1：Experimental Design and Method Selection:

Nanopowders were synthesized using co-precipitation method, and transparent ceramics were fabricated by hot pressing. The study focused on characterizing optical properties and energy transfer mechanisms.

2：Sample Selection and Data Sources:

Er:CaF2 nanoparticles and ceramics with Er3+ concentrations from 1.0 to 10.0 at.% were prepared. Data included XRD, SEM, ICP-OES, transmittance, absorption, emission spectra, and lifetime measurements.

3：0 to 0 at.% were prepared. Data included XRD, SEM, ICP-OES, transmittance, absorption, emission spectra, and lifetime measurements. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Raw materials included calcium nitrate tetrahydrate, potassium fluoride dehydrate, and erbium trinitrate pentahydrate. Equipment included XRD (D/Max-RB, Rigaku), FESEM (Zeiss Ultra Plus), ICP-OES (Prodigy 7, Leeman), spectrophotometer (Lambda 750, PerkinElmer), and fluorescence spectrophotometer (FLS980, Edinburgh Instruments).

4：Experimental Procedures and Operational Workflow:

Nanoparticles were synthesized via chemical reaction, centrifuged, washed, dried, and crushed. Ceramics were sintered at 800°C under vacuum with axial pressure, then polished. Measurements involved phase composition, morphology, doping concentrations, transmittance, absorption, and emission spectra upon 980 nm excitation.

5：Data Analysis Methods:

Data were analyzed using Scherrer equation for grain sizes, Bragg's Law for lattice constants, and exponential decay fitting for lifetimes. Energy transfer mechanisms were discussed based on spectra.