A new ternary Mg_(1.4)Co_(21.6)B_(6) compound in the Mg-Co-B system was synthesized via a conventional solid-state reaction method and the effect of Ni-substitution on its crystal structure,thermal stability,solid sol...A new ternary Mg_(1.4)Co_(21.6)B_(6) compound in the Mg-Co-B system was synthesized via a conventional solid-state reaction method and the effect of Ni-substitution on its crystal structure,thermal stability,solid solubility and physical properties were systematically investigated.The crystal structure of the Mg_(1.4)Co_(21.6)B_(6) compound was fully determined by the X-ray diffraction technique with Rietveld refinement method.It is found that Mg_(1.4)Co_(21.6)B_(6) crystallizes in the form of C_(6)Cr_(23) structure type(space group:Fm-3m(No.225),a=10.5617(2)A,Z=4).The results showed that the 4a sites have been occupied completely by Co atoms in present compound which with M_(2-x)Ni_(21+x)B_(6) form belonging to the W_(2)Cr_(21)C_(6)-type.When Mg_(1.4)Co_(21.6)B_(6) is repeatedly sintered at elevated temperatures,it becomes unstable and decomposes into Co3B and Mg.The lattice parameters of the Mg_(1.4)Co_(21.6)B_(6) solid solution alters dramtically with increasing Ni substitution,with no regular trend being observed.The electrical and magnetic performances of the 3.6Mg:3Co:17Ni:6B and 3.6Mg:3Co:18Ni:6B(nominal compositions)samples suggest that both samples are typical ferromagnetic materials.The temperature in the maximum drop of theρ(T)curve decreases as a function of the Ni content.Base on the correlation between the critical temperature and Ni content,a linear fitting equation is obtained and the critical temperature of Mg_(1.4)Co_(21.6)B_(6) calculated utilizing the linear fitting equation.The findings in this work may provide certain reference values for material science on electrical magnetic properties and other references for researching the material further.展开更多
The effects of NiO on microstructure and magnetic properties of Mn-Zn ferrite with a nominal composition of Zn_(0.32)Mn_(0.60-x)Ni_(x)Fe_(2.08)O_(4)were investigated.The calcined powder of Mn-Zn ferrite was characteri...The effects of NiO on microstructure and magnetic properties of Mn-Zn ferrite with a nominal composition of Zn_(0.32)Mn_(0.60-x)Ni_(x)Fe_(2.08)O_(4)were investigated.The calcined powder of Mn-Zn ferrite was characterized by X-ray diffraction(XRD),the fracture surface of Mn-Zn ferrite was checked by scanning electronic microscope(SEM),and then the magnetic properties were measured.As a result,the substitution of Ni can cause the crystal lattice constant of MnZn ferrite to decline,and the grain size to decrease,therefore improve the magnetic performance of MnZn ferrite whose density exceeds 5.0 g·cm^(-3).展开更多
To improve the cycle performance of spinel LiMn204 as the cathode material of 4 V class Li secondary batteries, LiNixMn2-xO4 （x=0-0.3） samples were prepared using a simple precipitation method, and the effects of Ni...To improve the cycle performance of spinel LiMn204 as the cathode material of 4 V class Li secondary batteries, LiNixMn2-xO4 （x=0-0.3） samples were prepared using a simple precipitation method, and the effects of Ni doping on the physical properties and electrochemical performance of the samples were investigated using various methods. All LiNixMn2-xO4 （x=0-0.3） compounds show a single spinel phase, and the lattice parameter （a）, the unit cell volume （v） and particle size decrease with increasing Ni content. The results of the electrochemical experiments showed that the initial charge-discharge capacity of LiNixMn2-xO4 samples in the 3.0-4.4 V range decreases with increasing Ni content except for pure LiMn2O4; however, the capacity in the 4.4-4.9 V range increases with the increasing Ni content. For spinel samples Ni substitution can contribute to the improvement of their cycle performance due to the formation of the stronger Ni-O bond, homogeneous morphology, and sub-micron sized particles, and the sample with x=0.05 has larger peak currents, higher initial capacity and better cycling capability due to its lower electrochemical and diffusion polarization than those of other samples.展开更多
