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Atomic structure and transition properties of H-like Al in hot and dense plasmas 被引量:1
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作者 Xiang-Fu Li Gang Jiang +1 位作者 Hong-Bin Wang Qian Sun 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第1期160-169,共10页
The atomic structure and transition properties of H-like Al embedded in hot and dense plasmas are investigated using modified GRASP2 K code. The plasma screening effect on the nucleus is described using the self-consi... The atomic structure and transition properties of H-like Al embedded in hot and dense plasmas are investigated using modified GRASP2 K code. The plasma screening effect on the nucleus is described using the self-consistent field ion sphere model. The effective nuclear potential decreases much more quickly with increasing average free electron density,but increases slightly with increasing electron temperature. The variations of the transition energies, transition probabilities,and oscillator strengths with the free electron density and electron temperature are the same as that of the effective nuclear potential. The results reported in this work agree well with other available theoretical results and are useful for plasma diagnostics. 展开更多
关键词 H-like Al strongly-coupled plasmas atomic structure transition properties
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A Precise Description of the Electronic Structures and Spin-Allowed Transition Properties of PF and Its Cation:All-Electron Configuration-Interaction Investigations Including Relativistic Effect 被引量:1
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作者 李奇楠 赵书涛 +3 位作者 张晓美 罗旺 李瑞 闫冰 《Chinese Physics Letters》 SCIE CAS CSCD 2015年第7期42-46,共5页
The electronic structures of PF and PF+ are calculated with the high-level configuration interaction method. To improve the precision of calculations, the spin-orbit coupling effect, the scalar relativistic effect, a... The electronic structures of PF and PF+ are calculated with the high-level configuration interaction method. To improve the precision of calculations, the spin-orbit coupling effect, the scalar relativistic effect, and the Davidson correction(q-Q) are also considered. The spectroscopic parameters of bound states are derived by the electronic structures of PF and PF+, which are in good accordance with the measurements. The transition dipole moments of spin-allowed transitions are evaluated, and the radiative lifetimes of several A S states of PF and PF+ are obtained. 展开更多
关键词 A Precise Description of the Electronic Structures and Spin-Allowed transition properties of PF and Its Cation:All-Electron Configuration-Interaction Investigations Including Relativistic Effect PF TDM
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Tunable Electronic and Magnetic Properties from Structure Phase Transition of Layered Vanadium Diselenide 被引量:1
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作者 张会 SUN Liting +2 位作者 DAI Yumei TONG Chuanjia 韩笑 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2017年第3期574-578,共5页
The atomic geometry, structure stability, electronic and magnetic properties of VSe2 were systematically investigated based on the density functional theory(DFT). Varying from 3D to 2D four VSe2 structures, bulk 2H-... The atomic geometry, structure stability, electronic and magnetic properties of VSe2 were systematically investigated based on the density functional theory(DFT). Varying from 3D to 2D four VSe2 structures, bulk 2H-VSe2 and 1T-VSe2, monolayer H-VSe2 and T-VSe2 are all demonstrated as thermodynamically stable by lattice dynamic calculations. More interestingly, the phase transition temperature is dramatically different due to the lattice size. Finally, owing to different crystal structures, H-VSe2 is semimetallic whereas T-VSe2 is totally metallic and also they have different magnetic moments. Our main argument is that being exfoliated from bulk to monolayer, 2H-VSe2 transforms to T-VSe2, accompanied by both semimetallic-metallic transition and dramatic magnetic moment variation. Our calculations provide a novel structure phase transition and an efficient way to modulate the electronic structure and magnetic moment of layered VSe2, which suggests potential applications as high-performance functional nanomaterial. 展开更多
关键词 density functional theory vanadium diselenide structure phase transition magnetic property
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Theoretical Study on the Spectroscopic Parameters and Transition Properties of MgH Radical Including Spin-orbit Coupling
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作者 伍冬兰 谭彬 +4 位作者 曾学锋 万慧军 谢安东 闫冰 丁大军 《Chinese Physics Letters》 SCIE CAS CSCD 2016年第6期12-16,共5页
