Broadband and Microwave Dielectric Studies on Ba5Nb4O15 Ceramics Supplemented with Its Nanoparticles for Cryogenic Electronic Applications

Ba5Nb4O15 (BNO) nanopowders were prepared by sol–gel process. The effect of BNO nanopowders (x = 1 wt.%, 2 wt.%, and 3 wt.%) on micron-sized BNO polycrystalline powders were studied systematically. Transmission electron microscope (TEM) images of BNO nanoparticles revealed spherical and cylindrical shapes with average particle sizes of 45 nm and 60 nm, respectively. Further, the dielectric response of BNO ceramics with x wt.% of nanosized particles (x = 1–3) measured in the temperature range of 80°C to 200°C showed relaxation behaviour and is described by using Havriliak–Negami equation. The best microwave dielectric properties of er and Q × f0 values of 39.2 GHz and 59,000 GHz, at 6.52 GHz are obtained for the x = 3 wt.% sample, sintered at 1100°C, and is attributed to maximum density, large and uniform microstructure. The acquired static dielectric response of BNO ceramics with x wt.% of nanosized particles (x = 1–3) are suitable for cryogenic electronic and dielectric resonator applications.