Sc2(MO4)3 （M= Cr，Mo，W）纳米材料的负热膨胀与光电性质研究

作为最轻的稀土家族成员，钪在元素周期表中处于一个独特的位置：稀土元素族最顶端和过渡金属区最开始。这种交叉位置赋予了钪独特的物理化学性质。确实，钪没有4f电子，Sc3+具有和K+，Ca2+，Ti4+ 等相同的电子构型。我们的研究也证实钪基氟化物纳米晶在上转换发光和化学活性上有着显著的不同于其他稀土纳米晶的表现。另外，作为负热膨胀领域的明星材料，钨酸钪还有着突出的性能和最宽的工作区间（10-1300 K）。同时钨酸钪还因其Sc3+在高温下的迁移而成为第三代固体电池的热门材料。但对于拥有上述两大关键功能的材料的光学性质却未有报道。初步结果表明，和普通的荧光热猝灭现象相反，钨酸钪在900 °C时的上转换发光比其室温时增强了567倍。因此，本项目拟系统研究该多功能材料在纳米尺度下的反常发光行为并揭示其工作机理，制备具有负热膨胀功能的高温强荧光固体电解质。该研究也将对提高上转换发光效率提供借鉴。

As the lightest element in the rare earth family, Scandium (Sc) sits at a unique position in the periodic table: very top of the rare earth column and the beginning of the transition metal zone. This junction position has imparted Sc unique physical and chemical properties. Indeed, Scandium has no 4f electrons and Sc3+ has the same configuration as K+, Ca2+, Ti4+, and so on. Our studies have proved that the upconversion luminescence (UCL) and chemical reactivity of scandium fluoride nanocrystals are markedly different from those of other rare earths. In addition, Sc2(WO4)3 is also a star material with decent negative thermal expansion (NTE) performance and so far the widest working range (10-1300 K). Meanwhile Sc2(WO4) has become a promising candidate in the 3rd-generation solid state cells due to the migration of Sc3+ at high temperature. However, there is still no reports on the optical properties of such multi-functional materials. Our preliminary results have shown that the UCL of Sc2(WO4):Yb/Er at 900 °C is 567 times stronger than that at room temperature. Thus we will perform systematic study on the abnormal optical properties of Sc2(WO4) at the nanoscale, disclose the mechanisms behind, and synthesize solid state electrolyte that simultaneously possesses functionalities of NET and strong UCL at high temperature. The principles obtained will also be instructive to further improvement of the UCL efficiency.