The crystallographic and the magnetic structures of the composite compound Nd2Co7 at 300 K are investigated by a combined refinement of X-ray diffraction data and high-resolution neutron diffraction data. The compound crystallizes into a hexagonal Ce2NiT-type structure and consists of alternately stacking MgZn2-type NdCo2 and CaCus-type NdCo5 structural blocks along the c axis. A magnetic structure model with the moments of all atoms aligning along the c axis provides a satisfactory fitting to the neutron diffraction data and coincides with the easy magnetization direction revealed by the X-ray diffraction experiments on magnetically pre-aligned fine particles. The refinement results show that the derived atomic moments of the Co atoms vary in a range of 0.7 μB-1.1 μB and the atomic moment of Nd in the NdCo5 slab is close to the theoretical moment of a free trivalent Nd3＋ ion, whereas the atomic moment of Nd in the NdCo2 slab is much smaller than the theoretical value for a free Nd3＋ ion. The remarkable difference in the atomic moment of Nd atoms between different structural slabs at room temperature is explained in terms of the magnetic characteristics of the NdCo2 and NdCo5 compounds and the local chemical environments of the Nd atoms in different structural slabs of the Nd2Co7 compound.
Our recent studies of the crystal structures, phase transitions, and magnetic properties of intermetallic compounds RsM4 （R = rare earths; M = Si, Ge） are reviewed briefly. First, crystal structures, phase relationships, and magnetic prop- erties of several 5：4 compounds, including Nd5 Si4-xGex, Pr5 Si4_xGex, Gds-xLaxGe4, La5 Si4, and Gd5 Sn4, are presented. In particular, the canted spin structures as well as the magnetic phase transitions in PrsSi2Ge2 and PrsGe4 investigated by neutron powder diffractions and small-angle neutron scattering are reviewed. Second, the crystal structures and magnetic properties of the most studied compounds Gds（Si,Ge）4 are summarized. The focus is on the parent compound GdsGe4, which is an amazing material exhibiting magnetic anisotropy, angular dependent spin-flop transition, metastable magnetic response, Griffiths-like phase, thermal effect under pulsed fields, antiferromagnetic and ferromagnetic resonances, pro- nounced effects of impurities, and high-field induced magnetic transitions.
The isothermal section of the Ce-Co-Al ternary system at 573 K was investigated by X-ray powder diffraction （XRD）, scanning electron microscopy （SEM） and energy dispersive X-ray spectroscopy （EDS） techniques. It consisted of 19 single-phase regions, 46 two-phase regions and 25 three-phase regions. Four ternary compounds, namely CeCoAl, Ce2Co15Al2, CeCoAl4, CeCo2Al8, were confirmed in this system. At 573 K, the maximum solid solubilities of Co in CeAl2 and Al in CeCo2 were about 10.4 at.% and 10.0 at.%, respectively. The homogeneity range of CoAl phase extended from about 46.0 to 56.0 at.% Al.
