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Photostructural transformations in amorphous chalkogenide nanolayered films produced by thermal vapour deposition
\
Pergamon
Vacuum/volume 50/number 3–4/pages 507 to 509/1998 © 1998 Elsevier Science Ltd All rights reserved. Printed in Great Britain 0042–207X/98 $19.00+.00
PII : S0042–207X(98)00091–8
Photostructural transformations in amorphous chalkogenide nanolayered films produced by thermal vapour deposition A Imre,a* V Fedor,b M Kis-Varga,c A Mishakb and M Shipljak,b aLajos Kossuth University, Department of Solid State Physics, H-4010 Debrecen, P.O. Box 2, Hungary ; bUzhgorod State University, Department of Solid State Electronics, Uzhgorod, Ukraine ; cInstitute of Nuclear Research of the Hungarian Academy of Sciences, H-4001 Debrecen, P.O. Box 51, Hungary received for publication 20 January 1998
Photo- and thermoinduced changes of As2S3 /SexTe1−x (0.1 ³ x ³ 0.5) multilayer structures were investigated by optical and electrical methods as well as by low angle X-ray diffraction (LAXD). It was shown that samples with total thicknesses up to 0.7–0.8 mm of 4–20 nm thick alternating layers with good periodicity, may be prepared by cyclic thermal vapour deposition. The structure of this multilayer may be changed by thermal treatment or illumination with focused laser beam due to the interdiffusion. The corresponding photoinduced changes of optical parameters (absorption, refraction) are useful for optical reading. © 1998 Elsevier Science Ltd. All rights reserved
Introduction Various types of superlattices and nanostructured materials\ especially their structure and time stability are the subject of intensive scienti_c researches[0\1 It may be a problem to fabricate nanostructures with stable dimensions and structure of com! ponents or just the opposite ] to enhance the interdi}usion between neighbour components with the aim to create new properties\ for example memory e}ects[ The electrical and optical properties of these nanolayered _lms change under thermal "photo#!treating or ageing[ Optical methods\ conductivity measurements and LAXD technics were used in this work as methods to control structural changes under the conditions of light and heat treatment of nanolayered _lms[ They consist of wide band gap non!crystalline stable As1S2 layers as barriers\ and non!crystalline SexTe0−x "9[5 ³ x ³ 0[9# layers as wells with smaller band gap and rather high crystallisation ability[ The As1S2 barrier layers are transparent at the spectral region of SexTe0−x absorption "curve c in Fig[ 0#\ therefore the latter can be optically treated and investigated[ Earlier\ a new type of amorphous multilayer structure based on AsSe\ As1S2\ and SexTe0−x chalcogenide materials was pro! posed for optical recording[2\ 3 The fundamental scienti_c prob! lem is the following ] may the known photostructural changes in AsSe!type glasses3\ 4 be in~uenced by size e}ects< It means that the medium!range ordering of the nucleation and crystallisation
Corresponding author[
Figure 0[ Absorption spectra of initial "b#\ annealed at 212 K "c# and at 232 K "d# As1S2:Se9[5Te9[3 multilayers[ "a# and "c# curves are the absorption spectra of 9[6 mm Se9[5Te9[3 and As1S2 _lms\ respectively[
processes in amorphous material may be in~uenced not only by illumination but also by the size!determined surface and volume energies in very thin layers of certain compositions[ In these cases the role of the interdi}usion between thin layers of the multilayer structure may be negative because of the composition changes[ Thermally enhanced interdi}usion processes are useful for ano! ther possible type of recording media as well as for creating new multicomponent layer materials[ In this paper the results of interdi}usion induced changes of structure and of other parameters of As1S2:SexTe0−x multilayers are presented[ The main attention was focused on As1S2:Se9[5Te9[3 507
A Imre et al : Transformations in amorphous chalkogenide nanolayered films
structure because of large di}erence between optical bandgaps of components and because this Se!Te composition easily crys! tallises in bulk samples\ but it is stable in amorphous form due to the size!restriction e}ects in thin layers[2\ 4
