A series of nitrogen-doped SrMoO_(4) with different Sr/N mole ratio (R=0,0.05,0.10,0.15,0.20,0.40,and 0.60) were synthesized using urea as the N source via the vapor-thermal method.The photocatalytic degradation abili...A series of nitrogen-doped SrMoO_(4) with different Sr/N mole ratio (R=0,0.05,0.10,0.15,0.20,0.40,and 0.60) were synthesized using urea as the N source via the vapor-thermal method.The photocatalytic degradation ability of all samples was evaluated using methylene blue (MB) as a target contaminant.The band gaps of N-doped samples are all higher than that of pristine ones,which is only 3.12 eV.BET specific surface area S_(BET) and pore volume are increased due to the N doping.And the greater increase of S_(BET),the faster the photodegradation speed of methylene blue on SrMoO_(4).More specifically,the degradation efficiency of MB is improved up to 87%in 100 min.展开更多
The hadal zone represents one of the last great frontiers in modern marine science,and deciphering the provenance of sediment that is supplied to these trench settings remains a largely unanswered question.Here,we exa...The hadal zone represents one of the last great frontiers in modern marine science,and deciphering the provenance of sediment that is supplied to these trench settings remains a largely unanswered question.Here,we examine the mineralogical and geochemical composition of a sediment core(core CD-1)that was recovered from the southwestern margin of the Challenger Deep within the Mariana Trench.Major element abundances and rare-earth element patterns from these sediments require inputs from both terrigenous dust and locally sourced volcanic debris.We exploit a two-endmember mixing model to demonstrate that locally sourced volcanic material dominates the sediment supply to the Challenger Deep(averaging^72%).The remainder,however,is supplied by aeolian dust(averaging^28%),which is consistent with adjacent studies that utilized Sr-Nd isotopic data.Building on a growing database,we strengthen our understanding of Asian aeolian dust input into the northwestern Pacific,which ultimately improves our appreciation of sedimentation in,and around,the hadal zone.展开更多
A geochemical analysis of rare-earth elements (REEs) in 97 samples collected from the core of deep-water Well LS-A located at the Lingnan Low Uplift Area of the Qiongdongnan Basin is conducted, with the pur-pose of ...A geochemical analysis of rare-earth elements (REEs) in 97 samples collected from the core of deep-water Well LS-A located at the Lingnan Low Uplift Area of the Qiongdongnan Basin is conducted, with the pur-pose of revealing the changes of sedimentary source and environment in the study region since Oligocene and evaluating the response of geochemical characteristics of REEs to the tectonic evolution. In the core samples, both∑REE and∑LREE (LREE is short for light-group REEs) fluctuate in a relatively wide range, while∑HREE (HREE is short for heavy-group REEs) maintains a relatively stable level. With the stratigraphic chronology becoming newer, both∑REE and∑LREE show a gradually rising trend overall. The∑REE of the core is relatively high from the bottom of Yacheng Formation (at a well depth of 4 207 m) to the top of Ledong Formation, and the REEs show partitioning characteristics of the enrichment of LREE, the stable content of HREE, and the negative anomaly of Eu to varying degrees. Overall the geochemical characteristics of REEs are relatively approximate to those of China's neritic sediments and loess, with significant "continental ori-entation". The∑REE of the core is relatively low in the lower part of Yacheng Formation (at a well depth of 4 207-4 330 m), as shown by the REEs partitioning characteristics of the depletion of LREE, the relative enrich-ment of HREE, and the positive anomaly of Eu; the geochemical characteristics of REEs are approximate to those of oceanic crust and basalt overall, indicating that the provenance is primarily composed of volcanic eruption matters. As shown by the analyses based on sequence stratigraphy and mineralogy, the provenance in study region in the early Oligocene mainly resulted from the volcanic materials of the peripheral uplift ar-eas; the continental margin materials from the north contributed only insignificantly; the provenance devel-oped to a certain extent in the late Oligocene. Since the Miocene, the provenance has ceaselessly expanded from proximal to distal realm, embodying a characteristic of multi-source sedimentation. In the core strata with 31.5, 28.4, 25.5, 23, and 16 Ma from today, the geochemical parameters of REEs and Th/Sc ratio have significant saltation, embodying the tectonic movement events in the evolution of the Qiongdongnan Basin. In the tectonic evolution history of the South China Sea, the South China Sea Movement (34-25 Ma BP, early expansion of the South China Sea), Baiyun Movement (23 Ma BP), late expansion movement (23.5-16.5 Ma BP), expansion-settlement transition, and other important events are all clearly recorded by the geochemi-cal characteristics of REEs in the core.展开更多
