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

Two novel microwave dielectric ceramics Na(2)AMg(2)V(3)O(12) (A=Nd, Sm) with cubic garnet structure were obtained by the conventional solid-state reaction method. Both ceramics could be well densified at 850 degrees C for 4 h. The Na2NdMg2V3O12 (NNMV) ceramic exhibited good microwave dielectric properties with a permittivity epsilon(r) of 12, a quality factor Q(u)xf value of 26,544 GHz (at 10 GHz) and a negative temperature coefficient of resonant frequency tau(f) value of -63 ppm/degrees C and the Na2SmMg2V3O12 (NSMV) ceramic had a epsilon(r) of 12.1, a Q(u)xf value of 36,207 GHz (at 9.8 GHz) and a negative tau(f) value of -69 ppm/degrees C. The large negative tau(f) values could be compensated by forming solid solution with LiCa2Mg2V3O12 and 0.7Na(2)AMg(2)V(3)O(12) (A=Nd, Sm)(0.3)LiCa2Mg2V3O12 sintered at 880 degrees C for 4 h exhibited a near zero tau(f) similar to-4.5 ppm/degrees C and 5.5 ppm/degrees C, respectively. Both ceramics were found to be chemically compatible with Ag electrode at 850 degrees C for 4 h. These merits make them promising candidates for low-temperature co-fired ceramic technology (LTCC).