Abstract
KSrY(BO 3 ) 2: Tb 3+ and Tb 4+ solid solutions have been obtained using the solid-state synthesis and top-seeded solution growth method from the KF flux. Comparing the two types of Tb spectra 3d 3/2 TbO 2 (Tb 4+ ) and Na 3 Tb(BO 3 ) 2 (Tb 3+ ) with annealing in air of the KSrTb(BO 3 ) 2 crystal, X-ray photoelectron spectroscopy (XPS) revealed that the crystal contains about 15% of Tb 4+ . The entire Y/Tb series has polymorphic phase transitions that occur at temperatures between 550 and 600 °C. Synthesis and subsequent treatment methodology have an impact on the resulting Tb 3+ /Tb 4+ ratio in the sample. The best luminescent properties were measured on the composition KSrY 0.9 Tb 0.1 (BO 3 ) 2, which was annealed at 700 °C under a hydrogen flow and cooled slowly.