Crystal structure and microwave dielectric properties of novel (1−x)ZnZrNb2O8−xTiO2 ceramics

The crystal structural variations of (1−x)ZnZrNb2O8−xTiO2 ceramics sintered at 1150 °C for 4 h were investigated, and the relationship of these changes and the microwave dielectric properties were studied. Three types of crystal structures were identified with increasing x: wolframite, ixiolite, and rutile. While x≤0.4, the single-phase solid solution of wolframite structure was found. For 0.6≤x≤0.7, the ceramics formed a single-phase solid solution of ixiolite structure. And when x=0.8, the mixture of two solid solution phases based on the ixiolite and rutile structures was obtained. The microwave dielectric properties of specimens were changed with the crystal structural transitions. Moreover, with the help of TiO2, τf value of the 0.3ZnZrNb2O8−0.7TiO2 ceramic was adjusted to near zero of −2.4 ppm/°C, accompanied with excellent microwave dielectric properties of εr~41.4, Q×f~38,500 GHz. This constitutes a very promising material for microwave applications.