Chinese Physics Letters
The magnetic properties of 1 T-TaS2 and 1 T-Fe-0.07 Ta-0.93 S-2 have been studied, Experimental results show that the phase transition temperature of 1 T-TaS2 is a function of the magnetic field, At low temperatures, both compounds are in a mixed state of charge density wave -spin density wave due to the coherent superposition of antiferromagnetic coupling.
关键词:
density
Journal of Magnetism and Magnetic Materials
The temperature dependence of the magnetocrystalline anisotropy field (mu-0H(a)) of R2Fe14B(1-y)C(y) and Nd2Fe12Co2B(1-y)C(y) (R = Nd, Pr; y = 0, 0.5) compounds has been determined by applying the SPD (singular point detection) technique in a high pulse magnetometer in the temperature range of 300-600 K. To determine the Curie temperature (T(c)) of the compounds, the ac initial susceptibility measurement was employed. It was found that the influences of carbon substituting for boron and cobalt substituting for iron on the Curie temperature are independent of each other and the latter has been understood as the case where all 2p electrons which transferred from carbon to 3d bands localize around Fe. The effect of crystal electric field acting on the rare earth site is dominant at temperatures below 400 K in R2Fe14B (R = Nd, Pr) compounds. The substitution of small amounts of cobalt for Fe does not affect the crystal electric field acting on the rare earth site very much.
关键词:
Journal of Alloys and Compounds
High field magnetization curves have been measured at 4.2 K on magnetically aligned R2Co14B1-xCx (R = Pr, Nd; x = 0.0, 0.2 and 0.5) samples with the magnetic field applied parallel and perpendicular to the alignment direction. It is found that, for both the praseodymium and the neodymium compounds, the saturation magnetization decreases on substitution of carbon for boron. In the Nd2Co14B1-xCx system, the critical field of the first-order magnetization process (FOMP) increases with increasing carbon content. No FOMP is observed in the Pr2Co14B1-xCx system. The temperature dependence of the a.c. susceptibility shows that in Nd2Co14B1-xCx the spin reorientation temperature decreases with increasing carbon content. A spin reorientation phenomenon is also observed in Pr2Co14B0.8C0.2 and in Pr2Co14B0.5C0.5. Also in these compounds, the spin reorientation temperature decreases with increasing carbon content.
关键词:
nd2fe14b;exchange;r2fe14b;field
Physica B-Condensed Matter
X-ray powder diffraction and magnetization measurements reveal that light rare earth and heavy rare earth have different effects on the structure, Curie temperature and magnetic phase transition of the compounds R(Co1-xGax)(2) (R = Nd, Gd, Tb, Dy) (x = 0.0-0.3). The lattice constant exhibits a giant increase with increasing Ga concentration in all compounds. The Curie temperature shows no variation for R = Nd, a monotonic decrease for R = Gd and a maximum for R=Tb and Dy, respectively. The Curie temperature is strongly related with volume expansion, in which a critical value of a(c) approximate to 7.26 Angstrom is reached. The observed magnetic transition in all compounds is well explained within the framework of the Inoue-Shimizu model. It is revealed that both the lattice constant and the Curie temperature have a strong relationship with the order of the magnetic phase transition. (C) 2003 Elsevier B.V. All rights reserved.
关键词:
structure;Curie temperature;magnetic phase transition;itinerant-electron metamagnetism;intermetallic compounds;ac;susceptibility;order;temperature;behavior;r(co;yco2
Communications in Theoretical Physics
By means of both a theory for pressure-induced shifts (PS) of energy spectra and a theory for shifts of energy spectra due to electron-phonon interaction (EPI), the 'pure electronic' PS and the PS due to EPI of R-1 line, R-2 line, and U band of GSGG:Cr3+ at 300 K have been calculated, respectively. The calculated results are in good agreement with all the experimental data. Their physical origins have also been explained. It is found that the mixing-of degree \t(2)(2)(T-3(1))e(4)T(2)> and \t(2)(3) 2E> base-wavefunctions in the wavefunctions of R-1 level of GSGG:Cr3+ at 300 K is remarkable under normal pressure, and the mixing-degree rapidly decreases with increasing pressure. The change of the mixing-degree with pressure plays a key role not only for the 'pure electronic' PS of R-1 line and R-2 line but also the PS of R-1 line and R-2 line due to EPI. The pressure-dependent behaviors of the 'pure electronic' PS of R-1 line (or R-2 line) and the PS Of R-1 line (or R-2 line) due to EPI are quite different. It is the combined effect of them that gives rise to the total PS of R-1 line (or R-2 line). In the range of about 15 kbar similar to 45 kbar, the mergence and/or order-reversal between t(2)(2)(T-3(1))e(4)T(2) levels and t(2)(32)T(1) levels take place, which cause the fluctuation of the rate of PS for t(2)(2)(T-3(1))e(4)T(2) (or t(2)(3) T-2(1)) with pressure. At 300 K, both the temperature-dependent contribution to R-1 line (or R-2 line or U band) from EPI and the temperature-independent one are important.
