Structural Study, Mössbauer Spectra and Electrical Properties of R5Fe6Sn18 (R = Tm, Lu) Compounds

Ternary intermetallic R5Fe6Sn18 (R = Tm, Lu) compounds have been synthesized from the elements by arc melting, annealed at 670 K and characterized by X-ray powder diffraction and energy dispersive X-ray analyses. Performed structure refinements have shown that they crystallize in the cubic Tb5Rh6Sn18 structure type (space group Fm-3m, a = 13.55399(4) angstrom, a = 13.53243(5) angstrom for Tm and Lu compounds, respectively). Using( 57)Fe Mossbauer spectroscopy it has been found that the magnetic state of the Fe atoms in the Tm5Fe6Sn18 and Lu5Fe6Sn18 stannides is paramagnetic. The value of the isomer shifts for Lu5Fe6Sn18 and Tm5Fe6Sn18 is positive relative to pure Fe. The Fe-57 Mossbauer spectra for Lu(5)Fe(6)Sn(18 )and Tm5Fe6Sn18 stannides have shown that the quadrupole splitting for the Fe position (24e) have magnitudes of 0.43 and 0.45 mm/s, respectively. The similarity of these values is consistent with a qualitative crystal structure analysis. The examined Tm(5)Fe(6)Sn(18 )and Lu5Fe6Sn18 compounds have been found to be characterized by metallic-like conductivity and high values of electrical resistivity (672.9 mu Omega cm, 623.8 mu Omega cm at 300 K for Tm and Lu, respectively).