Microstructures and Microwave Dielectric Properties of Na0.5Nd0.2Sm0.3Ti1−x Sn x O3 Ceramics (x = 0.00 to 0.50)

In this work, frequency-stable Na0.5Nd0.2Sm0.3Ti1−x Sn x O3 (x = 0.00, 0.01, 0.02, 0.05, 0.09, 0.14, 0.20, 0.30, 0.40, 0.50) ceramics with low dielectric loss were prepared by the conventional solid-state route. The effects of the Sn ratio on the structure, sintering behavior, and microwave dielectric properties of Na0.5Nd0.2Sm0.3Ti1−x Sn x O3 (NNST) were systematically investigated. All samples were indexed as having orthorhombic perovskite structure; replacement of Ti4+ by Sn4+ at the B-site occurred and increased the lattice parameters for x ≤ 0.4. e r decreased monotonically with increasing Sn concentration. The quality factor could be significantly enhanced because of the improved densification, reaching a maximum value at x = 0.3. It was remarkable that the τ f value could be effectively tuned from a large value of 206 ppm/°C to near zero due to a continuously dramatic change of lattice structure. The results showed that the Sn content significantly influenced the microstructure and sintering behavior because of the appearance of liquid phase. NNST ceramic with x = 0.3 sintered at 1350°C for 2 h showed good microwave dielectric properties of e r = 56, Q × f = 10,734 GHz, and τ f = 22 ppm/°C.