Development of VUV-excited phosphors based on correlation between quantum cutting and acceptor-site arrangement within coordination

基于量子切割和配位内受体位点排列之间的相关性开发真空紫外激发荧光粉

基本信息

批准号：
17360317
负责人：
KODAMA Nobuhiro
金额：
$ 10.3万
依托单位：
Akita University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

项目摘要

We study quantum cutting via downconversion for the couple of R_1^<3+>-R_2^<3+>, R_1^<3+>-R_2^<3+>-R_3^<3+> (R_1=Gd, R_2=Eu, Tb, R_3=Er), and R_2^<3+>-R_2^<3+> (R_2=Tb), and investigate the dynamics and mechanisms of the energy transfer of their systems. In this research the results obtained are as follows.(1) In CsGd_2F_7: Er^<3+>, Tb^<3+> and CsGd_<2-x>, Y_xF_7: Er^<3+>, Tb^<3+> (x=0.2-0.4) mixed phosphors, the quantum cutting effect takes place upon VUV excitation in the 4f_<10> 5d levels of Er^<3+>. The dependence of the cross-relaxation efficiency ηCR on the Er^<3+> and Tb^<3+> concentrations are examined. The cross-relaxation efficiency ηCR decreases for CsGd_2F_7: Er^<3+>, Tb^<3+> as Er^<3+> concentration increases. With increasing Tb^<3+> concentration, the cross-relaxation efficiency ηCR CsGd_2F_7: Er^<3+> Tb^<3+> passes through a maximum. The cross-relaxation efficiency ηCR for CsGd_<2-x> Y_xF_7: Er^<3+> (1at.%), Tb^<3+> (0.2at.%) mixed crystals decreases with increasing Y^<3 … More +> concentration. We have also investigated the dynamics of the quantum cutting in CsGd_2F_7: Er^<3+>, Tb^<3+> by means of measurements of time-resolved luminescence spectra. The experimentally observed decay curves are explained by the two energy-transfer processes. The present analysis provides more insight in the dynamics of down conversion processes in the quantum cutting model.(2) Visible quantum cutting upon VUV and short-UV excitations in the 4f^75d states of Tb^<3+> in CsGd_2F_7: Tb^3 and KGd_3F_10: Tb^<3+> CsGd_2F_7: Tb^<3+>, via downconversion mechanism has been observed. The dependence of the cross-relaxation efficiency ηCR on the Tb^<3+> concentrations is examined. The cross-relaxation efficiency ηCR for CsGd_2F_7: Tb^<3+> KGd_3F_10: Tb^<3+> and KGd_3F_10: Tb^<3+> fluorides increases with increasing Tb^<3+> concentration upon VUV and short-UV excitations at 172 nm and 212 nm. We have obtained a green-emitting quantum cutting phosphor CsGd_2F_7: Tb_<3+> for which the calculated ηCR achieves 0.53 and 0.64 for VUV excitations. The time-resolved emission spectra of Tb^<3+> in CsGd_2F_7: Tb^<3+> suggest the a two-step energy transfer process by cross relaxation and direct energy transfer from one Tb^<3+> to a neighbouring Tb^<3+> and/or a neighbouring Gd^<3+>, -downconversion mechanism as proposed in the quantum cutting model.(3) Visible quantum cutting through downconversion is observed for the Gd^<3+>-Eu^<3+> couple in KLiGdF_5: Eu^<3+> (KLGF: Eu^<3+>) In this Gd^<3+>-based fluoride, visible quantum cutting, occurs upon VUV excitation of Gd^<3+> at the 6G_J level via two-step energy transfer from Gd^<3+> to Eu^<3+> by cross-relaxation and sequential transfer of the remaining excitation energy. The dependence of the efficiency of cross-relaxation on the Eu^<3+> doping concentration is discussed in terms of the probability of energy transfer, and it is found that KLGF crystal doped with 2 at.% Eu^<3+> exhibits the maximum cross-relaxation efficiency of 0.4. Based on thr number of nearest neighbors around Gd^<3+> ions and the ^5D_0 emission intensity, energy transfer from excited Gd^<3+> ions appears to extend to the fourth-nearest Eu^<3+> neighbors in the quantum cutting process.(4)Ce^<3+> doped SrMgF_4 and BaMgF_4 crystals have the absorption and luminescence spectra in the VUV and UV ranges, respectively, so that wide pumping and tuning ranges are expended for laser operation. The persistent spectral hole burning (PSHB) in KLaF_4: Sm^<2+> has been observed at 12K. UV or visible excitation for Eu^<2+-> doped Ba_2SiO_4 and Ba_3SiO_5 crystals produces broadband luminescence in the green and yellow regions, respectively. The temperature dependence of the long-lasting phosphorescence suggest that electrons and holes produced by UV excitation move back to Eu^<2+> sites in the crystals through hopping and tunneling, and recombine radiatively at Eu^<2+>. Less

