Effects of Tungsten Doping on the Electrical Properties of Hydrothermally Synthesized Aluminum Niobate

The conditions for the synthesis of aluminum tungstate Al2(WO4)3 and aluminum niobate AlNbO4 were clarified using hydrothermal treatment and post-heating. Single-phase Al2(WO4)3 can be synthesized through the hydrothermal treatment of the starting materials at a mixing ratio of Al:W = 5:5 at 250 °C for 5 h and post-heating at 840 °C for 6 h. The AlNbO4 was synthesized using the same method, under a hydrothermal treatment of Al:Nb = 2:8 and post-heating. As a result of investigating the products under various mixing conditions based on the synthesis of pure Al2(WO4)3 and AlNbO4, Nb could not be doped into Al2(WO4)3, but W-doped AlNbO4 was synthesized. The electric conductivity was measured for several samples of sintered W-doped AlNbO4, and the results showed that the electrical conductivity was improved within a higher temperature region by doping with W.