High densification of BaZrS3 powder inspired by the cold-sintering process

We report on the sintering of powders of the chalcogenide perovskite BaZrS3 at low and intermediate temperatures. BaZrS3 is the most widely studied chalcogenide perovskite semiconductor. Most experimental results to-date have been made using loose powder and cold-pressed pellets (i.e. green bodies). Straightforward sintering methods to achieve dense ceramics are challenging because BaZrS3 decomposes and oxidizes in air above 550 °C. Here, we take inspiration from the cold-sintering process to develop a low-to-intermediate densification process for chalcogenide perovskites. Typical additives for cold sintering of oxides do not accelerate BaZrS3 sintering. At higher temperature, iodine is remarkably successful as an additive to accelerate densification. We achieve density up to 92% for sintering at 450 °C and 425 MPa. Our sintering process does not cause significant oxidation. Thermogravimetric measurements reveal the formation of an intergranular phase. Impedance spectroscopy measurements reveal that the bulk dielectric properties are unaffected by ball milling and subsequent sintering.