This study evaluated the Cretaceous(Campanian–Maastrichtian) kaolinitic sediments of the Ajali/Mamu and Enugu/Nkporo Formations from the Lower Benue Trough of Nigeria. A combined method of inductively coupled plasma...This study evaluated the Cretaceous(Campanian–Maastrichtian) kaolinitic sediments of the Ajali/Mamu and Enugu/Nkporo Formations from the Lower Benue Trough of Nigeria. A combined method of inductively coupled plasma–mass spectrometry and isotope ratio mass spectrometry was used to investigate trace and rareearth element geochemistry and hydrogen and oxygen isotopic compositions. These data were then used to infer the sediments' provenance and paleoclimatic conditions during their deposition. The sediments contained low concentrations of most trace elements, with the exceptions of Zr(651–1352 ppm), Ba(56–157 ppm), V(38–90 ppm),and Sr(15.1–59.6 ppm). Average values of Co and Ni were1.5 and 0.7 ppm, respectively. Trace and rare earth element values were lower than corresponding values for upper continental crust and Post-Archean Australian Shale, with the exception of Zr. The samples showed only slight light rare-earth enrichment and nearly flat heavy rare-earth depletion patterns, with negative Eu and Tm anomalies,typical of felsic sources. Geochemical parameters such as La/Sc, Th/Sc, and Th/Co ratios support that the kaolinitic sediments were derived from a felsic rock source, likely deposited in an oxic environment.^(18 )O values ranged from+ 15.4 to + 21.2% for the investigated samples, consistent with a residual material derived from chemicalweathering of felsic rock and redeposited in a sedimentary basin(typical values of + 19 to + 21.2%). While in the basin, the sediments experienced extended interactions with meteoric water enriched in d D and d16 O. However,the variation in d D and d16 O values for the investigated samples is attributed to the high temperature of formation(54–91 °C). The d D and d^(18 )O values suggest that the sediments, although obtained from different localities within the Lower Benue Trough, formed under similar hot,tropical climatic conditions.展开更多
The mechanism of interaction relation between the rare-earth element Ce and elements Pb and Bi in Ag-based filler metal has been studied. The results show that the compounds CePb and CeBi with high melting point can b...The mechanism of interaction relation between the rare-earth element Ce and elements Pb and Bi in Ag-based filler metal has been studied. The results show that the compounds CePb and CeBi with high melting point can be easily produced between these three elements in the filler metal, which greatly limited the formation of the isolated phase Pb or Bi and also eliminated the bad effect of impurity elements Pb and Bi on the spreading property of Ag-based filler metal. The metallurgical and quantum-mechanical bond formation analysis show that a strong chemical affinity was existed between the rare-earth element Ce and impurity elements Pb and Bi, which was proved by the XRD analysis results.展开更多
Cu46Zr47-xA17Mx (M = Ce, Pr, Tb, and Gd) bulk metallic glassy (BMG) alloys were prepared by copper-mold vacuum suction casting. The effects of rare-earth elements on the glass-forming ability (GFA), thermal stab...Cu46Zr47-xA17Mx (M = Ce, Pr, Tb, and Gd) bulk metallic glassy (BMG) alloys were prepared by copper-mold vacuum suction casting. The effects of rare-earth elements on the glass-forming ability (GFA), thermal stability, and mechanical properties of Cu46Zr47-xA17Mx were investigated. The GFA of Cu46Zr47-xA17Mx (M = Ce, Pr) alloys is dependent on the content of Ce and Pr, and the optimal content is 4 at.%. Cu46Zr47-xA17Thx(X = 2, 4, and 5) amorphous alloys with a diameter of 5 mm can be prepared. The GFA of Cu46Zr47-xA17Gdx(x = 2, 4, and 5) increases with increasing Gd. Tx and Tp of all decrease. Tg is dependent on the rare-earth element and its content. ATx for most of these alloys decreases except the Cu46Zra2Al7Gd5 alloy. The activation energies △Eg, △Ex, and △Ep for the Cu46Zr42A17Gd5 BMG alloy with Kissinger equations are 340.7, 211.3, and 211.3 kJ/mol, respectively. These values with Ozawa equations are 334.8, 210.3, and 210.3 kJ/mol, respec- tively. The Cu46Zr45Al7Tb2 alloy presents the highest microhardness, Hv 590, while the Cu46Zr43A17Pr4 alloy presents the least, Hv 479. The compressive strength (at.f.) of the Cu46Zra3A17Gd4 BMG alloy is higher than that of the Cu46Zr43Al7Tb4 BMG alloy.展开更多
