J. Klikorka

The composition dependence of the gap in amorphous films of SixGe1−x, SbxSe1−x and AsxTe1−x systems

Abstract The gap energies of the amorphous thin films of Si x Ge 1− x , Sb x Se 1− x and As x Te 1− x systems were correlated with the “mean” bond energy using Mancas relation. The best fit between calculated and experimental values of the gap obtained using random covalent network model (RCNM) is valid. In accordance with Shimakawa the RCNM idea is applicable for chemical bonds network in these thin films.

Qualitative calorimetry of some sulphur rich glasses

Abstract By DS calorimetry of Ge 30 S 70 (a), Ge 20 S 80 (b), Ge 20 Sb 2.5 S 77.5 (c) and Ge 20 Bi 5 S 75 (d) crystalline sulphur was identified in (b), (c) and (d) glasses, respectively. It means that these compositions are heterogeneous. Thus the application of the Phillips topological model for estimation of the “ideal” glassy composition in Ge x S 1− x system seems to be open.

Influence of oxygen traces on physical properties of glassy GeSe2

The influence of oxygen impurities on some physical properties (optical absorption in the infrared spectral region, slope of short wavelength edge, d.c. conductivity, crystallization) of glassy GeSe2 studied. It was shown that incorporation of traces of GeO2 (UP to 1000 p.p.m. by weight of oxygen) into the glassy matrix of GeSe2 is connected with an increase of the slope of the exponential absorption edge and also with the shift of this edge to higher energies. D. c. electrical conductivity slightly decreases on doping of GeSe2 with oxygen, which probably reflects the increase of the gap. The crystallization of GeSe2 in the course of differential thermal analysis seems to be suppressed by oxygen. It is supposed that this can be connected to the interaction of GeO2 with both the homonuclear Se-Se bonds on the surface of the outrigger rafts and the Ge-Ge bonds in ethane-like units, respectively.

Optical properties of Ge40−xSbxSe60 glasses

The optical properties of Ge40-xSbxSe60 glasses have been studied in the infrared spectral region and also in the short wavelength region. The spectral dependence of the absorption coefficient in the region of multiphonon absorption, optical gap and average gap was discussed in relation to the chemical composition. It is supposed that the structure of these glasses is complicated due to structural units containing mainly Ge-Se, Sb-Se and also Ge-Ge, Ge-Sb and Sb-Sb bonds.

Intercalation of aliphatic alcohol mixtures into the layered lattice of unhydrated vanadyl sulphate

Abstract The mixed intercalates of the type VOSO4·(2 − x)Cp·xCq have been prepared by reaction of unhydrated layered VOSO4 with liquid binary mixtures of the aliphatic alcohols. Symbols Cp and Cq mark two different unbranched primary aliphatic alcohols, p and q are numbers of carbon atoms in their molecules (p p + 2 these values range in intervals 〈0–0.05〉, 〈0.9–1.1〉 and (1.75−2). Relations between basal spacings of the formed layered complexes and their composition and the composition of the liquid alcohol (C2 to C7) mixtures were studied for fifteen systems. The schematic explanation of the arrangement of the alcohol molecules in van der Waals gap is proposed.

Electrical and optical properties of Ge20Sb15−xBixBi65 glasses

Preliminary results of a study on the preparation, optical and electrical properties of Ge20Sb15-xBixS65 glasses are presented. It is shown that the substitution of antimony by bismuth atoms results in the red shift of the short wave length absorption edge in decreasing resistivity and in the appearance of n-type conductivity. The p to n transition is in the vicinity of 3.5 < × < 5.

Crystallization kinetics of GexS1−x glasses

The crystallization processes of GexS1−x glasses were studied by means of heat flux DSC. It was shown that germanium disulphide crystallizes atx⩽1/3. On the other hand, a higher germanium content (x>1/3) led to the crystallization of both GeS2 and GeS. Kinetic analysis of the processes of crystallization of the studied glasses was performed using the Arrhenius rate constant and the Šesták-Berggren kinetic model. The kinetic parameters were calculated through non-linear regression of the experimental DSC curves.ZusammenfassungDie Kristallisationsprozesse von Gläsern GexS1−x wurden durch Wärmefluss-DSC untersucht. Beix⩽0,33 kristallisiert GeS2, während bei höherem Germaniumgehalt (x>0,333) Kristallisation von GeS2 und GeS eintritt.Für die kinetische Analyse des Kristallisationsprozessen wurden Arrhenius-Geschwindigkeitskonstanten und das Šesták-Berggren-Modell verwendet. Die kinetischen Parameter wurden durch nichtlineare Regression der experimentellen DSC-Kurven berechnet.РезюмеМетодом ДСК тепловог о потока изучены проц ессы кристаллизации стек лообразных GexS1−x. Показано, что в сте клах сх ⩽ 1/3 кристаллизуется дис ульфид германия, а в ст еклах с более высоким содерж анием германия (х>1/3) — к ристаллизуются как сульфид, так и дисульфид германия. К инетический анализ п роцесса кристаллизации в изу ченных стеклах был проведен на основе ко нстанты скорости аррениусовского тип а и кинетической моде ли ШестакаБерггрена. ШестакаБерггрена. Кинетические параме тры были вычислены на основе нелинейного регресс ионного анализа эксперимент альных кривых ДСК.

Temperature dependence of slope of exponential absorption edge and the temperature shift of absorption edge in Ge20SbxS80−x glasses

Abstract The temperature dependence of the slope exponential absorption edge of glasses Ge20SbxS80−x (for x = 5, 10, 20, 25) has been determined and the results described using Mahrs formula. Adopting the idea of phonons-generated microfields given by Yacobi et al., the temperature shift of exponential edge is described in the weak field approximation of Franz.

Influence of the thermal treatment on the Urbach edge of glassy As2S3

Abstract The temperature dependence of the Urbach edges was studied for glassy As 2 S 3 prepared by slow (≈10 −3 K sec −1 ) cooling and rapid (into cold water) quenching from temperature 600°C. The results of the X-ray diffraction, DSC measurements and density determination indicate an increase of the structure order with the decrease of cooling rate. Simultaneously, the decrease of the reciprocal slope and the blue shift of the Urbach edge with the cooling rate decrease was observed. It was found that the disorder contribution to the reciprocal slope of Urbach edge decrease for low cooling rate.

Conductivity measurements during the crystallization of Bi2S3 in Ge20Bi15S65 glass

Etude par mesure de conductivite electrique en courant continu, du mecanisme de cristallisation des Bi 2 S 3 dans le verre Ge 20 Bi 15 S 65