Relationship between bond characteristics and microwave dielectric properties of REVO4 (RE = Yb, Ho) ceramics
Relationship between bond characteristics and microwave dielectric properties of REVO4 (RE = Yb, Ho) ceramics
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DOI：
10.1016/j.ceramint.2022.09.060
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发表时间：
2022-09
影响因子：
5.2
通讯作者：
Yimin Dai;Jinwu Chen;Ying Tang;H. Xiang;Jie Li;L. Fang
中科院分区：
文献类型：
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作者：
Yimin Dai;Jinwu Chen;Ying Tang;H. Xiang;Jie Li;L. Fang
采用固态法制备了两种新型低ε rrevo4 （RE = Yb, Ho）微波介电陶瓷，具有锆石结构对称的空间群pi41 /amd。在1200°C和1160°C烧结的致密REVO4（RE = Yb, Ho）陶瓷的εr ~ 12.3±0.1和13.3±0.1,Q×f ~ 28,200±300 GHz和24,100±300 GHz,τf ~−18.8±0.5 ppm/°C和−17.4±0.5 ppm/°C，热膨胀系数（αL）分别为9.0 ppm/°C和8.1 ppm/°C。键价结果表明，两种陶瓷均出现了a位RE3+的轻微振动和b位V5+的压缩。通过clusius - mosotti方程计算得到的孔隙度校正εr（Corr）与ybvo4和HoVO4的正偏差（Δεr）分别为8.1%和17.7%，表明RE3+在十二面体a位的振动效应大于压缩V5+在四面体b位的振动效应。与其他具有较大负τf的锆结构的REVO4（RE = Ce, Nd, Sm, Eu）陶瓷相比，摇响效应导致REVO4（RE = Yb, Ho）陶瓷的εr较高，τε和ταm较小，且τf值更接近于零。利用拉曼模式的填充率、半最大值全宽度（FWHM）和philips - van veechten - levine （P-V-L）理论讨论了两种陶瓷的烧结温度和微波介电性能的差异。
Two novel low-εrREVO4(RE = Yb, Ho) microwave dielectric ceramics with the symmetry of the zircon structure, space groupI41/amd, were prepared using the solid-state method. Dense REVO4(RE = Yb, Ho) ceramics sintered at 1200 °C and 1160 °C performedεr∼ 12.3 ± 0.1 and 13.3 ± 0.1,Q×f∼ 28,200 ± 300 GHz and 24,100 ± 300 GHz,τf∼ −18.8 ± 0.5 ppm/°C and −17.4 ± 0.5 ppm/°C, along with thermal expansion coefficient (αL) 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 (Δεr) of porosity correctedεr(Corr)from those calculated by the Clausius-Mosotti equationεr(C-M), 8.1% for YbVO4and 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 higherεr, and smallerτεandταm, then closer to zeroτfvalues than other zircon-structured REVO4(RE = Ce, Nd, Sm, Eu) ceramics with large negativeτf. 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.