The magnetic particles of nickel-zinc ferrite with chemical composition Ni1-xZnxFe2O4 were synthesized successfully by citrate precursor auto-combustion method using high purity nitrates and citric acid as chelating a...The magnetic particles of nickel-zinc ferrite with chemical composition Ni1-xZnxFe2O4 were synthesized successfully by citrate precursor auto-combustion method using high purity nitrates and citric acid as chelating agent. The prepared powder of nickel-zinc ferrites was sintered at 1000℃ for 1 hr to obtain good crystalline phase and was used for further study. The X-ray diffraction technique was employed to confirm the single phase formation of nickel ferrite. The X-ray diffraction pattern shows the Bragg’s peak which belongs to cubic spinel structure. The values of lattice constant, X-ray density, bulk density, and porosity were calculated. The temperature dependence of the electrical conductivity plot shows the kink, which can be attributed to ferromagnetic-paramagnetic transition. The activation energy obtained from resistivity plots in paramagnetic region is found to be more than that in ferrimagnetic region. The conduction mechanism in nickel-zinc ferrite particles has been discussed on the basis of hopping of electrons.展开更多
Potassium promoted iron–zinc catalysts prepared by co-precipitation method(C–Fe–Zn/K),solvothermal method(S–Fe–Zn/K)and hydrothermal method(H–Fe–Zn/K)could selectively convert CO_2to light olefins,respectively....Potassium promoted iron–zinc catalysts prepared by co-precipitation method(C–Fe–Zn/K),solvothermal method(S–Fe–Zn/K)and hydrothermal method(H–Fe–Zn/K)could selectively convert CO_2to light olefins,respectively.The physicochemical properties of the obtained catalysts were determined by SEM,N_2physisorption,XRD,H_2-TPR,CO_2-TPD and XPS measurements.The results demonstrated that preparation methods had great influences on the morphology,phase structures,reduction and adsorption behavior,and hence the catalytic performance of the catalysts.The samples prepared by hydrothermal and co-precipitation method generated small uniform particles and led to lower specific surface area.In contrast,microspheres with larger specific surface area were formed by self-assembly of nanosheets using solvothermal method.ZnFe_2O_4was the only detectable phase in the fresh C–2Fe–1Zn/K,S–3Fe–1Zn/K and S–2Fe–1Zn/K samples.ZnFe_2O_4and ZnO co-existed with increasing Zncontent in S–1Fe–1Zn/K sample,while ZnO and Fe_2O_3could be observed over H–2Fe–1Zn/K sample.All the used samples contained Fe_3O_4,ZnO and Fe_5C_2.The peak intensity of ZnO was strong in the AR-H–2Fe–1Zn/K sample while it was the lowest in the AR-C–2Fe–1Zn/K sample after reaction.The formation of ZnFe_2O_4increased the interaction between iron and zinc for C–2Fe–1Zn/K and S–Fe–Zn/K samples,causing easier reduction of Fe_2O_3to Fe_3O_4.The surface basicity of the sample prepared by co-precipitation method was much more than that of the other two methods.During CO_2hydrogenation,all the catalysts showed good activity and olefin selectivity.The CO selectivity was increased with increasing Zncontent over S–Fe–Zn/K samples.H–2Fe–1Zn/K catalyst preferred to the production of C_5^+hydrocarbons.CO_2conversion of 54.76%and C_2~=–C_4~=contents of 57.38%were obtained on C–2Fe–1Zn/K sample,respectively.展开更多
A type of carbonate-hosted lead–zinc(Pb–Zn)ore deposits, known as Mississippi Valley Type(MVT)deposits, constitutes an important category of lead–zinc ore deposits. Previous studies proposed a fluid-mixing model to...A type of carbonate-hosted lead–zinc(Pb–Zn)ore deposits, known as Mississippi Valley Type(MVT)deposits, constitutes an important category of lead–zinc ore deposits. Previous studies proposed a fluid-mixing model to account for metal precipitation mechanism of the MVT ore deposits, in which fluids with metal-chloride complexes happen to mix with fluids with reduced sulfur, producing metal sulfide deposition. In this hypothesis, however, the detailed chemical kinetic process of mixing reactions, and especially the controlling factors on the metal precipitation are not yet clearly stated. In this paper, a series of mixing experiments under ambient temperature and pressure conditions were conducted to simulate the fluid mixing process, by titrating the metal-chloride solutions, doping withor without dolomite, and