1：Experimental Design and Method Selection:

The phosphors were synthesized using a solid-state reaction ceramic method in a three-step sintering process. Structural analysis was performed using XRD with Rietveld refinements to confirm phase formations. Luminescence properties were characterized through photoluminescence excitation and emission spectra, decay lifetime measurements, quantum efficiency, and thermal stability tests.

2：Sample Selection and Data Sources:

Samples of Na1-xKxBaY0.5Eu0.5(BO3)2 with x ranging from 0.1 to 1.0 were prepared. Raw materials included Eu2O3 (99.99%), BaCO3 (99%), H3BO3 (99.5%), Y2O3 (99.99%), Na2O (≥99.5%), and K2O (≥99.5%).

3：5Eu5(BO3)2 with x ranging from 1 to 0 were prepared. Raw materials included Eu2O3 (99%), BaCO3 (99%), H3BO3 (5%), Y2O3 (99%), Na2O (≥5%), and K2O (≥5%). List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment included a Rigaku D/Max diffractometer for XRD, a scanning electron microscope (SEM) with EDS for surface analysis, a luminescence spectrometer for PL and PLE spectra, a pulsed Nd:YAG laser for decay curves, a 75 cm monochromator (ActonResearch Corp. Pro-750), a PMT for detection, and a LeCroy 9301 digital storage oscilloscope for data recording.

4：Experimental Procedures and Operational Workflow:

Raw materials were mixed in stoichiometric ratios, pre-sintered at 350°C for 4 hours, ground, heated at 550°C for 4 hours, finely ground, and sintered at 900°C for 6 hours in air. XRD patterns were recorded with Cu-Kα radiation, SEM and EDS were used for morphological and elemental analysis, and luminescence measurements were conducted under specific excitations.

5：Data Analysis Methods:

XRD data were refined using Rietveld methods. Luminescence intensities and decay curves were analyzed to calculate quantum efficiencies and lifetimes. Thermal stability was evaluated using the Arrhenius equation to determine activation energies.