Effect of crystal structure of Ca2AMg2Ge2VO12 (A = Y, Eu) garnets on microwave dielectric properties

作者：Duan, Lian; Liu, Mingxin; Tang, Ying; Li, Jie; Xiang, Huaicheng^*; Fang, Liang^*; Luo, Xianrong

来源：Materials Today Communications, 2022, 33: 104706.

DOI：10.1016/j.mtcomm.2022.104706

• Microwave dielectric properties
• Garnet structure
• Rattling and compressed effect
• Bond valence

The optimal microwave dielectric properties of Ca2AMg2Ge2VO12 (A = Y, Eu) garnets are reached at the sintering temperature of 1300 degrees C for 6 h (epsilon r = 10.1, Qxf = 65,600 GHz and tau f =-53 ppm/degrees C for Ca2YMg2Ge2VO12; epsilon r = 9.4, Qxf = 37,900 GHz and tau f =-55 ppm/degrees C for Ca2EuMg2Ge2VO12). The dielectric loss of Ca2AMg2Ge2VO12 (A = Y, Eu) has been measured at a frequency of 13 GHz, and the dielectric loss of these ceramics is mainly affected by the pore volume and atomic packing fraction. The Ca-O and Mg-O bonds are compressed, while the Y-O, Eu,-O, Ge-O, and V-O bonds are in an expanded state. The higher epsilon r(C-M) calculated by the Clausius-Mossotti (C-M) equation than the measured epsilon r is attributed to the compression state of 24c-site (Ca2/A). The negative tau fvalue of Ca2AMg2Ge2VO12 is derived from the positive tau alpha m value greater than 3 alpha L. And the slight difference in tau f of Ca2YMg2Ge2VO12 and Ca2EuMg2Ge2VO12 is also slightly compressed at the Ca/A-site.

• 单位
  广西大学; 桂林理工大学