Chemical control of the electronic properties in the amorphous alloys M 2SnTe 4 (M=Mn, Fe, Co, Cu)

Abstract

Using a new room temperature method for the synthesis of alloys, the oxidation of metal polyanions with transition metal cations in solution, it is possible to vary smoothly and continuously the electrical resistivity over nine orders of magnitude. This method of alloy synthesis consists of the high temperature reaction of elements to form Zintl phase type materials, extraction of metal polyanions from the Zintl phase followed by oxidation of the metal polyanions by a metal cation in solution to give amorphous alloys. In the systems M 2SnTe 4 (M= Mn, Fe, Co, Cu) and Co 2−xMn xSnTe 4 both the resistivity and optical bandgap of the alloy appear to correlate with the degree of electron transfer from anion to cation in the alloy, i.e. the electronegativity difference between the metal anion and metal cation.