Structure-property relationships of perovskite-structured Ca0.61Nd0.26Ti1-x(Cr0.5Nb0.5)xO3 ceramics

A series of Ca0.61Nd0.26Ti1-x(Cr0.5Nb0.5)xO3 (CNTCNx) (0 ≤ x ≤ 0.1) ceramics were prepared via a solid state reaction method. All CNTCNx samples were crystallized into the orthorhombic perovskite structure. The SEM micrographs indicated that the average grain sizes of samples depended on (Cr0.5Nb0.5)4+ concentration. And as (Cr0.5Nb0.5)4+ concentration increased, the average grain size of samples decreased significantly. The short range order (SRO) structure and structural distortion of oxygen octahedra proved to exist in CNTCNx crystals from Raman spectra analysis results. The microwave dielectric properties highly depended on the B-site bond strength, oxygen octahedra distortion, reduction of Ti4+ to Ti3+ and internal strain η. At last, the CNTCN0.06 ceramic sintered at 1400 °C for 4 h exhibited good and stable comprehensive microwave dielectric properties of εr = 92.3, Q × f = 13,889 GHz, τf = + 152.8 ppm/°C.