NUCLEAR-MAGNETIC-RESONANCE STUDY OF EXPANDED LATTICE PERMANENT-MAGNETNITRIDES AND CARBIDES AT HIGH-PRESSURE

The nuclear magnetic resonance spin-echo spectra of Y-89 and Sm-147 fo r Y2Fe17, Y2Fe17C0.4, Y2Fe17C1.5, Y2Fe17N2.5, Y2Fe17CN1.5, Y2Fe17H1.6, and Sm2Fe17 have been measured at pressures up to 10 kbar at 4.2 K. A reduction of the magnitude of the valence electron polarization contr ibution to the effective field B-e at Y and Sm sites with pressure is observed. The effect is strongly related to the nearest neighbor envir onment of the site. A significant reduction of partial derivative B/pa rtial derivative p is observed for the sites with nitrogen neighbors. Carbon increases (decreases) partial derivative B/partial derivative p in the rhombohedral (hexagonal) structure of the compound. A decrease of the lattice electric field gradient at the Sm site in Sm2Fe17 with pressure is observed. A corresponding decrease of the crystal electri c field coefficient A(2)(0) at the Sm site with pressure of 0.7% per k bar is derived, indicating an anisotropic compressibility of the mater ial. (C) 1996 American Institute of Physics.