Doping of different rare-earth metals (Pr, Nd, Y and La) had an evident influence on the catalytic performance of CuO-CeO2 for the preferential oxidation (PROX) of CO in excess hydrogen. As for Pr, the doping enha...Doping of different rare-earth metals (Pr, Nd, Y and La) had an evident influence on the catalytic performance of CuO-CeO2 for the preferential oxidation (PROX) of CO in excess hydrogen. As for Pr, the doping enhanced the catalytic activity of CuO-CeO2 for PROX. For example, the CO conversion over the above catalyst for PROX was higher than 99% at 120 °C. Especially, the doping of Pr widened the temperature window by 20 °C over CuO-CeO2 with 99% CO conversion. For Nd, Y, and La, the doping depressed the catalytic activity of CuO-CeO2 for PROX. However, the doping of transition metals markedly improved the selectivity of CuO-CeO2 for PROX.展开更多
Zinc Sulfide (ZnS) thin film has attracted increasing attention due to their potential applications in the new generation of nano-electronics and opto-electronics devices. The physical and chemical properties of ZnS h...Zinc Sulfide (ZnS) thin film has attracted increasing attention due to their potential applications in the new generation of nano-electronics and opto-electronics devices. The physical and chemical properties of ZnS have outstanding quality for different applications. Moreover, ZnS doped with various elements are creating a new era for both academic research and industrial applications. So, the optical properties of modified ZnS thin film will help us to find a suitable doping element for convenient deposition which may enhance the conductance and transmitting properties of the film. This review work has been carried out to explore the four-modification elements that constitute Cu, Ni, Co & Fe as descending order of atomic number corresponding to Zn, along with some potential applications considering the recent research work with other doping elements too such as Al, C, Pt etc. For example, FE, FET, Catalytic, Solar cell, Electroluminescence, Fuel cell, different sensors (Chemical sensors, Bio-sensors, Humidity sensors, light sensors, UV light sensors) and nanogenerators use ZnS thin film.展开更多
The microstructures of doped tungsten deformed by multi-pass hot continuous rolling were investigated, and the stress and strain fields were simulated by finite element(FE) method. After the continuous rolling, the gr...The microstructures of doped tungsten deformed by multi-pass hot continuous rolling were investigated, and the stress and strain fields were simulated by finite element(FE) method. After the continuous rolling, the grains of the tungsten rod were refined, and the microhardness was improved; however, a ring region of abnormal grain growth was present at a distance of about 3/5 R(R is the radius of the rod) from the center of the cross section. FE modeling results showed that the equivalent residual strains were minimum around the region of abnormal grain growth; this was due to the release of strain energy by severe plastic deformation, leading a situation where the migration force of grain boundaries was higher than the pinning force of potassium bubbles. By decreasing the initial rolling temperature and rolling speeds, the inhomogeneity of the equivalent residual stain decreased, improving the microstructure uniformity of the doped tungsten.展开更多
The effects of small amounts of added elements such as aluminum, titanium and zirconium to MlNi 3.8(CoMn) 1.2 on its electrochemical performances and performances at high temperatures were investigated.It is fou...The effects of small amounts of added elements such as aluminum, titanium and zirconium to MlNi 3.8(CoMn) 1.2 on its electrochemical performances and performances at high temperatures were investigated.It is found that the addition of aluminum brings about a significant increase in the discharge capacity at high temperatures,and the capacity decay during repeated charge-discharge cycles and the self-discharge are both suppressed, while the rate capability decreases.The alloy containing zirconium exhibits a longer cycle life and a better rate capability,but a much lower discharge capacity.The addition of titanium improves the rate capability, but the capacity decreases greatly.An X-ray diffraction analysis indicates that a second phase exists in the alloy with additive Zr or Ti,which improves the discharge-rate characteristics,and the superior stability of the alloy with additive Al may be due to the expansion of lattice parameters and cell volume.展开更多
The influence of rare-earth elements,La,Ce,Pr,Nd,Sm,Eu,Gd,Dy,Ho,Er and Yb on the thermal stability of PdSi_(16.5) glass was studied systematically by means of DSC.All rare-earth elements,especially heavy ones,increase...The influence of rare-earth elements,La,Ce,Pr,Nd,Sm,Eu,Gd,Dy,Ho,Er and Yb on the thermal stability of PdSi_(16.5) glass was studied systematically by means of DSC.All rare-earth elements,especially heavy ones,increase obviously the thermal stability parameters,including T_θ(T_g ,T_x ,T_g),T_(rg) and ΔE etc.The crystallization temperatures T_(p1) and T_(p2) increase linearly with the lanthanide constriction increasing,but Eu shows an anomalous influence:Pd-Si-Eu metallic glass possesses the highest thermal stability and the lowest concentration limit of glass forming among Pd-Si-R glasses.展开更多