using NaHS solution. Experimental results, combined with the thermodynamic calculations, suggest that H_2S, rather than HS^-or S^(2-),dominated the reactions of Pb and/or Zn precipitation during the fluid mixing process, in which metal precipitation was influenced by the stability of metal complexes and the pH. Given the constant concentrations of metal and total S in fluids, the pH was a primary factor controlling the Pb and/or Zn metal precipitation. This is because neutralizing or neutralized processes for the ore-forming fluids can cause instabilities of Pb and/or Zn chloride complexes and re-distribution of sulfur species, and thus can facilitate the hydrolysis of Pb and Zn ions and precipitation of sulfides. Therefore, a weakly acidic to neutral fluid environment is most favorable for the precipitation of Pb and Zn sulfides associated with the carbonate-hosted Pb–Zn deposits.展开更多
In this work, a method based on scanning Kelvin probe microscopy is proposed to separately extract source/drain（S/D） series resistance in operating amorphous indium–gallium–zinc–oxide（a-IGZO） thin-film transist...In this work, a method based on scanning Kelvin probe microscopy is proposed to separately extract source/drain（S/D） series resistance in operating amorphous indium–gallium–zinc–oxide（a-IGZO） thin-film transistors. The asymmetry behavior of S/D contact resistance is deduced and the underlying physics is discussed. The present results suggest that the asymmetry of S/D contact resistance is caused by the difference in bias conditions of the Schottky-like junction at the contact interface induced by the parasitic reaction between contact metal and a-IGZO. The overall contact resistance should be determined by both the bulk channel resistance of the contact region and the interface properties of the metalsemiconductor junction.展开更多
It is know from literature that small additions(<1 wt%)of Ca,Al and Zn significantly improve the intrinsic ductility of Mg.The exact role of each element,both qualitatively and quantitatively,and their combined eff...It is know from literature that small additions(<1 wt%)of Ca,Al and Zn significantly improve the intrinsic ductility of Mg.The exact role of each element,both qualitatively and quantitatively,and their combined effects,however,are poorly understood.Here we achieved a much clearer view on the quantitative role of each element with respect to ductility improvement and on the collaborative effect,particularly of Ca and Zn in Mg.Some of our findings and conclusions are in disagreement with data and interpretation found in literature.Four different alloys,namely,Mg-0.1 Ca,Mg-0.1 Ca-1 Al,Mg-0.05 Ca-1 Al,Mg-0.1 Ca-2 Al-1 Zn(all are in wt%)were selected for this investigation.All alloys were treated such that approx.similar grain sizes and textures were obtained.This largely excludes the effect of extrinsic factors on ductility.EBSD-guided slip trace analyses reveal that the addition of Ca eases activation of prismatic and pyramidal II slip systems.Using in-situ deformation experiments in SEM and atom probe tomography observations of grain boundaries direct evidence is given for the individual and synergetic effects of Ca and Zn on grain boundary cohesion as an important contribution to improve the ductility of these alloys.We conclude that Ca reduces the slip anisotropy and ameliorates ductility,however,the weak grain boundary cohesion in the Mg-0.1 wt%Ca alloy limits the material’s tensile ductility.The addition of Zn alters the Ca segregation at the grain boundaries and helps to retain their cohesive strength,an effect which thus enables higher ductility and strength.The further addition of Al primarily improves the strength.The results show that the balanced influence of reduced slip anisotropy on the one hand and increased grain boundary cohesion on the other hand allow to design a high strength high ductility rare-earth free Mg alloy.展开更多
