Growth, Thermal, and Spectroscopic Properties of YbBa₃(PO₄)₃ Single Crystal: A New Stoichiometric Lasing Material

Yb-doped materials can incorporate particularly high concentrations of Yb ion with weak concentration quenching, where high laser ion-doped materials with short absorption lengths permit the use of thin crystals with high absorption efficiencies. Herein, a new stoichiometric single crystal of YbBa₃(PO₄)₃ with dimensions of ϕ 15 × 30 mm³ was grown via the Czochralski pulling method. Rocking curve characterization showed that the as-obtained YbBa₃(PO₄)₃ crystal was of high quality, and the full-width at half-maximum measured from the (111) wafer was determined to be 28.8″. The crystal structure was characterized using single-crystal X-ray diffraction analysis. The results indicated that the crystal belongs to the cubic space group I4̅3d (No. 220) with cell parameters of a = b = c = 10.4352 (4) Å, V = 1136.32 (13) ų, and Z = 4. The thermal and spectroscopic properties were evaluated, including the coefficient of thermal expansion, specific heat, thermal conductivity, and absorption and fluorescence spectra. The absorption cross-section at 975 nm and fluorescence lifetime were calculated as 1.02 × 10^–20 cm² and 220 μs, respectively. The emission cross-section at 1008 nm was determined to be 4.07 × 10^–20 cm² at room temperature, where the full-width at half-maximum of the emission peak was 75 nm, indicating that the stoichiometric crystalline YbBa₃(PO₄)₃ is a promising laser crystal material.