Nanocrystals (NCs) of refractory oxides are widely used in both industry and fundamental research, despite their strong covalent bonding posing a serious obstacle to crystallisation under moderate liquid-phase environments. Here, we demonstrate a facile high-liquid-phase synthetic route for the fabrication of a refractory oxide, ZrO₂, by employing molten metal chloride salt as the liquid reaction medium. The molten-salt-derived ZrO₂ NCs exhibit an average size of approximately 120 nm with a limited size distribution. We also show that the molten-salt process allows for the direct doping of ZrO₂ NCs with rare earth (RE) ions using soluble salt precursors, which results in the strong photoluminescence of the products. These luminescent refractory oxides based on RE-doped ZrO₂ could be promising candidates for high-temperature sensing applications in industry. Furthermore, the molten-salt process could be generalised for the production of refractory metal oxide NCs that are otherwise not easily produced by ordinary wet-chemistry processes.

难熔氧化物的纳米晶体 (NCs) 广泛用于工业和基础研究，尽管它们的强共价键在中等液相环境下严重阻碍了结晶。在这里，我们展示了一种简便的高液相合成路线，用于通过采用熔融金属氯化物盐作为液体反应介质来制造耐火氧化物 ZrO ₂。熔融盐衍生的 ZrO ₂ NCs 的平均尺寸约为 120 nm，尺寸分布有限。我们还表明熔盐工艺允许直接掺杂 ZrO ₂使用可溶性盐前体制备具有稀土 (RE) 离子的 NC，这会导致产品发出强烈的光致发光。这些基于稀土掺杂的 ZrO _{2 的}发光耐火氧化物可能是工业高温传感应用的有希望的候选者。此外，熔盐工艺可以推广用于生产难熔金属氧化物 NCs，否则普通湿化学工艺不容易生产。