Processing and characterization of A-site deficient [(Ca,Sr) x (La,Nd)2/3?2x/3]TiO3 dielectric ceramics

A-site deficient perovskite ceramics in the (Ca, Sr) _x (La, Nd)_2/3?2x/3]TiO₃ (x = 0.1–0.9) system were prepared by a mixed-oxide solid state sintering route. Synchrotron X-ray diffraction and Raman spectroscopy revealed a tetragonal (I4/mcm) symmetry for the compositions with x = 0.1–0.7 and orthorhombic (Pbnm) symmetry for the x = 0.8 and 0.9 compositions. The grain size increased with an increase in x up to 0.7 and then decreased upon further increase in x to 0.8 and 0.9. The optimum microwave dielectric properties (ε_r ~ 48, Q × f = 3,664 GHz and τ _f  ~ +61 GHz) were recorded for the compositions with x = 0.1.