Developing efficient catalysts and photosensitizers is crucial for the construction of effective photocatalytic H2-evolving systems.Here,we report the facile preparation of Coumarin-modified Ir(III)complexes(PS-2 and ...Developing efficient catalysts and photosensitizers is crucial for the construction of effective photocatalytic H2-evolving systems.Here,we report the facile preparation of Coumarin-modified Ir(III)complexes(PS-2 and PS-3)and their utilization as chromophores to drive favorable photocatalytic H2 evolution using Ni-substituted polyoxometalate(Ni_(3)PW_(10))catalyst and triethanolamine(TEOA)as an electron donor.Compared with the commercially available unmodified Ir(III)complex(PS-1),both PS-2 and PS-3 displayed intensive absorption in the range of 400–550 nm with ε_(max) of 110,620 and 91,430 M^(−1) cm6(−1),respectively.Varying the substitutes on the bipyridine ligand affected their physicochemical properties and the corresponding photocatalytic activity dramatically.Under photocatalytic conditions,the quantity of H2 molecules generated by PS-2-and PS-3-containing systems were 13.1 and 2.1 times,respectively,that of the PS-1-containing system.When PS-2 was used as a photosensitizer,the highest turnover number(TON)of 19,739 was obtained versus Ni_(3)PW_(10) catalyst.Various spectroscopic and computational studies have revealed that factors such as strong and broad visible-light-absorbing ability,long-lived triplet state,suitable redox potential,opposed by using polyoxometalate(POM)catalyst,and large highest occupied molecular orbital(HOMO)–lowest unoccupied molecular orbital(LUMO)gap of PS-2 attributed to drastically enhanced photocatalytic activity.展开更多
基金China’s Sichuan Science and Technology Program(2019YJ0441)Chengdu Normal University First-class Discipline Construction Major Scientific Research Projects(CS18ZDZ03)+1 种基金Chengdu Normal University Talent introduction scientificresearch special project(YJRC2015-3)The National Natural Science Foundation of China(11647095,51708143,22076034)。
文摘A new ternary Mg_(1.4)Co_(21.6)B_(6) compound in the Mg-Co-B system was synthesized via a conventional solid-state reaction method and the effect of Ni-substitution on its crystal structure,thermal stability,solid solubility and physical properties were systematically investigated.The crystal structure of the Mg_(1.4)Co_(21.6)B_(6) compound was fully determined by the X-ray diffraction technique with Rietveld refinement method.It is found that Mg_(1.4)Co_(21.6)B_(6) crystallizes in the form of C_(6)Cr_(23) structure type(space group:Fm-3m(No.225),a=10.5617(2)A,Z=4).The results showed that the 4a sites have been occupied completely by Co atoms in present compound which with M_(2-x)Ni_(21+x)B_(6) form belonging to the W_(2)Cr_(21)C_(6)-type.When Mg_(1.4)Co_(21.6)B_(6) is repeatedly sintered at elevated temperatures,it becomes unstable and decomposes into Co3B and Mg.The lattice parameters of the Mg_(1.4)Co_(21.6)B_(6) solid solution alters dramtically with increasing Ni substitution,with no regular trend being observed.The electrical and magnetic performances of the 3.6Mg:3Co:17Ni:6B and 3.6Mg:3Co:18Ni:6B(nominal compositions)samples suggest that both samples are typical ferromagnetic materials.The temperature in the maximum drop of theρ(T)curve decreases as a function of the Ni content.Base on the correlation between the critical temperature and Ni content,a linear fitting equation is obtained and the critical temperature of Mg_(1.4)Co_(21.6)B_(6) calculated utilizing the linear fitting equation.The findings in this work may provide certain reference values for material science on electrical magnetic properties and other references for researching the material further.
