Densification of thermodynamically unstable tin monoxide using cold sintering process

SnO is a thermodynamically unstable phase and undergoes thermal decomposition into SnO₂ and Sn at a relatively low temperature when heating under ambient conditions. With the cold sintering process (CSP), SnO can be densified up to 89% of theoretical density within 100 min by applying uniaxial pressure of 350 MPa and transient liquid phase. 15-fold BET specific surface area reduction is observed between the ball-milled powder and the cold-sintered pellet, indicating experimental evidence of sintering. The temperature profiles of 70–265 °C show densification while maintaining the phase purity. Water and 2 M acetic acid solution are studied as transient liquid phases which promotes dissolution-precipitation on the particle surface and induces crystalline texture. Electrical properties of the cold sintered bulk, notably electrical conductivity and Seebeck coefficient, are measured as a function of temperature.