Synthesis,structure and magnetic properties of Sm_(1.2)Ho_(0.8)Fe_(17)H_x(x=0;4.4)

Intermetallic compounds based on rare-earth metals and iron are by far the most promising materials for permanent magnets.In this work,the multicomponent compound Sm_(1.2)Ho_(0.8)Fe_(17) was prepared by induction melting.The hydride Sm_(1.2)Ho_(0.8)Fe_(17)H_(4.4) with a high hydrogen content was obtained by direct hydrogenation of the intermetallic compound.The rhombohedral Th_2 Zn_(17)-type of structure(space group R3 m) is inherent to parent compound and hydride as well.The effect of hydrogenation on the magnetic properties of Sm_(1.2)Ho_(0.8)Fe_(17) was investigated.Curie temperature of the hydride Sm_(1.2)Ho_(0.8)-Fe_(17)H_(4.4) is higher than that of parent compound by ΔT_C=138 K.The hydrogen embedded in Sm_(1.2)Ho_(0.8)Fe_(17) crystal lattice increases the saturation magnetization(σs) at T=300 K,but does not significantly affect σ_S at T=4.2 K.The ferrimagnetic structure is retained in magnetic fields up to 58 T in the parent compound,while,in the hydride,there is a spin-reorientation phase transition observed at 55 T.It is found that the parameter of the intersublattice exchange interaction decreases significantly in the hydride Sm_(1.2)Ho_(0.8)Fe_(17)H_(4.4)(and in the nitride Sm_(1.2)Ho_(0.8)Fe_(17)N_(2.4)) which is associated with boosting of the unit-cell volume and distances between magnetic ions.     

双钙钛矿化合物Sr2Mn1-xGaxMoO6（x=0,0.1,0.2,0.3）的晶体结构与磁性

用非磁性Ga3+部分替代Sr2MnMoO6中的Mn2+,获得Sr2Mn1-xGaxMoO6(x=0,0.1,0.2,0.3)多晶样品,通过X射线衍射(XRD)分析和磁性能测量研究Ga3+对晶体结构和磁性的影响。XRD谱Rietveld结构精修分析表明,Sr2Ga1-xMnxMoO6具有四方对称晶体结构(空间群I4/m)。随着Ga含量增加,B/B-原子占位有序度降低,平均键长减小,而平均键长增大,平均键角保持180o不变,平均键角逐渐扩张。5 K及300 K温度下,样品均为反铁磁体,但低掺杂样品在低温(5 K)下表现出微弱的铁磁性。上述结果表明,Ga3+对Mn2+的电子掺杂引起部分Mo离子价态由+6价转变为+5价。     

Relations between Quenching Rate and Electrochemical Characteristics of Mm (NiCoMnA1) 5Bx (x=0～0.2) Electrode Alloys

Low-Co AB5-type Mm(NiCoMnA1)5Bx (x = 0, 0.1, 0.2 ) electrode alloys were prepared by casting and rapid quenching.The effects of the rapid quenching on the lattice constants, microstructures and electrochemical characteristics of the alloys were investigated in detail.The obtained results show that the rapid quenching made lattice constants and cell volume increased.In a range of the quenching rate, rapid quenching can increase the discharge capacities of the alloys.However, the discharge capacity of the as-quenched alloy is lower than that of the as-cast alloy when quenching rate is more than a critical value.The cycle lives of the alloys increase monotonously with the increase of the quenching rate.     

A high-resolution NMR study (1H, 13C, 31P) of the interaction of paramagnetic ions with phospholipids in aqueous dispersions

In the surgical treatment of hernias in children, many differences of opinion still exist, especially in the selection of the type of procedure to be used. The authors have applied the Ferguson Method in the repair of Inguinal hernias as a method of choice. Along with a high resection of Processus Vaginalis of the peritoneum, the anterior wall of Canalis Inguinalis is reinforced without transposing the Funiculus Spermaticus. To evaluate the success of this method, the authors made a late postoperative analysis. Examinations were made on 106 children of various ages who had unilateral inguinal hernia repairs one to two years prior. The unoperated contralateral inguinal canal served as a control by which eventual changes of testis could be evaluated. Clinical examinations involved determination of whether or not a recidive hernia exits, as well as the condition, size and consistency of the testis. Accordingly, poor postoperative results using the Ferguson method were less than one percent.     

Magnetic properties and microstructure of Fe_(69.5-x)Nd_7B_(21)Nb_(2.5)Ga_x(x=0-1)alloys

The Fe_(69.5-x)Nd_7 B_(21)Nb_(2.5)Ga_x(x = 0-1)permanent magnets in the form of rods were prepared by annealing the bulk amorphous alloys.The magnetic properties,phase evolution and microstructure of the alloys were investigated systematically.It is found that the glass forming ability(GFA), microstructure and magnetic properties are sensitive to Ga content for Fe_(69.5-x)Nd_7 B_(21)Nb_(2.5)Ga_x(x = 0-1)bulk alloys.The annealed alloys are mainly composed of soft α-Fe,hard Nd_2 Fe_(14)B and nonmagnetic Nd_(1.1)Fe_4 B_4 phases.When x = 0.3,the optimally annealed magnets exhibit magnetic properties of the remanence Br = 0.63 T,intrinsic coercivity H_(cj) = 368.68 kA/m and maximum energy product(BH)_(max) = 33.73 kJ/m~3.Furthermore,magnetic field heat treatment at the temperature close to Curie temperature of Nd_2 Fe_(14)B phase was applied to the annealed Fe_(69.2)Nd_7 B_(21)Nb_(2.5)Ga_(0.3) magnet.The results of X-ray diffraction(XRD)and transmission electron microscopy(TEM)indicate that the magnetic field heat treatment can be beneficial for the precipitation of α-Fe.Thus,the B_r,H_(cj) and(BH)_(max) are enhanced by 8.7%,6.3% and 16.3%,respectively.