研究目的
Investigating the synthesis of micrometer-sized diamond crystals at extreme conditions of pressure and temperature, and the reaction of carbon with potential thermal insulating mediums in laser-heated diamond anvil cell experiments.
研究成果
The study successfully synthesizes micrometer-sized diamond crystals at 18 GPa and 1785 K, confirming the transformation of graphite to diamond. It highlights the reaction of carbon with Fe and Al2O3, suggesting the avoidance of steel gaskets and Al2O3 in LHDAC experiments. The developed double-sided LHDAC facility can accurately measure temperature and study phase transitions at extreme conditions.
研究不足
The study notes the restriction on using steel gaskets and Al2O3 as thermal insulating mediums due to their reaction with carbon. The accuracy of temperature measurement is ±25 K.
1：Experimental Design and Method Selection:
The study utilizes a double-sided laser-heated diamond anvil cell (LHDAC) facility for creating extreme conditions of pressure and temperature. The methodology includes the use of a continuous wave Ytterbium fiber laser for heating and a blue laser for observing laser speckle motion on the sample surface during melting. Thermal emission spectra are collected for temperature measurement.
2：Sample Selection and Data Sources:
High-purity graphite plates and mixtures of Fe and C, and Al2O3 and C are used as samples. Pressure inside the DAC is calculated from the shift of ruby fluorescence peak.
3：List of Experimental Equipment and Materials:
Equipment includes a diode pumped continuous wave Ytterbium fiber laser system, SP 150 Acton series spectrometer, and high-power wave plate. Materials include graphite, Fe, C, Al2O3, and NaCl.
4：Experimental Procedures and Operational Workflow:
Samples are heated to extreme conditions, and temperature is measured with an accuracy of ±25 K. The formation of micrometer-sized diamond crystals is confirmed by visual inspection, micro-Raman, and FESEM measurements.
5：Data Analysis Methods:
Thermal radiation spectra are analyzed to estimate temperature. Raman spectroscopy and XRD measurements are used to confirm phase transitions and reactions.
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