Preparation of In0.5Sc1.5Mo3O12 nanofibers and its negative thermal expansion property

Abstract

Orthorhombic In0.5Sc1.5Mo3O12 nanofibers were prepared by electrospinning followed by a heat treatment. The effects of post-annealing temperatures on the phase composition, microstructure and morphology were investigated by XRD, SEM, HRTEM and XPS. Negative thermal expansion (NTE) behaviors of the In0.5Sc1.5Mo3O12 nanofibers were analyzed by high-temperature XRD. Results indicate that the as-prepared In0.5Sc1.5Mo3O12 nanofibers show an amorphous structure with smooth and homogeneous shape. The average diameter of the as-prepared In0.5Sc1.5Mo3O12 nanofibers is around 515 nm. Well crystallized orthorhombic In0.5Sc1.5Mo3O12 nanofibers could be prepared after post-annealing at 550 °C for 2 h with an average diameter of about 192 nm. The crystallinity of In0.5Sc1.5Mo3O12 nanofibers gradually improved with the increase of annealing temperature. However, too high post-annealing temperature leads to a damage of sample's fiber structure. The high-temperature XRD results reveal that In0.5Sc1.5Mo3O12 nanofibers show an anisotropic NTE, and the coefficients of thermal expansion (CTEs) along a-axis and c-axis were −5.95 × 10−6 °C−1 and -3.54 × 10−6 °C−1, while the one along b-axis is 5.61 × 10−6 °C−1. The volumetric CTE of In0.5Sc1.5Mo3O12 nanofibers is −3.90 × 10−6 °C−1 and the linear one is 1.3 × 10−6 °C−1 in 25–700 °C.