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AgCu 1 − x Fe x S compounds were synthesized by partial Cu → Fe replacement in the AgCuS crystal at a concentration range of 0 ≤ x ≤ 0.03. In the differential thermal analysis spectrum obtained at a temperature range of 300 K ≤ T ≤ 1300 K, endoeffect corresponding to the structural phase transition in the AgCuS compound was observed at the temperature T = 938 K. It has been determined that this result is also observed in the AgCu 0. 9 9 Fe 0. 0 1 S compound obtained by partial replacement of Cu atoms by Fe atoms. However, in the compound of AgCu 0. 9 7 Fe 0. 0 3 S this effect was observed at higher temperatures. The thermal capacities and enthalpies of phase transitions were calculated for the given compounds. [ABSTRACT FROM AUTHOR]

Polycrystalline garnet ferrites Dy3-xNix Fe5O12, where (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) have been prepared by the standard ceramic technique and their crystalline structure were identified by X-ray diffraction and IR spectroscopy. The differential thermal analysis (DTA) reveals two peaks. It is observed that an endothermic peak between 587 and 498 K for all samples which is due to the magnetic phase change from ferrimagnetic to paramagnetic state. The exothermic peak at about 700 K may be attributed to the crystallization of Dy3-x NixFe5O12 with garnet structure. DC electrical resistivity, thermoelectric power, charge carrier concentration and charge carrier mobility have been studied at different temperatures: It was found that the DC electrical conductivity increases linearly with increasing temperature ensuring the semiconducting nature of samples. The values of the thermoelectric power were negative for samples of 0.0 < x < 0.4 indicating that the majority of the charge carrier are electrons in these samples while it was positive for sample of x = 0.5 at room temperature, and negative at high temperature. Using the values of the DC electrical conductivity and thermoelectric power, the values of the charge carrier concentration and the charge carrier mobility were calculated. Finally thermal properties have been studied. [ABSTRACT FROM AUTHOR]