Synthesis and characterization of new intermetallic compounds M-3(AsTe3)(2) (M=Cr, Fe, Co)

The new amorphous intermetallic compounds, M-3(AsTe3)(2):M=Cr, Co, Fe, were synthesized by the precipitation reaction of the Zintl anion AsTe33- with the divalent transition metal halides in aqueous solution and analyzed by EDS equipped with SEM and PIXE. The empirical formula of the specimens was found to be Fe30As1.8Te5.9, CO(3.0)AS(2.1)Te(6.5), and Cr3.0As2.0Te6.9 by the quantitative elemental analysis. The de specific resistivity of the materials was measured as a function of temperature in the range from 20 to 300 K, in which their resistivities were decreased with increasing temperature, indicating the specimens to be semiconductors. The resistivity of Cr-3(AsTe3)(2) was largely dependent on temperature, while those of Co-3(AsTe3)(2) and Fe-3(AsTe3)(2) were only slightly dependent on temperature. To characterize the spin glass state of the specimens, the ac and de magnetic susceptibility were measured and it was found that Co-3(AsTe3)(2) and Fe-3(AsTe3)(2) undergo a transition to a spin glass state at 6 K and 38 K, respectively. Magnetization data are reported as both thermal remanent magnetization (TRM) and isothermal remanent magnetization (IRM) as a function of magnetizing field and temperature.