Poly(vinyl pyrrolidone)-assisted hydrothermal synthesis of erythrocyte-like Sc2W3O12 with negative thermal expansion

In this study, orthorhombic Sc2W3O12 with an erythrocyte structure has been successfully prepared by poly(vinyl pyrrolidone) (PVP)-assisted hydrothermal method. The effects of PVP additive on the phase composition, morphology and negative thermal expansion (NTE) behavior of Sc2W3O12 were studied. Results indicate that pure orthorhombic Sc2W3O12 can be synthesized at 220 °C via the hydrothermal method with 0.25–0.6 g PVP additives. PVP additive has great influences on the synthesis of Sc2W3O12. It can inhabit the formation of impurity during hydrothermal reaction. With the increase of PVP contents, the flake Sc2W3O12 started to aggregate and transformed into the uniform erythrocyte-like Sc2W3O12 with a size of 2 × 4 μm. Erythrocyte-like Sc2W3O12 shows anisotropic NTE in 25–700 °C. The coefficients of thermal expansion (CTE) along a, b and c-axes directions are −6.10 × 10−6, 3.10 × 10−6 and −4.96 × 10−6 K−1, and the corresponding linear CTE is −2.65 × 10−6 K−1.