Magnetic transitions intermetallic compound

The crystal structures of the binary rare earth-3d transition metal compounds are typical for all rare earth-transition metal compounds. We concentrate on the 3d transition metals Mn, Fe, Co and Ni because, of all 3d metals these four metals are the only ones which form intermetallic compounds with the rare earth metals. The 3d transition metals Ti, V, Cr do not form a single intermetallic compound with any of the rare earth metals. The crystal chemistry of the rare earth-intermetallic compounds is discussed in the foregoing chapter (13) by landelli and Palenzona. Here we shall discuss the specifics of the rare earth-transition intermetallic compounds, as far as their crystal structure is important for the understanding of the magnetic properties. 

Nevertheless deviations from eq. (9.19) have been observed for the intermetallic compound Auln2 [108,109] and for T1 [110,111], Requirements for the validity of eq. (9.19) are the absence of changing internal fields due to nuclear magnetic or electronic magnetic ordering in the relevant temperature range, the absence of nuclear electronic quadrupole interactions and no superconductive transition. 

The intrinsic magnetic properties of the Er2Fei4B intermetallic compound have been previously investigated [1], According to the literature data [1,2] the magnetic ordering temperature of this compound is Tc = 554 K. Er2Fei4B exhibits one successive spin reorientation transition (SRT) at about 325 - 327 K. 

Nikitin S.A., Tishin A.M., Kuz min M.D., Spichkin Yu.I. (1991) A pressure-induced magnetic phase transition in Y2Fci7 intermetallic compounds. Phys.Lett. A 153, 155-161. 

Few materials show up the limitations of the two extreme viewpoints of magnetic moment formation in transition metal systems ( localized or itinerant ) more than do their intermetallic compounds. In some compounds, e.g., the (non-integral) magnetic moment may vary from one type of site to another and the moment associated with a particular transition metal atom is often different in its different compounds. The interest in the wide variety of properties exhibited by intermetallic compounds stems as much from the opportunity they offer for the understanding of magnetism in metallic systems at a fundamental level as from the possibility of producing materials of technological importance. 

The magnetism of the transition metals and their alloys and intermetallic compounds has been a focal point for discussion since the 1930s. In some instances it... 

It would not be appropriate here to discuss the many points at issue in the intense international debate which has been going on for some time in this area. The comments of the discussion panel at the international conference on magnetism in Kyoto, ICM 82, provide a convenient summary (Kanamori 1983) and a book dedicated to itinerant magnetism is now available (CapeUmann 1987). We shall therefore give only a brief outline of the expectations of those theories which are currently used by the majority of experimentalists in attempting to explain the observed ferromagnetic behaviour of the transition metal intermetallic compounds. 

Magnetic properties of the transition metal intermetallic compounds with yttrium. Detailed references are given in the article by Buschow (1977). 

It is also interesting to note that the decomposition of pseudobinary intermetallic compounds (LaNi4Fe and CeNis-jCo ) leads to the formation of bimetallic transition metal particles which display different selectivities than the catalysts derived from the related binary intermetallic compound (Paul-Boncour et al. 1991, France and Wallace 1988). The characterization of the bimetallic particles by XRD, Mossbauer spectroscopy and magnetism indicated that their composition was close to that of the starting alloy. 

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