The etch characteristics of Si_1-xGex films in HNO3:H2O:HF were examined. The etch rate ratio (etch selectivity) between Si_1-xGex and Si escalated with the growth of HNO3 concentration at low concentration level, and...The etch characteristics of Si_1-xGex films in HNO3:H2O:HF were examined. The etch rate ratio (etch selectivity) between Si_1-xGex and Si escalated with the growth of HNO3 concentration at low concentration level, and when the HNO3 concentration exceeded a critical level the etch selectivity descended with higher HNO3 concentration. The dependence of etch selectivity on the HNO3 concentration was due to the higher critical HNO3 concentration for etching Si than that for etching Si1-xGex. Since the Ge-Ge bond energy was weaker than that of Si-Si and Si-Ge, the Ge atoms were oxidized preferentially once the HNO3 composition exceeded the critical concentration of etching Si1-xGex,which was manifested by the XPS spectra of Si1-xGex etched in HNO3:H2O:HF. When the HNO3 volume rose to another critical value, the significant growth of the Si etch rate low-ered the etch selectivity. Although both the etch rates of Si1-xGex and Si dropped with lower HF concentration, the etch rate ra-tio of Si1-xGex to Si boosted remarkably due to the water-soluble characteristics of GeO2.展开更多
Silver surfaces producing enhancement of the Raman scattering for adsorbed molecules have been simply prepared by etching them in HNO<sub>3</sub> solution. The dependence of the enhancement on etching time...Silver surfaces producing enhancement of the Raman scattering for adsorbed molecules have been simply prepared by etching them in HNO<sub>3</sub> solution. The dependence of the enhancement on etching time at different concentrations of the etching solution has also been investigated. When etched with 2.5 mol/L HNO<sub>3</sub> for 10-20 min, silver surfaces can all produce strong enhancement, and the surface-enhanced Raman scattering （SERS） activity can survive for more than 10 h in air. For Kr<sup>+</sup> laser excitation at 647.1 nm, the observed展开更多
The development of new and efficient extractants plays a key role in the separation and recovery of rare earth elements.In this pape r,the extractant(N,N-methyl py ridineethyl-N',N'-dicyclohexyl-3-oxadiglycola...The development of new and efficient extractants plays a key role in the separation and recovery of rare earth elements.In this pape r,the extractant(N,N-methyl py ridineethyl-N',N'-dicyclohexyl-3-oxadiglycolamide,MPyEDChDGA) with a new structure was synthesized,and the pyridine group was successfully grafted onto the 3-oxadiglycolamide structure.Using MPyEDChDGA for efficient enrichment of rare earth ions,the self-assembled solids were recovered by simple filtration without further backextraction and final precipitation,achieving a one-step strategy for the recovery of rare earth ions.Several important parameters affecting the self-assembly extraction,including pH,diluent,temperature,and extractant concentration,were systematically evaluated using La(NO_(3))_(3),Tb(NO_(3))_(3),and Lu(NO_(3))_(3) as representatives.The self-assembled solids were investigated in detail by X-ray diffraction(XRD),scanning electron microscopy(SEM),1H nuclear magnetic resonance(1H NMR),Fourier transform infrared spectroscopy(FT-IR),Raman,and X-ray photoelectron spectroscopy(XPS) analyses.The stoichiometry of the extraction species was characterized using the Job's method and electrospray ionization mass spectrometry(ESI-MS).In addition,MPyEDChDGA was applied to the recovery of Sm in SmCoCu simulated liquid,and the results show that MPyEDChDGA has good selectivity of Sm from transition metals(Co,Cu).The separation factor of Sm/Co can reach 6281±117,which provides a new approach to recovering Sm from SmCoCu scrap magnets.This study presents an efficient and convenient new strategy for the recovery and separation of rare earth elements.展开更多
The loss pathways of Ni and Co during Al and Sc enrichment were analyzed in the HNO_(3) leach liquor of saprolitic laterite ore.Although over 99%of Al and Sc can be enriched,about 40%of Ni and Co are also lost.The ads...The loss pathways of Ni and Co during Al and Sc enrichment were analyzed in the HNO_(3) leach liquor of saprolitic laterite ore.Although over 99%of Al and Sc can be enriched,about 40%of Ni and Co are also lost.The adsorption of Al-Sc precipitate is an important cause of Ni and Co loss.Subsequently,the precipitation behavior of metal ions in the different nitrate solutions was studied.The results confirm that Ni^(2+)and Co^(2+)do not hydrolyze to form their respective hydroxides.Ni^(2+),Co^(2+)and Mg^(2+)can form composite hydroxides with precipitated Al(OH)3,decreasing the pH at which Ni^(2+)and Co^(2+)begin to precipitate,causing their co-precipitation loss.A high Mg^(2+)concentration enhances the formation of these composite hydroxides.Finally,titration curves for different nitrate systems were determined,further demonstrating the formation of Me-Al composite hydroxides and revealing a formation trend of Mg-Al>Co-Al>Ni-Al.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 61006088)the National Basic Research Program of China (973 Program) (Grant No. 2010CB832906)the Natural Sci-ence Foundation of Shanghai (Grant No. 10ZR1436100)
