Dielectric relaxor behavior of ZnWO4 content on Ba0.5Sr0.5TiO3 composite ceramics for tunable microwave applications

ZnWO4-doped Ba0.5Sr0.5TiO3 (BST) composite ceramics were prepared by the conversional solid-state route. Their phase compositions and microstructures were systematically characterized. A significant relaxor and diffuse phase transition were observed in the samples doped with 5.0-25.0 wt% ZnWO4. It was found that permittivity peaks of the samples gradually shifted to low temperatures with increasing content of ZnWO4. Meanwhile, tunabilities of the composite ceramics decreased, but their Q values increased gradually. The sample with 35.0 wt% ZnWO4 has an appropriate permittivity of 72 (∼3.307 GHz), an acceptable tunability of 12.3% (∼10 kHz) and a considerable high Q value of 650 (∼3.307 GHz), which makes it a promising candidate for applications in electrically tunable microwave devices.