Large-scale synthesis of isotropic single-crystalline ScF ₃ cubes by hydrothermal method

Scandium fluoride (ScF₃) belongs to one of the rare compounds which exhibit isotropic negative thermal expansion. Here, a facile and environmentally friendly hydrothermal synthesis method has been presented. High-quality single-crystalline ScF₃ cubes, with an average size of 200 nm, can be easily fabricated in a large scale. Sc(NO₃) ₃ and NH₄HF₂ were used as precursors. The as-prepared ScF₃ demonstrates cubic symmetry (Pm-3 m), which was confirmed by X-ray diffraction and selected-area electron diffraction. Its uniform morphology and size were characterized by high-resolution transmission electron microscopy. Furthermore, thermal analysis was also performed in argon gas atmosphere to investigate its thermal stability.