The influence of RE (RE = La, Ce. Pr. Nd, Sm, Eu, Gd. Tb. Dy, Er, Yb) additives with dilute concentrations on the electrical properties of Pd has been studied. All RE elements increase the specific resistivity (ρ) an...The influence of RE (RE = La, Ce. Pr. Nd, Sm, Eu, Gd. Tb. Dy, Er, Yb) additives with dilute concentrations on the electrical properties of Pd has been studied. All RE elements increase the specific resistivity (ρ) and decrease the resistance temperature coefficient (α) of Pd. and (ρ.α) Pd-RE ls equal to (ρ· α)Pd.The RE elements before Gd reduce the thermo-emf of Pd on Cu. other heavy RE enhance the thermo-emf.The experimental data of normalized Pd-0.1 at.-%RE alloys indicate that the effect of light RE additives on the specific resistivity of Pd is larger than that of heavy RE and Ce. Eu and Yb show anomalous strong effect. The valence and atomic size are main factors influencing the electrical properties.展开更多
In this work wavelength sensitivity in mechanically induced long period fiber gratings (MLPFG) is analyzed. This analysis is first carried out both in standard single-mode fiber SMF-28 and in Er-doped fibers. The mech...In this work wavelength sensitivity in mechanically induced long period fiber gratings (MLPFG) is analyzed. This analysis is first carried out both in standard single-mode fiber SMF-28 and in Er-doped fibers. The mechanical analysis for both types of fibers under different torsion conditions is presented. In order to apply the torsion one of the fiber ends is fixed while torsion is applied on the other end. A MLPFG whose period is 503 μm is used to press the fiber after torsion is applied. This allows for micro curvatures to be formed on the fiber, which in turn generates a periodical index perturbation on it. Here, it was noted that the sensitive wavelength shift of the rejection bands is bigger for Er-doped fibers. For a torsion of 6 turns applied to 10 cm of doped fiber the wavelength peaks can be moved up to 25 nm, which is longer to what was detected on standard fibers. Therefore, by using Er-doped fibers to monitor torsion on structures will give more sensitive and accurate results than using standard fibers. These results can be employed for sensing applications, especially for small to medium size structures, which can be mechanical, civil or aeronautics.展开更多
Rare-earth ion doped crystals for hybrid quantum technologies are an area of growing interest in the solid-state physics community. We have earlier theoretically proposed a hybrid scheme of a mechanical resonator whic...Rare-earth ion doped crystals for hybrid quantum technologies are an area of growing interest in the solid-state physics community. We have earlier theoretically proposed a hybrid scheme of a mechanical resonator which is fabricated out of a rare-earth doped mono-crystalline structure. The rare-earth ion dopants have absorption energies which are sensitive to crystal strain, and it is thus possible to couple the ions to the bending motion of the crystal cantilever. This type of resonator can be useful for either investigating the laws of quantum physics with material objects or for applications such as sensitive force-sensors. Here, we present the design and fabrication method based on focused-ion-beam etching techniques which we have successfully employed in order to create such microscale resonators, as well as the design of the environment which will allow studying the quantum behavior of the resonators.展开更多
Infrared emissivity was studied in Zn0.99M0.01O(M is Mn,Fe or Ni) and Zn1-xCoxO(x=0.01,0.02,0.03 and 0.04) powders synthesized by solid-state reaction at various temperatures.XRD patterns confirm the wurtzite structur...Infrared emissivity was studied in Zn0.99M0.01O(M is Mn,Fe or Ni) and Zn1-xCoxO(x=0.01,0.02,0.03 and 0.04) powders synthesized by solid-state reaction at various temperatures.XRD patterns confirm the wurtzite structure of the prepared samples.No peaks of other phases arising from impurities are detected in Mn-and Co-doped ZnO,but the peaks of ZnFe2O4 and NiO are observed in Zn0.99Fe0.01O and Zn 0.99 Ni 0.01 O.The SEM observations indicate that with larger grain sizes than those of Zn0.99Fe0.01O and Zn0.99Ni0.01O,Co-doped ZnO exhibits smooth grain surfaces.The infrared absorption spectra show that infrared absorptions related to oxygen in Zn0.99M0.01O are much stronger than those in Co-doped ZnO.Co ions are dissolved into the ZnO lattice with Co2+ state from XPS spectra analysis.The infrared emissivity results imply that the emissivity of Zn0.99Ni0.01 O is the highest(0.829) and that of Zn 0.99 Co 0.01 O is the lowest(0.784) at 1 200 C.The emissivity of Zn0.99Co0.01O decreases to the minimum(0.752) at 1 150 C and then increases with growing calcination temperature.As the Co doping content grows,the emissivity of Co-doped ZnO calcined at 1 200 C falls to 0.758 in the molar fraction of 3% and then ascends.展开更多
