| Summary: | 碩士 === 國立臺灣師範大學 === 物理學系 === 99 === In this research, our samples were calcined ( 400 oC, 3 hours) mixtures of MgO and V2O5 powders in different proportions. We irradiated our sample powders with laser beams, and samples that heated by laser were examined by Raman spectroscopy to determine the crystalline structure. Controlling the laser heating time and power, and heated powder samples formed similar crystal as found in conventional hearting. This study can resolve the process and mechanism of MgV2O6 and Mg2V2O7 crystalline formation.
When we treated the samples with Gaussian beams, we found that there is a positive correlation between the degree of phase transition and Gaussian energy distribution. Using 514.5nm and 532nm laser as irradiating light and controlled the laser power, the heating result we analyze from Raman spectra told us the energy cause crystalline were originated from photons. Plus X-ray absorption spectrum(XAS) and Photoluminescence(PL) result, we could build a very possible model of energy transfer for laser heating.
Furthermore, we could get the continuous information of phase transition by heating our samples uninterruptly and recording Raman spectra in the same time. There spectra showed us the high temperature messages of our sample, and the change of phonon vibration during the heating process. Because of the changes of phonon vibration reflect the structure change, we could ratiocination the way of our sample crystalline with the help of group theory analysis and X-ray absorption spectrum.
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