An accurate theoretical study on the MgH radical is reported by adopting the high-level relativistic MRCI+Q method with a quintuple-zeta quality basis set. The reliable potential energy curves of the five A-S states ... An accurate theoretical study on the MgH radical is reported by adopting the high-level relativistic MRCI+Q method with a quintuple-zeta quality basis set. The reliable potential energy curves of the five A-S states of MgH are derived. Then the associated spectroscopic parameters are determined and found to be in good accordance with the available experimental results. The permanent dipole moments (PDMs) and the spin-orbit (SO) matrix elements of A-S states are computed. The results show that the abrupt changes of PDMs and SO matrix elements are attributed to the variations of electronic configurations at the avoided crossing point. The SOC effect leads to the five A-S states split into ten Ω states and results in the double potential well of (2)1//2 state. Finally, the transition properties from the (2)1//2, (1)3//2 and (3)1//2 states to the ground state X2∑+1//2 transitions are obtained, including the transition dipole moments, Franck-Condon factors and radiative lifetimes. 展开更多
关键词 of on in Theoretical Study on the Spectroscopic Parameters and transition properties of MgH Radical Including Spin-orbit Coupling SOC been that MRCI
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Configuration interaction calculations on the spectroscopic and transition properties of magnesium chloride
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作者 Dong-lan Wu Cheng-quan Lin +2 位作者 Yu-feng Wen An-dong Xie Bing Yan 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第8期187-195,共9页
The potential energy curves (PECs) of 14 A-S states for magnesium chloride (MgC1) have been calculated by using multi-reference configuration interaction method with Davidson correction (MRCI + Q). The core-val... The potential energy curves (PECs) of 14 A-S states for magnesium chloride (MgC1) have been calculated by using multi-reference configuration interaction method with Davidson correction (MRCI + Q). The core-valence correlation (CV), scalar relativistic effect, and spin-orbit coupling (SOC) effect are considered in the electronic structure computations. The spectroscopic constants of X2∑+ and A2П states have been obtained, which are in good agreement with the existing theoretical and experimental results. Furthermore, other higher electronic states are also characterized. The permanent dipole moments (PDMs) of A-S states and the spinorbit (SO) matrix elements between A-S states are also computed. The results indicate that the abrupt changes of PDMs and the SO matrix elements are attributed to the avoided crossing between the states with the same symmetry. The SOC effect is taken into account with Breit-Panli operator, which makes the 14 A-S states split into 30 Ωstates, and leads to a double-well potential of the Ω =(3)1/2 state. The energy splitting for the A2I-I is calculated to be 53.61 cm-1 and in good agreement with the experimental result 54.47 cm-1. The transition dipole moments (TDMs), Franck-Condon factors (FCFs), and the corresponding radiative lifetimes of the selected transitions from excited Ω states to the ground state X2∑+ 1/2 have been reported. The computed radiative lifetimes tV1, of low-lying excitesΩ states are all on the order of 10 ns. Finally, the feasibility of laser cooling of MgC1 molecule has been analyzed. 展开更多
关键词 MgC1 MRCI+Q spectroscopic and transition properties spin-orbit coupling
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Spontaneous Magnetic Transitions and Corresponding Magnetoelastic Properties of Intermetallic Compounds RMn_2Ge_2(R=Gd, Tb and Dy)
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作者 张光富 TIAN Ye DENG Yangbao 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2018年第3期566-570,共5页
The spontaneous magnetic transitions and corresponding magnetoelastic properties of intermetallic compounds RMn2Ge2(R=Gd, Tb and Dy) were investigated by using the X-ray diffraction method and magnetic measurement. ... The spontaneous magnetic transitions and corresponding magnetoelastic properties of intermetallic compounds RMn2Ge2(R=Gd, Tb and Dy) were investigated by using the X-ray diffraction method and magnetic measurement. The results showed that the compounds experience two magnetic transitions, namely the second-order paramagnetic to antiferromagnetic transition at temperature TN(TN=368, 423 and 443 K for Gd Mn2 Ge2, Tb Mn2 Ge2 and Dy Mn2 Ge2, respectively) and the first-order antiferromagnetic-ferrimagnetic transition at temperature Tt(Tt=96, 80 and 40 K for Gd Mn2 Ge2, Tb Mn2 Ge2 and Dy Mn2 Ge2, respectively) as the temperature decreases. The temperature dependence of the lattice constant a(T) displays a negative magnetoelastic anomaly at the second-order transition point TN and, at the first-order transition Tt, a increases abruptly for Gd Mn2 Ge2 and Tb Mn2 Ge2, Da/a about 10^(-3). Nevertheless, the lattice constant c almost does not change at these transition points indicating that such magnetoelastic anomalies are mainly contributed by the Mn-sublattice. The transitions of the magnetoelastic properties are also evidenced on the temperature dependence of magnetic susceptibility χ. The first-order transition behavior at Tt is explained by the Kittel mode of exchange inversion. 展开更多
