1：Experimental Design and Method Selection:

The study used hydrothermal synthesis to prepare Ba3[Ge2B7O16(OH)2](OH)(H2O):Eu3+ phosphors with different morphologies by varying boron sources (H3BO3, NH4B5O8·4H2O, Na2B4O7·10H2O). Ba3Ge2B6O16:Eu3+ was prepared by calcining the precursor at 900°C for 5 hours and compared with a sample made by high-temperature solid-state reaction. Characterization methods included XRD, EDS, FT-IR, TG-DTA, SEM, HRTEM, PL spectroscopy, lifetime measurements, and quantum yield measurements.

2：Sample Selection and Data Sources:

Analytical grade reagents (BaCO3, Eu2O3, GeO2, H3BO3, NH4B5O8·4H2O, Na2B4O7·10H2O) were used without purification. Samples were synthesized in a Teflon-lined autoclave at 200°C for varying times (24-96 hours).

3：List of Experimental Equipment and Materials:

Autoclave, oven, filter, deionized water, ethanol, drying oven. Characterization equipment: XRD (Rigaku D/MAX-C, Cu Kα radiation), FT-IR (Nicolet NEXUS 670 spectrometer), TG-DTA (TA-SDT Q600), EDS (Hitachi JEOL-6700F), SEM (Philips-FEI Quanta 200), TEM (Tecnai G2 F20), PL spectrometer (FL-4600 Hitachi), lifetime apparatus (FLS920P Edinburgh Analytical Instrument), quantum yield apparatus (Hamamatsu C9920-02G).

4：Experimental Procedures and Operational Workflow:

For hydrothermal synthesis, raw materials were sealed in an autoclave, heated at 200°C for specified times, cooled, filtered, washed, and dried. Calcination was done at 900°C for 5 hours. Characterization involved standard procedures for each technique, e.g., XRD for structure, SEM for morphology, PL for emission spectra.

5：Data Analysis Methods:

XRD patterns were compared with simulated structures. FT-IR peaks were assigned based on literature. PL spectra were analyzed for emission peaks and intensities. Lifetime decay curves were fitted with double-exponential functions. Quantum yield was calculated as the ratio of emitted to absorbed photons.