The Mengya’a Lead–zinc deposit is a large skarn deposit in the north of the eastern segment of Gangdese metallogenic belt.The garnet is the main altered mineral in the Mengya’a area.The color of the garnet varies f...The Mengya’a Lead–zinc deposit is a large skarn deposit in the north of the eastern segment of Gangdese metallogenic belt.The garnet is the main altered mineral in the Mengya’a area.The color of the garnet varies from chartreuse to dark yellow brown and to russet.The brown garnet(Grt1)is related to pyrrhotite and chalcopyrite,and the green garnet(Grt2)is associated with lead–zinc mineralization.LA-ICP-MS is the induced coupled plasma mass spectrometry.This paper has used this technique to investigate Grt1 and Grt2.Grt1 develops core–rim textures with strong oscillation zone occurring in rim,whereas Grt2lacks core–rim textures and featured by oscillation zone.LA–ICP–MS analysis shows that garnets of Mengya’a are rich in CaO(29.90–37.52%)and FeO(21.17–33.35%),but low in Al_(2)O_(3)(0.05–4.85%).The calculated end members belong to grandite(grossular–andradite)garnets andradite.The negative Al(IV)versus Fe^(3+),positive Al(IV)versus total Al stoichiometric number,the positive Al(IV)versus Fe^(3+),and the negative Al(IV)versus total REE,all indicate that the substitution of REEs in garnets is controlled by YAG.All Garnets are depleted in large lithophile elements(e.g.,Rb=0.00–4.01 ppm,Sr=0.03–8.56 ppm).The total REE in Grt1 core is high(ΣREE=233–625 ppm),with HREE enriched pattern(LREE/HREE=0.33–1.69)and weak negative Eu anomalies(δEu=0.21–0.47).In contrast,the total REEs in the Grt1 rim and Grt2 are low(ΣREE=12.4–354 ppm;ΣREE=21.0–65.3 ppm),with LREE enriched pattern(LREE/HREE=0.54–34.4;LREE/HREE=11.4–682)and positive Eu anomalies(δEu=0.35–27.2;δEu=1.02–30.7).After data compilation of garnet chemicals,we found that the early fluid responsible for the core of Grt1 was a relatively closed and chloride-depleted fluid system.It was close-to-neutral,with a low water–rock ratio.The core of garnet was formed by fluid diffusion in metasomatic processes.The fluid was changed into a relatively open system with reduced,chloride-rich,and weakacid fluid.It was fluid infiltra展开更多
A sodium–zinc sorbent based flue gas desulfurization technology(Na–Zn-FGD) was proposed based on the experiments and analyses of the thermal decomposition characteristics of Ca SO3 and Zn SO3·2.5H2 O, the waste...A sodium–zinc sorbent based flue gas desulfurization technology(Na–Zn-FGD) was proposed based on the experiments and analyses of the thermal decomposition characteristics of Ca SO3 and Zn SO3·2.5H2 O, the waste products of calcium-based semi-dry and zinc-based flue gas desulfurization(Ca–SD-FGD and Zn–SD-FGD) technologies, respectively. It was found that Zn SO3·2.5H2 O first lost crystal H2 O at 100 °C and then decomposed into SO2 and solid Zn O at 260 °C in the air, while Ca SO3 is oxidized at 450 °C before it decomposed in the air. The experimental results confirm that Zn–SD-FGD technology is good for SO2 removal and recycling, but with problem in clogging and high operational cost. The proposed Na–Zn-FGD is clogging proof, and more cost-effective. In the new process, Na2CO3 is used to generate Na2SO3 for SO2absorption, and the intermediate product Na HSO3 reacts with Zn O powders, producing Zn SO3·2.5H2 O precipitate and Na2SO3 solution. The Na2SO3 solution is clogging proof, which is re-used for SO2 absorption. By thermal decomposition of Zn SO3·2.5H2 O, Zn O is re-generated and SO2 with high purity is co-produced as well. The cycle consumes some amount of raw material Na2CO3 and a small amount of Zn O only. The newly proposed FGD technology could be a substitute of the traditional semi-dry FGD technologies.展开更多
文摘The magnetic particles of nickel-zinc ferrite with chemical composition Ni1-xZnxFe2O4 were synthesized successfully by citrate precursor auto-combustion method using high purity nitrates and citric acid as chelating agent. The prepared powder of nickel-zinc ferrites was sintered at 1000℃ for 1 hr to obtain good crystalline phase and was used for further study. The X-ray diffraction technique was employed to confirm the single phase formation of nickel ferrite. The X-ray diffraction pattern shows the Bragg’s peak which belongs to cubic spinel structure. The values of lattice constant, X-ray density, bulk density, and porosity were calculated. The temperature dependence of the electrical conductivity plot shows the kink, which can be attributed to ferromagnetic-paramagnetic transition. The activation energy obtained from resistivity plots in paramagnetic region is found to be more than that in ferrimagnetic region. The conduction mechanism in nickel-zinc ferrite particles has been discussed on the basis of hopping of electrons.