关键词 rare earth-transition metal compound magnetic transition magnetoelastic property
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Mechanical Properties and Microstructure of Portland Cement Concrete Prepared with Coral Reef Sand 被引量:22
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作者 王乾坤 LI Peng +2 位作者 田亚坡 CHEN Wei SU Chunyi 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2016年第5期996-1001,共6页
The feasibility of using coral reef sand(CRS) in Portland cement concrete is investigated by testing the mechanical property and microstructure of concrete. The composition, structure and properties of the CRS are a... The feasibility of using coral reef sand(CRS) in Portland cement concrete is investigated by testing the mechanical property and microstructure of concrete. The composition, structure and properties of the CRS are analyzed. Mechanical properties and microstructure of concrete with CRS are studied and compared to concrete with natural river sand. The relationship between the microstructure and performance of CRS concrete is established. The CRS has a porous surface with high water intake capacity, which contributes to the mechanical properties of concrete. The interfacial transition zone between the cement paste and CRS is densified compared to normal concrete with river sand. Hydration products form in the pore space of CRS and interlock with the matrix of cement paste, which increases the strength. The total porosity of concrete prepared with CRS is higher than that with natural sand. The main difference in pore size distribution is the fraction of fine pores in the range of 100 nm. 展开更多
关键词 coral reef sand concrete mechanical properties microstructure interfacial transition zone
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INVESTIGATION OF HYDROGEN INDUCED DUCTILE BRITTLE TRANSITION IN 7175 ALUMINUM ALLOY 被引量:8
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作者 R.G.Seng: B.J Zhong, MG. Zeng and P. Geng(Department of Materials Scierce, Science College,Northearstern Univeisity, Shenyang 110006, China 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 1996年第4期287-290,共4页
Effects of hydrogen on the mechanical properties of differently aged 7175 aluminum alloys were investigated by using cathodic H-permeation, slow strain rate tension and so on. The results indicate that both the yield ... Effects of hydrogen on the mechanical properties of differently aged 7175 aluminum alloys were investigated by using cathodic H-permeation, slow strain rate tension and so on. The results indicate that both the yield stress and the percentage reduction of area decrease with increasing hydrogen charging time, and the degree of reduction decreases as aging time increases for the same hydrogen charging time. 展开更多
关键词 hydrogen induced ductile-brittle transition 7175 aluminum alloy mechanical property cathodic H-permeation
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Relativistic calculations on the transition electric dipole moments and radiative lifetimes of the spin-forbidden transitions in the antimony hydride molecule
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作者 Yong Liu Lu-Lu Li +1 位作者 Li-Dan Xiao Bing Yan 《Chinese Physics B》 SCIE EI CAS CSCD 2022年第8期125-130,共6页
Calculations on the spectroscopic constants and transition properties of the first three states(a^(1)△,b^(1)Σ^(+),and X3Σ-)of the Sb H molecule were performed under the relativistic framework using the exact two-co... Calculations on the spectroscopic constants and transition properties of the first three states(a^(1)△,b^(1)Σ^(+),and X3Σ-)of the Sb H molecule were performed under the relativistic framework using the exact two-component Hamiltonian(X2C).The potential energy curves in the Franck-Condon region were computed and compared with the previous values.Furthermore,the transition dipole moments for the weak spin-forbidden transitions(b0^(+)-X10^(+),b0^(+)-X_(2)1,X10^(+)-X_(2)1,and X_(2)1-a2)were reported.The spontaneous radiative lifetime of the b1Σ^(+)(υ′=0)state was calculated as 163.5±7.5μs,which is in reasonable agreement with the latest experimental value of 173±3μs.The spontaneous radiative lifetimes of the X_(2)1(υ′=0)state and the a2(υ′=0)state were calculated to be 48.6 s and~8 ms,respectively.Our study is expected to be a benchmark transition property computation for comparison with other theoretical and experimental results.The datasets presented in this paper,including the transition dipole moments,are openly available at https://dx.doi.org/10.11922/sciencedb.j00113.00018. 展开更多
