【摘要】 本文利用Judd-Ofelt理论求得TbP₅O₁₄晶体的振子强度参数Ω_λ,计算了⁵D₃、⁵D₄到⁷F_J能级的电偶极和磁偶极辐射跃迁几率及⁵D₃-⁵D₄和⁷F₆-⁷F₀能级对间的多极矩耦合的迁移几率。讨论了⁵D₃、⁵D₄能级发射强度的浓度效应,并给出了发射强度的表达式和强度随浓度和激发光引起的基态到激发态的跃迁几率的变化图。更多还原

【Abstract】 The earlier experimental results showed that the luminescent characteristics of Tb3+ ion depend on Tb3+ ion concentration and crystal hosts.In this paper theoretical investigation of Tb3+ luminescent characteritics in pentaphosphate and mixing pentaphosphate single crystals (TbP5O14 and Tbx Y1-xP5 O14) has been carried out. By using the Judd-Ofelt theory and absorption spectra, the parameters of the oscillator strengh were first obtained in TbP5O15 crystals, resulting in O2 = 2.13×10-20cm2, 4=3.76×10-20 cm2 ,6 = 2.98×10-20 cm2.The probabilities of electric dipole and magnetic dipole radiative transition from 5D3 and 5D4 to 7FJ were calculated. The lifetime of electron in 5D4 obtained is 4.4ms, which agrees with experimental value.The multipolar coupling transfer probabilities-between the 5D3-5D4 and 7F8~7F0 pairs were calculated on the basis of the Dexter model, resulting in Pdd =8296 ×x2(s~1), Pdg=96420×x8/3(s-1)> where Pdd,Pdq are transfer probability of dipole-dipole and dipole-quadripole, respectively;x is Tb3+ ion concentration.The rate equations of population for transition between 5D3, 5D4 and 7FJ energy levels were established, and 5D3,5D4 energy level populations N3, N2 and emission intensities I31, I21 were obtained in steady state as follows.I31 = a N3 A31 he a13 I21 =a N2 A21 he o12where W is the probability per unit time for the induced transition (7F6-5D3) caused by the exciting radiation of wave number o13, A;j are the probability of the spontaneous radiation from i state to j state, h is the Planck constant, C the speed of light, and the geometrical factor.Thus, the relationship between emission intensities and the concentration of Tb3+ ion have been found.The phenomenon that 5D3 emission intensities increase with the decrease in Tb3+ ion concentration was explained and the diagrams that emission intensities of 5D3 and 5D4 depend on the Tb3+ ion concentration x and the induced transition probability W of exciting light were given. So we can utilize them and adjust Tb3+ ion concentration to change the fluorescence color in order to meet the requirement of practical applied.We also obtained the I31/I21 ratio. It was found that this value is independent of W, which is determined by the crystal property.更多还原