Effect of the particle diameters of raw materials on the structure, micromorphology, dielectric, and tunable performance of (Ba0.91Ca0.09)(Zr0.2Ti0.8)O3 ceramics

Ceramics' micromorphology plays a pivotal role on their dielectric and tunable properties. Thus, many methods are used to modify the micromorphology of ceramics to improve the dielectric and tunable properties. However, the mechanisms about the influence of raw materials' particle diameters on the dielectric and tunable properties have seldom been investigated. In this study, the (Ba0.91Ca0.09)(Zr0.2Ti0.8)O-3 ceramics were synthesized using the nanoscale BaTiO3 (BT) powders as Ti sources to study the effect of the BT particle diameters on the structure, micromorphology, dielectric properties, and tunable performance. When the BT particle diameters decreased from 500 nm (BT05) to 400 nm (BT04), the grain size sharply increased and then slightly decreased as the particle diameter further decreased to 100 nm (BT01) due to the influence of oxygen vacancies. The generated oxygen vacancies, which were verified by the XPS results, introduced compressive stress, resulting in the reduction of the cell volume and Curie temperature. A large epsilon value (-17,500) was achieved at room temperature when the particle diameters were 100 nm. The large epsilon contributed to the high tunability (-70%), which was greater than that of the BT05 ceramic (-49%). Due to the high tunability, the BT01 ceramic's figure of merit was more than twice as that of the BT05 ceramic. This study demonstrated that the dielectric and tunable properties of (Ba0.91Ca0.09)(Zr0.2Ti0.8)O-3 ceramics can also be controlled by the raw materials' particle diameters.