We propose the quantitative method of evaluating the purity of multiwall carbon nanotubes (MWCNTs) using Raman spectroscopy. High purity MWCNTs were prepared by chemical vapor deposition (CVD) to be used as a reference material with 100% purity. Since the intensity and wavenumber ofD′′-band located at around 1500 cm−1were found to be independent of the excitation wavelength of a laser, the purity of MWCNTs was measured by comparing the intensity ratio ofD′′-band toG-band (ID′′/IG) of the sample with that of a reference material. The established method was verified by testing the mixture of amorphous carbon particles and reference MWCNTs.
Efficient phosphors based on YNbO 4 and doped by Eu 3+ , Ga 3+ , Al 3+ were synthesized and investigated under UV, and X-ray excitation in luminescence and Raman spectroscopy. Monoclinic fergusonite crystal structure and excellent luminescent properties under X-ray excitation allow recommend these phosphors as good candidates for different applications.
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