Research of Structural Quality of Big-Size KDP Crystals
The faulted structure formation at a rapid growing of big-size KDP crystals has been analyzed. A transitional zone with high degree of lattice faultness has been revealed between the seed and the pure zone of the grown crystal by X-ray diffraction methods with high resolution. It has been determi...
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
2008
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| Назва видання: | Semiconductor Physics Quantum Electronics & Optoelectronics |
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| Цитувати: | Research of Structural Quality of Big-Size KDP Crystals / V. I. Salo, V. F. Tkachenko, V.M. Puzikov // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2008. — Т. 11, № 2. — С. 132-135. — Бібліогр.: 7 назв. — англ. |
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nasplib_isofts_kiev_ua-123456789-1188532025-06-03T16:25:29Z Research of Structural Quality of Big-Size KDP Crystals Salo, V.I. Tkachenko, V.F. Puzikov, V.M. The faulted structure formation at a rapid growing of big-size KDP crystals has been analyzed. A transitional zone with high degree of lattice faultness has been revealed between the seed and the pure zone of the grown crystal by X-ray diffraction methods with high resolution. It has been determined that, regardless of the seed form, the transitional layer in grown crystals reaches the value of~12 mm. The nonmonotone variation of the crystal lattice parameter (∆d/d) within ±2.5·10⁻⁵ and the halfwidth of a diffraction reflection curve (β = 5.5÷8 arcs for direction [103] and β = 7÷9 arcs for direction [100]) and the increase of the integral power of reflection of the X-ray beam IR by 1.5 times are observed in the transitional lay 2008 Article Research of Structural Quality of Big-Size KDP Crystals / V. I. Salo, V. F. Tkachenko, V.M. Puzikov // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2008. — Т. 11, № 2. — С. 132-135. — Бібліогр.: 7 назв. — англ. 1560-8034 PACS 61.10.-i https://nasplib.isofts.kiev.ua/handle/123456789/118853 en Semiconductor Physics Quantum Electronics & Optoelectronics application/pdf Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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English |
| description |
The faulted structure formation at a rapid growing of big-size KDP crystals has
been analyzed. A transitional zone with high degree of lattice faultness has been revealed
between the seed and the pure zone of the grown crystal by X-ray diffraction methods with
high resolution. It has been determined that, regardless of the seed form, the transitional layer
in grown crystals reaches the value of~12 mm. The nonmonotone variation of the crystal
lattice parameter (∆d/d) within ±2.5·10⁻⁵ and the halfwidth of a diffraction reflection curve
(β = 5.5÷8 arcs for direction [103] and β = 7÷9 arcs for direction [100]) and the increase of
the integral power of reflection of the X-ray beam IR
by 1.5 times are observed in the
transitional lay |
| format |
Article |
| author |
Salo, V.I. Tkachenko, V.F. Puzikov, V.M. |
| spellingShingle |
Salo, V.I. Tkachenko, V.F. Puzikov, V.M. Research of Structural Quality of Big-Size KDP Crystals Semiconductor Physics Quantum Electronics & Optoelectronics |
| author_facet |
Salo, V.I. Tkachenko, V.F. Puzikov, V.M. |
| author_sort |
Salo, V.I. |
| title |
Research of Structural Quality of Big-Size KDP Crystals |
| title_short |
Research of Structural Quality of Big-Size KDP Crystals |
| title_full |
Research of Structural Quality of Big-Size KDP Crystals |
| title_fullStr |
Research of Structural Quality of Big-Size KDP Crystals |
| title_full_unstemmed |
Research of Structural Quality of Big-Size KDP Crystals |
| title_sort |
research of structural quality of big-size kdp crystals |
| publisher |
Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
| publishDate |
2008 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/118853 |
| citation_txt |
Research of Structural Quality of Big-Size KDP Crystals / V. I. Salo, V. F. Tkachenko, V.M. Puzikov // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2008. — Т. 11, № 2. — С. 132-135. — Бібліогр.: 7 назв. — англ. |
| series |
Semiconductor Physics Quantum Electronics & Optoelectronics |
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AT salovi researchofstructuralqualityofbigsizekdpcrystals AT tkachenkovf researchofstructuralqualityofbigsizekdpcrystals AT puzikovvm researchofstructuralqualityofbigsizekdpcrystals |
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2025-11-30T21:55:33Z |
| last_indexed |
2025-11-30T21:55:33Z |
| _version_ |
1850254015600787456 |
| fulltext |
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2008. V. 11, N 2. P. 132-135.
