Magnetic properties and magnetic entropy changes in LaFe11.5Si1.5 have been investigated by partially substituting Pr by La. It is found that La1-xPrxFe11.5Si1.5 compounds remain cubic NaZn13-type structures even when...Magnetic properties and magnetic entropy changes in LaFe11.5Si1.5 have been investigated by partially substituting Pr by La. It is found that La1-xPrxFe11.5Si1.5 compounds remain cubic NaZn13-type structures even when the Pr content is increased to 0.5, i.e. x = 0.5. Substitution of Pr for La leads to a reduction in both the crystal constant and the Curie temperature. A stepwise magnetic behaviour in the isothermal magnetization curves is observed, indicating that the characteristic of the itinerant electron metamagnetic （IEM） transition above Tc becomes more prominent with the Pr content increasing. As a result, the magnetic entropy change is remarkably enhanced from 23.0 to 29.4 J/kg·K as the field changes from 0 to 5T, with the value of x increasing from 0 to 0.5. It is more attractive that the magnetic entropy changes for all samples are shaped into high plateaus in a wide range of temperature, which is highly favourable for Ericsson-type magnetic refrigeration.展开更多
First-principles have been calculated to investigate the phase stabilities of the intermetallic phase of MgAl2 compounds by electronic structures and the charge distribution maps. The first-prin- ciples employed the n...First-principles have been calculated to investigate the phase stabilities of the intermetallic phase of MgAl2 compounds by electronic structures and the charge distribution maps. The first-prin- ciples employed the norm-conserving pseudo potential density functional method. They were calcu- lated both with the Ceperley and Alder data as parameterized by Perdew and Zunger（CA-PZ） of local-density approximation （LDA） and with the Perdew Burke Eruzerh （PBE） form of gradient-corrected approximation （GGA）. A better method was found by comparing results from these two ultrasoft pseudo potentials. The present calculations indicate that LDA is better than GGA compared with references. This work also compared the lattice parameters, cohesive energy, formation enthalpy and electronic structure between theoretical results and experimental measurements （where available ）. The calculations indicate that the unit cell volume get smaller after optimized and cohesive energy and formation enthalpy of C14 structure is the highest. The calculated structures are stable and the stability is aligned as C36 〈 C15 〈 C14.展开更多
Kinetic and conductivity of new Schiff bases compounds such （（12Z）N-（5Z）-1-bromo-5-（phenylimino）-1H- pyrrol-2（5 H）-ylidene）benzenamine {ArN（CNBrCCHCH）NAr} （Ar = C6H5） incorporating the chelating diamino ...Kinetic and conductivity of new Schiff bases compounds such （（12Z）N-（5Z）-1-bromo-5-（phenylimino）-1H- pyrrol-2（5 H）-ylidene）benzenamine {ArN（CNBrCCHCH）NAr} （Ar = C6H5） incorporating the chelating diamino has been studied in this paper and was found a second order of this reaction. Electronic Properties using hyperchem program study has been improved for this compound such angel and bond distance, and then this compound was defining as electric conductivity and did prove to be useful for conduclively compound.展开更多
为研究不同剂量(0.2、0.6、1.0 μL/L)1-甲基环丙烯(1-methylcyclopropene,1-MCP)处理对‘亚特’猕猴桃香气成分的影响,用固相微萃取-气相色谱-质谱(solid phase microextraction and gas chromatography-mass spectrometry,SPME-GC-MS...为研究不同剂量(0.2、0.6、1.0 μL/L)1-甲基环丙烯(1-methylcyclopropene,1-MCP)处理对‘亚特’猕猴桃香气成分的影响,用固相微萃取-气相色谱-质谱(solid phase microextraction and gas chromatography-mass spectrometry,SPME-GC-MS)联用和电子鼻技术对可食期对照果及3种剂量1-MCP处理果的香气物质进行测定及分析。结果表明,经SPME-GC-MS测定,对照果及3种处理果中共检测出45种香气成分,正己醛、(E)-2-己烯醛、丁酸乙酯和1-辛烯-3-醇等对果实香气贡献较大。3种剂量1-MCP处理果的香气含量均低于对照,0.6 μL/L 1-MCP处理果香气含量最高;经电子鼻测定,对照果、0.2、0.6、1.0 μL/L 1-MCP处理果的香气物质差异显著,用主成分分析法可以将各组果实完全区分开。综上,从保留香气角度考虑,不建议‘亚特’猕猴桃贮藏前进行1-MCP处理,但从对果实香气影响最小、并延长贮藏期和货架期的角度考虑,建议用‘亚特’猕猴桃1-MCP处理的最适剂量为0.6 μL/L。展开更多
