Departamento Física Aplicada, Facultad de Ciencias, Universidad de Cantabria, Santander, Spain.
Nanotechnology. 2011 Jul 1;22(26):265707. doi: 10.1088/0957-4484/22/26/265707. Epub 2011 May 17.
Since the crystal-field strength at the Cr(3+) site is very close to the excited-state crossover (ESCO), this work investigates the optical properties of Cr(3+)-doped Gd(3)Ga(5)O(12) (GGG) nanoparticles as a function of temperature and pressure in order to establish the effect of the ESCO on the optical behaviour of nanocrystalline GGG. Luminescence, time-resolved emission and lifetime measurements have been performed on GGG:0.5% Cr(3+) nanoparticles in the 25-300 K temperature range, as well as under hydrostatic pressure up to 20 GPa. We show how low temperature and high pressure progressively transforms Cr(3+)(4)T(2) --> (4)A(2) broadband emission into a ruby-like (2)E --> (4)A(2) luminescence. This behaviour together with the lifetime dependence on pressure and temperature are explained on the basis of the spin-orbit interaction between the (4)T(2) and (2)E states of Cr(3+).
由于 Cr(3+) 位点的晶场强度非常接近激发态交叉（ESCO），因此本工作研究了 Cr(3+) 掺杂 Gd(3)Ga(5)O(12)（GGG）纳米粒子的光学性质作为温度和压力的函数，以确定 ESCO 对纳米晶 GGG 光学行为的影响。在 25-300 K 的温度范围内以及在高达 20 GPa 的静水压力下，对 GGG：0.5% Cr(3+) 纳米粒子进行了发光、时间分辨发射和寿命测量。我们展示了低温和高压如何将 Cr(3+)(4)T(2) --> (4)A(2) 宽带发射逐渐转变为类似于红宝石的 (2)E --> (4)A(2) 发光。这种行为以及压力和温度对寿命的依赖性基于 Cr(3+) 的 (4)T(2) 和 (2)E 态之间的自旋轨道相互作用来解释。
