Microwave Properties of Yttrium Vanadate Crystals at Cryogenic Temperatures

Yttrium Vanadate is a birefringent crystal material used in optical isolators and circulators with potentials for application in cryogenic microwave devices. As microwave properties of YVO₄ are not known, we measured the complex permittivity at frequency of 25 GHz using the Hakki-Coleman dielectric resonator technique in the temperature range from 13 K to 80K. The ε_r of YVO₄ turned out to be similar to that of sapphire, one of popular dielectric materials used at microwave frequencies. Measured loss tangent of YVO₄ was of the order of 10⁻⁶ at cryogenic temperatures. As Yttrium Vanadate is easy to fabricate and machine, it may replace the expensive sapphire in some microwave applications.