基金Supports by the National Natural Science Foundation of China(21666030,21366025)National First-rate Discipline Construction Project of Ningxia(NXYLXK2017A04)
文摘Potassium promoted iron–zinc catalysts prepared by co-precipitation method(C–Fe–Zn/K),solvothermal method(S–Fe–Zn/K)and hydrothermal method(H–Fe–Zn/K)could selectively convert CO_2to light olefins,respectively.The physicochemical properties of the obtained catalysts were determined by SEM,N_2physisorption,XRD,H_2-TPR,CO_2-TPD and XPS measurements.The results demonstrated that preparation methods had great influences on the morphology,phase structures,reduction and adsorption behavior,and hence the catalytic performance of the catalysts.The samples prepared by hydrothermal and co-precipitation method generated small uniform particles and led to lower specific surface area.In contrast,microspheres with larger specific surface area were formed by self-assembly of nanosheets using solvothermal method.ZnFe_2O_4was the only detectable phase in the fresh C–2Fe–1Zn/K,S–3Fe–1Zn/K and S–2Fe–1Zn/K samples.ZnFe_2O_4and ZnO co-existed with increasing Zncontent in S–1Fe–1Zn/K sample,while ZnO and Fe_2O_3could be observed over H–2Fe–1Zn/K sample.All the used samples contained Fe_3O_4,ZnO and Fe_5C_2.The peak intensity of ZnO was strong in the AR-H–2Fe–1Zn/K sample while it was the lowest in the AR-C–2Fe–1Zn/K sample after reaction.The formation of ZnFe_2O_4increased the interaction between iron and zinc for C–2Fe–1Zn/K and S–Fe–Zn/K samples,causing easier reduction of Fe_2O_3to Fe_3O_4.The surface basicity of the sample prepared by co-precipitation method was much more than that of the other two methods.During CO_2hydrogenation,all the catalysts showed good activity and olefin selectivity.The CO selectivity was increased with increasing Zncontent over S–Fe–Zn/K samples.H–2Fe–1Zn/K catalyst preferred to the production of C_5^+hydrocarbons.CO_2conversion of 54.76%and C_2~=–C_4~=contents of 57.38%were obtained on C–2Fe–1Zn/K sample,respectively.
