Synthesis of temperature-stable microwave dielectric ceramics NiNb2O6 with TiO2 addition

NiNb(2)O(6) ceramics with 8-10 mol% TiO(2) were investigated. A mixture of raw materials was sintered into ceramics by bypassing calcination and subsequent pulverization stages. The addition of TiO(2) resulted in the formation of a Ni(4)Nb(2)O(9) phase and phases with the same structure as that of a Ni(0.5)Ti(0.5)TbO(4) phase. An increase in the TiO(2) content resulted in an increase in the content of the Ni(0.5)Ti(0.5)NbO(4)-like phase, especially at high sintering temperatures. The dielectric constant increased from 29.2 at 1170 degrees C to 31.1 at 1230 degrees C in NiNb(2)O(6) ceramics with 9 mol% TiO(2). Qxf reached 36800 GHz in NiNb(2)O(6) ceramics with 8 mol% TiO(2). It decreased as the TiO(2) content increased with the content of the Ni(0.5)Ti(0.5)NbO(4)-like phase with a low Qxf tau(f) between -2 and 2 ppm/degrees C could be obtained in NiNb(2)O(6) ceramics with 9 and 10 mol% TiO(2). (C) 2008 Elsevier B.V. All rights reserved.