Anti-reduction mechanism of Ba4.2Sm9.2Ti18O54 ceramics by Mg2+/Ta5+ complex ion co-doping.

In this work, a novel anti-reduction mechanism was put up by substituting (Mg 1/3 Ta 2/3)4+ complex ion for Ti4+ ion in Ba 4.2 Sm 9.2 Ti 18-x (Mg 1/3 Ta 2/3) x O 54 (0 ≤ x ≤ 0.1) ceramics. The influence of (Mg 1/3 Ta 2/3)4+ complex ion on the sintering behavior, crystal structure, anti-reduction mechanism and microwave dielectric properties of Ba 4.2 Sm 9.2 Ti 18-x (Mg 1/3 Ta 2/3) x O 54 ceramics was investigated. The results indicated that Ba 4.2 Sm 9.2 Ti 18-x (Mg 1/3 Ta 2/3) x O 54 ceramics maintained a typical single-phase tungsten bronze structure. After doping, the ceramic exhibited dense structure and typical columnar grains. Raman spectroscopy and XPS analysis confirmed the reduction of oxygen vacancies and obtained a 7.86 % decrease of Ti3+ ions. Due to the anti-reduction of Ti4+ ions, Ba 4.2 Sm 9.2 Ti 18-x (Mg 1/3 Ta 2/3) x O 54 ceramics possessed an improvement in microwave dielectric properties. In Ba 4.2 Sm 9.2 Ti 18-x (Mg 1/3 Ta 2/3) x O 54 (0 ≤ x ≤ 0.1) ceramics, the Ba 4.2 Sm 9.2 Ti 17·95 (Mg 1/3 Ta 2/3) 0.05 O 54 (x = 0.05) ceramic sintered at 1350 °C for 4 h showed the best integrated microwave dielectric properties with ε r = 79.62, Q f = 10,450 GHz and τ f = −10.66 ppm/°C. [ABSTRACT FROM AUTHOR]