Energy transfer in CaSiO3 phosphors doped with Ce3+ and Tb3+

Calcium metasilicate phosphors activated by Ce³⁺ and Tb³⁺ have been studied for their emission characteristics. In two series of phosphors, one activator was kept at its optimum value while the other was varied. In another two series, one activator was kept below its optimum value and the other was varied. Concentration quenching effects start when each activator gives its maximum emission. There is clear evidence of an energy transfer from Ce³⁺ to Tb³⁺ because the⁵ D ₃ lines appear on addition of Ce³⁺ while they were conspicuously absent when Tb³⁺ alone was present. Their absence in singly activated phosphors could not have been due to cross-relaxation. Obviously X-ray excitation does not lead to⁵ D ₃ transitions which are achieved only by energy transfer. Further, considering the features of the emission spectra and the concentrations of activators used, the transfer could only be of the dipole-dipole type.     

Luminescence properties of the compounds of Eu3+ and Tb3+ with some aromatic acids

The excited states of some organic acids are calculated in the electron approximation taking into account the n electrons. The calculations were performed by two methods: in the frozen core approximation (method of the potential V(^N–1)) and by a method which enables taking into account the relaxation of the electronic core accompanying the excitation of the electron in the molecule. The luminescence properties of the compounds studied with Eu³⁺ and Tb³⁺ are studied based on the calculations performed. The results are compared with experimental data.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 53–57, February, 1986.     

掺杂镧、钇的铽(Ⅲ)乙酰丙酮三元配合物的合成及荧光性质研究

合成了四个系列稀土掺杂铽乙酰丙酮(Hacac)三元配合物RExTb1-x(acac)3phen和RExTb1-x(acac)3bipy(RE=La,Y;x=0,010,020,030,050,070,090,100;phen1,10邻菲罗啉;bipy2,2’联吡啶)。通过红外光谱、X射线粉末衍射对配合物进行了表征。对各系列配合物进行荧光光谱研究,发现La3+,Y3+对Tb3+离子均有荧光增敏作用,并且La3+>Y3+。当x=01～03,多数掺杂配合物比未掺杂铽三元配合物具有更好的发光性能。     

Relaxation dynamics of excited states of Tm3+ in SrGdGa3O7 crystals activated with Tm3+ and Tb3+

3 H₄ and ³F₄ states of Tm in SrGdGa₃O₇ single crystal was evaluated. Tm-Tb energy transfer reduces effectively the lifetime of terminal level in a potential ³H₄-³F₄ laser transition but gives rise to parasitic nonradiative relaxation of the initial ³H₄ level. SrGdGa₃O₇ crystal single doped with thulium possesses combination of properties advantageous for laser oscillations near 1.9 μm, namely high rate of cross relaxation process leading to population buildup on the initial ³F₄ level and relatively high crystal field splitting of the ground ³H₆ level. Received: 25 April 1996/Revised version: 10 October 1996     

Down-conversion process in Tb3+–Yb3+ co-doped Calibo glasses

The down-conversion process in Tb³⁺–Yb³⁺ co-doped Calibo glasses was studied. The emission, excitation and time-resolved measurements indicated the existence of an energy conversion through the excitation of Tb³⁺ ions to near-infrared emission by Yb³⁺ ions. The emission intensity dependence on excitation power confirms that the one-photon process is responsible for the Yb³⁺ emission. An enhanced Yb³⁺ emission was observed with Yb³⁺ doping and an optimal energy transfer efficiency of 32% was obtained before reaching near-infrared emission quenching. The mechanism of the non-resonant energy transfer from Tb³⁺ to Yb³⁺ is discussed in terms of the Tb³⁺–Yb³⁺ cross-relaxation and multiphonon decay processes.     