Experimental The As1S2:SeTe multilayers were deposited onto Si single crystal and Corning 6948 glass substrates by means of cyclic thermal vapour deposition of the given glasses[ The pressure in a vacuum chamber during evaporation was about 4=09−3 mbar[ The period of multilayer structure was usually in the 09Ð19 nm range\ the thicknesses of barrier and well layer were equal and the number of sublayers was enough to achieve 9[6Ð9[7 mm total thicknesses[ Previous transmission electron microscopy investigations of cross sections of similar structures showed that it was possible to get a good quality multilayer structure from the above mentioned materials with ½1 nm thick transition layers between components[5 The thermal and photo!optical treatments and all measure! ments were made in air[ Low angle X!ray di}raction experiments were performed with a laboratory equipment using CuÐKa radi! ation[ Optical absorption spectra were measured in the spectral range of fundamental absorption edge of appropriate sem! iconductor by SF!36!type spectrophotometer[ The direct measurement of electrical parameters across the multilayer is di.cult because of the small total thickness "d ³ 0 mm#[ Therefore the method of surface potential measurements in elec! trophotogra_c regime was chosen for this purpose[ Optical investigations were performed on the samples prepared on Corning glass substrates which are transparent in the 9[4Ð0[9 mm range and have smooth surface[
Figure 1[ Transmittance dependence on exposure time in As1S2:Se9[5Te9[3 multilayer irradiated with He0Ne laser "l 9[52 mm# at di}erent laser intensities[ 0Ð9[1\ 1Ð5[4\ 2Ð09 W cm−1 "T 184 K#[
Figure 2[ Low angle di}raction patterns of As1S2:Se9[5Te9[3 multilayer at initial state "0# and annealed at T 222 K "1# for 04 min[
Results The absorption curve of as!deposited multilayer "curve b in Fig[ 0# is shifted towards higher energies in comparison with thick Se9[3Te9[5 layer "curve a in Fig[ 0# at the same total thickness[ It means that size determined optical e}ect connected with Eg bandgap shift exists in the multilayer where the thickness of Se9[3Te9[5 sublayer is less than 5 nm[ The same e}ect of E g shift towards higher energies was observed in As1S2:a!Se multilayers[4 This type of multilayers were stable against thermally induced degradation ] no interdi}usion processes were observed after heat treatments up to 262 K[ Only the well known photoinduced e}ects determined the changes of optical parameters[3\ 5 Therefore only As1S2:Se9[5Te9[3 structures and interdi}usion in them are studied in this work[ When the As1S2:Se9[5Te9[3 multilayer is annealed for 09Ð19 minutes at temperatures higher than 212 K the changes dem! onstrated in Fig[ 0 were observed ] curve "b# shifts towards higher energies indicating that the absorption at the He0Ne laser wave! length "l 9[52 mm# became smaller[ The transmittance of multilayers as a function of annealing time was studied by irradiating the samples with low intensity He0Ne laser beam "P ³ 09−2 W cm−1#[ The transmittance is increasing with annealing time at temperatures higher than 202 K[ This behaviour is similar to the results shown in Fig[ 0[ After annealing at 232 K for 199 s the optical changes became negligible[ The e}ect of the laser beam power density on the transmittance 508
of multilayers was also studied[ Figure 1 presents transmittance dependence on exposure time for As1S2:Se9[5Te9[3 sample irradiated by the He0Ne laser beam with di}erent intensity[ The maximum power density was 09 W cm−1\ so the thermal heating e}ects took place in the absorbing parts "Se9[5Te9[3 layers# of the multilayer[ The light stimulated local heating induced an increased transmittance of the sample "Fig[ 1#\ and the low angle X!ray di}raction pattern has also been changed due to the inter! di}usion "Fig[ 2#\ which is analogous to a simple annealing[ The results of the surface potential decay in corona charged samples before and after annealing "Fig[ 3# showed that the total resistivity of the structure across the layers decreased\ the initial potentials and their relaxation times became smaller\ hence the electrical barriers between adjacent sublayers also disappeared[ Discussion The most convenient explanation of the presented results is the light "heat# simulated interdi}usion of {dark and light| sublayers[ It means that some kind of ternary As!Se!S\ As!S!Te and even As!S!Se!Te solid solutions may be formed[ The band gaps of these solutions are larger than a Se9[5Te9[3 "E g30[4 eV# layer which is placed between the As1S2 barriers larger E g31[5 eV[ Probably a quasi!homogeneous layer is formed at the _nal stage of intermixing[ The elimination of the energy barriers between
