【摘要】 在 10 5～ 30 0K温区内 ,测量了X射线激发下Ce3+ ∶LiSrAlF6晶体发光强度的温度依赖 (I T) ,在 2 37～30 0K温区内发光强度有特殊的增强结构 ,结合 10 5～ 30 0K温区内热释光的测量 ,证实这种发光强度的增强效应是由于陷阱参与发光过程所导致。通过对热释光曲线的进一步分析 ,得到深度分别为 0 5 1eV和 0 5 5eV的陷阱能级 ,这些陷阱主要源于Ce3 + 取代Sr2 + 所形成的杂质缺陷和基质LiSrAlF6中的F-空位以及Li+ 空位所形成的本征缺陷。更多还原

【Abstract】 Ce 3+ ∶LiSrAlF 6 crystal is a solid state laser material potentially capable of efficiently producing tunable ultraviolet (UV) output. Recent results suggest that it may be the most efficient continuously tunable , rare earth doped UV laser material reported to date. There are some defects in Ce 3+ ∶LiSrAlF 6 crystal . These defects will affect the laser and luminescence properties of crystal. In this paper, the temperature dependence of luminescent intensity ( I T) of Ce 3+ ∶LiSrAlF 6 crystal with X ray excitation from 105K to 300K has been studied. The luminescent intensity is enhanced " specially " in the range of 237～300K, which is probably caused by traps. In order to verify our surmise, we investigated the thermoluminescence of Ce 3+ ∶LiSrAlF 6 crystal from 105～300K with X ray excitation at 105K for two minutes. From 237～300K, two peaks locate at 258K and 274K respectively. These two peaks are accord to two kinds of traps, whose depth are 0 51eV (258K) and 0 55eV (274K). Comparing I T curve with TL curve, the enhanced part of I T curve is coincided with temperature range in which TL peaks locate. Because the TL peaks originate from traps, we suggest that the special structure of I T curve is caused by the traps effect. That is, during the period of measuring the I T , at lower temperature, some charge carriers relax to luminescent center and luminesce, while some other charge carriers is captured by traps. The release probability of bonded carriers is described as C ×exp(- E/kT ), where C is a constant, E is the depth of trap and T is temperature. With the temperature rising, the bonded charge carriers will release from the traps at higher temperature, via conduct band then relax to luminescent center and give out light, which make the intensity of luminescence enhanced. The origination of defects of Ce 3+ ∶LiSrAlF 6 crystal is discussed too. It is primary that Ce 3+ occupies the sublattice of Sr 2+ in Ce 3+ ∶LiSrAlF 6 crystal, forming Ce Sr 3+ defect. Generally, fluorine vacancies ( V F) always exist in fluoride. Ce Sr 3+ and V F are negative charge center, which form electron traps. The lithium vacancies ( V Li ) are principal positive charges, which compensate the negative charge Ce Sr 3+ and V F, V Li form hole traps. In conclusion, the "special" structures of I T curve in the range of 237～300K is explained by the traps effect, which is verified by means of TL. The depths of two traps are 0 51eV and 0 55eV respectively . These traps mainly originate from Ce Sr 3+ and some intrinsic defects such as V F and V Li .更多还原