Fabrication, negative thermal expansion and optical properties of scandium molybdate thin films.

Negative thermal expansion (NTE) Sc2(MoO4)3 thin films were fabricated on quartz substrates via facile sol–gel spin coating technique. Effects of process parameters on the phase composition, morphology, thermal expansion behavior and optical property of the Sc2(MoO4)3 thin films were investigated. XRD analysis reveals that as-deposited Sc2Mo3O12 thin films show amorphous phase. Orthorhombic Sc2(MoO4)3 thin films were prepared after annealing in 500–780 °C for 1 h, the crystalline quality of the post-annealed Sc2(MoO4)3 thin films gradually improved, and the grain size also increased as annealing temperature rises. Both as-deposited and post-annealed Sc2(MoO4)3 thin films show a smooth and compact surface. Low heating and cooling rates have contributed to the improvement of quality of the Sc2(MoO4)3 thin films. Orthorhombic Sc2(MoO4)3 thin films show anisotropic NTE. Its coefficient of thermal expansion is − 1.86 × 10−6 °C−1 in 25–700 °C. The transmittance of orthorhombic Sc2(MoO4)3 thin film post-annealed at 780 °C is measured as well and which is about 82% in the visible light range. [ABSTRACT FROM AUTHOR]