文摘The etch characteristics of Si_1-xGex films in HNO3:H2O:HF were examined. The etch rate ratio (etch selectivity) between Si_1-xGex and Si escalated with the growth of HNO3 concentration at low concentration level, and when the HNO3 concentration exceeded a critical level the etch selectivity descended with higher HNO3 concentration. The dependence of etch selectivity on the HNO3 concentration was due to the higher critical HNO3 concentration for etching Si than that for etching Si1-xGex. Since the Ge-Ge bond energy was weaker than that of Si-Si and Si-Ge, the Ge atoms were oxidized preferentially once the HNO3 composition exceeded the critical concentration of etching Si1-xGex,which was manifested by the XPS spectra of Si1-xGex etched in HNO3:H2O:HF. When the HNO3 volume rose to another critical value, the significant growth of the Si etch rate low-ered the etch selectivity. Although both the etch rates of Si1-xGex and Si dropped with lower HF concentration, the etch rate ra-tio of Si1-xGex to Si boosted remarkably due to the water-soluble characteristics of GeO2.
文摘Silver surfaces producing enhancement of the Raman scattering for adsorbed molecules have been simply prepared by etching them in HNO<sub>3</sub> solution. The dependence of the enhancement on etching time at different concentrations of the etching solution has also been investigated. When etched with 2.5 mol/L HNO<sub>3</sub> for 10-20 min, silver surfaces can all produce strong enhancement, and the surface-enhanced Raman scattering （SERS） activity can survive for more than 10 h in air. For Kr<sup>+</sup> laser excitation at 647.1 nm, the observed
基金Project supported by the Natural Science Foundation of Shandong Province (ZR2022QB067)。
文摘The development of new and efficient extractants plays a key role in the separation and recovery of rare earth elements.In this pape r,the extractant(N,N-methyl py ridineethyl-N',N'-dicyclohexyl-3-oxadiglycolamide,MPyEDChDGA) with a new structure was synthesized,and the pyridine group was successfully grafted onto the 3-oxadiglycolamide structure.Using MPyEDChDGA for efficient enrichment of rare earth ions,the self-assembled solids were recovered by simple filtration without further backextraction and final precipitation,achieving a one-step strategy for the recovery of rare earth ions.Several important parameters affecting the self-assembly extraction,including pH,diluent,temperature,and extractant concentration,were systematically evaluated using La(NO_(3))_(3),Tb(NO_(3))_(3),and Lu(NO_(3))_(3) as representatives.The self-assembled solids were investigated in detail by X-ray diffraction(XRD),scanning electron microscopy(SEM),1H nuclear magnetic resonance(1H NMR),Fourier transform infrared spectroscopy(FT-IR),Raman,and X-ray photoelectron spectroscopy(XPS) analyses.The stoichiometry of the extraction species was characterized using the Job's method and electrospray ionization mass spectrometry(ESI-MS).In addition,MPyEDChDGA was applied to the recovery of Sm in SmCoCu simulated liquid,and the results show that MPyEDChDGA has good selectivity of Sm from transition metals(Co,Cu).The separation factor of Sm/Co can reach 6281±117,which provides a new approach to recovering Sm from SmCoCu scrap magnets.This study presents an efficient and convenient new strategy for the recovery and separation of rare earth elements.
基金supported by the National Natural Science Foundation of China(No.U2202254).
文摘The loss pathways of Ni and Co during Al and Sc enrichment were analyzed in the HNO_(3) leach liquor of saprolitic laterite ore.Although over 99%of Al and Sc can be enriched,about 40%of Ni and Co are also lost.The adsorption of Al-Sc precipitate is an important cause of Ni and Co loss.Subsequently,the precipitation behavior of metal ions in the different nitrate solutions was studied.The results confirm that Ni^(2+)and Co^(2+)do not hydrolyze to form their respective hydroxides.Ni^(2+),Co^(2+)and Mg^(2+)can form composite hydroxides with precipitated Al(OH)3,decreasing the pH at which Ni^(2+)and Co^(2+)begin to precipitate,causing their co-precipitation loss.A high Mg^(2+)concentration enhances the formation of these composite hydroxides.Finally,titration curves for different nitrate systems were determined,further demonstrating the formation of Me-Al composite hydroxides and revealing a formation trend of Mg-Al>Co-Al>Ni-Al.
