Photoluminescence of a BaSiO3:Yb3+ crystal

Abstract

We present the results of a study of the luminescence and luminescence excitation spectra, and also the luminescence kinetics of a BaSiO 3 :Yb 3+ crystal. We have established the mechanism for emission by the matrix and energy transfer from the matrix to the rare earth ion.Introduction. In a study of a series of sections in the system BaO-SiO 2 -GeO 2 , the authors of [1, 2] indicated the possibility of the existence of broad regions of substitutional solid solutions between compounds of analogous composition. The compound BaSiO 3 crystallizes in two polymorphic varieties, with a ring structure (pseudowollastonite, a = 7.50 Å, c = 10.58 Å) and a chain structure (pyroxenoid, a = 4.54 Å, b = 5.56 Å, c = 12.27 Å). In solidphase synthesis, BaSiO 3 is crystallized in the chain polymorphic form. The ring form of BaSiO 3 was synthesized for the first time by the hydrothermal method in [3]. In [4], the crystal phases and luminescent properties were studied for the ternary system SrO-BaO-SiO 2 , activated by Ce 3+ ions. The excitation spectrum consists of three bands with maxima at 190 nm, 230 nm, and 320 nm, and in the emission spectrum there are maxima at 392 nm and 475 nm, associated with Ce 3+ ions. In [4], an effect from different compensation charges on the excitation and emission spectra was also demonstrated.Review of literature data shows that the luminescent properties of a BaSiO 3 crystal activated by Yb 3+ ions have not been studied. In [5], results are presented from an investigation of luminescence of Eu 2+ ions in SrSiO 3 and CaSiO 3 crystals that are isostructural to the BaSiO 3 crystal (for SrSiO 3 :Eu 2+ and CaSiO 3 :Eu 2+ at 4.2 K, the emission maxima are found at 440 nm and 465 nm). In [6], a broad band with maximum at 550 nm is observed in the emission spectrum of a BaSiO 3 :Eu 2+ crystal. When the temperature is raised from 4.2 K to room temperature, a shift of the emission maximum is observed, from 550 nm to 575 nm. The halfwidth of the emission band also increases, but at 90 K it suddenly decreases. When the temperature again increases, the halfwidth increases. The authors of [6] asssociated such behavior of the temperature dependence of the halfwidth with a phase transition in the BaSiO 3 :Eu 2+ crystal. The luminescent properties of metal silicates MO-SiO 2 :Eu 2+ (where M is Ca, Sr, Ba) are considered in [7].As an activator for crystalline matrices, in many respects ytterbium occupies a special position among other rare earth elements. The Yb 3+ ion has a very simple system of electronic states, and no intermediate coupling problems arise in its calculation. The only term, 2 F, is split by spin-orbit coupling into two multiplets, spaced far apart (≈10000 cm -1 ). A feature of this level system is the fact that owing to the absence of close multiplets, when considering some electron-phonon coupling phenomena such as the temperature shift of phononless lines, for Yb 3+ ions we can consider mixing of only electronic states within the multiplets, and we can neglect intermultiplet mixing.The Yb 3+ io...

Blue-White-Yellow Tunable Emission from Ce3+ and Eu2+ Co-Doped BaSiO3 Phosphors

“…There exist low temperature and high temperature two polymorphs for BaSiO 3 , the former belongs to the pseudowollastonite type with a ring structure and the latter has a orthorhombic structure with a chain form and space group P2 1 2 1 2 1 . 21,22 In compound BaSiO 3 , we suggest that the Ce 3+ and Eu 2+ ions prefer to occupy the sits of Ba 2+ ions. The phase purities and crystal structures of the synthesized samples were characterized by powder x-ray diffraction, and Figure 1 displays the XRD patterns of Ba 1.96 SiO 3 :0.02Ce 3+ , 0.02Na + , Ba 1.98 SiO 3 : 0.02Eu 2+ and Ba 1.94 SiO 3 :0.02Ce 3+ , 0.02Na + , 0.02Eu 2+ phosphors as representatives.…”

A new precipitation based method for preparation of metasilicate phosphors

“…A phase stable in the interval 34-59 kbar was originally assigned orthorhombic structure which was later corrected to monoclinic. In alpha SrSiO 3 [27] the Sr atoms occupy three kinds of sites [Sr(1), Sr(2) and Sr (3) The compound BaSiO 3 crystallizes in two polymorphic varieties, with a ring structure (pseudowollastonite, a = 7.50Å, c = 10.58Å) (also known as hexagonal, alpha) and a chain structure (pyroxenoid, a = 4.54Å, b = 5.56Å, c = 12.27Å) (also known as orthorhombic, beta) [28,29]. In solid phase synthesis, BaSiO 3 is crystallized in the chain polymorphic form.…”

Study of Conditions for the Associated Extraction of Vanadium and Gallium During Alkaline Leaching of Raw Alunite Ore

“…The literature describes a large number of various methods for processing alunitized rock [13,14]. In almost all sources, crushed alunite rock is roasted and reduced in fluidized bed furnaces.…”