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ZnO:Al ceramics (Zn:Al, 0.95:0.05) were prepared by using sol-gel derived nanocrystalline powders. XRD patterns of the doped ceramics revealed the existence of both zincite (JCPDS 36-1451) and gahnite (JCPDS 5-0669) phases. Gahnite phase (ZnAl 2 O 4 ) was segregated along the ZnO grain boundaries. At the sintering temperature of 1200 °C, relative density of the undoped and Al doped ceramics were measured as 0.695 and 0.628, respectively. Both grain size and relative density of the ceramics decreased with Al doping.

TlBiS 2 is a narrow-gap semiconductor with a layered structure, isoelectronically analogous to PbS. Large single crystals were grown by the Bridgman-Stockbarger method from the melt and characterized by x-ray diffraction. The lattice parameters were determined and the discrepancy between those already reported was removed. From IR reflectivity measurements in the plasma region, the number of carriers was calculated. Also a strong anisotropy of the electrical conductivity was detected and the narrow-gap character of the material was supported by electrical measurements in the range of 10-300 K.

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Large single crystals of the family of layered compounds (TlBiSe 2 ) 1−x -(TlBiS 2 ) x were grown by the Bridgman-Stockbarger method for x = 0.0, 0.25, 0.50, 0.75 and 1.0. The structures of the as-grown single crystals were determined by x-ray diffraction and the lattice parameters and unit cell volumes were obtained. Infrared reflectivity measurements were also performed in the range 600-4000 cm −1 . From the analysis, the parameters ε ∞ , ω p and were calculated. The electrical resistivities ρ and ρ ⊥ (parallel and perpendicular to the layers, respectively) were measured as a function of temperature. From the ρ measurements the plot of the Debye temperature versus x was calculated. An attempt was also made to correlate these physical properties with the compositional parameter x .