A series of La0.7-xSmxSr0.3MnO3, La0.7-xGdxSr0.3MnO3, and La0.7-xDyxSr0.3MnO3 （x=0.00, 0.10, 0.20, 0.30） samples were prepared by the solid-state reaction method. The influence of the substitution of Sm, Gd, and Dy ...A series of La0.7-xSmxSr0.3MnO3, La0.7-xGdxSr0.3MnO3, and La0.7-xDyxSr0.3MnO3 （x=0.00, 0.10, 0.20, 0.30） samples were prepared by the solid-state reaction method. The influence of the substitution of Sm, Gd, and Dy for La on the magnetic and electric properties and on the magnetoresistance （MR） was studied through measurements of M-T curves and p-T curves. The results showed that： lattice distortion induced by substitution of Sm, Gd, and Dy for La and extra magnetism of substitution had great influence on the magnetic and electric properties of pcrovskite manganites; substitution of magnetic rare earth element for La was an effective way to change Curie temperature and to strengthen MR in perovskite manganites; and appropriate substitution proportion would generate large MR near room temperature.展开更多
A selective method has been developed for the extraction chromatography of aluminium(Ⅲ) and its separation from several metal ions with a chromatographic column containing N-n-octylaniline ( a liquid anion exchanger)...A selective method has been developed for the extraction chromatography of aluminium(Ⅲ) and its separation from several metal ions with a chromatographic column containing N-n-octylaniline ( a liquid anion exchanger) coated on silanized silica gel as a stationary phase. The aluminium(Ⅲ) was quantitatively extracted with the 0. 065 mol / L N-n-octylaniline in 0. 013 to 0. 05 mol / L sodium succinate at a flow rate of 1. 0 mL / min. The extracted metal ion has been recovered by eluting with 25. 0 mL of 0. 05 mol / L hydrochloric acid and estimated spectrophotometrically with aurintricarboxylic acid. The effects of the acid concentration,the reagent concentration,the flow rate and the eluting agents have been investigated. The log-log plots of distribution coefficient ( K d ( Al(Ⅲ) ) ) versus N-n-octylaniline concentration in 0. 005 and 0. 007 mol / L sodium succinate gave the slopes of 0. 5 and 0. 7 respectively and showed the probable composition of the extracted species was 1∶ 1 ( metal to amine ratio ) and the nature of extracted species was [RR' NH + 2 Al succinate 2 ] org. . The extraction of aluminium(Ⅲ) was carried out in the presence of various ions to ascertain the tolerance limit of individual ions. Aluminium(Ⅲ) has been separated from multicomponent mixtures,pharmaceutical samples and synthetic mixtures corresponding to alloys. A scheme for mutual separation of aluminium(Ⅲ) ,indium(Ⅲ) ,gallium(Ⅲ) and thallium(Ⅲ) has been developed by using suitable masking agents. The method is fast,accurate and precise.展开更多
As no complete and comprehensive studies have been previously reported for La-doped nanocrystalline SrZrO_(3)(SZO),we researched herein a detailed investigation for pure and La-doped samples.A modified solid-state rea...As no complete and comprehensive studies have been previously reported for La-doped nanocrystalline SrZrO_(3)(SZO),we researched herein a detailed investigation for pure and La-doped samples.A modified solid-state reaction process,including successive cycles of milling and sintering at high temperature,was followed to produce SZO and Sr_(0.9)La_(0.1)ZrO_(3)(SLZO)powdered ingots.Rietveld analysis of X-ray diffractometer data predicts that the two samples exhibit orthorhombic structure with an increase in crystallite size by~25%for doped sample.A great reduction in Raman modes intensity(~60%)and an annihilation of several vibration modes were detected using Raman spectroscopy.The degree of ordering on the B-site was recorded to be higher in La-doped sample.According to ultraviolet-visible(UV-Vis)absorption,a decrease in the optical gap width(E_(g))from 4.40 eV to 4.21 eV was achieved by La incorporation due to the presence of additional defect states such as oxygen and Sr vacancies at the band edge.The process of electron-hole recombination was studied using photoluminescence(PL)spectroscopy.Deconvolution of PL spectra yielded four emission bands:one green band,one blue band,and two violet bands.Highly intense violet emission atλ=393 nm approximately five times greater than that detected for pure SZO is realized as La^(3+)substitutes for Sr^(2+).Such property nominates SLZO for technological applications requiring highly intense violet emission,e.g.,light-emitting diodes.展开更多
基金supported by the Key Programme of the National Natural Science Foundation of China (19934003)the Grand Programme of the Natu-ral Science Research of Education Bureau of Anhui Province (ZD2007003-1)+1 种基金 Natural Science Research Programme of Colleges and Universi-ties of Anhui Province (KJ2008A19ZC) Professors’ and Doctors’ Research Foundation of Suzhou College (2006jb02)
文摘A series of La0.7-xSmxSr0.3MnO3, La0.7-xGdxSr0.3MnO3, and La0.7-xDyxSr0.3MnO3 （x=0.00, 0.10, 0.20, 0.30） samples were prepared by the solid-state reaction method. The influence of the substitution of Sm, Gd, and Dy for La on the magnetic and electric properties and on the magnetoresistance （MR） was studied through measurements of M-T curves and p-T curves. The results showed that： lattice distortion induced by substitution of Sm, Gd, and Dy for La and extra magnetism of substitution had great influence on the magnetic and electric properties of pcrovskite manganites; substitution of magnetic rare earth element for La was an effective way to change Curie temperature and to strengthen MR in perovskite manganites; and appropriate substitution proportion would generate large MR near room temperature.