基金Funded by National Key Research and Development Program of China (No.2021YFA1600203)。
文摘A series of nitrogen-doped SrMoO_(4) with different Sr/N mole ratio (R=0,0.05,0.10,0.15,0.20,0.40,and 0.60) were synthesized using urea as the N source via the vapor-thermal method.The photocatalytic degradation ability of all samples was evaluated using methylene blue (MB) as a target contaminant.The band gaps of N-doped samples are all higher than that of pristine ones,which is only 3.12 eV.BET specific surface area S_(BET) and pore volume are increased due to the N doping.And the greater increase of S_(BET),the faster the photodegradation speed of methylene blue on SrMoO_(4).More specifically,the degradation efficiency of MB is improved up to 87%in 100 min.
基金Supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB06020204)the National Key Basic Research and Development Program of China(Nos.2017YFC0307704,2017YFC0307600)the Marine Geological Survey Program of China Geological Survey(No.DD20160218)
文摘The hadal zone represents one of the last great frontiers in modern marine science,and deciphering the provenance of sediment that is supplied to these trench settings remains a largely unanswered question.Here,we examine the mineralogical and geochemical composition of a sediment core(core CD-1)that was recovered from the southwestern margin of the Challenger Deep within the Mariana Trench.Major element abundances and rare-earth element patterns from these sediments require inputs from both terrigenous dust and locally sourced volcanic debris.We exploit a two-endmember mixing model to demonstrate that locally sourced volcanic material dominates the sediment supply to the Challenger Deep(averaging^72%).The remainder,however,is supplied by aeolian dust(averaging^28%),which is consistent with adjacent studies that utilized Sr-Nd isotopic data.Building on a growing database,we strengthen our understanding of Asian aeolian dust input into the northwestern Pacific,which ultimately improves our appreciation of sedimentation in,and around,the hadal zone.
基金The National Major Project of Science and Technology of China under contract No.2011ZX05025-002-03
文摘A geochemical analysis of rare-earth elements (REEs) in 97 samples collected from the core of deep-water Well LS-A located at the Lingnan Low Uplift Area of the Qiongdongnan Basin is conducted, with the pur-pose of revealing the changes of sedimentary source and environment in the study region since Oligocene and evaluating the response of geochemical characteristics of REEs to the tectonic evolution. In the core samples, both∑REE and∑LREE (LREE is short for light-group REEs) fluctuate in a relatively wide range, while∑HREE (HREE is short for heavy-group REEs) maintains a relatively stable level. With the stratigraphic chronology becoming newer, both∑REE and∑LREE show a gradually rising trend overall. The∑REE of the core is relatively high from the bottom of Yacheng Formation (at a well depth of 4 207 m) to the top of Ledong Formation, and the REEs show partitioning characteristics of the enrichment of LREE, the stable content of HREE, and the negative anomaly of Eu to varying degrees. Overall the geochemical characteristics of REEs are relatively approximate to those of China's neritic sediments and loess, with significant "continental ori-entation". The∑REE of the core is relatively low in the lower part of Yacheng Formation (at a well depth of 4 207-4 330 m), as shown by the REEs partitioning characteristics of the depletion of LREE, the relative enrich-ment of HREE, and the positive anomaly of Eu; the geochemical characteristics of REEs are approximate to those of oceanic crust and basalt overall, indicating that the provenance is primarily composed of volcanic eruption matters. As shown by the analyses based on sequence stratigraphy and mineralogy, the provenance in study region in the early Oligocene mainly resulted from the volcanic materials of the peripheral uplift ar-eas; the continental margin materials from the north contributed only insignificantly; the provenance devel-oped to a certain extent in the late Oligocene. Since the Miocene, the provenance has ceaselessly expanded from proximal to distal realm, embodying a characteristic of multi-source sedimentation. In the core strata with 31.5, 28.4, 25.5, 23, and 16 Ma from today, the geochemical parameters of REEs and Th/Sc ratio have significant saltation, embodying the tectonic movement events in the evolution of the Qiongdongnan Basin. In the tectonic evolution history of the South China Sea, the South China Sea Movement (34-25 Ma BP, early expansion of the South China Sea), Baiyun Movement (23 Ma BP), late expansion movement (23.5-16.5 Ma BP), expansion-settlement transition, and other important events are all clearly recorded by the geochemi-cal characteristics of REEs in the core.
