Two novel low-firing Na2AMg2V3O12(A=Nd, Sm) ceramics and their chemical compatibility with silver

Two novel microwave dielectric ceramics Na2AMg2V3O12 (A=Nd, Sm) with cubic garnet structure were obtained by the conventional solid-state reaction method. Both ceramics could be well densified at 850 °C for 4 h. The Na2NdMg2V3O12 (NNMV) ceramic exhibited good microwave dielectric properties with a permittivity er of 12, a quality factor Qu×f value of 26,544 GHz (at 10 GHz) and a negative temperature coefficient of resonant frequency τf value of −63 ppm/°C and the Na2SmMg2V3O12 (NSMV) ceramic had a er of 12.1, a Qu×f value of 36,207 GHz (at 9.8 GHz) and a negative τf value of −69 ppm/°C. The large negative τf values could be compensated by forming solid solution with LiCa2Mg2V3O12 and 0.7Na2AMg2V3O12 (A=Nd, Sm)–0.3LiCa2Mg2V3O12 sintered at 880 °C for 4 h exhibited a near zero τf ~−4.5 ppm/°C and 5.5 ppm/°C, respectively. Both ceramics were found to be chemically compatible with Ag electrode at 850 °C for 4 h. These merits make them promising candidates for low-temperature co-fired ceramic technology (LTCC).