A Imre et al : Transformations in amorphous chalkogenide nanolayered films
D l1:05t
Figure 3[ Surface charge decay for positively charged As1S2:Se9[5Te9[3 multilayer before "0# and after "1# annealing at 232 K[ The arrows indicate the time of switching on the light[
sublayers in the initial multilayer makes the resistivity of resulting mixed layer lower[ Previous transmission electron microscopy investigations have shown\ that the materials of the multilayer do not crystallise after heat treatment[ All the observed changes may be connected _rst of all with interdi}usion[ Some photoinduced structural changes may also take place as it is usual in light sensitive chalcogenides materials\ but it seems that they are much smaller in the case of the SexTe0−x system than in the AsSe glass[ It is also interesting that crystallisation e}ects in SeTe sublayers were not observed even at large illumination intensities[ This fact can be explained by the strong in~uence of surface energies on the phase transition conditions "temperature\ entalphy#[ The strong decrease of the Bragg!peak intensity above 222 K is in accordance with the results obtained for optical and electrical parameters ] the periodic structure is destroyed by interdi}usion[ From the slope of the decay plot of the _rst Bragg!peak inten! sities "I# versus annealing time "t# the di}usion coe.cient can be calculated\ but the scatter of the intensities measured at sub! sequent annealings was large and made it di.cult to follow the standard way of evaluation\ i[e[ to calculate the slope of the ln"I:I9# vs t curve[ Still an order of magnitude of the interdi}usion coe.cient in As1S2:Se9[5Te9[3 system has been estimated[ From the position of the _rst order Bragg!peak a modulation length of l¼4 nm was calculated[ The peak was totally destroyed after 0 h "t¼2[5× 092 s# annealing period[ The di}usion length X\ according to the complete homogenisation can be given as
l:1 X 1"Dt#0:1 Hence\
"0#
"1#
Using the l and t determined from LAXD measurements\ the coe.cient of interdi}usion is about D 3[2×09−11 m1:s at T 222 K[ There are no published di}usion coe.cient data in the litera! ture for this system[ For the similar chalcogenide system of amorphous Se:CdSe Vateva and Nesheva5 give interdi}usion coe.cient of D 1×09−11 m1:s at T 270 K[ If the heating is performed by focused laser beam rather large optical density changes can be produced in such structures[ Sel! ecting suitable pairs of chalcogenide glasses with di}erent optical gaps one can modify the parameters of the light sensitive layer\ and use them for optical recording with a given exposure thres! hold\ laser intensity and spectral sensitivity[ Conclusion Good quality nanolayered _lms can be produced from As1S2 and SexTe0−x glasses by cyclic thermal vacuum evaporation[ Inter! di}usion processes take place upon light and heat treatment of samples[ According to the results obtained\ the interdi}usion is the dominant reason for photooptical transformation with heat! ing induced by laser irradiation[ The interdi}usion coe.cient at 222 K was estimated to be ] D 3[2×09−11 m1:s in the As1S2: Se9[5Te9[3 system[ Changing the type of the components and treat! ment of the samples the parameters of sensitive layer structures can be tailored[ Acknowledgements This research was performed by collaboration of the Solid State Electronics Department of Uzhgorod State University and Solid State Physics Department of Lajos Kossuth University Debrecen[ We are very grateful to Prof[ Alexander Kikineshi and Prof[ Dezso½ Beke for their continuous encouragement and support during this work[ This work _nancially was partly supported by the Grant of Hungarian Ministry of Education "FKFP 9342:0886#[ References 0[ 1[ 2[ 3[ 4[
Radnoczy\ G[ and Petz\ B[\ Thin Solid Films\ 0882\ 121"0#\ 57[ Gleiter\ H[\ Nanostructured Materials\ 0884\ 5\ 2[ Kikineshi\ A[ and Sterr\ A[\ Ukr[ Phys[ Journ[\ 0889\ 24"3#\ 488[ Kikineshi\ A[\ Optical En`ineerin`\ 0884\ 235"3#\ 0939[ Kikineshi\ A[\ Mishak\ A[ and Sterr\ A[\ Soviet!Chinese Joint Seminar on Holo`raphy and Optical Information Processin`\ ed[ Andrei L[ Mikaelian\ Proc[ SPIE 0620\ 062\ 0881[ 5[ Vateva\ E[ and Nesheva\ D[\ J[ Non!Cryst[ Sol[\ 0884\ 080\ 194[
