研究目的
Investigating the spectroscopic properties and martensitic phase transition of Y4Al2O9:Ce single crystals under high pressure.
研究成果
The study concludes that Y4Al2O9:Ce crystals exhibit four different Ce3+ centers, with two showing luminescence at ambient pressure and two requiring high pressure to emit light. A martensitic phase transition occurs between 8 and 11 GPa, significantly affecting the luminescence properties. A second phase transition likely to a hexagonal structure occurs around 16 GPa. The findings have implications for the Dorenbos theory and the understanding of rare-earth ion behavior in low symmetry crystal fields.
研究不足
The study is limited by the resolution of the spectroscopic techniques used at high pressures and the challenges in maintaining perfectly hydrostatic conditions at very high pressures. Additionally, the theoretical calculations underestimate the bandgap energy, which is a common drawback of the method used.
1：Experimental Design and Method Selection:
The study involved high-pressure optical and structural studies of Y4Al2O9:Ce single crystals, including absorption measurements, luminescence spectra, Raman spectroscopy, and synchrotron angle dispersive x-ray diffraction under high pressure.
2：Sample Selection and Data Sources:
YAM:Ce single crystals with Ce concentrations varying up to 1% were grown by the micro-pulling-down method. High-pressure experiments were performed under hydrostatic conditions.
3：List of Experimental Equipment and Materials:
The study utilized synchrotron angle dispersive x-ray diffraction, Raman spectroscopy, and luminescence spectroscopy equipment.
4：Experimental Procedures and Operational Workflow:
The experimental process included measuring absorption and luminescence spectra at various temperatures and pressures, performing Raman spectroscopy under high pressure, and conducting synchrotron XRD measurements under high pressure.
5：Data Analysis Methods:
The data were analyzed using Rietveld refinement for XRD patterns, fitting temperature dependencies of luminescence intensities with theoretical models, and calculating electronic band structures using ab initio methods.
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