文摘This study evaluated the Cretaceous(Campanian–Maastrichtian) kaolinitic sediments of the Ajali/Mamu and Enugu/Nkporo Formations from the Lower Benue Trough of Nigeria. A combined method of inductively coupled plasma–mass spectrometry and isotope ratio mass spectrometry was used to investigate trace and rareearth element geochemistry and hydrogen and oxygen isotopic compositions. These data were then used to infer the sediments' provenance and paleoclimatic conditions during their deposition. The sediments contained low concentrations of most trace elements, with the exceptions of Zr(651–1352 ppm), Ba(56–157 ppm), V(38–90 ppm),and Sr(15.1–59.6 ppm). Average values of Co and Ni were1.5 and 0.7 ppm, respectively. Trace and rare earth element values were lower than corresponding values for upper continental crust and Post-Archean Australian Shale, with the exception of Zr. The samples showed only slight light rare-earth enrichment and nearly flat heavy rare-earth depletion patterns, with negative Eu and Tm anomalies,typical of felsic sources. Geochemical parameters such as La/Sc, Th/Sc, and Th/Co ratios support that the kaolinitic sediments were derived from a felsic rock source, likely deposited in an oxic environment.^(18 )O values ranged from+ 15.4 to + 21.2% for the investigated samples, consistent with a residual material derived from chemicalweathering of felsic rock and redeposited in a sedimentary basin(typical values of + 19 to + 21.2%). While in the basin, the sediments experienced extended interactions with meteoric water enriched in d D and d16 O. However,the variation in d D and d16 O values for the investigated samples is attributed to the high temperature of formation(54–91 °C). The d D and d^(18 )O values suggest that the sediments, although obtained from different localities within the Lower Benue Trough, formed under similar hot,tropical climatic conditions.
文摘The mechanism of interaction relation between the rare-earth element Ce and elements Pb and Bi in Ag-based filler metal has been studied. The results show that the compounds CePb and CeBi with high melting point can be easily produced between these three elements in the filler metal, which greatly limited the formation of the isolated phase Pb or Bi and also eliminated the bad effect of impurity elements Pb and Bi on the spreading property of Ag-based filler metal. The metallurgical and quantum-mechanical bond formation analysis show that a strong chemical affinity was existed between the rare-earth element Ce and impurity elements Pb and Bi, which was proved by the XRD analysis results.
文摘Cu46Zr47-xA17Mx (M = Ce, Pr, Tb, and Gd) bulk metallic glassy (BMG) alloys were prepared by copper-mold vacuum suction casting. The effects of rare-earth elements on the glass-forming ability (GFA), thermal stability, and mechanical properties of Cu46Zr47-xA17Mx were investigated. The GFA of Cu46Zr47-xA17Mx (M = Ce, Pr) alloys is dependent on the content of Ce and Pr, and the optimal content is 4 at.%. Cu46Zr47-xA17Thx(X = 2, 4, and 5) amorphous alloys with a diameter of 5 mm can be prepared. The GFA of Cu46Zr47-xA17Gdx(x = 2, 4, and 5) increases with increasing Gd. Tx and Tp of all decrease. Tg is dependent on the rare-earth element and its content. ATx for most of these alloys decreases except the Cu46Zra2Al7Gd5 alloy. The activation energies △Eg, △Ex, and △Ep for the Cu46Zr42A17Gd5 BMG alloy with Kissinger equations are 340.7, 211.3, and 211.3 kJ/mol, respectively. These values with Ozawa equations are 334.8, 210.3, and 210.3 kJ/mol, respec- tively. The Cu46Zr45Al7Tb2 alloy presents the highest microhardness, Hv 590, while the Cu46Zr43A17Pr4 alloy presents the least, Hv 479. The compressive strength (at.f.) of the Cu46Zra3A17Gd4 BMG alloy is higher than that of the Cu46Zr43Al7Tb4 BMG alloy.