含Ce3+,Tb3+简单氟化物磷光体的荧光特性

采用溶液反应和固相反应合成了ＣａＦ２：Ｃｅ,Ｔｂ和ＡｌＦ３：Ｃｅ,Ｔｂ磷光体,研究了它们的光谱特性,结果发现,在ＣａＦ：Ｃｅ,Ｔｂ和ＡｌＦ３：Ｃｅ,Ｔｂ中Ｃｅ＾３＋对Ｔｂ＾３＋的能量传递不能有效进行,有时Ｔｂ＾３＋甚至对Ｃｅ＾３＋起猝灭作用。     

Ce~(3+)和Tb~(3+)掺杂钆-钡-硅酸盐闪烁玻璃的发光性能

采用高温熔融法制备Ce~(3+)或Tb~(3+)单掺和Ce~(3+)/Tb~(3+)共掺钆-钡-硅酸盐闪烁玻璃。通过透射光谱、光致激发和发射光谱、X射线激发发射光谱及荧光衰减曲线等手段对其发光性能进行研究。实验结果表明:在紫外光的激发下,Tb~(3+)掺杂闪烁玻璃发出明亮的绿光(544 nm),而Ce~(3+)掺杂闪烁玻璃发出蓝紫光。对于Ce~(3+)/Tb~(3+)共掺闪烁玻璃,在紫外光和X射线激发下均观察到Ce~(3+)离子敏化Tb~(3+)离子发光的现象,这是由于存在Ce~(3+)→Tb~(3+)的能量转移。Ce~(3+)/Tb~(3+)共掺闪烁玻璃的最佳Ce2O3掺杂摩尔分数为0.2%,此时Ce~(3+)离子向Tb~(3+)离子的能量传递效率为45.7%。在X射线激发下,Ce_2O_3摩尔分数为0.2%的Ce~(3+)/Tb~(3+)共掺闪烁玻璃在544 nm处的发光强度是Bi_4Ge_3O_(12)(BGO)闪烁晶体在500 nm处发光强度的4.2倍,积分闪烁效率达到BGO晶体的55.6%,这有利于在高分辨率医学成像中降低辐射剂量。     

二元羧酸-联吡啶稀土双核配合物中镧、铽对铕发光的增强作用

合成了以邻苯二甲酸、２,２’－联吡啶为配体,分别以Ｅｕ＾３＋－Ｔｂ＾３＋ｙ离子和Ｅｕ＾３＋－Ｌａ＾３＋离子为中心体的双核稀土配合物;在３２３ｎｍ紫外光激发与的的荧光光谱。结果表明,在该两系列双核稀土配合物中,无 发光的Ｔｂ＾３＋离子还是不发光的Ｌａ＾３＋离子,都对Ｅｕ＾３＋离子的发光有增强作用。     

NaZnLa(PO4)2中Ce3+和Tb3+的发光

采用高温固相反应合成了NaZnLa(PO₄)₂中掺杂Ce³⁺、Tb³⁺的荧光体,对其晶体结构、发光行为进行了研究,并尝试对NaZnLa(PO₄)₂:Ce,Tb荧光体进行调制。NaZnLa(PO₄)₂是LaPO₄的同构物,为单斜晶系独居石结构,从XRD谱数据得到NaZnLa(PO₄)₂基质的晶胞参数为a=0.6823nm,b=0.7045nm,c=0.6497nm,β=1039°,v=0.303nm³,其晶胞参数与单斜LaPO₄的晶胞参数相似。在NaZnLa(PO₄)₂:Ce,Tb荧光体中,Ce³⁺对Tb³⁺有良好的敏化作用,掺杂适量的BO₃^3-、Al³⁺、Dy³⁺,可以增强发光亮度。     

Fluoreszenzlebensdauern und Mehrphononenprozesse in wasserhaltigen Salzen von Eu3+ und Tb3+

The lifetimes of the fluorescent levels⁵ D ₀ and⁵ D ₁ of Eu³⁺ and⁵ D ₄ of Tb³⁺ were measured in the hydrated ethylsulfate, bromate, chloride, nitrate, and sulfate at 4.2°K, 77°K and 300°K. In the case of the ethylsulfate and chloride, the lifetimes were also measured in deuterated crystals and in crystals diluted with diamagnetic Yttrium. The results show that the lifetimes of the fluorescent levels are determined by spontaneous radiationless energy transfer from the rare earth ion to the optical vibrational modes of the water of crystallisation. Assuming a Coulomb interaction between the ion and the surrounding water molecules, the probability for the radiationless transition⁵ D ₁→⁵ D ₀ of the Eu³⁺-ion in the ethylsulfate was calculated in the low temperature limit. The agreement between the theoretical and experimental value is satisfactory. For the probabilities of radiationless desactivation of the fluorescent levels⁵ D ₀ of Eu³⁺ and⁵ D ₄ of Tb³⁺, the empirical form of a product [1] of two factors, one depending only on the rare earth ion and the other only on the lattice, was derived theoretically. Both fluorescent levels are desactivated by a 5-phonon process with the stretching vibrations of the surrounding water molecules.     

