RECo_(10)V_2(RE=Y,Gd)化合物中的磁作用

用两格点分子场理论分析了RECo1 0 V2 (RE =Y ,Gd)化合物的磁矩随温度的变化。采用数值拟合的方法计算出了描述 3种磁作用的分子场系数nRECo,nCoCo和nRERE,并且计算出了居里温度TC。对于YCo1 0 V2 ,分子场理论仅以nCoCo给出了很好的描述。而对于GdCo1 0 V2 ,3个分子场系数中nCoCo最大 ,这意味着磁作用主要由钴 3d电子间的交换所支配。另外 ,为了便于分析磁晶各向异性能与温度的关系 ,本文还给出了分子场强度随温度变化的曲线     

Determination of the standard gibbs energy for the reaction of 3BaO (s) + 2Cr (s) + 3/2O2 (g) = 3Ba0 · Cr2O3 (s)

The standard Gibbs energy of formation of 3BaO · Cr₂O₃ has been measured by a chemical equilibrium technique and is expressed as follows: 3BaO (s) + 2Cr (s) + 3/2 O₂ (g) = 3BaO · Cr₂O₃ (s) ΔG^o = -1,260,000 (±3000) + 282 (±24)r(J/mol) The activity coefficient of chromium in copper, which was needed for the foregoing measurement, may be expressed by the following equation: 5790 log γ _Cr ^{o =5790/T-2.10} The value of standard Gibbs energy at 1573 K was found to be close to that of reaction of formation of CaO · Cr₂O₃ expressed in the similar form. The BaO saturated BaF₂ flux is shown to be far more promising in the oxidative dephosphorization of chromium-containing hot metal in comparison with the CaO-SiO₂-CaF₂ flux doubly saturated with CaO and 3CaO-Cr₂O₃.     

Kinetics of metal/slag reactions during spontaneous emulsification

An approach for accommodating the interfacial area changes in kinetic equations for heterogeneous reactions in the presence of spontaneous emulsification has been proposed. The kinetics were analyzed by incorporating time-averaged interfacial areas in the rate equations. The approach was found to be applicable for the experimental data and to satisfactorily describe the reaction kinetics. In the case of a high-temperature reaction between 2.35 g Fe-5 wt pct Al alloy metal droplets with CaO-SiO₂-Al₂O₃ slag at 1650 °C, it was found that the kinetics follow a first-order relationship with respect to aluminum in the metal, and it was concluded that they were controlled by mass transport in the metal phase. The calculated metal mass-transfer coefficient k _m was 1.7×10⁻⁶ m/s.     

Magnetocaloric Effect of Alloys Gd（Al1-x Cox ）2

The magnetocaloric effect in alloys Gd（Al1-xCox）2 with x = 0, 0.05, and 0.10 were investigated using X-ray diffraction （XRD） and magnetization measurements. It was found that three alloys crystallized in a single phase with MgCu2-type structure. The lattice parameter and Curie temperature decreased with increasing Co content, whereas the magnetic-entropy change increased. With a magnetic-field change of 2 T, the maximum of the magnetic-entropy change reached 4.6 J·kg^-1·K^-1 near Curie temperature at approximately 95 K in the alloy GdAl1.8Co0.2, which appeared to be an alternative candidate for active magnetic refrigerants working in the temperature range centered at 100 K.     

RECo10V2(RE=Y,Gd)化合物中的磁作用

用两格点分子场理j沧分析了RECo10V2(RE=Y,Gd)化合物的磁矩随温度的变化。采用数值拟合的方法计算出了描述3种磁作用的分子场系数nRECo，ncoch和nRERE，并且计算出了居里温度Tc。对于YC10V2，分子场理论仅以ncoco给出了很好的描述。而对于GdCo10V2,3个分子场系数中ncoco最大。这意味着磁作用主要由钴3d电子间的交换所支配。另外。为了便于分析磁晶各向异性能与温度的关系,本文还给出了分子场强度随温度变化的曲线。     

Fabrication and Properties of （Y, Gd）BCO Superconductors

MelttexturingYBCObulksuperconductorexhibitsthecriticalcurrentdensity(Jc)exceeding 1× 10 4 A·cm 2at 77Kandhaspotentialforvariousengineeringappli cations .Recently ,itwasfoundthatREBa2 Cu3Oy(RE :lightrareearthelement)canexhibithigherJcvaluesun derrelativelyhighfieldsduetoasecondpeakthanthatofYBCO[1] .Anditiswidelyacceptedthatthesecondpeakoriginatesfromthepresenceoffield inducedpin ningbyRE rich(12 3)clusters[2 ,3] .MelttexturinggrowthofRE Ba Cu Odependsonthereducedoxygenatmo sphere ,…