Crystal structure, Raman spectra and microwave dielectric properties of Li2Mg3Ti1-x(Mg1/3Nb2/3)(x)O-6 (0 = x = 0.25) ceramics

摘要

Li2Mg3Ti1-x(Mg1/3Nb2/3)(x)O-6 (0 = x = 0.25) ceramics were prepared by a conventional solid-state reaction process Their crystal structures, sintering characteristics, Raman spectra and microwave dielectric properties were then investigated. XRD patterns of the sintered samples indicated that all compositions showed a single phase and the rock-salt structure. As the (Mg1/3Nb2/3)(4+) contents increase, the variations of epsilon(r) values showed a downward trend, which could be explained by the changes of polarizabihties and the shift of Raman vibration modes. Q center dot f values initially increased to a maximum value and then decreased with increasing of x values In addition, tau(f) values decreased almost linearly with the x values, which significantly correlated with the thermal expansion coefficient. Excellent combined microwave dielectric properties with epsilon(r) = 14.79, Q center dot f = 204,900 GHz and tau(f) = -18.43 ppm/degrees C were obtained for Li2Mg3Ti.95(Mg1/3Nb2/3)(.05)O-6 ceramic sintered at 1550 degrees C.