We study quantum cutting via downconversion for the couple of R_1^<3+>-R_2^<3+>, R_1^<3+>-R_2^<3+>-R_3^<3+> (R_1=Gd, R_2=Eu, Tb, R_3=Er), and R_2^<3+>-R_2^<3+> (R_2=Tb), and investigate the dynamics and其系统能量传输的机制。在这项研究中，获得的结果如下。（1）在CSGD_2F_7：er^<3+>中，TB^<3+>和CSGD_ <2-x>，y_xf_7：er^<3+>，tb^<3+>（x = 0.2-0.4）在vuv excit上进行量子的5d excitement在vuv excit上。 ER^<3+>。检查了跨浮气效率ηcr对ER^<3+>和TB^<3+>浓度的依赖性。 CSGD_2F_7：ER^<3+>，Tb^<3+> aS er^<3+>浓度增加的跨递延效率ηcr降低。随着TB^<3+>浓度的增加，交叉 - 递延效率ηcrcsgd_2f_7：er^<3+> tb^<3+>通过最大值。 CSGD_ <2-X> y_xf_7：er^<3+>（1at。％），TB^<3+>（0.2AT。％）混合晶体随着Y^<3的增加而减小的CSGD_ <2-x> y_xf_7：er^<3+>（1AT。％）的交叉递延效率ηcr随着Y^<3…更高+>浓度而减小。我们还通过测量时间分辨的发光光谱研究了CSGD_2F_7：er^<3+>，tb^<3+>中量子切割的动力学。实验观察到的衰减曲线通过两个能量转移过程来解释。目前的分析在量子切割模型中的下降转换过程动态方面提供了更多的见解。（2）在CSGD_2F_7中的4f^75d状态下的VUV和短-UV兴奋时可见的量子切割，tb^<3+>中的短-UV兴奋状态：tb^3和tb^3和kgd_3f_10：kgd_3f_10：tb^<3+> cssgd_2_2 debe depe^<3;观察到。检查了交叉递延效率ηcr对TB^<3+>浓度的依赖性。 CSGD_2F_7：TB^<3+> kgd_3f_10：Tb^<3+>和KGD_3F_10：TB^<3+>氟化物的互交点效率ηcr增加，随着Tb^<3+>在172 nm和212 nm和212 nm和212 nm和Short-uv兴奋时的浓度增加。我们已经获得了绿色发射量子切割磷光CSGD_2F_7：tb_ <3+>，对于VUV兴奋，计算出的ηCr实现了0.53和0.64。 CSGD_2F_7：TB^<3+>中TB^<3+>的时间分辨发射光谱表明，通过交叉放松和直接能量转移从一个TB^<3+>直接转移到相邻的TB^<3+>和/或一个相邻的tb^<3+>和/或一个相邻的GD^<3+downdownsportion Issupsim Isspositim（3）的量子（3）在kligdf_5：eu^<3+>（klgf：eu^<3+>）中观察到的gd^<3+> - eu^<3+>夫妇在此gd^<3+> - 基于可见的量子切割中，在6g_j paive twe e gd^<3+> e^3 gd e> e gd exe <3+e^3 sep^ex e^3+e^3+e^ex^3+e^3+e^3+e^3+的基于6g_j <3+剩余的刺激能量的交叉解释和顺序转移。讨论了能量转移的概率讨论跨浮肿效率对Eu^<3+>掺杂浓度的依赖性，并且发现KLGF晶体用2个AT。％Eu^<3+>掺杂的KLGF晶体表现出最大的交叉延迟效率为0.4。 Based on thr number of nearest neighbors around Gd^<3+> ions and the ^5D_0 Emission intensity, energy transfer from excited Gd^<3+> ions appear to extend to the fourth-nearest Eu^<3+> neighbors in the quantum cutting process.(4)Ce^<3+> doped SrMgF_4 and BaMgF_4 crystals have the abstraction and luminescence spectra in the VUV and UV范围分别为激光操作探索宽大的泵送和调谐范围。在12K处观察到KLAF_4：SM^<2+>中的持续光谱孔燃烧（PSHB）。 EU^<2+ - >掺杂的BA_2SIO_4和BA_3SIO_5晶体的紫外线或可见兴奋分别在绿色和黄色区域产生宽带发光。持续磷光的温度依赖性表明，紫外线兴奋产生的电子和孔通过跳和隧穿移回晶体中的Eu^<2+>位点，并在Eu^<2+>上径向重新散发。较少的