1：Experimental Design and Method Selection:

Hydrothermal synthesis at 200°C was used to prepare orthoborate samples. X-ray diffraction, IR spectroscopy, photoluminescence spectroscopy, and morphology studies were employed to analyze the samples.

2：Sample Selection and Data Sources:

Samples were prepared using aqueous solutions of rare-earth nitrates, boric acid, and ammonia. Specific compositions included Y1-x-yCexTbyBO3, Gd1-x-yCexTbyBO3, and solid solutions like Lu0.5Gd0.39Ce0.01Tb0.1BO

3：5Gd39Ce01Tb1BOList of Experimental Equipment and Materials:

3. 3. List of Experimental Equipment and Materials: Equipment included a SIEMENS D-500 diffractometer for X-ray studies, VERTEX 80v Fourier spectrometer for IR absorption spectra, Supra 50VP X-ray microanalyzer for morphology, and a setup with DKSSh-150 lamp, MDR-4 and MDR-6 monochromators, and FEU-106 photomultiplier for photoluminescence measurements. Materials included REE oxides, nitrates, boric acid, ammonia, and chemical reagents of analytical grade.

4：Experimental Procedures and Operational Workflow:

Synthesis involved mixing solutions, precipitation, hydrothermal treatment in an autoclave at 200°C for 20 hours, filtering, washing, drying, and annealing at temperatures up to 1000°C. Measurements were conducted at room temperature.

5：Data Analysis Methods:

X-ray patterns were interpreted using lattice parameters and space groups. IR spectra were analyzed for vibrational modes. Luminescence intensities and excitation spectra were measured and compared to determine energy transfer efficiencies.