基金supported by BCUD,Pune University for providing financial assistance in form of a research project
文摘A selective method has been developed for the extraction chromatography of aluminium(Ⅲ) and its separation from several metal ions with a chromatographic column containing N-n-octylaniline ( a liquid anion exchanger) coated on silanized silica gel as a stationary phase. The aluminium(Ⅲ) was quantitatively extracted with the 0. 065 mol / L N-n-octylaniline in 0. 013 to 0. 05 mol / L sodium succinate at a flow rate of 1. 0 mL / min. The extracted metal ion has been recovered by eluting with 25. 0 mL of 0. 05 mol / L hydrochloric acid and estimated spectrophotometrically with aurintricarboxylic acid. The effects of the acid concentration,the reagent concentration,the flow rate and the eluting agents have been investigated. The log-log plots of distribution coefficient ( K d ( Al(Ⅲ) ) ) versus N-n-octylaniline concentration in 0. 005 and 0. 007 mol / L sodium succinate gave the slopes of 0. 5 and 0. 7 respectively and showed the probable composition of the extracted species was 1∶ 1 ( metal to amine ratio ) and the nature of extracted species was [RR' NH + 2 Al succinate 2 ] org. . The extraction of aluminium(Ⅲ) was carried out in the presence of various ions to ascertain the tolerance limit of individual ions. Aluminium(Ⅲ) has been separated from multicomponent mixtures,pharmaceutical samples and synthetic mixtures corresponding to alloys. A scheme for mutual separation of aluminium(Ⅲ) ,indium(Ⅲ) ,gallium(Ⅲ) and thallium(Ⅲ) has been developed by using suitable masking agents. The method is fast,accurate and precise.
基金the Grants Commission of Al-Azhar University,Cairo,Egypt for supporting this work。
文摘As no complete and comprehensive studies have been previously reported for La-doped nanocrystalline SrZrO_(3)(SZO),we researched herein a detailed investigation for pure and La-doped samples.A modified solid-state reaction process,including successive cycles of milling and sintering at high temperature,was followed to produce SZO and Sr_(0.9)La_(0.1)ZrO_(3)(SLZO)powdered ingots.Rietveld analysis of X-ray diffractometer data predicts that the two samples exhibit orthorhombic structure with an increase in crystallite size by~25%for doped sample.A great reduction in Raman modes intensity(~60%)and an annihilation of several vibration modes were detected using Raman spectroscopy.The degree of ordering on the B-site was recorded to be higher in La-doped sample.According to ultraviolet-visible(UV-Vis)absorption,a decrease in the optical gap width(E_(g))from 4.40 eV to 4.21 eV was achieved by La incorporation due to the presence of additional defect states such as oxygen and Sr vacancies at the band edge.The process of electron-hole recombination was studied using photoluminescence(PL)spectroscopy.Deconvolution of PL spectra yielded four emission bands:one green band,one blue band,and two violet bands.Highly intense violet emission atλ=393 nm approximately five times greater than that detected for pure SZO is realized as La^(3+)substitutes for Sr^(2+).Such property nominates SLZO for technological applications requiring highly intense violet emission,e.g.,light-emitting diodes.
