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0.25Ca_0.8Sr_0.2TiO₃–0.75Li_0.5Nd_0.5TiO₃; microwave dielectric properties; microstructures; LiF.

The effects of LiF addition on sinterability, microstructure and microwave dielectric properties of 0.25Ca_0.8Sr_0.2TiO₃–0.75Li_0.5Nd_0.5TiO₃ ceramics were investigated. The LiF addition enhanced the sintering temperature of 0.25Ca_0.8Sr0.2TiO3–0.75Li0.5Nd0.5TiO3 ceramics from 1200 to 1300°C, because the LiF addition could compensate the evaporation of Li during the sintering process. It was found that the bulk density and dielectric constant (𝜀_r) gradually decreased, the quality factor (𝑄_f) greatly increased and the temperature coefficient of resonant frequency (𝜏_f) shifted to a near-zero value with the increase in LiF addition. Obviously, excess Li addition could efficiently improve the microwave dielectric properties. In addition, 0.25Ca_0.8Sr_0.2 TiO₃–0.75Li_0.5Nd_0.5TiO₃ + 4.0 wt% LiF ceramics sintered at 1350°C for 4 h exhibited good microwave dielectric properties of 𝜀_r ∼ 123.4, 𝑄_f ∼ 2209 GHz (at 2.43 GHz) and 𝜏_f ∼ 12.3 ppm °C^–1.

Fei Liu¹ Changlai Yuan² Xinyu Liu^{1 2} Jing Jing Qu³

1. College of Material Science and Engineering, Central South University, Changsha 410083, PR China
2. College of Material Science and Engineering, Guilin University of Electronic Technology, Guilin 541004, PR China
3. Department of Information Engineering, Guilin University of Aerospace Technology, Guilin 541004, PR China

Manuscript received

7 April 2014

Accepted

7 April 2015