A novel method to synthesize bulk super saturated solid solutions Ge1-xSnx (x≤5.0%)

Sn substituted Ge1-xSnx type phases can have a variety of optoelectronic and energy applications as the band gap in these materials is tunable by varying x. Super saturated solid solutions Ge1-xSnx (x ≤ 5.0%) have been synthesized by ball milling the elements Ca, Ge and Sn together for a period of 6 h. Extended ball milling beyond 6 h has only a marginal effect on the incorporation of Sn in Ge. By treating the ball milled product in concentrated HCl and subsequently washing in distilled water, the impurity phases CaSn and Sn can be washed away. Spark plasma sintering (SPS) at 500 °C for 5 min at a pressure of 350 MPa has yielded discs of 70% theoretical density. However, the amount of Sn incorporated in the spark plasma sintered discs have been reduced to 2.5 at.%. Resistivity and Seebeck coefficient measurements show the semiconducting nature of these samples and the capability of p- and n-type doping with Ga and P, respectively.