摘要
研究了GdVO4 ∶Eu3 + 在高压汞灯的 3 1 3和 3 65nm激发下室温以上 ( 3 0 0～ 60 0K)发光的温度依赖关系。发现来自5D0 的发射强度随温度的升高而显著增强 ,直到 60 0K也未见饱和。其中5D0 →7F2 的 61 9nm发射在60 0K温度时的强度是室温下的 2 0多倍。我们认为Eu3 + 的电荷迁移态作为中间态是造成其发光增强的根本原因。激发过程中 ,先激发到Eu3 + 本身的5DJ(J=1 ,2 ,3… )激发态 ,然后在温度的作用下上升到电荷迁移态(CTS) ,温度升高时传递几率显著增强 ,并按5D3 ,5D2 ,5D1依次使被激发的电子转入CTS态 ,从电荷迁移态直接弛豫传递给5D0 态 ,由于5D0 态电子数不断增多 ,致使来自5D0 的发射随温度升高而增强。
The temperature dependence of GdVO 4∶Eu 3+ luminescence from Eu 3+ 5D 0 → 7F J transition excited by 313 and 365nm of high pressure mercury lamp above room temperature has been studied including the emission spectra at different temperature and the emission intensity of Eu 3+ as function of temperature.In addition,the excitation spectrum of GdVO 4∶Eu 3+ with emission wavelength 619nm at RT was measured. The characteristic emissions of Eu 3+ were observed,including 608,616,619nm of 5D 0 → 7F 2 transition,594,598nm of 5D 0 → 7F 1 transition and 538nm of 5D 1 → 7F 1 transition.Each of them increases with rising temperature.And the relative intensity of the emission lines maintains constant each other.In the range of 300～600K,each emission line increases as temperature rises, especially above 400K,and there is a rapid increase without intensity saturation up to 600K.The emission intensity at 600K is twenties time stronger than that at 300K.We observed that the excitation spectrum of 619nm emission contains two main excitation bands peaked at about 250 and 310nm,beside the intrinsic excitation of Eu 3+ .But the intensity of intrinsic excitation is weaker than that of the excitation bands at 250,310nm. When Eu 3+ is excited by 365nm which is Eu 3+ intrinsic excitation,there are two ways to deplete its energy.One is cascade down to 5D J states according to the order of 5D 3 , 5D 2 , 5D 1 , 5D 0 .The other is to be promoted thermally to charge transfer state and sequentially to feed 5D 0 without passing by cascade from higher 5D state by which 5D 0 can be excited more effectively.The possibility of the latter process depends on temperature intensively.Therefore,when temperature rises,more Eu 3+ can be excited into 5D 0 .Using this model the experimental result can be explained reasonably.If Eu 3+ is excited by 313nm which can be the sorption by VO 4 3- ,it can also be promoted thermally into charge transfer state. In conclusion,the intensity of the luminescence excited by 313,365nm increases rapidly as temperature rises up to 600K.The CTS of Eu 3+ as a middle state plays an important role which can make the excitation energy transfer to 5D 0 effectively.Such process is more remarkable when the temperature rises.With high temperature property,GdVO 4∶Eu can be used in high temperature environment.
出处
《发光学报》
EI
CAS
CSCD
北大核心
2001年第2期111-114,共4页
Chinese Journal of Luminescence
基金
国家自然科学基金资助项目 ( 5 973 2 0 40和 197740 5 3 )
