Papers by Keyword: Tantalates

Abstract: Solid solutions with defect perovskite structure have been obtained in the systems Li_0,5-уNa_yLa_0,5TiO₃, Li_0.5-yNa_yLa0.5◊Nb₂O₆ and Li_0.5-yNa_yLa0.5◊Та₂O₆ at 0 ≤ y ≤ 0.5. Their structure has been shown to undergo partial disordering with increasing sodium content in the system Li_0.5-yNa_yLa0.5◊Nb₂O₆ as in the system Li_0.5-yNa_yLa0.5◊Та₂O₆ structure has been ordering. Lithium diffusion in system Li_0,5-уNa_yLa_0,5TiO₃ follows a percolation model for the lithium diffusion. The ionic conductivity as a function of sodium content in the system Li_0.5-yNa_yLa0.5◊Nb₂O₆ has a maximum. The ionic conductivity of Li_0.5-yNa_yLa0.5◊Ta₂O₆ samples decreases with sodium content.

Abstract: Dense Li2O excess (Na0.49K0.49Li0.02)(Nb0.8Ta0.2)O3 [NKLNT] ceramics were developed by conventional sintering process without any special technique. The electrical properties of NKNLT ceramics were investigated as a function of Li2O concentration. When the sample sintered at 1050 oC for 4 h with the addition of 1 mol% Li2O, electro-mechanical coupling factor (kP) and piezoelectric coefficient (d33) were found to reach the highest values of 0.42 and 260 pC/N, respectively.

Abstract: The catalytic photodegradation of Rhodamine B with UV irradiation over NaMO3 (M= Ta and Nb) doped with Y2O3, La2O3, Nd2O3 and Sm2O3 has been studied in our laboratories. All catalysts were characterized by different techniques such as X-ray powder diffraction (XRD) and thermal analysis (DTA/TGA). Surface characterization of the solids was carried out from adsorption isotherms and infrared spectroscopy (FTIR). The band gap energy (Eg) of materials ranged from 4.1 to 2.9 eV. For comparative purpose the materials studied as catalysts were also synthesized by classical solid state reaction.