关键词 Sb H transition properties radiative lifetimes
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Phase Transition and Negative Thermal Expansion Property of ZrMnMo_3O_(12)
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作者 葛向红 毛彦超 +6 位作者 李林 李丽平 袁娜 程永光 郭娟 晁明举 梁二军 《Chinese Physics Letters》 SCIE CAS CSCD 2016年第4期104-107,共4页
A novel material of ZrMnMo3012 with negative thermal expansion is presented. The phase transition temperature and coemcient of thermal expansion (CTE) are investigated by temperature-dependent x-ray diffraction and ... A novel material of ZrMnMo3012 with negative thermal expansion is presented. The phase transition temperature and coemcient of thermal expansion (CTE) are investigated by temperature-dependent x-ray diffraction and Raman spectra. It is shown that ZrMnMo3012 adopts monoclinic structure with space group P21/a (No. 14) from 298 to 358K and transforms to orthorhombic with space group Pnma (No. 62) above 363K. The linear CTE obtained from the results of XRD refinement is -2.80 × 10-6 K-1 from 363 to 873 K. The CTE of the bulk cylinder ceramic measured by a thermal dilatometer is -4.7× 10-6 K-1 from 373 to 773K approximatively. 展开更多
关键词 of ZR in IT on as MO Phase transition and Negative Thermal Expansion Property of ZrMnMo3O XRD CTE
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Properties and Microstructures of Full Graded Concrete Containing Varied Impurity Aggregate
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作者 杨梦卉 何真 LIN Yuqiang 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2017年第2期321-329,共9页
We investigated mechanical properties of concretes made with impurity aggregates of different combinations. Besides the mechanisms were explored by EDS, CT, and hardness testing. The results showed that fully rust-sta... We investigated mechanical properties of concretes made with impurity aggregates of different combinations. Besides the mechanisms were explored by EDS, CT, and hardness testing. The results showed that fully rust-stained and surface rust-stained sandstone aggregate had significant adverse impact on the compressive strength of concrete while sandstone aggregate had a much more obvious impact on the ultimate tension of concrete. Concrete crack was more prone to expand along surfaces and the micro-hardness of interfacial transition zone of different aggregates was ranked in decreasing trend as sandstone, slate, SR sandstone, marble, and FR sandstone. The cluster growth of long needle-like ettringite crystal and strong preferential growth trend of Ca(OH)2 crystals would result in wider interfacial transition zone range of concretes made with fully rust-stained sandstone and marble aggregate, respectively. Therefore, the impurity aggregate content should be strictly controlled during aggregate selection. 展开更多
关键词 aggregate concrete mechanical property interfacial transition zone
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Configuration interaction studies on the spectroscopic properties of PbO including spin-orbit coupling
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作者 罗旺 李瑞 +4 位作者 盖志强 艾瑞波 张宏民 张晓美 闫冰 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第7期185-191,共7页
Lead oxide(Pb O), which plays the key roles in a range of research fields, has received a great deal of attention. Owing to the large density of electronic states and heavy atom Pb including in Pb O, the excited sta... Lead oxide(Pb O), which plays the key roles in a range of research fields, has received a great deal of attention. Owing to the large density of electronic states and heavy atom Pb including in Pb O, the excited states of the molecule have not been well studied. In this work, high level multireference configuration interaction calculations on the low-lying states of Pb O have been carried out by utilizing the relativistic effective core potential. The effects of the core-valence correlation correction, the Davidson modification, and the spin–orbital coupling on the electronic structure of the Pb O molecule are estimated. The potential energy curves of 18 Λ-S states correlated to the lowest dissociation limit(Pb(~3P_g) + O(~3P_g)) are reported. The calculated spectroscopic parameters of the electronic states below 30000 cm^(-1), for instance, X^1Σ~+, 1~3Σ~+,and 1~3Σ^-, and their spin–orbit coupling interaction, are compared with the experimental results, and good agreements are derived. The dipole moments of the 18 Λ-S states are computed with the configuration interaction method, and the calculated dipole moments of X^1Σ~+and 1~3Σ~+are consistent with the previous experimental results. The transition dipole moments from 1~1Π, 2~1Π, and 2~Σ to X^1Σ~+and other singlet excited states are estimated. The radiative lifetime of several low-lying vibrational levels of 1~1Π, 2~1Π, and 2~1Σ~+ states are evaluated. 展开更多
