1：Experimental Design and Method Selection:

The study used sol-gel synthesis to fabricate Yb3+, Er3+, Tm3+: Y2Si2O7 nano powders, followed by annealing at 1050°C and 1480°C for 12 hours to investigate phase effects. Structural analysis was performed using XRD and SEM, while optical characterization involved diffuse reflectance and up-conversion luminescence measurements under 975 nm laser excitation.

2：Sample Selection and Data Sources:

Five different dopant concentrations of Yb3+, Er3+, Tm3+: Y2Si2O7 powders were prepared, labeled as YSYET1 to YSYET5, with specific atomic percentages of dopants as detailed in Table 1. Powders were annealed at two temperatures to form α and β phases.

3：Powders were annealed at two temperatures to form α and β phases. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment included a Bruker D2 Phaser X-ray diffractometer, FEI Inspect S50 SEM, EDAX Octane Prime for EDX, Perkin-Elmer Lambda 35 UV-VIS spectrophotometer, CNI MDL-H-975 laser diode, Acton series-SI 440 silicon detector, Princeton Instruments SP2500i monochromator, Edmund optics 950 nm short pass filter, Coherent Field Max II - TOP power meter, and Asense Tek Lighting Passport illuminance meter. Materials included TEOS, Yb(NO3)·H2O, Er(NO3)·5H2O, Tm(NO3)·5H2O, and Y(NO3)·6H2O from Sigma-Aldrich.

4：Experimental Procedures and Operational Workflow:

Powders were synthesized via sol-gel, annealed, and characterized. XRD patterns were measured from 10-55° (2θ) with a step size of 0.02. SEM and EDX were used for morphology and elemental analysis. Diffuse reflectance spectra were recorded from 400-1100 nm. UC spectra were measured from 400-850 nm under 975 nm excitation, with laser power varied and filters used to block scattered light. CIE-1931 coordinates were measured using an illuminance meter.

5：SEM and EDX were used for morphology and elemental analysis. Diffuse reflectance spectra were recorded from 400-1100 nm. UC spectra were measured from 400-850 nm under 975 nm excitation, with laser power varied and filters used to block scattered light. CIE-1931 coordinates were measured using an illuminance meter. Data Analysis Methods:

5. Data Analysis Methods: XRD data were compared to JCPDS standards. Crystallite sizes were determined using Scherrer’s equation. UC emission intensities were analyzed as a function of excitation power to determine photon numbers for up-conversion processes. CIE-1931 coordinates were used for color quality analysis.