KAlF4：Ce,Tb磷光体的发光特性及Ce^3＋对Tb^3＋的敏化作用

采用溶液反应法和高温固相反应法合成了ＫＡ１Ｆ４基质化合物及ＫＡ１Ｆ：Ｃｅ，Ｔｂ磷光体，测定了磷光体的激发光谱和发射光谱，研究了在碱金属氟铝酸盐基质中Ｃｅ＾３＋对Ｔｂ＾３＋的能量传递，根据Ｃｅ＾３＋，Ｔｂ＾３＋在ＫＡｌＦ４中的能级关系，分析了其发光特性和Ｃｅ＾３＋对Ｔｂ＾３＋能量传递过程。     

Stark splitting and energy transfer between Dy3+-Ho3+ and between Tb3+-Er3+ in calcium-lithium borate glass

Fluorescence spectrum of Dy³⁺, Dy³⁺-Ho³⁺, Tb³⁺ and Tb³⁺-Er³⁺ doped in calibo glass have been studied using Ar⁺ and excimer lasers. Non-radiative energy transfer from trivalent dysprosium and terbium (donors) to holmium and erbium (acceptors) respectively has been observed on the basis of decrease in the life time of the levels and reduction in fluorescence intensity of Dy³⁺ and Tb³⁺ on increasing Ho and Er concentrations. The interaction mechanism of donor and acceptor ions is found to be dipole-dipole in both cases. Various parameters such as donor-acceptor distances, non-radiative energy transfer efficiency (η) and energy transfer probability (P _da) have been computed. Stark splitting have also been marked in several intense transition of the two.     

Eu3+和Tb3+掺杂的Y2SiO5体系发光特性研究

采用溶胶－凝胶法合成了Eu^3 和Tb^3掺杂的Y2SiO5基发光材料，通过测量它们的激发光谱和发射光谱，研究了它们的发光特性，探讨了材料中Tb^3和Eu^3 两种发光中心间的能量关系。结果表明，Eu^3＋在其中的特征发射以^5D0→^7F2电偶极跃迁为，Eu^3处于非反演对称中心格位；Tb^3在其中的发射为^5D4→^7FJ(J＝4－6）跃迁发射。当Eu^3和Tb^3共存于Y2SiO5基质中时Eu^3的发射增强，Tb^3的发射减弱，存在Tb^3→Eu^3能量传递，Tb^3对Eu^3具有敏化作用。     

Sb3+对Tb3+激活硅酸盐玻璃发光性能的影响

利用高温熔融法分别制备了Sb3 ,Tb3 单掺和共掺的硅酸盐发光玻璃,并分析了它们的光谱性质。根据对Sb3 和Tb3 掺杂硅酸盐玻璃的激发光谱、发射光谱和发光衰减时间等特性的分析,研究了澄清剂Sb2O3的加入对Tb3 激活硅酸盐玻璃发光性能的影响。结果表明,在紫外光激发下,Tb3 激活硅酸盐玻璃中存在Sb3 离子至Tb3 离子的能量传递,但能量传递效率较低,能量传递表现为Sb3 离子的3P1能级与Tb3 离子的5D3能级之间的能量无辐射共振转移。同时Sb3 离子的加入将在Sb3 离子和Tb3 离子的激发重叠区域(200～350nm)对Tb3 离子的激发产生不小的负面影响,尚不足以通过Sb3 离子至Tb3 离子的能量传递得以弥补。因此在使用Sb2O3作为Tb3 激活硅酸盐发光玻璃的澄清剂时,应当注意权衡Sb3 离子对Tb3 离子发光性能的影响。