基金the National Basic Research Program of China (973 program, No. 2004 CB 7195040)
文摘Doping of different rare-earth metals (Pr, Nd, Y and La) had an evident influence on the catalytic performance of CuO-CeO2 for the preferential oxidation (PROX) of CO in excess hydrogen. As for Pr, the doping enhanced the catalytic activity of CuO-CeO2 for PROX. For example, the CO conversion over the above catalyst for PROX was higher than 99% at 120 °C. Especially, the doping of Pr widened the temperature window by 20 °C over CuO-CeO2 with 99% CO conversion. For Nd, Y, and La, the doping depressed the catalytic activity of CuO-CeO2 for PROX. However, the doping of transition metals markedly improved the selectivity of CuO-CeO2 for PROX.
文摘Zinc Sulfide (ZnS) thin film has attracted increasing attention due to their potential applications in the new generation of nano-electronics and opto-electronics devices. The physical and chemical properties of ZnS have outstanding quality for different applications. Moreover, ZnS doped with various elements are creating a new era for both academic research and industrial applications. So, the optical properties of modified ZnS thin film will help us to find a suitable doping element for convenient deposition which may enhance the conductance and transmitting properties of the film. This review work has been carried out to explore the four-modification elements that constitute Cu, Ni, Co & Fe as descending order of atomic number corresponding to Zn, along with some potential applications considering the recent research work with other doping elements too such as Al, C, Pt etc. For example, FE, FET, Catalytic, Solar cell, Electroluminescence, Fuel cell, different sensors (Chemical sensors, Bio-sensors, Humidity sensors, light sensors, UV light sensors) and nanogenerators use ZnS thin film.
基金financially supported by Shandong Provincial Key Research and Development Program, China (No. 2017GGX20140)Shandong Provincial Natural Science Foundation, China (Nos. ZR2014JL031 and ZR2018MEE016)
文摘The microstructures of doped tungsten deformed by multi-pass hot continuous rolling were investigated, and the stress and strain fields were simulated by finite element(FE) method. After the continuous rolling, the grains of the tungsten rod were refined, and the microhardness was improved; however, a ring region of abnormal grain growth was present at a distance of about 3/5 R(R is the radius of the rod) from the center of the cross section. FE modeling results showed that the equivalent residual strains were minimum around the region of abnormal grain growth; this was due to the release of strain energy by severe plastic deformation, leading a situation where the migration force of grain boundaries was higher than the pinning force of potassium bubbles. By decreasing the initial rolling temperature and rolling speeds, the inhomogeneity of the equivalent residual stain decreased, improving the microstructure uniformity of the doped tungsten.
基金TheprojectisfinanciallysupportedbytheScienceResearchFoundationofOrdnanceEngineeringCollege (No .yjjxm0 0 0 6 )
文摘The effects of small amounts of added elements such as aluminum, titanium and zirconium to MlNi 3.8(CoMn) 1.2 on its electrochemical performances and performances at high temperatures were investigated.It is found that the addition of aluminum brings about a significant increase in the discharge capacity at high temperatures,and the capacity decay during repeated charge-discharge cycles and the self-discharge are both suppressed, while the rate capability decreases.The alloy containing zirconium exhibits a longer cycle life and a better rate capability,but a much lower discharge capacity.The addition of titanium improves the rate capability, but the capacity decreases greatly.An X-ray diffraction analysis indicates that a second phase exists in the alloy with additive Zr or Ti,which improves the discharge-rate characteristics,and the superior stability of the alloy with additive Al may be due to the expansion of lattice parameters and cell volume.
文摘The influence of rare-earth elements,La,Ce,Pr,Nd,Sm,Eu,Gd,Dy,Ho,Er and Yb on the thermal stability of PdSi_(16.5) glass was studied systematically by means of DSC.All rare-earth elements,especially heavy ones,increase obviously the thermal stability parameters,including T_θ(T_g ,T_x ,T_g),T_(rg) and ΔE etc.The crystallization temperatures T_(p1) and T_(p2) increase linearly with the lanthanide constriction increasing,but Eu shows an anomalous influence:Pd-Si-Eu metallic glass possesses the highest thermal stability and the lowest concentration limit of glass forming among Pd-Si-R glasses.
