Influence of V substitutions on sintering behaviors and microwave dielectric properties of Ba4LiNb3O12 ceramic

Abstract

In this study, a series of Ba₄Li(Nb_1-xV_x)₃O₁₂ (x = 0.05∼0.3) ceramics were synthesized using the solid-state reaction method. X-ray powder diffraction (XRD) analysis shows that the composite ceramics contain both Ba₄LiNb₃O₁₂ and Ba₃(VO₄)₂ phases, without any other phases present. The grains consist of Ba₄LiNb₃O₁₂ and Ba₃(VO₄)₂, as illustrated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Additionally, with the increase of V content, the grain size decreases, and the ${\epsilon }_r$ (microwave dielectric constant) decreases, the $\tau {}_f$ (resonant frequency temperature coefficient) value decreases, and the $Q\times f$ value increases (where $Q$ = quality factor = 1 / dielectric loss, and $f$ = resonant frequency). The densest Ba₄Li(Nb_0.7V_0.3)₃O₁₂, with a ${\epsilon }_r$ of 31.3, $\tau {}_f$ of + 70 ppm/°C, and high $Q\times f$ of 42 850 GHz, was obtained at a sintering temperature of 1350°C. Furthermore, the addition of 5 wt.% BaCu(B₂O₅) (BCB) into Ba₄Li(Nb_0.7V_0.3)₃O₁₂ resulted in obtaining dense ceramics at a sintering temperature of 925°C, with a ${\epsilon }_r$ of 23.5, a high $Q\times f$ value of 14 370 GHz, and $\tau {}_f$ of + 88 ppm/°C. Further investigations have shown that Ba₄Li(Nb_1-xV_x)₃O₁₂ ceramics are chemically compatible with Ag, suggesting its potential use in low-temperature cofired ceramics technology.