SITE AFFINITY OF SUBSTITUENTS IN ND2FE17-XTX (T=CU,ZR,MB,TI,V) ALLOYS

In order to understand the magnetic properties of the substituted rare -earth-iron alloys, it is especially important to know the location of the substitutional atoms within the iron lattice. The site distributi ons of some nontransition-metal substituents in the substituted Nd2Fe1 7-xTx alloys have previously been reported. Here we report the site di stributions of some transition-metal substituents (Cu,Zr,Nb,Ti,V) in t he Nd2Fe17-xTx alloys and compare them with those of the nontransition -metal substituted compounds. Rietveld analysis of neutron powder diff raction data indicates that the nontransition-metal substituents show very similar site affinity at low substituent content. For example Al, Ga, and Si all prefer the 18h sites. The transition-metal substituent s show a more complex site affinity. Ti acid V atoms strongly prefer t he 6c sites, Cu atoms prefer the 9d and 18f sites, Nb atoms prefer the 6c and 18h sites, and Zr atoms prefer 6c and 18f sites. It was also n oted that the site affinity can change if carbon is included in the me lting procedure of the sample preparation. The superconducting quantum interference device measurements show that all the substituted compou nds have a Curie temperature higher than the unsubstituted parent comp ound. The relationship between the site distribution of substituents a nd the magnetic properties of the substituted Nd2Fe17-xTx alloys is di scussed. (C) 1996 American Institute of Physics.