STRUCTURE AND MAGNETIC PROPERTIES OF LaCo13-BASED ALLOYS

The structure and magnetic properties of two series of LaCois-based alloys, LaCo_13-xFe_x(0≤x≤6) and La_1-xR_x(Co, Fe)₁₃ (x=0.1,0.2; R=Y, Ge, Pr, Nd Sm, Gd, Tb, Dy, Ho, Er, and Yb), are studied by X-ray diffraction and magnetic mea- surements. In the above-mentioned composotions, all the samples display a structure of NaZn₁₃ type (space group: Fm3c). In LaCo_13-xFe_x system, as the iron content increases, its Curie temperature decreases, while thc magnetic moment per 3d atom increases. This may be explained by a rigid band model. In the other alloy system, the Curie temperature goes through a maxium at R=Gd, and this reflects the influ- ence of R - T interaction. It is also observed that saturation magnetization varies with R and gets lower when R is a heavy rare earth element. The contribution of R is close to that of a free-ion moment. La_0.9Pr_0.1Co₉Fe₄ has the largest value 29μ_B/f.u.     

三元合金生成热的一种计算方法

本文将半经验模型计算二元合金生成熟的方法，推广至三元合金，计算了Ｌａ－Ｆｅ－Ａｌ，Ｆｅ－Ａｌ，Ｆｅ－Ｎｉ－Ｖ，Ｃｕ－Ｐｄ－Ｓｉ等三元合金体系生成热，并与实验结果比较，符合很好，这种计算方法可预测三元合金生成热及固溶区的范围，并可最终产物存在的可能性。     

双(π-芳烃)铁(II)化合物的Mossbauer分析

铁的简单配合物及羰基化合物的Mossbauer研究已有报道, 对有机铁化合物的相应工作进行得较少. 本文报道一类具有夹心结构的有机铁化合物的^5^7FeMossbauer参数及其与结构的一些关系.     

CALCULATION OF THE HEAT OF FORMATION OF TERNARY COMPOUNDS: P-Ga-As, N-Ga-As, N-Ga-P

Miedema method, which was proposed to calculate the heat of formation of binary alloy system, is extended for calculating the heat of formation of ternary system by using the Toop's model. The hypothetical metallic allotropes correspounding to the properties of nonmetallic elements are introduced. In our calculation, the structure-dependent energy contributions have not been taken into account. The heat of formation of GaAs_1-x P_x, GaAs_1-xN_x, and GaP_1-xN_x are obtained by projecting the heat of formation of ternary systems, P-Ga-As, N-Ga-As, and N-Ga-P onto the plane of the concentration of Ga, c₂ = 0.5, respectively. The possibility of existence of ordered ternary compound was predicted. The dependence of direct band gap, E^Γ, or indirect one, E^X, for GaP_1-xN_x and GaAs_1-xN_x, on x, the concentration of N, is obtained by using the dielectric theory of electronegativity.     

STRUCTURE AND MAGNETIC PROPERTIES OF LaCo13-BASED ALLOYS

The structure and magnetic properties of two series of LaCois-based alloys, LaCo_13-xFe_x(0≤x≤6) and La_1-xR_x(Co, Fe)₁₃ (x=0.1,0.2; R=Y, Ge, Pr, Nd Sm, Gd, Tb, Dy, Ho, Er, and Yb), are studied by X-ray diffraction and magnetic mea- surements. In the above-mentioned composotions, all the samples display a structure of NaZn₁₃ type (space group: Fm3c). In LaCo_13-xFe_x system, as the iron content increases, its Curie temperature decreases, while thc magnetic moment per 3d atom increases. This may be explained by a rigid band model. In the other alloy system, the Curie temperature goes through a maxium at R=Gd, and this reflects the influ- ence of R - T interaction. It is also observed that saturation magnetization varies with R and gets lower when R is a heavy rare earth element. The contribution of R is close to that of a free-ion moment. La_0.9Pr_0.1Co₉Fe₄ has the largest value 29μ_B/f.u.