Microwave Dielectric Characteristics Of High Permittivity Ca0.35li0.25nd0.35ti1-X(Zn1/3ta2/3)(X)O-3 Ceramics (X=0.00-0.12)

The Ca0.35Li0.25Nd0.35Ti1-x(Zn1/3Ta2/3)(x)O-3 (0 <= x <= s 0.12) ceramics were prepared using the solid-state reaction route. The influence of substitution of (Zn1/3Ta2/3)(4+) for TO4+ on microstructure and microwave dielectric properties of Ca0.35Li0.25Nd0.35Ti1-x(Zn1/3Ta2/3)(x)O-3 (CLNT(ZT)x) ceramics was investigated in this study. The X-ray diffraction patterns (XRD) of the specimens showed that the ceramics with x <= 0.06 were crystallized as an orthorhombic perovskite structure in Pnma space group. However, the secondary phase of Nd2Ti2O7 was observed with properties of 0.08 <= x <= 0.12. The analysis results of Raman spectra revealed the existence of oxygen octahedral distortion and the short-range ordering occurred in CLNT(ZT)x ceramics with the change of (Zn1/3Ta2/3)(4+) content. The dielectric constant (epsilon(r)) increased firstly and then decreased gradually when substitution increased, and the variation of E. was affected by the B-site bond valence. The quality factor value (Q x f) was improved by right amount of substitution when x <= 0.08, but deteriorated seriously as excessive (Zn1/3Ta2/3)(4+) content was added (x >= 0.10). The temperature coefficient of the resonant frequency (tau(f)) was effectively reduced from + 90.9 ppm/degrees C to + 30.3 ppm/degrees C with the increasing of substitution due to the declination of tolerant factor (t). At last, the CLNT(ZT)0.08 ceramics sintered at 1250 degrees C for 4 h exhibited the excellent comprehensive dielectric properties with epsilon(r) = 120.63,Q x f = 3889 GHz, tau(f) = + 60.9 ppm/degrees C.