基金supported jointly by the National Key R&D Program of China (No. 2016YFC0600408)the National Natural Science Foundation of China (Nos. 41572060, 41773054, U1133602, 41802089)+3 种基金China Postdoctoral Science Foundation (No. 2017M610614)projects of YM Lab (2011)Innovation Team of Yunnan Province and KMUST (2008 and 2012)Yunnan and Kunming University of Science and Technology Postdoctoral Sustentation Fund
文摘A type of carbonate-hosted lead–zinc(Pb–Zn)ore deposits, known as Mississippi Valley Type(MVT)deposits, constitutes an important category of lead–zinc ore deposits. Previous studies proposed a fluid-mixing model to account for metal precipitation mechanism of the MVT ore deposits, in which fluids with metal-chloride complexes happen to mix with fluids with reduced sulfur, producing metal sulfide deposition. In this hypothesis, however, the detailed chemical kinetic process of mixing reactions, and especially the controlling factors on the metal precipitation are not yet clearly stated. In this paper, a series of mixing experiments under ambient temperature and pressure conditions were conducted to simulate the fluid mixing process, by titrating the metal-chloride solutions, doping withor without dolomite, and using NaHS solution. Experimental results, combined with the thermodynamic calculations, suggest that H_2S, rather than HS^-or S^(2-),dominated the reactions of Pb and/or Zn precipitation during the fluid mixing process, in which metal precipitation was influenced by the stability of metal complexes and the pH. Given the constant concentrations of metal and total S in fluids, the pH was a primary factor controlling the Pb and/or Zn metal precipitation. This is because neutralizing or neutralized processes for the ore-forming fluids can cause instabilities of Pb and/or Zn chloride complexes and re-distribution of sulfur species, and thus can facilitate the hydrolysis of Pb and Zn ions and precipitation of sulfides. Therefore, a weakly acidic to neutral fluid environment is most favorable for the precipitation of Pb and Zn sulfides associated with the carbonate-hosted Pb–Zn deposits.
基金Project supported by the Key Industrial R&D Program of Jiangsu Province,China(Grant No.BE2015155)the Priority Academic Program Development of Higher Education Institutions of Jiangsu Province,Chinathe Fundamental Research Funds for the Central Universities,China(Grant No.021014380033)
文摘In this work, a method based on scanning Kelvin probe microscopy is proposed to separately extract source/drain（S/D） series resistance in operating amorphous indium–gallium–zinc–oxide（a-IGZO） thin-film transistors. The asymmetry behavior of S/D contact resistance is deduced and the underlying physics is discussed. The present results suggest that the asymmetry of S/D contact resistance is caused by the difference in bias conditions of the Schottky-like junction at the contact interface induced by the parasitic reaction between contact metal and a-IGZO. The overall contact resistance should be determined by both the bulk channel resistance of the contact region and the interface properties of the metalsemiconductor junction.
基金the financial support by the international doctoral school IMPRS,Surmat。
文摘It is know from literature that small additions(<1 wt%)of Ca,Al and Zn significantly improve the intrinsic ductility of Mg.The exact role of each element,both qualitatively and quantitatively,and their combined effects,however,are poorly understood.Here we achieved a much clearer view on the quantitative role of each element with respect to ductility improvement and on the collaborative effect,particularly of Ca and Zn in Mg.Some of our findings and conclusions are in disagreement with data and interpretation found in literature.Four different alloys,namely,Mg-0.1 Ca,Mg-0.1 Ca-1 Al,Mg-0.05 Ca-1 Al,Mg-0.1 Ca-2 Al-1 Zn(all are in wt%)were selected for this investigation.All alloys were treated such that approx.similar grain sizes and textures were obtained.This largely excludes the effect of extrinsic factors on ductility.EBSD-guided slip trace analyses reveal that the addition of Ca eases activation of prismatic and pyramidal II slip systems.Using in-situ deformation experiments in SEM and atom probe tomography observations of grain boundaries direct evidence is given for the individual and synergetic effects of Ca and Zn on grain boundary cohesion as an important contribution to improve the ductility of these alloys.We conclude that Ca reduces the slip anisotropy and ameliorates ductility,however,the weak grain boundary cohesion in the Mg-0.1 wt%Ca alloy limits the material’s tensile ductility.The addition of Zn alters the Ca segregation at the grain boundaries and helps to retain their cohesive strength,an effect which thus enables higher ductility and strength.The further addition of Al primarily improves the strength.The results show that the balanced influence of reduced slip anisotropy on the one hand and increased grain boundary cohesion on the other hand allow to design a high strength high ductility rare-earth free Mg alloy.
