BiVO₄ based high: K microwave dielectric materials: A review

The BiVO₄ material has attracted much attention in recent years due to its active photocatalytic properties under visible light, bright yellow color as a nontoxic pigment, and its high relative permittivity (ϵ_r) and Qf (quality factor, Q × resonant frequency, f) as a potential microwave dielectric ceramic. In this review, we introduce the origin, synthesis, crystal structure and phase transitions of the four polymorphic phases of BiVO₄: orthorhombic (pucherite), zircon (dreyerite), scheelite monoclinic (clinobisvanite) and scheelite tetragonal. We then precis recent studies on doped BiVO₄ ceramics in terms of A site, B site and A/B site complex substitutions. Low sintering temperature (<800 °C) and high ϵ_r values could be obtained in some solid solution ceramics and near zero temperature coefficient of resonant frequency (TCF/τ_f) values could be achieved in layered or granulated particle composite ceramics. Besides, a series of temperature stable high ϵ_r microwave dielectric ceramics can also be obtained for many co-fired composite ceramics, such as BiVO₄-TiO₂, and BiVO₄-TiO₂-Bi₂Ti₄O₁₁. The high ϵ_r, high Qf value, low sintering temperature and chemical compatibility with some base metals suggest that BiVO₄-based materials are strong candidates for both LTCC and other microwave device applications in current 4G and future 5G technologies.