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Long-Term Oxidation Susceptibility in Ambient Air of the Semiconductor Kesterite Cu[sub.2]ZnSnS[sub.4] Nanopowders Made by Mechanochemical Synthesis Method
Ist Teil von
Materials, 2023-09, Vol.16 (18)
Ort / Verlag
MDPI AG
Erscheinungsjahr
2023
Link zum Volltext
Quelle
EZB Electronic Journals Library
Beschreibungen/Notizen
The often overlooked and annoying aspects of the propensity of no-oxygen semiconductor kesterite, Cu[sub.2]ZnSnS[sub.4], to oxidation during manipulation and storage in ambient air prompted the study on the prolonged exposure of kesterite nanopowders to air. Three precursor systems were used to make a large pool of the cubic and tetragonal polytypes of kesterite via a convenient mechanochemical synthesis route. The systems included the starting mixtures of (i) constituent elements (2Cu + Zn + Sn + 4S), (ii) selected metal sulfides and sulfur (Cu[sub.2]S + ZnS + SnS + S), and (iii) in situ made copper alloys (from the high-energy ball milling of the metals 2Cu + Zn + Sn) and sulfur. All raw products were shown to be cubic kesterite nanopowders with defunct semiconductor properties. These nanopowders were converted to the tetragonal kesterite semiconductor by annealing at 500 °C under argon. All materials were exposed to the ambient air for 1, 3, and 6 months and were suitably analyzed after each of the stages. The characterization methods included powder XRD, FT-IR/UV-Vis/Raman/NMR spectroscopies, SEM, the determination of BET/BJH specific surface area and helium density (d[sub.He]), and direct oxygen and hydrogen-content analyses. The results confirmed the progressive, relatively fast, and pronounced oxidation of all kesterite nanopowders towards, mainly, hydrated copper(II) and zinc(II) sulfates, and tin(IV) oxide. The time-related oxidation changes were reflected in the lowering of the energy band gap E[sub.g] of the remaining tetragonal kesterite component.