标题： 间隙有序卤化物双钙钛矿 Cs$_2$TeCl$_6$在压力下的结构转变和发光增强 显示英文标题

标题： Structural transition and emission enhancement in vacancy ordered halide double perovskite Cs$_2$TeCl$_6$ under pressure

摘要： 压力对空位有序双卤化物钙钛矿 Cs$_2$TeCl$_6$的结构演化、光致发光强度增强和光学带隙的影响被系统地研究了。 我们使用同步辐射X射线衍射、拉曼光谱、光学带隙和光致发光测量来探索 Cs$_2$TeCl$_6$在高达30.0 GPa压力下的结构和光学性质。 我们发现Cs$_2$TeCl$_6$在低于1.0 GPa的非常低压下经历从立方Fm$\bar{3}$m到单斜P2$_1$/n的结构转变。观察到光致发光强度显著增加和光学带隙快速减小，这与八面体畸变和结构转变有关。有趣的是，随着压力增加，样品在约3.4 GPa时恢复其常压下的Fm$\bar{3}$m结构，并在高达30.0 GPa时保持立方相。样品在约14.1 GPa压力下经历同结构转变，压缩性略有降低。 显示英文摘要

摘要： The effect of pressure on the structural evolution, enhancement of photoluminescence intensity and optical band gap of a vacancy ordered double halide perovskite Cs$_2$TeCl$_6$ is investigated systematically. We use synchrotron x-ray diffraction, Raman spectroscopy, optical band gap and photoluminescence measurements to explore the structural and the optical properties of Cs$_2$TeCl$_6$ under pressure up to 30.0 GPa. We find that Cs$_2$TeCl$_6$ undergoes a structural transition from cubic Fm$\bar{3}$m to monoclinic P2$_1$/n at very low pressure below 1.0 GPa. A significant increase in photoluminescence intensity and a rapid decrease in optical band gap are observed, which are related to the octahedral distortion and structural transition. Interestingly, with increasing pressure, the sample regains its ambient Fm$\bar{3}$m structure at around 3.4 GPa maintaining the cubic phase up to 30.0 GPa. The sample undergoes an iso-structural transition at around 14.1 GPa pressure with a slight decrease in compressibility.