Departments of Chemistry and ‡Physics, CICECO Aveiro Institute of Materials, University of Aveiro , 3810-193 Aveiro, Portugal.
J Am Chem Soc. 2015 Mar 4;137(8):3051-8. doi: 10.1021/ja512745y. Epub 2015 Feb 19.
The hydrothermal synthesis of the novel Na[LnSiO4] (Ln = Gd, Eu, Tb) disordered orthorhombic system is reported. At 100 K, and above, these materials are best described in the centrosymmetric orthorhombic Pnma space group. At lower temperatures (structure solved at 30 K) the unit cell changes to body-centered with Imma symmetry. The materials exhibit unique photophysical properties, arising from both, this phase transformation, and the disorder of the Ln(3+) ions, located at a site with D2d point symmetry. Na[(Gd0.8Eu0.1Tb0.1)SiO4] is an unprecedented case of a luminescent ratiometric thermometer based on a very stable silicate matrix. Moreover, it is the first example of an optical thermometer whose performance (viz., excellent sensitivity at cryogenic temperatures <100 K) is determined mainly by a structural transition, opening up new opportunities for designing such devices.
本文报道了新型 Na[LnSiO4]（Ln = Gd、Eu、Tb）无序正交体系的水热合成。在 100 K 及以上温度下，这些材料最好用中心对称正交 Pnma 空间群来描述。在较低温度下（在 30 K 下解决结构），单元晶格变为具有 Imma 对称性的体心晶格。这些材料表现出独特的光物理性质，这既源于相转变，也源于位于具有 D2d 点对称的位置的 Ln(3+)离子的无序。Na[(Gd0.8Eu0.1Tb0.1)SiO4]是基于非常稳定的硅酸盐基质的发光比率温度计的空前实例。此外，它是光学温度计的首例，其性能（即，在<100 K 的低温下具有优异的灵敏度）主要由结构转变决定，为设计此类器件开辟了新的机会。