The present study aims to investigate the equation of state(EOS)parameters of CaMg3 in aReCh(D09),AIFR(DO3),CU3A11(LI2)and CuTi3(L60)structures,using full potential linear muffin-tin orbitals(FP-LMTO)approach based on...The present study aims to investigate the equation of state(EOS)parameters of CaMg3 in aReCh(D09),AIFR(DO3),CU3A11(LI2)and CuTi3(L60)structures,using full potential linear muffin-tin orbitals(FP-LMTO)approach based on the density functional theory(DFT).The local density approximation(LDA)and the generalized gradient approximation(GGA)were both applied for the exchange-correlation potential term.The calculated equation of slate parameters at equilibrium,in general,agreed well with the available data of the literature.The calculations showed that under compression CaMg3 transforms from DO3 to DO9 at about 29.96GPa,and 25.1 GPa using LDA and GGA,respectively.The elastic constants C,y,aggregate moduli,Vickers hardness,sound velocity,and Debye temperature of CaMg3 in D03 structure were also reported,discussed and analyzed.Using LDA(GGA),the calculated values of Hv andθD were found at around 5.80GPa(5.93GPa)and 393.44 K(389.91 K),respectively.Electronic band structure,total density of states(TDOS)as well as the partial density of states(PDOS)have been also obtained.The electronic band structure confirms the metallic behavior of CaMg3 in DO3 phase,the valence bands are dominated by the maximum contribution of‘d’like states of Ca in the energy ranging from 2 to 3 eV for GGA,and from 4.5 to 5 eV for LDA,respectively.展开更多
The addition of Pb in the superconductors of BiSrCaCuO system is very helpful for growth of the high-Tc phase (Tc 110K). We prepared a series of samples with nominal composition of Bi2-xPbxSr2Ca2Cu3Oy (0.1&lex&...The addition of Pb in the superconductors of BiSrCaCuO system is very helpful for growth of the high-Tc phase (Tc 110K). We prepared a series of samples with nominal composition of Bi2-xPbxSr2Ca2Cu3Oy (0.1&lex&le2). The zero resistance transition temperature Tc of 106K and the critical transport current density Jc of 1 × 103A/cm2 at 77K have been obtained for the samples of Bi2-xPbxSr2Ca2Cu3Oy (x=0.2 and 0.3). The X-ray diffraction analysis and measurement of AC magnetic susceptibility confirmed that the material is comprised of single high-Tc phase. We also report the magnetic properties of this material as well as the results of TEM observation.展开更多
Zn_(1-x)Mg_(x)O alloy films are important deep ultraviolet photoelectric materials.In this work,we used plasma-assisted molecular beam epitaxy to prepare Zn_(1-x)Mg_(x)O films with different magnesium contents on pola...Zn_(1-x)Mg_(x)O alloy films are important deep ultraviolet photoelectric materials.In this work,we used plasma-assisted molecular beam epitaxy to prepare Zn_(1-x)Mg_(x)O films with different magnesium contents on polar(0001)and nonpolar(1010)ZnO substrates.The nanoscale structural features of the grown alloy films as well as the interfaces were investigated.It was observed that the cubic phases of the alloy films emerged when the Mg content reached 20%and 37%for the alloy films grown on the(0001)and(1010)ZnO substrates,respectively.High-resolution transmission electron microscopy images revealed cubic phases without visible hexagonal phases for the alloy films with more than 70%magnesium,and the cubic phases exhibited three-fold and two-fold rotations for the alloy films on the polar(0001)and nonpolar(1010)ZnO substrates,respectively.This work aims to provide references for monitoring the Zn_(1-x)Mg_(x)O film structure with respect to different substrate orientations.展开更多
基金Project supported by the National Natural Science Foundation of China （Grant No 50571112）, the National Basic Reseaxch Program of China （Grant No 2006CB601101） and the Program of Chinese Academy of Sciences （Grant No KJCX2-YW-W02）.
文摘Magnetic properties and magnetic entropy changes in LaFe11.5Si1.5 have been investigated by partially substituting Pr by La. It is found that La1-xPrxFe11.5Si1.5 compounds remain cubic NaZn13-type structures even when the Pr content is increased to 0.5, i.e. x = 0.5. Substitution of Pr for La leads to a reduction in both the crystal constant and the Curie temperature. A stepwise magnetic behaviour in the isothermal magnetization curves is observed, indicating that the characteristic of the itinerant electron metamagnetic （IEM） transition above Tc becomes more prominent with the Pr content increasing. As a result, the magnetic entropy change is remarkably enhanced from 23.0 to 29.4 J/kg·K as the field changes from 0 to 5T, with the value of x increasing from 0 to 0.5. It is more attractive that the magnetic entropy changes for all samples are shaped into high plateaus in a wide range of temperature, which is highly favourable for Ericsson-type magnetic refrigeration.
