A comparison of spectroscopic properties of Dy3+-doped tetragonal tungsten bronze MTa2O6 (M = Sr, Ba, Pb) phosphors based on Judd–Ofelt parameters

Boron doping effect on the structural, spectral properties and charge transfer mechanism of orthorhombic tungsten bronze β-SrTa2O6:Eu3+ phosphor

“…51-1683. 17 However, Lee et al 7 reported that the crystal symmetry is suitable for the space group Pnam . Accordingly, the crystal symmetry of the orthorhombic TB samples was indexed with space group Pnam (no.…”

“…The χ ED and χ MD are the local field corrections for the ED and MD transitions which can be found by eqn (4) and (5) respectively: χ MD = n 3 where n is the refractive index of SrTa 2 O 6 which was taken as 1.828 from ref. 6 and 7 . The Judd–Ofelt intensity parameters ( Ω 2 , Ω 4 ) are given in Table 1 .…”

“…The b-SrTa 2 O 6 crystallizes at temperatures between 1300-1500 °C, while the b ′ -SrTa 2 O 6 forms at temperatures over 1500 °C. [6][7][8][9] The other polymorph is orthorhombic a-SrTa 2 O 6 occurs at about 1100 °C and below. However, the synthesis of a-SrTa 2 O 6 is difficult with the solid state reaction, so it can be produced by the ux method using strontium borate.…”

Influence of europium doping on the crystallization, morphology, and the cathodoluminescent properties of PbNb2O6:Eu3+ phosphors

“…Among Eu 3+ ion transitions, it is well known that the 5 D0→ 7 F1 magnetic dipole transition hardly changes with the crystal field around the Eu 3+ ions whereas 5 D0→ 7 F2 electric dipole transition is very sensitive to the crystal field changes (42). In radioluminescence (RL) mechanism, the excitation of holes and electrons by high-energy X-rays may create asymmetry differences with the UV-Vis excitation mechanism of PL, where X-ray excitation with a volumetric character can change the asymmetric ratio due to its deeper penetration (46)(47)(48). On the basis of the similarity of the CL mechanism to the RL mechanism due to the high-energy electron beam, it is possible that electron beam irradiation changed the dipole moments in the Eu 3+ doped host and caused the emission spectrum change.…”

“…Therefore, when PbNb2O6:Eu 3+ phosphor was exposed to irradiation with high-energy electrons of CL, the symmetry of the Eu 3+ local environment probably increased (46)(47)(48).…”