Radial deformation–driven sintering: Effects on the microstructure and dielectric tunability of Ba0.6Sr0.4TiO3

Controlling densification and grain growth during sintering is vital to optimizing the functionality of electroceramics. Here we show that Spark Plasma Texturing (SPT) - a pressure-driven, edge-free variant of spark plasma sintering - allows high densification and effective grain growth control in tunable ferroelectric Ba 0.6 Sr 0.4 TiO 3 . We investigate the SPT processing parameters and their influence on the final properties of BST ceramics, systematically varying the pre-sintering route and the onset temperature of pressure application. All SPT-processed ceramics reach near-theoretical densities (>98.6%) and ultrafine grains (0.44-0.76 µm). The most effective configuration, i.e., conventionally pre-sintered pellets subjected to pressure from room temperature, produces a dense, homogeneous microstructure with enhanced dielectric permittivity, tunability, and k-factor, while minimizing losses. These findings establish SPT as a powerful pathway for mechanically assisted microstructural engineering, offering new opportunities to design high-performance tunable dielectrics, with reduced grain growth and tailored dielectric properties, for adaptive microwave and electronic devices.