Crystal structure, far-infrared spectroscopy, and microwave dielectric properties of two novel vanadates CaRECeV3O12 (RE = Nd, Sm)

作者：Zhang, Zhiyuan; Chen, Jinwu; Tang, Ying^*; Xiang, Huaicheng; Li, Jie; Fang, Liang^*; Chen, Junqi^*

来源：Ceramics International, 2023, 49(14): 23173-23179.

DOI：10.1016/j.ceramint.2023.04.146

• Zircon structure
• Microwave dielectric properties
• Ion polarizability
• Bond valence
• Far-infrared spectroscopy

Two novel low-& epsilon;r CaRECeV3O12 (RE = Nd, Sm) microwave dielectric ceramics were prepared to utilize the solid-state method. According to XRD and Raman spectroscopy data, the CaRECeV3O12 (RE = Nd, Sm) ceramics had a tetragonal zircon-type with an I41/amd space group. Dense CaNdCeV3O12 and CaSmCeV3O12 ceramics sintered at 1225 degrees C and 1200 degrees C showed & epsilon;r-11.85 & PLUSMN; 0.1 and 11.33 & PLUSMN; 0.1, Q x f-40,100 & PLUSMN; 500 GHz and 43,290 & PLUSMN; 500 GHz, & tau;f --27.2 & PLUSMN; 0.5 ppm/degrees C and-22.4 & PLUSMN; 0.5 ppm/degrees C, along with & alpha;L of 9.4 ppm/degrees C and 8.5 ppm/degrees C, respectively. The measured & epsilon;r and corrected & epsilon;r(corr) values were larger than & epsilon;r(C-M) (9.41 and 9.47) in CaN-dCeV3O12 and CaSmCeV3O12 due to the cations being, on average, under-bonded and the overall structures being in a slightly expanded state. The slightly higher |< d > | value of CaNdCeV3O12 led to its higher & epsilon;r(corr) value, even though it had a lower & alpha;D/Vm value. The sign and magnitude of & tau;f values for CaNdCeV3O12 and CaSmCeV3O12 were mainly determined by their positive temperature coefficients of dielectric polarizability & tau;& alpha;m of +36.2 ppm/ degrees C and +32.1 ppm/degrees C, respectively. The inherent dielectric constant and dielectric loss were examined using far-infrared reflectivity spectra, Raman spectra, and the packing fraction.

• 单位
  桂林航天工业学院; 广西大学; y; 桂林理工大学