Relationship between bond characteristics and microwave dielectric properties of REVO4 (RE = Yb, Ho) ceramics

Authors：Dai, Yimin; Chen, Jinwu; Tang, Ying; Xiang, Huaicheng; Li, Jie^*; Fang, Liang^*

Source：Ceramics International, 2023, 49(1): 875-881.

DOI：10.1016/j.ceramint.2022.09.060

• Zircon structure
• REVO4 (RE
• Yb
• Ho)
• Microwave dielectric property
• Rattling effect

Two novel low-er REVO4 (RE = Yb, Ho) microwave dielectric ceramics with the symmetry of the zircon structure, space group I41/amd, were prepared using the solid-state method. Dense REVO4 (RE = Yb, Ho) ceramics sintered at 1200 degrees C and 1160 degrees C performed er similar to 12.3 +/- 0.1 and 13.3 +/- 0.1, Q x f similar to 28,200 +/- 300 GHz and 24,100 +/- 300 GHz, tf similar to 18.8 +/- 0.5 ppm/.C and 17.4 +/- 0.5 ppm/.C, along with thermal expansion coefficient (aL) of 9.0 ppm/.C and 8.1 ppm/.C, respectively. Bond valence results indicated that the slightly rattling RE3+ cations at the A-site and compressed V5+ at the B-site occurred in both ceramics. The positive deviations (.er) of porosity corrected er(Corr) from those calculated by the Clausius-Mosotti equation er(C-M), 8.1% for YbVO4 and 17.7% for HoVO4, were observed, implying that the rattling effect of RE3+ in dodecahedral A-site were greater than those of compressed V5+ in tetrahedral B-site. Rattling effect also led REVO4 (RE = Yb, Ho) to develop higher er, and smaller te and tam, then closer to zero tf values than other zircon-structured REVO4 (RE = Ce, Nd, Sm, Eu) ceramics with large negative tf. The differences in sintering temperature and microwave dielectric performance of both ceramics were discussed using the packing fraction, full width at half maximum (FWHM) of Raman modes and Phillips-Van Vechten-Levine (P-V-L) theory.

• Institution
  桂林理工大学; 桂林航天工业学院