1：Experimental Design and Method Selection:

The study employed a facile hydrothermal method for synthesis, chosen for its ability to produce nanoscale materials with controlled morphology and scalability. Theoretical models included the Debye-Scherrer equation and Williamson-Hall plot for crystallite size analysis, and biexponential decay kinetics for lifetime measurements.

2：Sample Selection and Data Sources:

Samples were prepared with varying concentrations of Yb3+ (0.03 to 0.07 mol%), Ho3+ (fixed at 0.01 mol%), and Tm3+ (0.01 to 0.033 mol%) in PbWO4 host. Data were acquired from synthesized nanomaterials.

3：03 to 07 mol%), Ho3+ (fixed at 01 mol%), and Tm3+ (01 to 033 mol%) in PbWO4 host. Data were acquired from synthesized nanomaterials. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment included X-ray diffractometer (BRUKER D8 Advance ECO), FTIR spectrometer (Shimadzu IR Affinity 1S), FEG-TEM (JEOL-JEM 2010), TGA/DTA (Shimadzu DTG-60H), and spectrofluorophotometer (Edinburgh FLS-980). Materials included lead nitrate, sodium tungstate, ytterbium oxide, holmium oxide, thulium oxide, ammonium hydroxide, and ethanol.

4：0). Materials included lead nitrate, sodium tungstate, ytterbium oxide, holmium oxide, thulium oxide, ammonium hydroxide, and ethanol. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: Synthesis involved hydrothermal reaction at 190°C for 18 hours at pH 9, followed by filtration, drying, and characterization. XRD, FTIR, TEM, TGA, absorption spectra, upconversion emission spectra, pump power dependency, and decay kinetics were performed step-by-step.

5：Data Analysis Methods:

Data were analyzed using Scherrer and Williamson-Hall equations for crystallite size, biexponential fitting for decay kinetics, CIE coordinates for color, and McCamy's approximation for CCT.