Photo-luminescence properties of nano-structured SiO_2 glasses doped with transition metal and rare earth ions

1)采用溶胶-凝胶法制备了掺杂半导体纳米晶[xZr_（0_2）100-x CdS：Mn^2+和Eu^3+（x=20，50，80）]的氧化锆薄膜，测量了薄膜在10 ~ 300 K温度范围内的发光，并测量了薄膜的时间分辨光谱（TRS）和寿命。所观察到的宽带发射由带边发射（CdS）、LMCT中心（ZrO_2）、深中心和晶格束缚的d-d（Mn^<2+>）或f-f（Eu^<3+>）跃迁组成。由于表面深中心的存在，其发光具有1 ns的快速弛豫过程和较高的热激活能。2）采用溶胶-凝胶法制备了掺杂过渡金属配合物的溶胶-凝胶二氧化硅玻璃，研究了Cr和V离子在介孔基质中的价态变化。在500 ℃以上退火的玻璃中，发现[Cr（VI）O_4]~（2+）和[V（V）O_4]~（2+）离子的LMCT跃迁产生的结构化宽带<2-><3->。在较高温度下，由于结构的变化，光谱形状、寿命和电子振动结构也发生了变化。3）类似地研究了15-冠-5铕配合物掺杂的干凝胶和退火溶胶-凝胶二氧化硅玻璃。^5D_0-&gt;^7F_1的转变证明了在100 ℃以下退火24小时的干凝胶和玻璃中络合物的稳定性。由^5D_0-&gt;^7F_1跃迁的分裂，导出了晶体场参数B_0^&lt;（2）&gt;，B_2^&lt;（2）&gt;。轴对称性随退火温度的升高而降低。

1) Thin zirconia film doped with semiconductor nanocrystals [xZr0_2 1OO-x CdS : Mn^<2+> and Eu^<3+> (x=20, 50, 80)] were prepared according to the sol gel method and luminescence was measured in the temperature range between 10 and 300 K.In addition time-resolved spectra (TRS) and lifetimes were measured. The observed broad band emission is composed of band-edge emission (CdS), LMCT centers (Zr0_2), deep centers and lattice-bound d-d (Mn^<2+>) or f-f (Eu^<3+>) transitions. The luminescence is characterized by very fast relaxation processes of 1 ns and high thermal activation energy due to the presence of surface-bound deep centers.2) Sol-gel silica glasses doped with transition metal complexes were prepared by the sol-gel method in order to investigate changes of valences of Cr and V ions in mesoporous matrices. In the glasses, annealed above 500 ℃, a structured broad band is found due to LMCT transitions in [Cr(VI)O_4]^<2-> and [V(V)0_4]^<3-> ions. The spectral shapes, lifetimes and vibronic structures change due to structural changes at higher temperatures.3) Xerogel and annealed sol-gel silica glasses doped with europium complexes of 15-crown-5 were studied similarly. The ^5D_0->^7F_1 transition gives evidence of the stabilization of the complex in xerogel and glasses annealed below 100 ℃ for 24 hrs. From the splitting of the ^5D_0->^7F_1 transition, crystal field parameters B_0^<(2)>, B_2^<(2)> are derived. Axial symmetry is decreasing with increase of annealing temperatures.