509
Pergamon
Vacuum/volume 50/number 3–4/pages 507 to 509/1998 © 1998 Elsevier Science Ltd All rights reserved. Printed in Great Britain 0042–207X/98 $19.00+.00
PII : S0042–207X(98)00091–8
Photostructural transformations in amorphous chalkogenide nanolayered films produced by thermal vapour deposition A Imre,a* V Fedor,b M Kis-Varga,c A Mishakb and M Shipljak,b aLajos Kossuth University, Department of Solid State Physics, H-4010 Debrecen, P.O. Box 2, Hungary ; bUzhgorod State University, Department of Solid State Electronics, Uzhgorod, Ukraine ; cInstitute of Nuclear Research of the Hungarian Academy of Sciences, H-4001 Debrecen, P.O. Box 51, Hungary received for publication 20 January 1998
Photo- and thermoinduced changes of As2S3 /SexTe1−x (0.1 ³ x ³ 0.5) multilayer structures were investigated by optical and electrical methods as well as by low angle X-ray diffraction (LAXD). It was shown that samples with total thicknesses up to 0.7–0.8 mm of 4–20 nm thick alternating layers with good periodicity, may be prepared by cyclic thermal vapour deposition. The structure of this multilayer may be changed by thermal treatment or illumination with focused laser beam due to the interdiffusion. The corresponding photoinduced changes of optical parameters (absorption, refraction) are useful for optical reading. © 1998 Elsevier Science Ltd. All rights reserved
Introduction Various types of superlattices and nanostructured materials\ especially their structure and time stability are the subject of intensive scienti_c researches[0\1 It may be a problem to fabricate nanostructures with stable dimensions and structure of com! ponents or just the opposite ] to enhance the interdi}usion between neighbour components with the aim to create new properties\ for example memory e}ects[ The electrical and optical properties of these nanolayered _lms change under thermal "photo#!treating or ageing[ Optical methods\ conductivity measurements and LAXD technics were used in this work as methods to control structural changes under the conditions of light and heat treatment of nanolayered _lms[ They consist of wide band gap non!crystalline stable As1S2 layers as barriers\ and non!crystalline SexTe0−x "9[5 ³ x ³ 0[9# layers as wells with smaller band gap and rather high crystallisation ability[ The As1S2 barrier layers are transparent at the spectral region of SexTe0−x absorption "curve c in Fig[ 0#\ therefore the latter can be optically treated and investigated[ Earlier\ a new type of amorphous multilayer structure based on AsSe\ As1S2\ and SexTe0−x chalcogenide materials was pro! posed for optical recording[2\ 3 The fundamental scienti_c prob! lem is the following ] may the known photostructural changes in AsSe!type glasses3\ 4 be in~uenced by size e}ects< It means that the medium!range ordering of the nucleation and crystallisation
Corresponding author[
Figure 0[ Absorption spectra of initial "b#\ annealed at 212 K "c# and at 232 K "d# As1S2:Se9[5Te9[3 multilayers[ "a# and "c# curves are the absorption spectra of 9[6 mm Se9[5Te9[3 and As1S2 _lms\ respectively[
processes in amorphous material may be in~uenced not only by illumination but also by the size!determined surface and volume energies in very thin layers of certain compositions[ In these cases the role of the interdi}usion between thin layers of the multilayer structure may be negative because of the composition changes[ Thermally enhanced interdi}usion processes are useful for ano! ther possible type of recording media as well as for creating new multicomponent layer materials[ In this paper the results of interdi}usion induced changes of structure and of other parameters of As1S2:SexTe0−x multilayers are presented[ The main attention was focused on As1S2:Se9[5Te9[3 507
A Imre et al : Transformations in amorphous chalkogenide nanolayered films
structure because of large di}erence between optical bandgaps of components and because this Se!Te composition easily crys! tallises in bulk samples\ but it is stable in amorphous form due to the size!restriction e}ects in thin layers[2\ 4