关键词 lead oxide MRCI+Q method dipole moments transitional properties
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Comprehensive Alcohol-/Ion-Responsive Properties of Poly(N-Isopropylacrylamide-co-Benzo-18-Crown-6-Acrylamide) Copolymers
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作者 巨晓洁 皮硕伟 +7 位作者 谢锐 郭晓静 柳杰译 余亚兰 江潞 陆小华 陈谦明 褚良银 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2014年第9期1038-1045,共8页
In this paper, we report on the comprehensive alcohol-/ion-responsive properties of a smart copolymer poly(N- isopropylacry]amide-co-benzo-18-crown-6-acrylamide) (P(NIPAM-co-BCAm)). The orthogonal design method ... In this paper, we report on the comprehensive alcohol-/ion-responsive properties of a smart copolymer poly(N- isopropylacry]amide-co-benzo-18-crown-6-acrylamide) (P(NIPAM-co-BCAm)). The orthogonal design method is adopted for experimental design. The experimental results show that alcohol can trigger the shrinking and Ba2t can induce the swelling of the P(NIPAM-co-BCAm) copolymer. According to the phase transition tempera- ture (LCST) change results of the copolymer, the influence of variables on the LCST changes weakens in the following order: alcohol concentration 〉 alcohol species 〉 metal ion species 〉 BCAm concentration 〉 ion concentration. The larger the alcohol concentration and the larger the molecular size of alcohols, the lower the LCST value; on the contrary, the more the BCAm content in the copolymer or the larger the BCAm/ion complex stability constant (IgK) or the larger the ion concentration is, the higher the LCST value. For a P(NIPAM-co-BCAm ) copolymer with a fixed BCAm content, a binary function of ion concentration and IgK of BCAm/ion is developed to precisely predict the LCST values of the copolymer in different metal ion solutions. The results provide valuable information for fabricating artificial biomimetic G-protein-gated inwardly rectifying potassium (GIRK) channels that are activated by alcohol and inhibited by Ba2+. 展开更多
关键词 Stimuli-responsive materialPhase transition behaviorAlcohol-responsive propertyIon-responsive property
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Thermal and Mechanical Properties of Epoxy Resin Modified with N-(4-hydroxyphenyl)terahydrophthalic Anhydrideimide
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作者 徐任信 CHENG Shixin +3 位作者 ZHOU Jing SHEN Jie LI Zheng TAN Xing 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2018年第3期744-748,共5页
A novel epoxy-imide resin based on diglycidyl ether of bisphenol-A and N-(4-hydroxyphenyl)terahydrophthalic anhydrideimide(HTAM) was synthesized. The structural characterization of the epoxy-imide resin was conduc... A novel epoxy-imide resin based on diglycidyl ether of bisphenol-A and N-(4-hydroxyphenyl)terahydrophthalic anhydrideimide(HTAM) was synthesized. The structural characterization of the epoxy-imide resin was conducted by FT-IR spectra. 4,4'-diaminodiphneylmethane(DDM) was used as a curing agent for the epoxy-imide resin. The thermal properties of the cured resin were evaluated with dynamic mechanical analyses(DMA) and thermogravimetric analysis(TGA). The results showed that the cured resin exhibited a high glass transition temperature(Tg) of 186 ℃ when the molar amount of HTAM was 0.04 mol in the resin. The yields of the cured resin at 800 ℃ raised from 16.45% to 19.41%. The flexural properties were also measured, the flexural strength raised from 79.4 to 95.7 MPa, and the flexural modulus exhibited from 2.6 to 3.0 GPa. 展开更多
关键词 epoxy-imide resin glass transition temperature char yield flexural properties
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SIGMAPLUG—A NEW TEMPERATURE INDICATOR FOR REMAINING LIFE ASSESSMENT OF HIGH TEMPERATURE COMPONENTS 被引量:2
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作者 J.K.L. Lai, C.H. Shek and K.W. Wong Department of Physics and Materials Science, City University of Hong Kong, 27887808, China 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 1999年第1期104-107,共4页
Improved life assessment techniques will enable engineering components to be replaced before failure, thereby reducing the risk of industrial accidents as well as minimizing financial loss due to unscheduled outages. ... Improved life assessment techniques will enable engineering components to be replaced before failure, thereby reducing the risk of industrial accidents as well as minimizing financial loss due to unscheduled outages. For components operating at high temperatures, temperature measurement is very important. In many situations, the environmental conditions are too hostile for conventional techniques to be used. Researchers over the world have been looking for new techniques for temperature measurement and one such device, called Feroplug, has been developed previously by the and coworkers. The Feroplug has been patented in USA, UK and Europe by the British Technology Group. The underlying principle of the Feroplug is based on the transformation of ferrite in some specially designed duplex stainless steels. This paper describes a new invention called Sigmaplug which is a new development of the Feroplug but using an entirely different physical principle. It was discovered that the sigma phase in Fe 展开更多
