Contribution of Structure to Temperature Dependence of Resonant Frequency in the (1 − x )La(Zn _1/2 Ti _1/2 )O ₃ · x ATiO ₃ (A = Ca, Sr) System

The crystal structure and microwave dielectric properties of the (1 − x ) La(Zn _1/2 Ti _1/2 )O ₃ · x SrTiO ₃ and (1 − x )La(Zn _1/2 Ti _1/2 )O ₃ · x CaTiO ₃ system were investigated. X‐ray powder diffraction showed that cation ordering disappeared at x > 0.3 for both systems. However, infrared spectra demonstrated that short‐range cation ordering could exist at x = 0.4. Permittivity and the temperature coefficient of the resonant frequency (τ _f ) of both systems exhibited nonmonotonic variations with composition. Both systems exhibited a τ _f of zero at the same composition of x = 0.5 although the τ _f of SrTiO ₃ was about two times larger than that of CaTiO ₃ . The behavior of the permittivity and τ _f were described by the tilting of oxygen octahedra and cation ordering. The relation between τ _f and cation ordering of La(Zn _1/2 Ti _1/2 )O ₃ was discussed in conjunction with the experimental results on metal halides. It is suggested that cation ordering induced a negative τ _f and suppressed the increase of permittivity for compositions between x = 0 to x = 0.5 for (1 − x )La(Zn _1/2 Ti _1/2 )O ₃ · x SrTiO ₃ and (1 − x )La(Zn _1/2 Ti _1/2 )O ₃ · x CaTiO ₃ systems.