关键词:
high-pressure effect;spin-orbit interaction;electron-phonon;interaction;d orbital;coupling between t(2)(2)(3T(1))e(4)T(2) and;t(2)(32)E;tunable laser crystal;theoretical calculations;temperature-dependence;thermal broadenings;garnet crystals;cr3+ ions;r-line;cr-3+;luminescence;ruby;spectroscopy
Journal of Alloys and Compounds
The structure, Curie temperature and magnetostriction of R(Fe1-xAlx)(2) alloys (R = Dy0.65Tb0.25Pr0.1) (x less than or equal to 0.3) have been investigated. It was found that the matrix structure of R(Fe1-xAlx)(2) alloys is cubic Laves (Dy,Tb,Pr)(Fe,Al)(2). Its lattice parameter increases linearly, while the Curie temperature decreases, with increasing x. The second phase of PuNi3-type (Dy,Tb,Pr)(Fe,Al)(3) was found when x < 0.15. The magnetostriction of R(Fe1-xAlx)(2) alloys decreases with increasing x in high magnetic fields; however, it exhibits a peak at x = 0.05 in low magnetic fields (H less than or equal to 2 kOe).
关键词:
rare earth transition metal compounds;Laves phases;magnetostriction;dy0.9-xprxtb0.1fe2
Physical Review B
The magnetic properties and phase transitions of 1T-TaS2 and 1T-Fe0.07Ta0.93S2 have been studied in the interval of 1.5-300 K and over the range of 100 Oe-60 kOe. Experimental results show that at high temperatures the compounds are in a diamagnetic state and the commensurate-charge-density-wave-triclinic-nearly-commensurate transition temperature of 1T-TaS2 decreases with increasing magnetic field. The amount of variation is a function of the magnetic field. At low temperatures both 1T-TaS2 and 1T-Fe0.07Ta0.93S2 are in a paramagnetic state owing to the localized moments that come from the single Anderson-Mott localization state. The curves of magnetization versus temperature do not follow the Curie law or Curie-Weiss law, but can be described fairly well as M = M(0) + gamma T--n. The fitting parameters of experimental curves show that a part of the neighboring moment appears as antiferromagnetic coupling due to exchange interaction between the moments. The magnetic-field dependence of magnetization exhibits a complicated feature at low temperature. It shows that the compounds may undergo a phase transition at the maximum value of magnetization and then they are probably in a mixed charge-density-wave-spin-density-wave (CDW-SDW) state or SDW state due to the coherent superposition of the antiferromagnetic coupling.
关键词:
metal-insulator-transition;density-wave domains;high magnetic-fields;charge-density;doped 1t-tas2;coexistence;microscopy;systems;silicon;2h-tas2
王庆琨
,
周利民
,
普绍平
,
朱泽兵
,
李学杰
,
吴富明
,
温志寿
,
金全
贵金属
doi:10.3969/j.issn.1004-0676.2012.01.013
为了合成新型铂抗癌药物米铂的代谢产物之一顺式-碘氯[(1R,2R) -(-)-1,2-环己二胺]合铂(Ⅱ),以K2 PtCl4为起始原料先后与二甲基亚砜、(1R,2R) -(-)-1,2-环己二胺、AgNO3、KI和KCl反应合成目标化合物.采用元素分析、质谱、核磁共振氢谱、红外光谱和热分析方法分析其组成和结构,结果显示合成的化合物结构与标题化合物一致.
关键词:
无机合成化学
,
米铂
,
代谢产物
,
合成
,
表征
姜洪生
,
宋冬利
,
张汉谦
,
丛郁
,
王国栋
材料热处理学报
通过12Cr2Mo1R厚钢板空冷过程的埋偶试验和ABAQUS软件计算机模拟对比,确认ABAQUS软件可以模拟12Cr2Mo1R 厚钢板的空冷过程.在此基础上,使用该软件模拟不同厚度下12Cr2Mo1R厚钢板芯部的冷却速度,结合其CCT曲线和工业生产工艺条件,确定临氢设备用12Cr2Mo1R厚钢板在正火后空冷条件下,使芯部能实现以贝氏体组织为主的厚钢板临界厚度为50mm.通过工业生产的50mm厚12Cr2Mo1R钢板组织和性能验证,证明所确定的临界厚度是安全的.
关键词:
临氢设备
,
12Cr2Mo1R钢
,
临界厚度
,
厚钢板
董学强
,
公茂琼
,
郭浩
,
吴剑峰
工程热物理学报
在243.168～293.182 K的温度范围内,采用自行设计搭建的高精度可视化相平衡实验系统测量了1,1,2,2四氟乙烷（R134）的饱和蒸气压实验数据,温度和压力的测量不确定度分别小于5 mK和0.5 kPa。用Wagner型方程对实验数据进行了关联,并与文献数据进行了对比,获得了良好的一致性。
关键词:
R134
,
Wagner方程
,
饱和蒸汽压
,
实验测量
