Synthesis and thermal expansion behaviors of spin-coated Sc2Mo3O12 thin films

Orthorhombic Sc 2 Mo 3 O 12 films have been successfully prepared via spin coating technique followed by annealing at 500–750 °C. The phase composition, microstructure, morphology and negative thermal behavior of the synthesized Sc 2 Mo 3 O 12 films were investigated. XRD and XPS analysis indicate that as-deposited film is amorphous . Orthorhombic Sc 2 Mo 3 O 12 films can be prepared after post-annealing at 500–750 °C for 1 h. The crystallinity of Sc 2 Mo 3 O 12 films gradually improved with the increase of post-annealing temperature. SEM analysis shows as-deposited film is smooth and compact, and the grain size of Sc 2 Mo 3 O 12 film grows up as the post-annealing temperature increases. Variable temperature XRD analysis demonstrates that the synthesized orthorhombic Sc 2 Mo 3 O 12 films show stable thermo-chemical and anisotropic NTE property in 25–700 °C. The corresponding coefficients of thermal expansion (CTEs) of the orthorhombic Sc 2 Mo 3 O 12 film in a, b and c directions are −6.68 × 10 −6  °C −1 , 5.08 × 10 −6  °C −1 and −4.76 × 10 −6  °C −1 , respectively. The whole unit cell of the orthorhombic Sc 2 Mo 3 O 12 film shrinks and the volumetric CTE of the Sc 2 Mo 3 O 12 thin film is −6.36 × 10 −6  °C −1 , and the linear CTE is about −2.12 × 10 −6  °C −1 ( α v  = 3 α l ).