Structure and microwave dielectric properties of (Zn1/3Nb2/3)4+ co-substituted MgTiO3 ceramic

In this work, MgTi1-x(Zn1/3Nb2/3)(x)O-3 (0 <= x <= 0.3) ceramics were synthesized by a solid-state reaction method. MgTiO3 is identified as main phase, while MgTi2O5 is detected as secondary phase at 0 <= x <= 0.3, in association with a minor Mg2TiO4 phase at x = 0. The (Zn1/3Nb2/3)(4+) co-substituted ions are responsible for the change of bond length and the TiO6 octahedral distortion. The quality factor (Q x f) depends on the electronegativity difference (Delta e) and average covalency. The dielectric constant (epsilon(r)) is related to molecular polarizability (alpha(theo)) and tolerance factor (t). Besides, the temperature coefficient of resonance frequency (tau(f)) strongly correlates with TiO6 octahedral distortion and the secondary phase. In comparison to pure MgTiO3, desirable microwave dielectric properties of epsilon(r) = 17.59, Q x f = 211 600 GHz, and tau(f) = -50 ppm/degrees C were obtained when x = 0.12 sintered at 1250 degrees C. The MgTi0.88(Zn1/3Nb2/3)(0.)O-12(3) ceramic is a candidate material for the wireless communication applications.