Microstructure and Dielectric Properties of Gradient Composite BaxSr1−xTiO3 Multilayer Ceramic Capacitors

Abstract

Multilayer ceramic capacitors (MLCCs) prepared using Ba1−xSrxTiO3 (BST) ceramics exhibit high dielectric constants (~1000), low dielectric loss (<0.01), and high breakdown voltage, with particularly significant tunability in dielectric properties (>50%) and with poor temperature stability. Doping-dominated temperature stability improvements often result in unintended loss of dielectric properties. A non-doping method has been proposed to enhance the temperature stability of BST capacitors. The composite gradient multilayer (CGML) ceramic capacitors with BaxSr1−xTiO3, where 0.5 < x < 0.8, as the dielectric, were prepared using a tape-casting method and sintered at 1250 °C. There exists a dense microstructure and continuous interface between the BaxSr1−xTiO3 thick film and the Pt electrodes. CGML ceramic capacitors feature a high dielectric constant at 1270, a low dielectric loss of less than 0.007, and excellent frequency and temperature stability. The capacitor showcases remarkable dielectric properties with a substantial tunability of 68% at 100 kV/cm, along with a notably consistent tunability ranging from 20% to 28% at 15 kV/cm across temperatures spanning from 30 to 100 °C, outperforming single-component BST-MLCCs in dielectric performance.

The Integrated Preparation of Porous Tungsten Gradient Materials with a Wide Porosity Range

“…This research illustrated the capability to customize functional gradients and continuously arranged pore structures by modifying the morphology of the pore-forming agent and the tape casting process. Several studies have shown that the tape casting method can accurately control the thickness and composition of a single layer of materials and prepare gradient composites that can be designed and controlled; secondly, these studies have shown that cast molding is suitable for the rapid and large-scale production of gradient composites, providing a cost-effective and efficient manufacturing process with significant advantages [26][27][28][29][30].…”