© 2008, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
132
PACS 61.10.-i
Research of Structural Quality of Big-Size KDP Crystals
V. I. Salo, V. F. Tkachenko, V.M. Puzikov
STC "Institute for Single Crystals," the NAS of Ukraine
60, Lenin Ave., Kharkiv 61001, Ukraine
E-mail: vilsa@isc.kharkov.ua
Abstract. The faulted structure formation at a rapid growing of big-size KDP crystals has
been analyzed. A transitional zone with high degree of lattice faultness has been revealed
between the seed and the pure zone of the grown crystal by X-ray diffraction methods with
high resolution. It has been determined that, regardless of the seed form, the transitional layer
in grown crystals reaches the value of~12 mm. The nonmonotone variation of the crystal
lattice parameter (∆d/d) within ±2.5·10-5 and the halfwidth of a diffraction reflection curve
(β = 5.5÷8 arcs for direction [103] and β = 7÷9 arcs for direction [100]) and the increase of
the integral power of reflection of the X-ray beam IR by 1.5 times are observed in the
transitional layer.
Keywords: KDP single crystals, structural quality, X-ray diffraction, crystal lattice
parameter.
Manuscript received 14.04.08; accepted for publication 15.05.08; published online 30.06.08.
1. Introduction
Formation of inherent lattice defects in the process of
growth of potassium dihydrogen phosphate (KDP) crystals
leads to a considerable change of the characteristics of wide-
aperture nonlinear elements at the influence of the high-
power laser irradiation with a radiation density energy of ~
50 J/sm2 on them.
Development of sensitive X-ray methods of crystal
research gives a possibility to determine the correlation
between the crystal characteristics and parameters
characterizing their structural quality [1, 2].
Seed crystals of various forms and crystallographic
orientations are used for the KDP crystal growth. As a
result of the seed growth, the defects located on its
surface are inherited by the growing crystal. This
influences considerably the structural quality of the
grown crystal, its optical homogeneity, and the bulk
laser damage threshold. This effect is observed
especially when KDP crystals grow in directions [100] and
[010] of a prism [3, 4]. We would like to note that most of
the work done [5, 6] is devoted to the research of the
dislocation structure of grown crystals. No information
concerning the research of the transitional layer and its
influence on the subsequent growth of the crystal is
available.
Here, we present the results of X-ray diffraction
studies of a structural quality of the transitional zone
«seed - grown crystal» formed at the initial growth stage.
2. Experimental methods
Big-size KDP crystals were grown from the water solutions
by the method of solvent recirculation on various kinds of
seeds: pyramidal seeds, point seeds with facet orientations
[001], [100], and [010], as well as on the Z-cut plate. For
the investigations carried out, the experimental samples of
50×50×50 mm3 in size which had been cut out from various
parts of the grown crystals with a section of 300×300×300
mm3 were used. The samples were oriented in the
crystallographic directions [001], [100], and [010] with an
accuracy of 0.05º and then were subjected to the standard
chemical and mechanical treatment providing the strained
layer thickness which did not exceed 2 µm.
Structural investigations were conducted by the
method of sensitive three-crystal X-ray diffractometry
(TXD) in Cukα1-radiation [1]. The depth of X-ray beam
penetration into the crystal amounted to dozens of microns.
Higher diffractometer measurement precision was achieved
by the formation of the initial X-ray beam with small
angular and spectral divergence which allowed us to obtain
diffraction reflection curves (DRCs) having the halfwidth
ß = 7÷10 arcs. This method gives a possibility to minimize
mistakes of the reproduction of the form and the halfwidth
of DRC ß and the value of the integral power of reflection
of the X-ray beam IR, as well as to increase the accuracy of
the lattice parameter determination to 2·10-7, while values of
ß, IR, and ∆d/d are used as the measure of the structural
perfection of the grown crystals. Linear scanning of the
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2008. V. 11, N 2. P. 132-135.
