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A series of samples with nominal compositions of AgSb 1Àx Sn x Se 2 (with x = 0.0, 0.1, 0.2, and 0.3) and AgSbSe 2Ày Te y (with y = 0.0, 0.25, 0.5, 0.75, and 1.0) were prepared. The crystal structure of both single crystals and polycrystalline samples was analyzed using x-ray and neutron diffractometry. The electrical conductivity, thermal conductivity, and Seebeck coefficient were measured within the temperature range from 300 K to 700 K. In contrast to intrinsic AgSbSe 2 , samples doped with Sn and Te exhibit apparent semiconducting properties (E g = 0.3 eV to 0.5 eV), lower electrical conductivity, and higher values of the Seebeck coefficient for a small amount of Sn (x = 0.1). Further doping leads to decrease of the thermoelectric power and increase of the electrical conductivity. In order to explain electron transport behavior observed in pure and doped AgSbSe 2 , electronic structure calculations were performed by the Korringa-Kohn-Rostoker method with coherent potential approximation (KKR-CPA).

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XRD and chemical analysis reveal that the orthorhombic unit cell of zeolite ZSM-5 structure undergoes linear contraction or expansion with increasing substitution level of B or Al, respectively. Evidence for a full substitution of B or Al in the framework to ca. three heteroatoms per unit cell is also provided by the "B MASNMR spectrum and a linear decrease in the framework vibration frequency with the increasing Al per unit cell, as observed in the IR spectra. Only the boralite with an analytical content of 3.7 B atoms per unit cell contained ca. 24% of extraframework B. The similar electronegativities of B and Si explain the structural vibration frequency in the IR region, which is independent of the amount of B per unit cell.

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