2023-Sustainable Industrial Processing Summit
Echegoyen Intl. Symp / Nanomaterials for Future Energy Demands
| Editors: | F. Kongoli, M.P. Brzezinska, M.A. Alario-Franco, F. Marquis, M.S. Noufal, E.Palomares, J.M. Poblet, D.M. Guldi, A.A. Popov, A.R. Puente Santiago, B. Raveau, D. G. Rodriguez, S. Stevenson, T. Torres, A. Tressaud, M. de Campos |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2023 |
| Pages: | 166 pages |
| ISBN: | 978-1-989820-78-0 (CD) |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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SOLID-STATE 65Cu/119Sn MAS NMR STUDY OF PROLONGED OXIDATION IN AMBIENT AIR OF SEMICONDUCTOR KESTERITE Cu2Zn2SnS4 NANOPOWDERS
Jerzy F. Janik1; Katarzyna Lejda2; Zbigniew Olejniczak3;1AGH UNIVERSITY OF KRAKOW, Kraków, Poland; 2AGH UNIVERSITY OF KRAKOW, FACULTY OF ENERGY AND FUELS, Kraków, Poland; 3INSTITUTE OF NUCLEAR PHYSICS, POLISH ACADEMY OF SCIENCES, 31 342 Kraków, Poland;
Type of Paper: Regular
Id Paper: 249
Topic: 16
Abstract:
The great potential in modern photovoltaics of semiconductor kesterite Cu2ZnSnS4 warrants continuing interest by researchers in developing new synthesis routes and in studies of the fundamental and application properties of the compound. One of the overlooked kesterite features is its susceptibility to oxidation when exposed to air, which is of utmost interest in synthesis, examination, and storage/applications. In this regard, kesterite is a quaternary sulfide which exhibits a wide range of lattice and compositional defects while kesterite’s nanopowders are also characteristic of increased specific surface area. These factors can impact its oxidation reactivity, especially, in ambient air where the presence of water vapor is known to accelerate oxidation processes.
Recently, we developed a few precursor systems for making kesterite via the mechanochemically-assisted synthesis method [1,2]. In all cases, the isolated raw powder is a cubic polytype of kesterite (tentatively called prekesterite) with no semiconductor properties. This variety is converted upon annealing in argon at 500 ºC to the tetragonal semiconductor kesterite. In this study, we prepared and investigated kesterite nanopowders (both cubic and tetragonal polytypes) from the metal sulfide (MS) system {Cu2S+ZnS+SnS+S → Cu2ZnSnS4} and from the Zn/Sn copper alloys (CA) system {2Cu+Zn+Sn → copper alloys} that further reacted with sulfur in-situ towards kesterite formation {alloys+4S → Cu2ZnSnS4}. After characterization, all freshly made nanopowders were exposed to ambient air for 6 months.
The solid-state 65Cu/119Sn MAS NMR study confirmed our earlier observations and neither 65Cu nor 119Sn resonance signals were observed for the prekesterites from both systems [1,2]. It was true for the freshly made and air-exposed samples. This is ascribed by us to the so-called d0 magnetism in such nanopowders. On the other hand, the annealed kesterite nanopowders clearly showed both these resonances as anticipated. For the fresh samples, the 65Cu signals were found at 779.6 and 799.0 ppm and the 119Sn signals were found at -134.1 and -133.7 ppm for the kesterite nanopowders from the MS and CA precursor systems, respectively. For the samples being oxidized in air for 6 months, the signals could also be seen although with the relatively decreased intensities, respectively, for 65Cu at 797.1 and 800.0 ppm, and for 119Sn at 134.1 and 134.3 ppm. This is an interesting observation since the XRD patterns for the oxidized nanopowders support there significant amounts of the hydrated copper and zinc sulfates with the former containing magnetically active Cu+2 ions. Apparently, the presence of Cu+2 in the aggregates of the copper sulfate, which are spatially separated from the kesterite particles, does not interfere with the overall advantageous NMR resonance conditions.
(NCN grant No. 2020/37/B/ST5/00151)
Keywords:
Characterization; Nanomaterials; Photovoltaic; Spectroscopy; SynthesisReferences:
[1] K. Kapusta, M. Drygas, J.F. Janik, Z. Olejniczak, J. Mater. Res. Technol. 9 (2020), 13320.[2] K. Lejda, M. Drygaś, J.F. Janik, J. Szczytko, A. Twardowski, Z. Olejniczak, Materials 13 (2020) 3487.