文摘The influence of RE (RE = La, Ce. Pr. Nd, Sm, Eu, Gd. Tb. Dy, Er, Yb) additives with dilute concentrations on the electrical properties of Pd has been studied. All RE elements increase the specific resistivity (ρ) and decrease the resistance temperature coefficient (α) of Pd. and (ρ.α) Pd-RE ls equal to (ρ· α)Pd.The RE elements before Gd reduce the thermo-emf of Pd on Cu. other heavy RE enhance the thermo-emf.The experimental data of normalized Pd-0.1 at.-%RE alloys indicate that the effect of light RE additives on the specific resistivity of Pd is larger than that of heavy RE and Ce. Eu and Yb show anomalous strong effect. The valence and atomic size are main factors influencing the electrical properties.
文摘In this work wavelength sensitivity in mechanically induced long period fiber gratings (MLPFG) is analyzed. This analysis is first carried out both in standard single-mode fiber SMF-28 and in Er-doped fibers. The mechanical analysis for both types of fibers under different torsion conditions is presented. In order to apply the torsion one of the fiber ends is fixed while torsion is applied on the other end. A MLPFG whose period is 503 μm is used to press the fiber after torsion is applied. This allows for micro curvatures to be formed on the fiber, which in turn generates a periodical index perturbation on it. Here, it was noted that the sensitive wavelength shift of the rejection bands is bigger for Er-doped fibers. For a torsion of 6 turns applied to 10 cm of doped fiber the wavelength peaks can be moved up to 25 nm, which is longer to what was detected on standard fibers. Therefore, by using Er-doped fibers to monitor torsion on structures will give more sensitive and accurate results than using standard fibers. These results can be employed for sensing applications, especially for small to medium size structures, which can be mechanical, civil or aeronautics.
基金YLC acknowledges support from the Ville de Paris Emergence Program and from the LABEX Cluster of Excellence FIRST-TF(ANR-10-LABX-48-01),within the Program“investissements d'Avenir”operated by the French National Research Agency(ANR)The project has also received funding from the European Union’Horizon 2020 research and innovation program under grant agreement No 712721(NanOQTech).
文摘Rare-earth ion doped crystals for hybrid quantum technologies are an area of growing interest in the solid-state physics community. We have earlier theoretically proposed a hybrid scheme of a mechanical resonator which is fabricated out of a rare-earth doped mono-crystalline structure. The rare-earth ion dopants have absorption energies which are sensitive to crystal strain, and it is thus possible to couple the ions to the bending motion of the crystal cantilever. This type of resonator can be useful for either investigating the laws of quantum physics with material objects or for applications such as sensitive force-sensors. Here, we present the design and fabrication method based on focused-ion-beam etching techniques which we have successfully employed in order to create such microscale resonators, as well as the design of the environment which will allow studying the quantum behavior of the resonators.
基金Project(2009K06_03) supported by the Scientific and Technological Program of Shaanxi Province,China
文摘Infrared emissivity was studied in Zn0.99M0.01O(M is Mn,Fe or Ni) and Zn1-xCoxO(x=0.01,0.02,0.03 and 0.04) powders synthesized by solid-state reaction at various temperatures.XRD patterns confirm the wurtzite structure of the prepared samples.No peaks of other phases arising from impurities are detected in Mn-and Co-doped ZnO,but the peaks of ZnFe2O4 and NiO are observed in Zn0.99Fe0.01O and Zn 0.99 Ni 0.01 O.The SEM observations indicate that with larger grain sizes than those of Zn0.99Fe0.01O and Zn0.99Ni0.01O,Co-doped ZnO exhibits smooth grain surfaces.The infrared absorption spectra show that infrared absorptions related to oxygen in Zn0.99M0.01O are much stronger than those in Co-doped ZnO.Co ions are dissolved into the ZnO lattice with Co2+ state from XPS spectra analysis.The infrared emissivity results imply that the emissivity of Zn0.99Ni0.01 O is the highest(0.829) and that of Zn 0.99 Co 0.01 O is the lowest(0.784) at 1 200 C.The emissivity of Zn0.99Co0.01O decreases to the minimum(0.752) at 1 150 C and then increases with growing calcination temperature.As the Co doping content grows,the emissivity of Co-doped ZnO calcined at 1 200 C falls to 0.758 in the molar fraction of 3% and then ascends.