MOSSBAUER SPECTROSCOPY AND ELECTRICAL CONDUCTIVITY OF FE-DOPED BETA-RHOMBOHEDRAL BORON

摘要

Iron and/or aluminum are doped to beta-rhombohedral boron and the electrical conductivity and Fe-57 Mossbauer effect are measured, The temperature dependence of the electrical conductivity is explained as a variable range hopping type, The conductivity increases with an increase in Fe concentration, but it is insensitive to Al concentration. The Mossbauer spectra measured at room temperature are resolved into three kinds, of doublets and a sextet due to ferromagnetic FeB, One doublet, gamma(0), is attributed to Fe3+ ions at A(1) sites, while the others, gamma(1) and gamma(2), occur from Fe2+ ions at D sites. When Fe and Al atoms are simultaneously doped into beta-boron, the intensity of the gamma(0) doublet decreases and, hence, those of the gamma(1) and gamma(2) doublets relatively increase, The results shows that Fe atoms are moved From A(1) sites to D sites by Al atoms, It is proposed that the gamma(1) doublet corresponds to Fe2+(D)-Fe2+(D) and the gamma(2) doublet to Fe2+(D) and that a part of Fe2+(D) is in the magnetic state at 4.2 K. (C) 1997 Academic Press. [References: 20]