研究目的
Investigating the high-pressure behavior of TiO2 nanorods with the rutile-type structure using in-situ Raman spectroscopy to understand the phase transitions and the impact of morphology on these transitions.
研究成果
The study concludes that TiO2 nanorods with rutile-type structure undergo a phase transition to a disordered baddeleyite structure under pressure, with the metastable α-PbO2 structure preserved down to ambient pressure upon decompression. The complexity of the experimental phase diagram is attributed to the observation of metastable phases favored by kinetics reasons associated to transition pathways and imbeded nucleation.
研究不足
The study acknowledges the difficulty in decoupling the effects of non-hydrostaticity and the extended pressure range where both phases coexist. The impact of sample preparation and experimental protocol on the observed phase transitions is also noted.
1：Experimental Design and Method Selection:
The study used Raman spectroscopy under high pressure to investigate TiO2 nanorods. The methodology included simulating the vibrational density of states (vDOS) for comparison with experimental spectra.
2：Sample Selection and Data Sources:
TiO2 nanorods with a diameter of 6-8 nm were synthesized and characterized at ambient pressure before high-pressure experiments.
3：List of Experimental Equipment and Materials:
A Horiba low frequency Labram Raman spectrometer operated with a 532 nm wavelength was used for Raman experiments. High pressure was generated using a membrane DAC with low-fluorescence diamonds.
4：Experimental Procedures and Operational Workflow:
Samples were placed into a 125 μm chamber drilled in an indented stainless steel gasket without a pressure transmitting medium. Pressure was probed by the shift of the R1 fluorescence line of a small ruby chip.
5：Data Analysis Methods:
Peak positions were fitted for each pressure point, and ω(P) functions were compared to results of simulations.
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