1：Experimental Design and Method Selection:

The study involved synthesizing La2O3:Yb3+,Ho3+ microcrystals via high-temperature solid-state reaction, optimizing doping concentrations, and characterizing structural and optical properties using XRD, SEM, DRS, and UC emission measurements.

2：Sample Selection and Data Sources:

Samples were prepared with varying Yb3+ and Ho3+ concentrations, using high-purity RE2O3 (RE = La, Yb, Ho) as starting materials.

3：List of Experimental Equipment and Materials:

Equipment included a Bruker D8 Discover XRD, Perkin-Elmer Lambda 950 spectrophotometer, Zeiss Supra 60 VP SEM, custom-built PL system with 980 nm laser diode, tunable Ti:sapphire laser, CCD spectrometer, and photomultiplier tube. Materials included RE2O3 (ChemPur), alumina crucibles, and rubber cement for security labeling.

4：Experimental Procedures and Operational Workflow:

Samples were calcined at 1300–1650°C, ground, and characterized. UC properties were measured under 980 nm excitation, with power density variations, and UCQY was determined using custom systems. Security labels were created by mixing phosphor with rubber cement and applying to banknotes.

5：Data Analysis Methods:

Data were analyzed using linear fitting for power dependence, CIE 1931 coordinates for color stability, and energy transfer models for UC mechanisms.