Photoluminescence of complete solid solutions α-Y1-xEuxB5O9 by sol-gel synthesis and thermal decomposition from Y1-xEux[B6O9(OH)3

Abstract

Completed solid solutions of Y1-xEux[B6O9(OH)3] were prepared by boric acid flux method and the structure of Eu[B6O9(OH)3] was determined by single crystal X-ray diffraction (XRD). The successful cationic doping was supported by the linear change of unit cell parameters obtained by Le Bail fitting on powder XRD. Thermal treatments on Y1-xEux[B6O9(OH)3] will lead to the dehydration, re-crystallization into TD-α-Y1-xEuxB5O9, and decomposition to α-Y1-xEuxB3O6 eventually. For comparison, the sol-gel method was also applied to prepare SG-α-Y1-xEuxB5O9. Rietveld refinements on powder XRD was applied to obtain the crystallographic data for α-YB5O9. PL investigation indicated that the existence of hydroxyl groups weakened the Eu3+ charge transfer (CT) in Y1-xEux[B6O9(OH)3]. In α-Y1-xEuxB5O9, an intense CT absorption was detected and a bright right emission was observed. Moreover, both series of phosphors exhibited a right shift of CT maximum wavelength due to the expansion of unit cell and the delayed concentration at x = 0.6.