【摘要】 BaFCl:Eu是一种优良的X射线发光材料,最近我们发现:虽然它的发光起源于Eu²⁺离子的4f⁶5d→4f⁷能级间的电子跃迁;但是晶体中同时存在的Eu³⁺离子的电荷转移跃迁对发光有很明显的增强作用。因此在研究Eu²⁺和Eu³⁺离子在发光过程中的作用时,必须首先要知道它们在发光材料中的浓度。我们提出了一种准确测定BaFCl:Eu中Eu²⁺和Eu³⁺离子含量的方法。这种方法是依据Eu²⁺离子的电子自旋共振（ESR）波谱以及Eu²⁺和Eu³⁺离子的发光光谱。我们合成了一系列含有不同Eu²⁺/Eu³⁺浓度比的BaFCl:Eu,并初步讨论了它们的发光现象。更多还原

【Abstract】 Europium activated barium fluoride chloride is an excellent X-ray phosphor. We have found that although its luminescence arises from the electronic transition of Eu²⁺ 4f⁶5d-4f⁷(⁸S_7/2)energy levels, this emission intensity is greatly enhanced by the presence of Eu³⁺ ions through their charge transfer transitions. Therefore it is a prerequisite to know the definite concentrations of Eu²⁺ and Eu³⁺ ions in this phosphor for studying their role in luminescence. A method for determining the content of europium ions in different oxidation state has been worked out. This method is based on the electron spin resonance spectroscopy of Eu²⁺ ions and the characteristic luminescence spectra of both Eu²⁺ and Eu³⁺ ions in relation to their concentrations in the host compound.The ESR spectra of Eu²⁺ in polycrystalline BaFCl are of Gauss curve type. Their relative intensities can be expressed by the areas confined to the curves. Experiments show that the ESR spectra intensities are linearly proportional to the concentrations of Eu²⁺ ions in the samples with a Eu²⁺ concentration renging from 0 to 5 mol％. At the same time the emission intensities of ⁵D_O-⁷F_J transitions of Eu³⁺ ions in BaFCl excited by UV light 260-360nm are linearly proportional to the concentrations of Eu³⁺ ions in samples. Therefore the ESR spectra intensities of Eu²⁺ ions and the emission intensities of Eu³⁺ ions can be used to evaluate the concentrations of Eu²⁺ and Eu³⁺ ions in BaFCl crystalline samples respectively.In this work seven samples of BaFCl with the same total europium content of 1 mole％ and different Eu²⁺ and Eu³⁺ concentrations have been prepared by solid state reaction under various atmospheric conditions. The concentratios of Eu²⁺ and Eu³⁺ ions in these samples have been determined by the above mentioned ESR spectroscopy and fluorescence sprctra respectively with confidential accuracy. The fluorescence phenomena of these phosphor samples were observed and preliminarily discussed.更多还原