Effect of Al₂O₃ and MgO Additives on Dielectric Properties of BaZr_xTi_1-xO₃-Based Ceramics

Abstract:

BaZr_xTi_1-xO₃-based (BZT) ceramics with Al₂O₃ and MgO addtives were prepared by the conventional solid state method with BaCO₃, ZrO₂, TiO₂, Al₂O₃ and MgO as raw materials and B₂O₃ and Li₂CO₃ as sintering additive. The morphologies were analysized by scanning electron microscopy (SEM). The dielectric constant and dielectric loss of ceramics were measured by LCR meter. The temperature dependences of dielectric constant were measured by high-low temperature incubator tank and LCR meter at 1 MHz and a temperature range-55 to 125 °C. The tunabilities were tested by C-T-V converter and LCR meter at 1 MHz at room temperature. The results show that with the increase of Zr/Ti, BZT ceramic dielectric constant increases, the loss increases, the Curie temperature moves to a lower temperature, and dielectric bias field coordination is relatively lower. The SEM images show that the grain size reaches about 1-2 μm when the sintering temperature is 1100 °C, and the addition of Al₂O₃ and MgO promote the grain growth and densification of the composite ceramics. The Curie peaks are broadened and depressed with the addition of Al₂O₃ and MgO. The tunability is improved to 9.59% under a DC electric field of 7.0 kV/cm after the addition of Al₂O₃. The dielectric constant and dielectric loss of BaZr_0.25Ti_0.75O₃-30wt%Al₂O₃ and BaZr_0.25Ti_0.75O₃-30wt%MgO are 586, 0.011 and 486, 0.003, respectively. The optimistic dielectric properties make it a promising candidate for the application of tunable capacitors and phase shifters.

• Periodical: Key Engineering Materials (Volumes 602-603)
• Pages: 714-718
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.602-603.714
• Online since: March 2014
• Authors: Hong Jun Feng, Hui Ming Ji*, Xiao Lei Li, Jian Wang, Da Hao Wang
• Keywords: Al₂O₃, BZT, Dielectric Property, MgO, Microstructure, Tunability

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