Stoichiometric CaAl2Si2O8 gels prepared by the Pechini process crystallize to triclinic anorthite via an intermediate, previously unknown pseudohexagonal phase. Hydrothermal treatment of this pseudohexagonal phase at 350 °C transforms it to hexagonal anorthite. These combined processes produce the hexagonal phase via a low-temperature, chemical route in contrast to the conventional high-temperature melting and crystallization method. Powder x-ray diffraction data and nuclear magnetic resonance (NMR) spectra of the hexagonal anorthite agree well with the published structure. They indicate a high degree of tetrahedral Si/Al ordering within the layers, but long-range disorder in the average structure due to (001) stacking faults present between the layers.

High quality ZnS epilayers were grown on GaAs and GaP substrates by hot wall epitaxy. The optimum temperature conditions for high quality ZnS epilayer were found. The photoluminescence(PL) spectrum of high quality ZnS epilayers showed sharp and narrow exciton peaks and no self-activated peaks. The room temperature energy gap of ZnS/GaAs was found to be 3.729 eV from the experimentally observed free exciton PL peaks. The temperature dependence of the PL intensity showed a two step quenching process and the temperature dependence of the PL linewidth broadening was tried to analyze in terms of exciton scattering process. From the splitting of the heavy hole and the light hole exciton peaks, the strain was identified.