The Yb 3+ doped Ba 2 YB O 6 (B=Ta 5+,Nb 5+) were prepared by high temperature solid-state reaction method,their structures were determined by x-ray diffraction and refined by Rietveld method.The diffuse reflection absorption,excitation and emission spectra of Yb 3+:Ba 2 YB O 6 (B=Ta 5+,Nb 5+) were measured at room temperature.Under the excitation of ultraviolet light,these phosphors exhibit broad charge transfer band emissions of TaO 6 or NbO 6 centre with large Stokes shift.The Yb 3+ doped into these hosts are situated at Y 3+ sites of cubic symmetry (O h).The experimental energy levels of Yb 3+ in Ba 2 YTaO 6 and Ba 2 YNbO 6 were determined by photoluminescence and diffuse reflection absorption spectra.Their wavefunctions and theoretical energy levels were obtained by diagonalising the Hamiltonian matrix.The experimental energy levels were fitted by Levenberg-Marquardt iteration algorithm to determine crystal field parameters.Then,the magnetic-pole transition line strengths of Yb 3+:Ba 2 YB O 6 (B =Ta 5+,Nb 5+) from (2 F 5/2)Γ 8 to the low-energy states were calculated.