基金This project was financially supported by the Ministry of Education of China(No.106138)Science and Technology Bureau of Sichuan Province(No.2006202-010-6).
文摘The effects of NiO on microstructure and magnetic properties of Mn-Zn ferrite with a nominal composition of Zn_(0.32)Mn_(0.60-x)Ni_(x)Fe_(2.08)O_(4)were investigated.The calcined powder of Mn-Zn ferrite was characterized by X-ray diffraction(XRD),the fracture surface of Mn-Zn ferrite was checked by scanning electronic microscope(SEM),and then the magnetic properties were measured.As a result,the substitution of Ni can cause the crystal lattice constant of MnZn ferrite to decline,and the grain size to decrease,therefore improve the magnetic performance of MnZn ferrite whose density exceeds 5.0 g·cm^(-3).
基金This work was supported by the National Natural Science Foundation of China(No.59902004).The authors also gratefully acknowledge the financial support of the State Key Laboratory for Corrosion and Protection of China.
文摘To improve the cycle performance of spinel LiMn204 as the cathode material of 4 V class Li secondary batteries, LiNixMn2-xO4 （x=0-0.3） samples were prepared using a simple precipitation method, and the effects of Ni doping on the physical properties and electrochemical performance of the samples were investigated using various methods. All LiNixMn2-xO4 （x=0-0.3） compounds show a single spinel phase, and the lattice parameter （a）, the unit cell volume （v） and particle size decrease with increasing Ni content. The results of the electrochemical experiments showed that the initial charge-discharge capacity of LiNixMn2-xO4 samples in the 3.0-4.4 V range decreases with increasing Ni content except for pure LiMn2O4; however, the capacity in the 4.4-4.9 V range increases with the increasing Ni content. For spinel samples Ni substitution can contribute to the improvement of their cycle performance due to the formation of the stronger Ni-O bond, homogeneous morphology, and sub-micron sized particles, and the sample with x=0.05 has larger peak currents, higher initial capacity and better cycling capability due to its lower electrochemical and diffusion polarization than those of other samples.
基金The authors gratefully acknowledge the financial support from the National Natural Science Foundation of China(nos.21871025 and 21831001)the Recruitment Program of Global Experts(Young Talents),and the BIT Teli Young Fellow Program.
文摘Developing efficient catalysts and photosensitizers is crucial for the construction of effective photocatalytic H2-evolving systems.Here,we report the facile preparation of Coumarin-modified Ir(III)complexes(PS-2 and PS-3)and their utilization as chromophores to drive favorable photocatalytic H2 evolution using Ni-substituted polyoxometalate(Ni_(3)PW_(10))catalyst and triethanolamine(TEOA)as an electron donor.Compared with the commercially available unmodified Ir(III)complex(PS-1),both PS-2 and PS-3 displayed intensive absorption in the range of 400–550 nm with ε_(max) of 110,620 and 91,430 M^(−1) cm6(−1),respectively.Varying the substitutes on the bipyridine ligand affected their physicochemical properties and the corresponding photocatalytic activity dramatically.Under photocatalytic conditions,the quantity of H2 molecules generated by PS-2-and PS-3-containing systems were 13.1 and 2.1 times,respectively,that of the PS-1-containing system.When PS-2 was used as a photosensitizer,the highest turnover number(TON)of 19,739 was obtained versus Ni_(3)PW_(10) catalyst.Various spectroscopic and computational studies have revealed that factors such as strong and broad visible-light-absorbing ability,long-lived triplet state,suitable redox potential,opposed by using polyoxometalate(POM)catalyst,and large highest occupied molecular orbital(HOMO)–lowest unoccupied molecular orbital(LUMO)gap of PS-2 attributed to drastically enhanced photocatalytic activity.