Experimental The As1S2:SeTe multilayers were deposited onto Si single crystal and Corning 6948 glass substrates by means of cyclic thermal vapour deposition of the given glasses[ The pressure in a vacuum chamber during evaporation was about 4=09−3 mbar[ The period of multilayer structure was usually in the 09Ð19 nm range\ the thicknesses of barrier and well layer were equal and the number of sublayers was enough to achieve 9[6Ð9[7 mm total thicknesses[ Previous transmission electron microscopy investigations of cross sections of similar structures showed that it was possible to get a good quality multilayer structure from the above mentioned materials with ½1 nm thick transition layers between components[5 The thermal and photo!optical treatments and all measure! ments were made in air[ Low angle X!ray di}raction experiments were performed with a laboratory equipment using CuÐKa radi! ation[ Optical absorption spectra were measured in the spectral range of fundamental absorption edge of appropriate sem! iconductor by SF!36!type spectrophotometer[ The direct measurement of electrical parameters across the multilayer is di.cult because of the small total thickness "d ³ 0 mm#[ Therefore the method of surface potential measurements in elec! trophotogra_c regime was chosen for this purpose[ Optical investigations were performed on the samples prepared on Corning glass substrates which are transparent in the 9[4Ð0[9 mm range and have smooth surface[
Figure 1[ Transmittance dependence on exposure time in As1S2:Se9[5Te9[3 multilayer irradiated with He0Ne laser "l 9[52 mm# at di}erent laser intensities[ 0Ð9[1\ 1Ð5[4\ 2Ð09 W cm−1 "T 184 K#[
Figure 2[ Low angle di}raction patterns of As1S2:Se9[5Te9[3 multilayer at initial state "0# and annealed at T 222 K "1# for 04 min[
Results The absorption curve of as!deposited multilayer "curve b in Fig[ 0# is shifted towards higher energies in comparison with thick Se9[3Te9[5 layer "curve a in Fig[ 0# at the same total thickness[ It means that size determined optical e}ect connected with Eg bandgap shift exists in the multilayer where the thickness of Se9[3Te9[5 sublayer is less than 5 nm[ The same e}ect of E g shift towards higher energies was observed in As1S2:a!Se multilayers[4 This type of multilayers were stable against thermally induced degradation ] no interdi}usion processes were observed after heat treatments up to 262 K[ Only the well known photoinduced e}ects determined the changes of optical parameters[3\ 5 Therefore only As1S2:Se9[5Te9[3 structures and interdi}usion in them are studied in this work[ When the As1S2:Se9[5Te9[3 multilayer is annealed for 09Ð19 minutes at temperatures higher than 212 K the changes dem! onstrated in Fig[ 0 were observed ] curve "b# shifts towards higher energies indicating that the absorption at the He0Ne laser wave! length "l 9[52 mm# became smaller[ The transmittance of multilayers as a function of annealing time was studied by irradiating the samples with low intensity He0Ne laser beam "P ³ 09−2 W cm−1#[ The transmittance is increasing with annealing time at temperatures higher than 202 K[ This behaviour is similar to the results shown in Fig[ 0[ After annealing at 232 K for 199 s the optical changes became negligible[ The e}ect of the laser beam power density on the transmittance 508
of multilayers was also studied[ Figure 1 presents transmittance dependence on exposure time for As1S2:Se9[5Te9[3 sample irradiated by the He0Ne laser beam with di}erent intensity[ The maximum power density was 09 W cm−1\ so the thermal heating e}ects took place in the absorbing parts "Se9[5Te9[3 layers# of the multilayer[ The light stimulated local heating induced an increased transmittance of the sample "Fig[ 1#\ and the low angle X!ray di}raction pattern has also been changed due to the inter! di}usion "Fig[ 2#\ which is analogous to a simple annealing[ The results of the surface potential decay in corona charged samples before and after annealing "Fig[ 3# showed that the total resistivity of the structure across the layers decreased\ the initial potentials and their relaxation times became smaller\ hence the electrical barriers between adjacent sublayers also disappeared[ Discussion The most convenient explanation of the presented results is the light "heat# simulated interdi}usion of {dark and light| sublayers[ It means that some kind of ternary As!Se!S\ As!S!Te and even As!S!Se!Te solid solutions may be formed[ The band gaps of these solutions are larger than a Se9[5Te9[3 "E g30[4 eV# layer which is placed between the As1S2 barriers larger E g31[5 eV[ Probably a quasi!homogeneous layer is formed at the _nal stage of intermixing[ The elimination of the energy barriers between
