Reddy C Parthasaradhi, Naresh V, Ramaraghavulu R, Rudramadevi B H, Reddy K T Ramakrishna, Buddhudu S
Department of Physics, Sri Venkateswara University, Tirupati 517 502, India.
Department of Physics, Sri Venkateswara University, Tirupati 517 502, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2015 Jun 5;144:68-75. doi: 10.1016/j.saa.2015.02.090. Epub 2015 Feb 26.
The present paper reports on the results pertaining to photoluminescence properties of Tb(3+), Sm(3+) and energy transfer from Tb(3+) to Sm(3+) ions in lithium zinc phosphate (LZP) glass matrix prepared by melt quenching method. Besides photoluminescence studies thermal stability for the LZP glass is also evaluated from TG-DTA measurement. Tb(3+) doped glasses have exhibited a prominent green emission at 547 nm assigned to (5)D4→(7)F5 transitions on exciting at λ(exci)=377 nm. The quenching phenomenon in Tb(3+) emission on varying its concentration has been discussed from cross-relaxations. Sm(3+) incorporated glasses have shown strong orange emission at 603 nm assigned to (4)G5/2→(6)H7/2 transition upon exciting with λ(exci)=404 nm. The possibility of energy transfer process taking place between these two ions is understood from the significant spectral overlap of Sm(3+) absorption and Tb(3+) emission. Migration of excitation energy from Tb(3+) ions to Sm(3+) ions at λ(exci)=375 nm is evaluated from the emission spectra of (0.5 mol.% Tb(3+)+(0.5-2.0 mol.%) Sm(3+)) co-doped glasses. The emission intensity of Sm(3+) has enhanced while Tb(3+) emission intensity decreased with an increase in Sm(3+) concentration suggesting the occurrence of energy transfer through cross-relaxations from Tb(3+) ((5)D4) to Sm(3+) ((4)G5/2). The mechanism behind energy transfer process has been further explained from energy level diagram, decay profiles and confirmed by calculating energy transfer parameters (energy transfer efficiency (η) and energy transfer probability (P)) of co-doped glasses. The dipole-dipole interaction is found to be more responsible for energy transfer Tb(3+) ((5)D4) to Sm(3+) ((4)G5/2) ions in LZP glass matrix.
本文报道了通过熔融淬火法制备的磷酸锂锌（LZP）玻璃基质中Tb(3+)、Sm(3+)的光致发光特性以及从Tb(3+)到Sm(3+)离子的能量转移结果。除了光致发光研究外，还通过热重-差示热分析（TG-DTA）测量评估了LZP玻璃的热稳定性。在λ(exci)=377nm激发下，掺杂Tb(3+)的玻璃在547nm处表现出显著的绿色发射，归属于(5)D4→(7)F5跃迁。通过交叉弛豫讨论了Tb(3+)发射随其浓度变化的猝灭现象。掺入Sm(3+)的玻璃在λ(exci)=404nm激发下，在603nm处表现出强烈的橙色发射，归属于(4)G5/2→(6)H7/2跃迁。从Sm(3+)吸收和Tb(3+)发射的显著光谱重叠可以理解这两种离子之间发生能量转移过程的可能性。通过(0.5mol.%Tb(3+)+(0.5 - 2.0mol.%)Sm(3+))共掺杂玻璃的发射光谱，评估了在λ(exci)=375nm下激发能量从Tb(3+)离子向Sm(3+)离子的迁移。随着Sm(3+)浓度的增加，Sm(3+)的发射强度增强，而Tb(3+)的发射强度降低，这表明通过交叉弛豫发生了从Tb(3+)((5)D4)到Sm(3+)((4)G5/2)的能量转移。通过能级图、衰减曲线进一步解释了能量转移过程背后的机制，并通过计算共掺杂玻璃的能量转移参数（能量转移效率(η)和能量转移概率(P)）得到证实。发现偶极-偶极相互作用对LZP玻璃基质中从Tb(3+)((5)D4)到Sm(3+)((4)G5/2)离子的能量转移起更大作用。
