Sphalerite-wurtzite phase transformation in CdS
Sphalerite-wurtzite phase transformation in CdS
复制标题
DOI：
10.1103/physrevb.62.13064
复制
发表时间：
2000-11
影响因子：
3.7
通讯作者：
O. Zelaya-Ángel;R. Lozada-morales
中科院分区：
文献类型：
--
作者：
O. Zelaya-Ángel;R. Lozada-morales
An analytical study of the solid-solid phase transformation from the cubic zinc blende or sphalerite (S) metastable modification of CdS (\ensuremath{\beta}-CdS) to the wurtzite (W) hexagonal stable phase (\ensuremath{\alpha}-CdS) is presented. Polycrystalline CdS layers in the cubic phase were prepared on glass substrates by means of chemical bath deposition. Films were heated in ${\mathrm{A}\mathrm{r}+\mathrm{S}}_{2}$ in the temperature (T) range 100\char21{}550 \ifmmode^\circ\else\textdegree\fi{}C. X-ray diffraction data of annealed samples allowed us to observe a process of gradual change from \ensuremath{\beta}- to \ensuremath{\alpha}-CdS. Optical absorption spectra let us obtain the band-gap energy ${(E}_{g})$ of samples (both as grown and annealed). The unit-cell volume $(V)$ vs T line shape was explained as an interface movement of the $S\ensuremath{-}W$ interdomain wall driven by T. The ${E}_{g}$ vs T plot exhibits a minimum as a sharp peak at 300 \ifmmode^\circ\else\textdegree\fi{}C, which is the T value assigned by us to the critical point ${(T}_{c})$ of the experimental structural transformation. The ${E}_{g}$ vs $V$ curve indicates an ${E}_{g}{=AV}^{2}+BV+C$ functional behavior. This ${E}_{g}$ vs $V$ dependence was explained through a relation between $(\ensuremath{\partial}{E}_{g}/\ensuremath{\partial}{T)}_{P}$ and ${C}_{P},$ where ${C}_{P}$ is the specific heat at constant pressure. The ${C}_{P}$ against T function was also calculated in the interval 300\char21{}800 K.
An analytical study of the solid-solid phase transformation from the cubic zinc blende or sphalerite (S) metastable modification of CdS (\ensuremath{\beta}-CdS) to the wurtzite (W) hexagonal stable phase (\ensuremath{\alpha}-CdS) is presented. Polycrystalline CdS layers in the cubic phase were prepared on glass substrates by means of chemical bath deposition. Films were heated in ${\mathrm{A}\mathrm{r}+\mathrm{S}}_{2}$ in the temperature (T) range 100\char21{}550 \ifmmode^\circ\else\textdegree\fi{}C. X-ray diffraction data of annealed samples allowed us to observe a process of gradual change from \ensuremath{\beta}- to \ensuremath{\alpha}-CdS. Optical absorption spectra let us obtain the band-gap energy ${(E}_{g})$ of samples (both as grown and annealed). The unit-cell volume $(V)$ vs T line shape was explained as an interface movement of the $S\ensuremath{-}W$ interdomain wall driven by T. The ${E}_{g}$ vs T plot exhibits a minimum as a sharp peak at 300 \ifmmode^\circ\else\textdegree\fi{}C, which is the T value assigned by us to the critical point ${(T}_{c})$ of the experimental structural transformation. The ${E}_{g}$ vs $V$ curve indicates an ${E}_{g}{=AV}^{2}+BV+C$ functional behavior. This ${E}_{g}$ vs $V$ dependence was explained through a relation between $(\ensuremath{\partial}{E}_{g}/\ensuremath{\partial}{T)}_{P}$ and ${C}_{P},$ where ${C}_{P}$ is the specific heat at constant pressure. The ${C}_{P}$ against T function was also calculated in the interval 300\char21{}800 K.