Effects of calcium doping on yttrium titanate for microwave absorbing applications

We reported on the dielectric and microwave absorbing properties of Ca-doped Y₂Ti₂O₇ prepared by hot-pressing sintering. The structure, thermogravimetric analysis, conductivity, dielectric and microwave absorbing properties were systematically investigated. The results indicated that the main charge compensation mechanism was oxygen vacancies at low Ca²⁺ doping concentration, while at high Ca²⁺ doping levels, oxygen vacancies and Ca interstitials coexisted in the Y_2-xCa_xTi₂O₇. The major types of polarization process involved in this study are electronic, atomic and space charge polarization and orientational polarization. The minimum reflection loss of Y_1.8Ca_0.2Ti₂O₇ can reach −40.9 dB with a thickness of 1.1 mm. These properties manifest that Ca-doped Y₂Ti₂O₇ ceramics have the potential applications as microwave absorbing materials.