електронів в твердому тілі і молекулах було розраховано структуру валентних електронів графіту і алмазу, щільність ковалентних електронів і відносні відмінності в щільності електронів в міжфазних межах зростання алмазу. Виявлено, що відносна різниця в щільності електронів в міжфазній межі графіт/алмаз дуже велика, а щільність ковалентних електронів переривчаста при апроксимації першого порядку. В умовах детонаційного синтезу не існує жодного значимого атомного стану структури графіту, яке б відповідало різниці у формулі довжини зв’язку. Відповідно, вважали, що пряме перетворення графіту в алмаз не може статися через структуру валентних електронів. Крім того, на основі структури валентних електронів графіту і алмазу обговорено механізм синтезу алмазу вибуховою детонацією. Определены параметры решеток алмаза кубического габитуса и ромбоэдрического графита в условиях вероятного прямого превращения с использованием коэффициента линейного расширения и упругой постоянной. На основе эмпирической теории электронов в твердом теле и молекулах были рассчитаны структура валентных электронов графита и алмаза, плотность ковалентных электронов и относительные различия в плотности электронов в межфазных границах роста алмаза. Обнаружено, что относительная разница в плотности электронов в межфазной границе графит/алмаз очень большая, а плотность ковалентных электронов прерывистая при аппроксимации первого порядка. В условиях детонационного синтеза не существует ни одного значимого атомного состояния структуры графита, которое бы соответствовало разнице в формуле длины связи. Соответственно, полагали, что прямое превращение графита в алмаз не может произойти из-за структуры валентных электронов. Кроме того, на основе структуры валентных электронов графита и алмаза обсужден механизм синтеза алмаза взрывной детонацией. This work was supported by the National Natural Science Foundation of China under grants Nos. 50972084 and 51101093, and the Natural Science Foundation of Shandong Province of China under grant No. Y2007F11. en Інститут надтвердих матеріалів ім. В.М. Бакуля НАН України Сверхтвердые материалы Получение, структура, свойства Analysis of direct transformation from graphite to diamond crystal Article published earlier |
| spellingShingle | Analysis of direct transformation from graphite to diamond crystal Tian, B. Xu, B. Xu, Y. Получение, структура, свойства |
| title | Analysis of direct transformation from graphite to diamond crystal |
| title_full | Analysis of direct transformation from graphite to diamond crystal |
| title_fullStr | Analysis of direct transformation from graphite to diamond crystal |
| title_full_unstemmed | Analysis of direct transformation from graphite to diamond crystal |
| title_short | Analysis of direct transformation from graphite to diamond crystal |
| title_sort | analysis of direct transformation from graphite to diamond crystal |
| topic | Получение, структура, свойства |
| topic_facet | Получение, структура, свойства |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/143839 |
| work_keys_str_mv | AT tianb analysisofdirecttransformationfromgraphitetodiamondcrystal AT xub analysisofdirecttransformationfromgraphitetodiamondcrystal AT xuy analysisofdirecttransformationfromgraphitetodiamondcrystal |