基金funded by the Surface Project of National Natural Science Foundation of China (41372093)。
文摘The Mengya’a Lead–zinc deposit is a large skarn deposit in the north of the eastern segment of Gangdese metallogenic belt.The garnet is the main altered mineral in the Mengya’a area.The color of the garnet varies from chartreuse to dark yellow brown and to russet.The brown garnet(Grt1)is related to pyrrhotite and chalcopyrite,and the green garnet(Grt2)is associated with lead–zinc mineralization.LA-ICP-MS is the induced coupled plasma mass spectrometry.This paper has used this technique to investigate Grt1 and Grt2.Grt1 develops core–rim textures with strong oscillation zone occurring in rim,whereas Grt2lacks core–rim textures and featured by oscillation zone.LA–ICP–MS analysis shows that garnets of Mengya’a are rich in CaO(29.90–37.52%)and FeO(21.17–33.35%),but low in Al_(2)O_(3)(0.05–4.85%).The calculated end members belong to grandite(grossular–andradite)garnets andradite.The negative Al(IV)versus Fe^(3+),positive Al(IV)versus total Al stoichiometric number,the positive Al(IV)versus Fe^(3+),and the negative Al(IV)versus total REE,all indicate that the substitution of REEs in garnets is controlled by YAG.All Garnets are depleted in large lithophile elements(e.g.,Rb=0.00–4.01 ppm,Sr=0.03–8.56 ppm).The total REE in Grt1 core is high(ΣREE=233–625 ppm),with HREE enriched pattern(LREE/HREE=0.33–1.69)and weak negative Eu anomalies(δEu=0.21–0.47).In contrast,the total REEs in the Grt1 rim and Grt2 are low(ΣREE=12.4–354 ppm;ΣREE=21.0–65.3 ppm),with LREE enriched pattern(LREE/HREE=0.54–34.4;LREE/HREE=11.4–682)and positive Eu anomalies(δEu=0.35–27.2;δEu=1.02–30.7).After data compilation of garnet chemicals,we found that the early fluid responsible for the core of Grt1 was a relatively closed and chloride-depleted fluid system.It was close-to-neutral,with a low water–rock ratio.The core of garnet was formed by fluid diffusion in metasomatic processes.The fluid was changed into a relatively open system with reduced,chloride-rich,and weakacid fluid.It was fluid infiltra
基金supported by the National Natural Science Foundation of China (51802029)the Scientific Research for the Introduction of Talents of Changsha University (SF1606)。
基金Supported by the National High Technology Research and Development Program of China(2009AA05Z302)
文摘A sodium–zinc sorbent based flue gas desulfurization technology(Na–Zn-FGD) was proposed based on the experiments and analyses of the thermal decomposition characteristics of Ca SO3 and Zn SO3·2.5H2 O, the waste products of calcium-based semi-dry and zinc-based flue gas desulfurization(Ca–SD-FGD and Zn–SD-FGD) technologies, respectively. It was found that Zn SO3·2.5H2 O first lost crystal H2 O at 100 °C and then decomposed into SO2 and solid Zn O at 260 °C in the air, while Ca SO3 is oxidized at 450 °C before it decomposed in the air. The experimental results confirm that Zn–SD-FGD technology is good for SO2 removal and recycling, but with problem in clogging and high operational cost. The proposed Na–Zn-FGD is clogging proof, and more cost-effective. In the new process, Na2CO3 is used to generate Na2SO3 for SO2absorption, and the intermediate product Na HSO3 reacts with Zn O powders, producing Zn SO3·2.5H2 O precipitate and Na2SO3 solution. The Na2SO3 solution is clogging proof, which is re-used for SO2 absorption. By thermal decomposition of Zn SO3·2.5H2 O, Zn O is re-generated and SO2 with high purity is co-produced as well. The cycle consumes some amount of raw material Na2CO3 and a small amount of Zn O only. The newly proposed FGD technology could be a substitute of the traditional semi-dry FGD technologies.