© 2008, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
133
sample relative to the initial X-ray beam (L-scanning)
having a step of 0.05÷2 mm allows us to obtain the
dependence of these parameters on the cross section of a
crystal.
When conducting the X-ray diffraction investigations
of the crystal samples, both symmetric and asymmetric
Bragg reflections were used. Investigations of crystals
grown on the various kinds of seeds were conducted in
four crystallographic directions ([001], [100], [010], and
[103]) in three typical areas: the seed, the transitional zone,
and the grown crystal. The rocking curves from reflections
{600}, {060}, {008}, and {206} were registered.
3. Results and discussion
Fig. l a-d shows the character of variations of the rocking
curve halfwidth at the L-scanning of a KDP crystal grown
on a pyramidal seed.
As one can see from Fig. 1, a significant nonmonotone
dependence ß(L) is observed, especially, in the area between
the grown crystal and the seed (transitional zone), the width
of which is about 12 mm. In this area, all the DRCs have
from 2 to 30 separate maxima which are caused by the
presence of low-angle quasi-boundaries with turn angles
of 0.5±4 arcs. This effect can be explained by fluctuations
of the growth rates by a layer-by-layer crystal growth
mechanism. As a result of growth rate fluctuations, the
nonuniform trapping and the spreading of polyvalent metal
impurities such as Cr3+, Fe3+, Al3+, Ti4+, etc. in the
transitional zone occur in the growing layers.
The mean concentration of trapped impurities in this
area of the crystal does not differ essentially from the
concentration of impurities in other zones such as the
seed and the grown crystal. However, an insignificant
local excess of the impurity content in the transitional zone
can lead to the crystal coloration. The authors visually
observed a colored band in the growing crystal of about
3 mm. The optical absorption value of the colored zone is
3-4 times higher than that in the seed or the grown crystal.
It should be noted that the width of this zone observed at
the X-ray diffraction analysis is 4 times larger than that at
a visual registration or by optical absorption spectra.
Fig. l. Variation of β(L) for KDP crystals grown on pyramidal
seeds: a – reflection {600}, direction [100], b – reflection
{060}, direction [010], c – reflection {008}, direction [001],
d – reflection {206}, direction [103].
Fig. 2. Variation of IR(L) for KDP crystals grown on pyramidal
seeds: a – reflection {600} direction [100], b – reflection {060},
direction [010], c – reflection {008}, direction [001], d –
reflection {206}, direction [103].
The X-ray diffraction methods of investigations fix
the presence of the transitional zone even if it is not seen
visually on the spectra of optical absorption. The authors
have found the increase of the integral reflection power of
the X-ray beam IR for this part of the crystal (Fig. 2, a-d).
Thus, in the zone neighboring to the crystal and the
seed (transitional zone), we have established the presence
of an impurity-striated structure which leads to the
splitting of DRCs and the increase of the content of
structural defects yielding an increase of the integral
reflection power IR.
The authors also investigated the behavior of ∆d/d
in three areas: the seed, the transitional zone, and the
grown crystal. The results of these measurements for
the crystallographic direction [100] are shown in Fig. 3.
As one can see from Fig. 3, the oscillations of ∆d/d for
the transitional zone are± 2.5·l0-5. At the same time, the
variation of ∆d/d in the seed does not exceed ±5·10-6,
while it is ±5·10–6 in the grown crystal in the studied
area. In the grown crystal, the authors found the
increase of ∆d/d by the value of ±1 · l0-5 with respect to
the seed.
Fig. 3. Variation of ∆d/d(L) for KDP crystals grown on
pyramidal seeds, reflection {600}, crystallographic direction
[100].
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2008. V. 11, N 2. P. 132-135.
© 2008, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
134
Fig. 4. Variation of β(L) and IR(L) for crystals grown on plane
seeds: a - β(L) reflection {206}, direction [103]; b - IR(L)
reflection {206}, direction [103].
