Phase field modelling and structure-property relationships of cold sintered barium titanate-lithium molybdate composites

Cold sintering is a promising technique to reduce the high processing temperatures associated with conventional solid-state sintering of electroceramics to below 250 °C. This paper examines the microstructure and properties of barium titanate–lithium molybdate composites fabricated by this emerging low energy sintering method. A phase field model was developed to understand the microstructural evolution of the composite during sintering that predicted, in line with experimental observations, that the more mobile lithium molybdate forms a matrix by redistributing effectively into the pore space, while the barium titanate grains have minimal interaction with one another. The electromechanical properties of the manufactured composites were characterized to assess their performance for energy storage and sensing. Permittivity and piezoelectric properties increased with BaTiO 3 volume fraction, with small particle composites with 20 vol.% LMO having the highest relative permittivity of 240 with a low dielectric loss tangent < 0.05, whilst composites with larger BaTiO 3 particles had improved piezoelectric properties achieving a charge coefficient of d 33 = 24 pC/N and a voltage coefficient of g 33 = 15 x 10 -3 Vm/N, the latter of which is comparable with conventionally sintered BaTiO 3 . This paper therefore provides new insights into the microstructural evolution and processing-structure-property relationships of cold sintered glass-piezoceramic composites.