Different Additives Doped Ca–Nd–Ti Microwave Dielectric Ceramics with Distorted Oxygen Octahedrons and High Q × f Value

[Image: see text] We investigated the structure and antireduction of Ti(4+) in orthorhombic perovskite Ca(0.61)Nd(0.26)TiO(3) (CNT) ceramic by doping with three different additives (Cr(2)O(3), MnO(2), and SnO(2)). The X-ray diffraction patterns showed that the main phase of orthorhombic perovskite was formed in all the samples. In addition, the substitution of M (M = Cr(3+), Mn(4+), Sn(4+)) for Ti(4+) resulted in the oxygen octahedral distortion and changes of order degree of B-site, which was confirmed by Raman spectra. The ε(r) and τ(f) values were concerned with the average ionicity of B–O bond f(i)(B-ave) and the linear expansion coefficient α, respectively. The X-ray photoelectron spectra indicated that three different additives could restrain the reduction of Ti(4+), which was beneficial to the improvement of the Q × f value for CNT ceramic. High Q × f value of 16 123 GHz was obtained in the CNT + 1 mol % Cr(2)O(3) ceramic compared with Q × f value of 11 207 GHz in pure CNT ceramic.