Efforts have been made to prepare nanocomposites of a-Fe2O3-ZnO by wet chemical route with varying concentrations of the precursors.The microstructural properties of the samples are investigated by powder X-ray diffra...Efforts have been made to prepare nanocomposites of a-Fe2O3-ZnO by wet chemical route with varying concentrations of the precursors.The microstructural properties of the samples are investigated by powder X-ray diffractometry（PXRD） and Transmission electron microscopy.Initial concentration of Zn ions（up to 20 at%） leads to the formation of nanocomposites of a-Fe2O3 and ZnO.Evolution of ZnFe2O4 phase is detected by the substitution of higher concentration of Zn2？（30 at%） in the sample.The average size of the nanoparticles remains in the range of 22–27 nm as obtained from XRD data.The results obtained from electron microscopic studies are also close to these values.Photoluminescence measurement shows the excitonic peak of ZnO around 390 nm which gets strengthened with Zn addition.FTIR spectra show the metal–oxygen band below 700 cm-1.Room temperature Mssbauer studies of the samples show the transition of iron oxide form antiferromagnetic state to paramagnetic state with increasing concentration of Zn2？.Sharp quenching of hyperfine field with Zn concentration is observed as the Hintvalue reduced to zero from 51 T.展开更多
An abrasive free chemical mechanical planarization（AFCMP） of semi-polar（1122） Al N surface has been demonstrated. The effect of slurry p H, polishing pressure, and platen velocity on the material removal rate（MRR...An abrasive free chemical mechanical planarization（AFCMP） of semi-polar（1122） Al N surface has been demonstrated. The effect of slurry p H, polishing pressure, and platen velocity on the material removal rate（MRR） and surface quality（RMS roughness） have been studied. The effect of polishing pressure on the AFCMP of the（1122） Al N surface has been compared with that of the（1122） Al Ga N surface. The maximum MRR has been found to be 562 nm/h for the semi-polar（1122） Al N surface, under the experimental conditions of 38 k Pa pressure,90 rpm platen velocity, 30 rpm carrier velocity, slurry p H 3 and 0.4 M oxidizer concentration. The best root mean square（RMS） surface roughness of 1.2 nm and 0.7 nm, over a large scanning area of 0.70×0.96 mm^2, has been achieved on AFCMP processed semi-polar（1122） AlN and（AlGaN） surfaces using optimized slurry chemistry and processing parameters.展开更多
文摘Efforts have been made to prepare nanocomposites of a-Fe2O3-ZnO by wet chemical route with varying concentrations of the precursors.The microstructural properties of the samples are investigated by powder X-ray diffractometry（PXRD） and Transmission electron microscopy.Initial concentration of Zn ions（up to 20 at%） leads to the formation of nanocomposites of a-Fe2O3 and ZnO.Evolution of ZnFe2O4 phase is detected by the substitution of higher concentration of Zn2？（30 at%） in the sample.The average size of the nanoparticles remains in the range of 22–27 nm as obtained from XRD data.The results obtained from electron microscopic studies are also close to these values.Photoluminescence measurement shows the excitonic peak of ZnO around 390 nm which gets strengthened with Zn addition.FTIR spectra show the metal–oxygen band below 700 cm-1.Room temperature Mssbauer studies of the samples show the transition of iron oxide form antiferromagnetic state to paramagnetic state with increasing concentration of Zn2？.Sharp quenching of hyperfine field with Zn concentration is observed as the Hintvalue reduced to zero from 51 T.
基金financial support from the Department of Science and Technology(DST),Government of India(No,SR/S2/Cmp-0009/2011)partial support from the Board of Research in Nuclear Sciences(BRNS),Department of Atomic Energy(DAE),Government of India(No.-34/14/43/2014-BRNS)with ATC
文摘An abrasive free chemical mechanical planarization（AFCMP） of semi-polar（1122） Al N surface has been demonstrated. The effect of slurry p H, polishing pressure, and platen velocity on the material removal rate（MRR） and surface quality（RMS roughness） have been studied. The effect of polishing pressure on the AFCMP of the（1122） Al N surface has been compared with that of the（1122） Al Ga N surface. The maximum MRR has been found to be 562 nm/h for the semi-polar（1122） Al N surface, under the experimental conditions of 38 k Pa pressure,90 rpm platen velocity, 30 rpm carrier velocity, slurry p H 3 and 0.4 M oxidizer concentration. The best root mean square（RMS） surface roughness of 1.2 nm and 0.7 nm, over a large scanning area of 0.70×0.96 mm^2, has been achieved on AFCMP processed semi-polar（1122） AlN and（AlGaN） surfaces using optimized slurry chemistry and processing parameters.
