1：Experimental Design and Method Selection:

Pr3+/Yb3+-codoped KNN ceramic materials were prepared by a conventional solid-state reaction method. The Pr3+ and Yb3+ ions were designed to occupy the sites of K+ or Na+ ions in the KNN host lattices. To obtain strong UC emission properties, the Yb3+ ions as a sensitizer were controlled at a constant mole content of 1%, and the compounds were designed according to the chemical formula (K

2：5Na5)99-xPrxYb01NbO3 (abbreviated as KNN:

xPr3+/0.01Yb3+, x=0.0006, 0.0008, 0.001, 0.002, 0.003 and 0.004).

3：01Yb3+, x=0006, 0008, 001, 002, 003 and 004). Sample Selection and Data Sources:

2. Sample Selection and Data Sources: Raw powders K2CO3 (99%), Na2CO3 (99.8%), Nb2O5 (99.5%), Pr2O3 (99.9%), and Yb2O3 (99.9%) were weighted and mixed in alcohol, and then ball milled for 8 h. The powders were dried and calcined at 850 °C for 5 h in air. The calcined powders were re-mixed in alcohol, mixed with 5 wt% poly (vinyl alcohol) (PVA) solution, pressed into disk-pellet samples, and sintered at 1175 °C for 4 h.

4：8%), Nb2O5 (5%), Pr2O3 (9%), and Yb2O3 (9%) were weighted and mixed in alcohol, and then ball milled for 8 h. The powders were dried and calcined at 850 °C for 5 h in air. The calcined powders were re-mixed in alcohol, mixed with 5 wt% poly (vinyl alcohol) (PVA) solution, pressed into disk-pellet samples, and sintered at 1175 °C for 4 h. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: X-ray diffraction (XRD, Advance, Bruker, Germany) with Cu Kα radiation for crystalline structure; scanning electron microscopy (SEM, SUS-700, Hitachi, Japan) for surface microstructure; UV-VIS-NIR spectrophotometer (Cary 5000, Agilent, USA) for diffuse reflective spectra; spectrofluorometer (FS5, Edinburgh Instrument, UK) for UC emission spectra under 980-nm diode laser excitation; xenon lamp in FS5 for light irradiation source; Agilent 4294A impedance analyzer and PTS-2000H measuring system (Partulab, Wuhan, China) for dielectric performance with temperature.

5：Experimental Procedures and Operational Workflow:

Powders were mixed, ball milled, dried, calcined, re-mixed, pressed with PVA, and sintered. XRD and SEM were used for structural and morphological analysis. Diffuse reflectance and UC emission spectra were measured. Temperature-dependent UC emission spectra were recorded from 123 to 573 K. Dielectric constant variation with temperature was tested.

6：Data Analysis Methods:

UC emission intensity was analyzed as a function of Pr3+ concentration and pump power. Luminescence quenching degree (ΔRt) was calculated. Fluorescence intensity ratio (FIR) technique was used for temperature sensing, with sensitivity calculated. Energy transfer mechanisms were discussed based on emission spectra and energy level diagrams.