Microwave properties of BaMo_1-xW_xO₄ ceramics and its chemical stability on electrode metals

This study investigated the influence of W⁶⁺ ions in BaMo_1-xW_xO₄ (0 ≤ x ≤ 0.2) ceramics on its crystallization, sintering behavior, microwave dielectric property and chemical stability with Ag/Cu electrode metals. BaMoO₄-based ceramics can be densified well, and its sintering temperature can be lowered below 900 °C due to the formation of a BaMo_1-xW_xO₄ solid solution with a tetragonal scheelite structure. The value of ε_r decreases from approximately 8.9 to 8.2 with the increase of the W⁶⁺ content from 0 to 20 mol%. Compared with BaMoO₄ ceramics, the incorporation of W⁶⁺ ions clearly increases the Q × f values of ceramics and increases the τ_f values from -95.14 ppm/°C to -50.51 ppm/°C. The BaMo_0.85W_0.15O₄ sample has the largest Q × f value and exhibits the optimal microwave dielectric property: ε_r =8.57 and Q × f = 33244 GHz. BaMo_1-xW_xO₄ ceramics exhibit chemical stability on two most promising electrode materials (i.e., Cu and Ag) during the cofiring process. This material is an inexpensive and high-performance LTCC candidate that advances the progress of microelectronic multilayer components.