1：Experimental Design and Method Selection:

The study synthesized a series of tridoped Y2-x-y-zHozYbyZnxTiO7 phosphor samples with fixed concentrations of Ho3+ and Yb3+ (z=1, y=3) and varying concentrations of Zn2+ (x=0–35 mol%) using the conventional solid state reaction route. The rationale was to study the effect of Zn2+ co-doping on the structural and optical properties, particularly upconversion emission. Theoretical models included the Debye-Scherrer method for crystallite size calculation and the Wood and Tauc formula for optical band gap determination.

2：Sample Selection and Data Sources:

Samples were prepared using analytical grade chemicals: yttrium oxide (Y2O3, 99.999%), holmium oxide (Ho2O3, 99.9%), ytterbium oxide (Yb2O3, 99.99%), zinc oxide (ZnO, 99%), and titanium dioxide (TiO2, 99%). The stoichiometric mixtures were homogenously mixed in an agate mortar with acetone as a mixing media, dried, and heated at 1200°C for 5 hours in ambient atmosphere.

3：999%), holmium oxide (Ho2O3, 9%), ytterbium oxide (Yb2O3, 99%), zinc oxide (ZnO, 99%), and titanium dioxide (TiO2, 99%). The stoichiometric mixtures were homogenously mixed in an agate mortar with acetone as a mixing media, dried, and heated at 1200°C for 5 hours in ambient atmosphere. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment included X-ray diffractometer (MiniFlex600: D/teX Ultra Rigaku, Japan), scanning electron microscope (EVO 18 SEM, Carl Zeiss, Germany), Fourier transform infrared spectrometer (model Spectrum-65 Perkin Elmer spectrometer), UV–vis-NIR spectrometer (Lambda 750, Perkin Elmer), dispersive monochromator (model: iHR 320 Horiba JovinYvon) with PMT detector (model no.1424M), 980 nm diode laser (CW, 2 W tunable source), mechanical chopper (model no. SR-540, Stanford Research Systems Inc.), and 150 MHz oscilloscope (model no. HM 1507, Hameg Instruments). Materials included the aforementioned oxides and acetone.

4：Experimental Procedures and Operational Workflow:

The synthesis involved mixing precursors, heating in an alumina crucible, and cooling to room temperature. Characterization steps included XRD for phase identification, SEM for morphological analysis, FTIR for vibrational groups, UV–vis-NIR for absorption spectra, upconversion emission spectra monitoring with a 980 nm laser, and lifetime measurements using a modulated laser and oscilloscope.

5：Data Analysis Methods:

Data analysis involved using the Debye-Scherrer equation for crystallite size, Wood and Tauc formula for band gap, single exponential fitting for lifetime calculation, and power-dependent studies with log-log plots to determine the number of photons involved in upconversion processes.