Phase transitions, laser heating

In recent years, it was reported that significant differences in specific heat, magnetization, and laser Raman spectroscopic properties between d- and /-alanine single crystals may be related to WNC and phase transition effects [136]. However, these results may originate from certain impurities incorporated in the crystals due to the lack of reproducibility which is carefully made by the other independent research groups [137]. 

Investigations of the amorphous-to-crystalline phase transition in electron-beam-evaporated silicon films using continuous wave (cw) laser heating have been reported by Bosch and Lemons (1982). Two facts are noteworthy (i) The amorphous-to-crystalline phase transition in a-Si starts at 600°C as determined by heating experiments and (ii) the crystallization process passes through two distinct states, possibly involving nano-crystallization. ... 

In conclusion, the Raman features observed and calculated for iron oxide crystals have been used as reference to identify Raman modes in their counterpart nanomaterials. Furthermore, it is known that the high power density from a laser excitation source can excessively heat a sample during a Raman experiment, as discussed previously. This effect becomes even more important for micro-Raman experiments of nanomaterials, where laser beams are focused to a spot size with a diameter of only a few micrometers, and nanoparticulates do not dissipate heat well. Moreover, an increase in the local sample temperature may cause a frequency shift in the Raman bands, or it may cause material degradation as the result of oxidation, recrystallization, order-disorder transitions, phase transition, or decomposition. 

To conclude, we have synthesized VO2 with a perfect crystal stmcture in opal pores using the chemical bath deposition technique. The parameters of the semiconductor-metal phase transition in the prepared material indicate the presence of a small amount of oxygen defects. We have achieved a controllable and reproducible variation of the PEG properties of the opal-V02 composite and inverted VO2 composite during heating and cooling. This is due to the change in the dielectric constant of VO2 at the phase transition. We demonstrated dynamical tuning of the PEG position in synthetic opals filled with VO2 imder laser pulses. 

Phase Transitions and Material Synthesis using the C02-Laser Heating Technique in a Diamond Cell... 

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