A Imre et al : Transformations in amorphous chalkogenide nanolayered films
D l1:05t
Figure 3[ Surface charge decay for positively charged As1S2:Se9[5Te9[3 multilayer before "0# and after "1# annealing at 232 K[ The arrows indicate the time of switching on the light[
sublayers in the initial multilayer makes the resistivity of resulting mixed layer lower[ Previous transmission electron microscopy investigations have shown\ that the materials of the multilayer do not crystallise after heat treatment[ All the observed changes may be connected _rst of all with interdi}usion[ Some photoinduced structural changes may also take place as it is usual in light sensitive chalcogenides materials\ but it seems that they are much smaller in the case of the SexTe0−x system than in the AsSe glass[ It is also interesting that crystallisation e}ects in SeTe sublayers were not observed even at large illumination intensities[ This fact can be explained by the strong in~uence of surface energies on the phase transition conditions "temperature\ entalphy#[ The strong decrease of the Bragg!peak intensity above 222 K is in accordance with the results obtained for optical and electrical parameters ] the periodic structure is destroyed by interdi}usion[ From the slope of the decay plot of the _rst Bragg!peak inten! sities "I# versus annealing time "t# the di}usion coe.cient can be calculated\ but the scatter of the intensities measured at sub! sequent annealings was large and made it di.cult to follow the standard way of evaluation\ i[e[ to calculate the slope of the ln"I:I9# vs t curve[ Still an order of magnitude of the interdi}usion coe.cient in As1S2:Se9[5Te9[3 system has been estimated[ From the position of the _rst order Bragg!peak a modulation length of l¼4 nm was calculated[ The peak was totally destroyed after 0 h "t¼2[5× 092 s# annealing period[ The di}usion length X\ according to the complete homogenisation can be given as
l:1 X 1"Dt#0:1 Hence\
"0#
"1#
Using the l and t determined from LAXD measurements\ the coe.cient of interdi}usion is about D 3[2×09−11 m1:s at T 222 K[ There are no published di}usion coe.cient data in the litera! ture for this system[ For the similar chalcogenide system of amorphous Se:CdSe Vateva and Nesheva5 give interdi}usion coe.cient of D 1×09−11 m1:s at T 270 K[ If the heating is performed by focused laser beam rather large optical density changes can be produced in such structures[ Sel! ecting suitable pairs of chalcogenide glasses with di}erent optical gaps one can modify the parameters of the light sensitive layer\ and use them for optical recording with a given exposure thres! hold\ laser intensity and spectral sensitivity[ Conclusion Good quality nanolayered _lms can be produced from As1S2 and SexTe0−x glasses by cyclic thermal vacuum evaporation[ Inter! di}usion processes take place upon light and heat treatment of samples[ According to the results obtained\ the interdi}usion is the dominant reason for photooptical transformation with heat! ing induced by laser irradiation[ The interdi}usion coe.cient at 222 K was estimated to be ] D 3[2×09−11 m1:s in the As1S2: Se9[5Te9[3 system[ Changing the type of the components and treat! ment of the samples the parameters of sensitive layer structures can be tailored[ Acknowledgements This research was performed by collaboration of the Solid State Electronics Department of Uzhgorod State University and Solid State Physics Department of Lajos Kossuth University Debrecen[ We are very grateful to Prof[ Alexander Kikineshi and Prof[ Dezso½ Beke for their continuous encouragement and support during this work[ This work _nancially was partly supported by the Grant of Hungarian Ministry of Education "FKFP 9342:0886#[ References 0[ 1[ 2[ 3[ 4[
Radnoczy\ G[ and Petz\ B[\ Thin Solid Films\ 0882\ 121"0#\ 57[ Gleiter\ H[\ Nanostructured Materials\ 0884\ 5\ 2[ Kikineshi\ A[ and Sterr\ A[\ Ukr[ Phys[ Journ[\ 0889\ 24"3#\ 488[ Kikineshi\ A[\ Optical En`ineerin`\ 0884\ 235"3#\ 0939[ Kikineshi\ A[\ Mishak\ A[ and Sterr\ A[\ Soviet!Chinese Joint Seminar on Holo`raphy and Optical Information Processin`\ ed[ Andrei L[ Mikaelian\ Proc[ SPIE 0620\ 062\ 0881[ 5[ Vateva\ E[ and Nesheva\ D[\ J[ Non!Cryst[ Sol[\ 0884\ 080\ 194[
509