研究目的
Investigating the low-temperature sensing performance of Gd3Ga5O12:Yb3+/Er3+ nanocrystals by partial or total substitution of Ga3+ with Fe3+ ions to improve sensitivity at very low temperatures.
研究成果
The substitution of Fe3+ ions in Gd3Ga5O12:Yb3+/Er3+ nanocrystals modulates the up-conversion luminescence and improves low-temperature sensing performance, enabling applications in optical thermometry down to liquid helium temperatures with high sensitivity.
研究不足
The study is limited to Gd3Ga5O12-based nanocrystals with specific doping levels; the presence of impurity phases in some samples (e.g., S5) may affect results, but it is assumed to have no influence on UC photoluminescence. The temperature range is constrained to 4.2-300 K, and the sensitivity evaluation relies on empirical fitting which may not be perfect for all samples.
1：Experimental Design and Method Selection:
The study synthesized Gd3Ga5-xFexO12:Yb3+/Er3+ nanocrystals using the sol-gel method to investigate the effects of Fe3+ substitution on structure, magnetization, and up-conversion luminescence for temperature sensing applications.
2：Sample Selection and Data Sources:
Samples with x = 0, 1, 2, 3, 4, 5 (marked S0 to S5) were prepared, where Gd3+ ions were partially replaced by Yb3+ and Er3+ ions at a 4.17% atomic ratio.
3：17% atomic ratio.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: X-ray diffraction (XRD) with Cu Kα irradiation (Philips X'pert pro), superconducting quantum interference device (SQUID-VSM, Quantum Design) for magnetization measurements, 980 nm solid-state laser for excitation, monochromator (SP500i, Acton) equipped with an electron-amplified charge-coupled device (Newton 970P, Princeton Instruments), and a homebuilt liquid helium cryostat for temperature control from 300 K to 4.2 K.
4：2 K.
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: XRD measurements were performed from 10° to 90° 2θ to characterize crystal structure; magnetization was measured using SQUID-VSM; UC luminescence spectra were excited by the 980 nm laser and recorded using the monochromator and CCD while cooling samples in the cryostat.
5：Data Analysis Methods:
Lattice constants and crystallite sizes were calculated using Jade 6.0 software and the Scherrer formula; magnetic susceptibility and inverse susceptibility were analyzed; UC luminescence intensity and fluorescence intensity ratio (FIR) were evaluated using a semi-empirical exponential-growth function for temperature sensitivity calculations.
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