关键词 ferrite sigma phase duplex stainless steel temperature indicator remaining life assessment roplug materials undergoes a ferromagnetic transition at low temperatures and this property can be used to indicate temperature. The new Sigmaplug can great
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Triethylammonium picrate: An above-room-temperature phase transition material to switch quadratic nonlinear optical properties
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作者 Muhammad Adnan Asghar Jing Zhang +4 位作者 Shiguo Han Zhihua Sun Chengmin Ji Aurang Zeb Junhua Luo 《Chinese Chemical Letters》 SCIE CAS CSCD 2018年第2期285-288,共4页
To switch quadratic nonlinear optical(NLO) effects has become an exciting branch of the NLO material science. However, solid-state molecular crystals showing tunable and switchable NLO behaviors remain scarce. Here,... To switch quadratic nonlinear optical(NLO) effects has become an exciting branch of the NLO material science. However, solid-state molecular crystals showing tunable and switchable NLO behaviors remain scarce. Here, we report an organic picrate-based binary molecular crystal, triethylammonium picrate(TEAP), which undergoes an above-room-temperature phase transition at T_c=319 K, being solidly confirmed by the thermal and dielectric measurements. A large thermal hysteresis of ~7 K discloses the first-order feature for its phase transition. More strikingly, the quadratic NLO effects of TEAP can be switched in the vicinity of Tc. That is, TEAP exhibits NLO-active response of ~1.5 times as large as that of KDP below T_c(i.e., NLO-on state), while its NLO effects totally disappear above T_c(NLO-off state). Structure analyses disclose that the order-disorder transformations of triethylammonium cations and picrate anions collectively contribute to its phase transition, as well as switchable NLO behaviors. This work opens up a new pathway to the designing and assembling of stimuli-responsive materials. 展开更多
关键词 Phase transition Nonlinear optical properties Dielectric properties Order-disorder
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Microstructures and mechanical properties of Nb-alloyed CoCrCuFeNi high-entropy alloys 被引量:8
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作者 Gang Qin Shu Wang +5 位作者 Ruirun Chen Xue Gong Liang Wang Yanqing Su Jingjie Guo Hengzhi Fu 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2018年第2期365-369,共5页
Nb has a positive effect on improving the mechanical properties of metal materials, and it is expected to strengthen CoCrCuFeNi high-entropy alloys (HEAs) with outstanding ductility and relatively weak strength. In ... Nb has a positive effect on improving the mechanical properties of metal materials, and it is expected to strengthen CoCrCuFeNi high-entropy alloys (HEAs) with outstanding ductility and relatively weak strength. In this paper, the alloying effects of Nb on the microstructural evolution and the mechanical properties of the (CoCrCuFeNi)100-xNbx HEA were investigated systematically. The result shows that Nb promotes the phase transition from FCC (face-centered cubic) to Laves phase, and the volume fractions of Laves phase increase from 0% to 58.2% as the Nb content increases, Compressive testing shows that the addition of Nb has a positive effect on improving the strength of CoCrCuFeNi HEA. The compressive yield strength of (CoCrCuFeNi)100-xNbx HEAs increases from 338 MPa to 1322 MPa and the fracture strain gradually reduces from 60.0% (no fracture) to 8.1% as the Nb content increases from 0 to 16 at.%. The volume fraction increase of hard Laves phase is the key factor for the strength increase, and the reduction of the VEC (valence electron concentration) value induced by the addition of Nb is beneficial for the increase of the Laves phase content in these alloys. 展开更多
关键词 High-entropy alloys Nb alloying Phase transition Mechanical properties Laves phase
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First principles study of structural, electronic, elastic and magnetic properties of cerium and praseodymium hydrogen system REH_x(RE:Ce, Pr and x=2, 3) 被引量:9
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作者 G.Sudha Priyanga R.Rajeswarapalanichamy K.Iyakutti 《Journal of Rare Earths》 SCIE EI CAS CSCD 2015年第3期289-303,共15页