基金Supported by the Natural Science Foundation of China(50874054)the Natural Science Joint Foundation of China(u0837601)the Natural Science Foundation of Yunnan Province of China(2009CD134)
文摘First-principles have been calculated to investigate the phase stabilities of the intermetallic phase of MgAl2 compounds by electronic structures and the charge distribution maps. The first-prin- ciples employed the norm-conserving pseudo potential density functional method. They were calcu- lated both with the Ceperley and Alder data as parameterized by Perdew and Zunger（CA-PZ） of local-density approximation （LDA） and with the Perdew Burke Eruzerh （PBE） form of gradient-corrected approximation （GGA）. A better method was found by comparing results from these two ultrasoft pseudo potentials. The present calculations indicate that LDA is better than GGA compared with references. This work also compared the lattice parameters, cohesive energy, formation enthalpy and electronic structure between theoretical results and experimental measurements （where available ）. The calculations indicate that the unit cell volume get smaller after optimized and cohesive energy and formation enthalpy of C14 structure is the highest. The calculated structures are stable and the stability is aligned as C36 〈 C15 〈 C14.
文摘Kinetic and conductivity of new Schiff bases compounds such （（12Z）N-（5Z）-1-bromo-5-（phenylimino）-1H- pyrrol-2（5 H）-ylidene）benzenamine {ArN（CNBrCCHCH）NAr} （Ar = C6H5） incorporating the chelating diamino has been studied in this paper and was found a second order of this reaction. Electronic Properties using hyperchem program study has been improved for this compound such angel and bond distance, and then this compound was defining as electric conductivity and did prove to be useful for conduclively compound.
文摘The present study aims to investigate the equation of state(EOS)parameters of CaMg3 in aReCh(D09),AIFR(DO3),CU3A11(LI2)and CuTi3(L60)structures,using full potential linear muffin-tin orbitals(FP-LMTO)approach based on the density functional theory(DFT).The local density approximation(LDA)and the generalized gradient approximation(GGA)were both applied for the exchange-correlation potential term.The calculated equation of slate parameters at equilibrium,in general,agreed well with the available data of the literature.The calculations showed that under compression CaMg3 transforms from DO3 to DO9 at about 29.96GPa,and 25.1 GPa using LDA and GGA,respectively.The elastic constants C,y,aggregate moduli,Vickers hardness,sound velocity,and Debye temperature of CaMg3 in D03 structure were also reported,discussed and analyzed.Using LDA(GGA),the calculated values of Hv andθD were found at around 5.80GPa(5.93GPa)and 393.44 K(389.91 K),respectively.Electronic band structure,total density of states(TDOS)as well as the partial density of states(PDOS)have been also obtained.The electronic band structure confirms the metallic behavior of CaMg3 in DO3 phase,the valence bands are dominated by the maximum contribution of‘d’like states of Ca in the energy ranging from 2 to 3 eV for GGA,and from 4.5 to 5 eV for LDA,respectively.
基金This work was supported by The National Center for Research and Development on Superconductivity.
文摘The addition of Pb in the superconductors of BiSrCaCuO system is very helpful for growth of the high-Tc phase (Tc 110K). We prepared a series of samples with nominal composition of Bi2-xPbxSr2Ca2Cu3Oy (0.1&lex&le2). The zero resistance transition temperature Tc of 106K and the critical transport current density Jc of 1 × 103A/cm2 at 77K have been obtained for the samples of Bi2-xPbxSr2Ca2Cu3Oy (x=0.2 and 0.3). The X-ray diffraction analysis and measurement of AC magnetic susceptibility confirmed that the material is comprised of single high-Tc phase. We also report the magnetic properties of this material as well as the results of TEM observation.
基金Project supported by the National Natural Science Foundation of China(Grant No.11804050).
文摘Zn_(1-x)Mg_(x)O alloy films are important deep ultraviolet photoelectric materials.In this work,we used plasma-assisted molecular beam epitaxy to prepare Zn_(1-x)Mg_(x)O films with different magnesium contents on polar(0001)and nonpolar(1010)ZnO substrates.The nanoscale structural features of the grown alloy films as well as the interfaces were investigated.It was observed that the cubic phases of the alloy films emerged when the Mg content reached 20%and 37%for the alloy films grown on the(0001)and(1010)ZnO substrates,respectively.High-resolution transmission electron microscopy images revealed cubic phases without visible hexagonal phases for the alloy films with more than 70%magnesium,and the cubic phases exhibited three-fold and two-fold rotations for the alloy films on the polar(0001)and nonpolar(1010)ZnO substrates,respectively.This work aims to provide references for monitoring the Zn_(1-x)Mg_(x)O film structure with respect to different substrate orientations.
