Abstract

Ca₃Al₂O₆ ceramics are synthesized using a standard solid-state reaction method and their microwave dielectric properties are systematically investigated. Pure phases with space group of Pa_3 are confirmed from X-ray diffraction patterns (XRD) and Rietveld refinements. ε_r and Q_f values of the present ceramics are mainly determined by the porosity, and the optimal values (ε_r = 14.5, Q_f = 24,500 GHz) are achieved when sintered at 1425 °C. Abnormally large negative τ_f values in the range of − 322 to − 354 ppm/°C are obtained, which are rare and extremely important in adjusting the positive τ_f values of other material systems. In addition, a large temperature sensitivity of − 4.19 MHz/°C is also confirmed in the present ceramics, which indicates great potential for temperature sensor applications. Moreover, the dielectric spectra measured under various radio frequencies reveal similar positive τ_ε values of 715.5 ppm/°C, which could account for the large negative τ_f values in the operating temperatures.

中文翻译：

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Ca 3 Al 2 O 6：负τf异常大的新型低介电常数微波介电陶瓷

摘要

采用标准的固态反应方法合成了Ca ₃ Al ₂ O ₆陶瓷，并对其微波介电性能进行了系统的研究。从X射线衍射图谱（XRD）和Rietveld精细化确定了具有Pa_3空间群的纯相。ε _{- [R}和Q _˚F本陶瓷的值主要由孔隙率决定的，和最优值（ε _{- [R}  = 14.5，Q _˚F 当在1425烧结得以实现= 24500千兆赫）℃。异常大的负τ _˚F322 - -在的范围内的值354 PPM /°获得C，其是罕见的，在调整正极为重要τ _˚F其它材料系统的值。另外，在本陶瓷中还确认到-4.19 MHz /°C的较大温度灵敏度，这表明温度传感器应用具有巨大潜力。此外，根据不同的无线电频率下测量的介电谱揭示了类似的积极τ _ε /℃，这可以解释为较大的负715.5 ppm的值τ _˚F在操作温度的值。