Ternary Ni−Sb−Te Nanoparticles by Co‐Reduction in a One‐Pot Microwave‐Assisted Polyol Process

Abstract Utilizing the polyol process to produce ternary or multinary phases is a challenge due to the different redox potentials of the components. We succeeded in synthesizing compounds in the composition range Ni 4−δ (Sb x Te 1−x ) 6 (−0.20≤ δ ≤0.36, 0.13≤ x ≤0.3) by heating a basic ethylene glycol solution containing nickel(II) acetate, antimony(III) acetate, and ammonium tellurate(VI) in a microwave at 280 °C for 25 min without adding auxiliary reducing agents. The products consist of thin nano‐platelets, which can be transformed into larger crystals by annealing. Single crystal X‐ray diffraction revealed a new structure type for the composition Ni 4−δ (Sb 0.25 Te 0.75 ) 6 ( x =0.25) in the space group P m 1 with a =3.897(1) Å and c =15.701(1) Å. The triple superstructure of the NiAs type is due to a complex concentration profile of the Ni atoms in the octahedral voids. The trigonal TlCdS 2 type is found for lower Sb contents (0≤ x ≤0.20), while for higher Sb contents ( x ≥0.28) the hexagonal Ni 2 SbTe 2 type is adopted, which both are ordering variants of the NiAs type. Ni 4−δ (Sb 0.25 Te 0.75 ) 6 is paramagnetic and exhibits poor metallic conductivity in the temperature range 6 K≤ T ≤300 K.