The analogous picture is also observed for KDP
crystals grown on plane seeds. In Fig. 4 a, b, we show the
dependences ß(L) and IR(L) for reflection {206} in the
crystallographic direction [103]. The transitional zone of
about 10 mm in width is characterized by the increased
content of structural defects resulting in the splitting and
smearing (broadening) of DRCs and an increase of the
integral reflection power IR. The authors associate the
higher values of ß and IR, as compared with analogous
values obtained for the crystals grown on the pyramidal
seeds, with the quality of a crystal used as a plane seed.
The variation of ∆d/d for the transitional zone in the case
of crystals grown on the plane seed was ± 3.5·10-5. The
variation of the ∆d/d value on the seed did not exceed ±
5·10-6, and it was ±5·10-6 on the grown crystal (Fig. 5). The
parameter ∆d/d of the seed exceeded that of the grown
crystal by the value of 2.5·l0-5.
KDP crystals grown on the point seed have also the
area with an elevated content of structural defects, which
results in a nonmonotone variation of ß (L), IR (L), and
∆d/d(L) in this part (see Fig. 6 a, b, c). The presence of an
angular turn of about 32 arcs between two prismatic growth
sectors was also revealed in these crystals. Figure 7 shows a
rocking curve (reflection {008}) for the case of a
simultaneous incidence of the beam onto the parts of the
crystal, whose growth proceeded in the crystallographic
directions [100] and [010]. This figure clearly
demonstrates the anisotropy of the impurity-striated
structure in different crystallographic directions.
The X-ray diffraction investigations of the structural
quality in the “crystal - restrictive plane” zone conducted
by the authors did not reveal a strained layer similar to the
transitional “crystal – seed” zone. In the “crystal -
restrictive plane” zone, the layers with increased content
of the structure defects with a size amounted to ~10 µm
were revealed. Such strained layer does not influence the
characteristics of both frequency multipliers for laser
emission and Pockels cells produced of fast-frown KDP
crystals in the direction of a given synchronism angle. The
strained layer can be removed in the process of the optical
and mechanical treatment of the crystal.
Fig. 5. Variation of ∆d/d(L) for KDP crystals grown on plane
seeds, reflection {600}, direction [100].
Fig. 6. Variation of β(L) – (a), IR(L) – (b), ∆d/d(L) – (c) for KDP
crystals grown on point seeds in the crystallographic direction
[100].
Fig. 7. The form of the rocking curve of the parts of a KDP crystal
grown on a point seed in the crystallographic directions [100] and
[010]; Cukα1, -radiation, reflection {008}.
The X-ray diffraction investigations of a fine faulty
structure in the bulk of KDP crystals showed that the
structural defects formed at the stages of crystal growth in
directions [100] and [010] are partially inherited by the
crystal growing in direction [001]. The splitting of DRCs
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2008. V. 11, N 2. P. 132-135.
© 2008, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
135
and an increase of ß and IR which were observed during
the investigations are caused by the impurity-striated
structure and the formation of low-angle boundaries by a
layer-by-layer mechanism of crystal growth. These
structural defects are formed under fluctuations of the
growth parameters and significantly deteriorate the bulk
laser damage threshold of KDP crystals [7].
4. Conclusions
While growing crystals from aqueous solutions on
the seeds of various forms (pyramidal, plane, and point-
like ones), a transitional zone with increased concentration
of structural defects is formed between the seed and the
grown crystal. It is characterized by a nonmonotone
variation of the rocking curve halfwidth, integral reflection
power of the X-ray beam, and crystal lattice parameter in
the limits of ±2.5·l0-5. This area reaches 12 mm. The
impurity-striated structure with quasiboundaries and
angular turns of 0.5÷4 arcs is clearly expressed in it.
At a break of the growth process, the further growth
of the crystal proceeds through the zone with increased
content of structural defects. The presence of the angular
turn of about 30 arcs was found between the parts of the
crystal, whose growth proceeded in directions [100] and
[010]. In the process of crystal growth in the
crystallographic directions [100] and [010], the formed
faulty zone can be inherited by the growing crystal in
direction [001].
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