蓝色长余辉材料Sr2MgSi2O7：Eu2+,Dy3+及其基质的VUV-UV激发特性

Sr₂MgSi₂O₇:Eu²⁺,Dy³⁺是一种有效的蓝色长余辉材料,采用高温固相法合成了Sr₂MgSi₂O₇,Sr₂MgSi₂O₇:Dy³⁺,Sr₂MgSi₂O₇:Eu²⁺及Sr₂MgSi₂O₇:Eu²⁺,Dy³⁺,利用同步辐射研究了它们的VUV-UV激发特性.在真空紫外光激发下,在基质中发现了稍弱的位于385nm的发射带,在双掺杂的样品中,除了Eu²⁺的4f5d→4f发射带(465nm)外,还观察到了575nm处的发射峰;通过和Dy³⁺单掺杂样品的发射谱比较,发现它是来自于Dy³⁺的4f-4f(⁴F_9/2→6H_13/2)跃迁.在它们的激发谱上可以看出Dy³⁺与基质发射的有效激发均处于真空紫外区,在近紫外及可见区激发下未见到它们发光.另外在Sr₂MgSi₂O₇:Eu²⁺,Dy³⁺中观察到Dy³⁺的发射也说明了Dy³⁺在该类长余辉材料中不仅作为陷阱用来延长余辉,而且也以发光中心形式存在于基质中.

VUV-UV Excitation Properties of Blue Long Afterglow Phosphor Sr2MgSi2O7: Eu2+,Dy3+ and Its Host

The Sr₂MgSi₂O₇:Eu²⁺,Dy³⁺ is an excellent blue long afterglow phosphor.Its afterglow can last longer than 20 h.But the mechanism of the afterglow luminescence is not clear so far.In order to study the physical process of the afterglow luminescence,Eu²⁺,Dy³⁺ singly doped or co-doped silicate:Sr₂MgSi₂O₇:Eu²⁺,Sr₂MgSi₂O₇:Dy³⁺,Sr₂MgSi₂O₇:Eu²⁺,Dy³⁺ and Sr₂MgSi₂O₇ were prepared and their VUV-UV excitation properties and temperature dependence were studied with synchrotron radiation VUV light.In emission spectrum of Sr₂MgSi₂O₇:Eu²⁺,Dy³⁺ under 300 nm excitation,a broad band emission around 465 nm due to(4f⁶5d→4f⁷)transition of Eu²⁺.Its excitation band lied around 360 nm.But under excitation at 172 nm,(besides)the broad band emission of Eu²⁺,a relative low line emission peaked at 575 nm can also be seen.Compared with the emission spectrum of Sr₂MgSi₂O₇:Dy³⁺,it could be assigned to 4f-4f transition of Dy³⁺.This implied that Dy³⁺ acted as not only traps,but luminescent centers also in the phosphor.In excitation spectra of Sr₂MgSi₂O₇:Dy³⁺ and Sr₂MgSi₂O₇ we could see that both host and Dy³⁺ excitation band were in VUV range.So when Sr₂MgSi₂O₇:Eu²⁺,Dy³⁺ was excited in UV-Vis range,only Eu²⁺ emission 465 nm band can be recorded and no Dy³⁺ and host emission existed.The phosphor is excited by daylight in applications,thus only the useful Eu³⁺ emission can be observed.These results made the long afterglow phosphor Sr₂MgSi₂O₇:Eu²⁺,Dy³⁺ very suitable for practical use.