The structural, electronic, elastic and magnetic properties of cerium, praseodymium and their hydrides REH x(RE=Ce, Pr and x=2, 3) were investigated by the first principles calculations based on density functional t... The structural, electronic, elastic and magnetic properties of cerium, praseodymium and their hydrides REH x(RE=Ce, Pr and x=2, 3) were investigated by the first principles calculations based on density functional theory using the Vienna ab-initio simulation package. At zero pressure all the hydrides were stable in the ferromagnetic state. The calculated lattice parameters were in good agreement with the experimental results. The bulk modulus decreased with the increase in the hydrogen content for these hydrides. The electronic structure revealed that di-hydrides were metallic whereas trihydrides were half metallic at zero pressure. A pressure-induced structural phase transition from cubic to hexagonal phase was predicted in these hydrides. The computed elastic constants indicated that these hydrides were mechanically stable at zero pressure. The calculated Debye temperature values were in good agreement with experimental and other theoretical results. A half metallic to metallic transition was also observed in REH3 under high pressure. Ferromagnetism was quenched in these hydrides at high pressures. 展开更多
关键词 ab-initio calculations electronic structure structural phase transition magnetic properties elastic properties rare earths
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Critical parameters near the ferromagnetic-paramagnetic phase transition in La_(0.67–x)Y_xBa_(0.23)Ca_(0.1)MnO_3 compounds(x=0.10 and x=0.15) 被引量:1
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作者 Mounira Abassi N.Dhahri +2 位作者 J.Dhahri K.Taibi E.K.Hlil 《Journal of Rare Earths》 SCIE EI CAS CSCD 2015年第3期263-270,共8页
The critical properties of the mixed manganite La0.67–x Y x Ba0.23Ca0.1Mn O3 with x=0.10 and x=0.15 around the paramagnetic(PM)-ferromagnetic(FM) phase transition were investigated through various techniques. The... The critical properties of the mixed manganite La0.67–x Y x Ba0.23Ca0.1Mn O3 with x=0.10 and x=0.15 around the paramagnetic(PM)-ferromagnetic(FM) phase transition were investigated through various techniques. These involved modified Arrott plots, Kouvel-Fisher method and Widom scaling relation. Magnetic data, analyzed in the critical region, using the above methods, yielded the critical exponents for(x=0.10) La0.57Y0.10Ba0.23Ca0.1Mn O3(β=0.312±0.002 and γ=1.147±0.003 at T C=299.23±0.05 K). Moreover, the estimated critical exponents of(x=0.15) La0.52Y0.15Ba0.23Ca0.1Mn O3 were β=0.286±0.004 and γ=0.943±0.002 at T C=289.53±0.06 K. The critical exponents' values were close to the theoretical values of 3D-Ising model and tricritical mean-field model. These results suggested that the present composition should be close to a tricritical point in the La0.67–x Y x Ba0.23Ca0.1Mn O3 phase diagram. Expressing the field dependence as ΔS M∝H n allowed us to establish a relationship between the exponent n and the critical exponents of the material and to propose a phenomenological universal curve for the field dependence of ΔS M. 展开更多
关键词 perovskite manganites phase transition entropy critical properties rare earths
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Investigation of Structural, Electronic and Mechanical Properties of Rubidium Metal Hydrides RbMH_4(M=B, Al, Ga)
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作者 Santhosh Manoharan Rajeswarapalanichamy Ratnavelu +2 位作者 Sudhapriyanga Ganesapandian Kanagaprabha Shanmugam Iyakutti Kombiah 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2015年第8期975-983,共9页
Ab initio calculations are performed to investigate the structural stability, electronic structure and mechanical properties of rubidium metal hydrides RbMH4(M = B, Al, Ga) for five different crystal structures, nam... Ab initio calculations are performed to investigate the structural stability, electronic structure and mechanical properties of rubidium metal hydrides RbMH4(M = B, Al, Ga) for five different crystal structures, namely hexagonal(P63mc), tetragonal(P42/nmc), tetragonal(P421c), orthorhombic(Pnma) and monoclinic(P21/c). Among the considered structures, tetragonal(P421c) phase is found to be the most stable one for these metal hydrides at normal pressure. A pressure-induced structural phase transition from tetragonal(P421c) to monoclinic(P21/c) phase is observed in all the three metal hydrides. The electronic structure reveals that these hydrides are wide band gap semiconductors. The calculated elastic constants indicate that these alkali metal tetrahydrides are mechanically stable at normal pressure. 展开更多
关键词 Ab initio calculations Crystal structure Phase transitions Electronic structure Mechanical properties
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