Verbindungen mit Schichtstrukturen in den Systemen CuGa5S8/CuIn5S8 und AgGa5S8/AgIn5S8

Abstract

Frau Professor Marianne Baudler zum 80. Geburtstag gewidmet Inhaltsu È bersicht. Wir haben die Systeme CuGa 5 S 8 /CuIn 5 S 8 und AgGa 5 S 8 /AgIn 5 S 8 an abgeschreckten Pra È paraten mit Ro È ntgenpulver-und Einkristallmethoden untersucht. Im System AgGa x In 5±x S 8 wird bis x < 2 eine Phase mit Spinellstruktur gebildet. Fu È r 2 < x £ 3 existiert eine Phase, die in einer hexagonalen Schichtstruktur kristallisiert. Die Struktur dieser Phase wurde an einem Einkristall der Zusammensetzung AgGa 3 In 2 S 8 bestimmt: P6 3 mc, Z = 2, a = 380,80, c = 3076,4 pm. Die Struktur ist isotyp zum Zn 2 In 2 S 5 (II a)Typ. Das Pra È parat der Zusammensetzung AgGa 4 InS 8 kristallisiert in einer Wurtzit-Defektstruktur mit a = 377,25 und c = 616,1 pm. Im System CuGa x In 5±x S 8 wird fu È r x = 1 und x = 2 ebenfalls eine Phase mit Schichtstruktur beobachtet mit den hexagonalen Gitterkonstanten a = 380.28 und c = 3073.4 pm (x = 2). Der Spinell CuIn 5 S 8 weist keine Phasenbreite auf, ein Austausch von In gegen Ga wird nicht beobachtet.Abstract. The title systems have been investigated by single crystal and powder X-ray diffraction methods on quenched samples. In the system AgGa x In 5±x S 8 spinel type phases are formed up to x < 2. A compound crystallising with a hexagonal layered structure is obtained for 2 < x £ 3. The crystal structure of this layered phase has been solved on a single crystal of composition AgGa 3 In 2 S 8 : space group P6 3 mc, Z = 2, a = 380.80 and c = 3076.4 pm. The structure is isotypic to the Zn 2 In 2 S 5 (II a) type. The sample AgGa 4 InS 8 crystallises in a Wurtzite like structure with a = 377.25 and c = 616.1 pm. In the system CuGa x In 5±x S 8 a new compound with layered structure has been detected for 1 £ x £ 2 which crystallises hexagonally with a = 380.28 and c = 3073.4 pm (x = 2). For the spinel CuIn 5 S 8 an exchange of In by Ga is not detected.

Solvent‐Free Synthesis of Quaternary Metal Sulfide Nanoparticles Derived from Thiourea

“…The broad peaks at ≈28° (multiple peaks including the (103) diffraction) and 48° ((112) diffraction) are consistent with the XRD pattern for previously reported CuGa 2 In 3 S 8 nanoparticles synthesized by a hot‐injection method. [12c] This result clearly indicates that wurtzite is a metastable phase, which is transformed into chalcopyrite while losing its high crystallinity. Upon further increasing the amount of thiourea to Cu:S = 1:210, the wurtzite structure was not observed even from the beginning of the reaction, and the XRD pattern corresponding to the chalcopyrite phase was attained.…”

“…The addition of Na 2 S (Na 2 S/Cu molar ratio = 16) to the precursor mixture mentioned above was examined (denoted as “CGIS‐300S”), possibly altering the reaction kinetics by the presence of Na 2 S. As a result, sharper peaks in the XRD pattern (Figure ) were evident when the material was synthesized in the presence of Na 2 S. CGIS with a wurtzite structure was most likely formed, consistent with the pattern of isostructural Ag 1.12 Ga 2.68 In 3.7 S 10 , PDF 01‐070‐8366 (Figure S3, Supporting Information). Clear differences in the diffuse reflectance UV–vis spectra were observed between the CGIS synthesized for CGIS‐300 and CGIS‐300S with Cu:S = 1:210 ( Figure ) . Although clear band edges are not defined from these data, the photon absorption for CGIS‐300 reaches beyond ≈800 nm, whereas the absorption for CGIS‐300S only reaches to 700 nm.…”

“…The HER apparent quantum efficiency was measured to be 8.7% at 420 nm assuming full absorption of the irradiated photons by the photocatalyst, which was comparable with our previously reported value for CGIS synthesized by a hot‐injection method. [12c] We also varied the amount of thiourea used for the synthesis keeping other reactants unaltered (1:53–421), and synthesized materials were tested for photocatalytic HER in order to have an idea on the effect of thiourea (Figure S14, Supporting Information). The results showed that optimum amount of thiourea is necessary to get good photocatalytic activity.…”

Solvent-induced deposition of Cu–Ga–In–S nanocrystals onto a titanium dioxide surface for visible-light-driven photocatalytic hydrogen production

“…From the XRD patterns presented in Figure 2, CuGaxIn5-xS8, nanocrystals where x = 1 and 2, exhibit four prominent peaks at 2θ = 21.5, 27.5, 47.6, and 56.2. These peaks are in good agreement with the structure for the AgGa2In3S8 reference pattern (PDF 01-070-8366), indicating that they have a layered structure with hexagonal crystal packing [17]. For CuGaxIn5-xS8 nanocrystals, where x = 3, major diffraction peaks for CGIS nanocrystals are observed at 2θ values of 28.9, 56.5, and 47.8, indicating the formation of CGIS nanocrystals with zincblende structure [18], whereas at higher gallium content, i.e., where x = 4 and 5, the XRD patterns of the CGIS nanocrystals showed major diffraction peaks at 2θ values of 27.6, 29.2, 31.2, 40.4, 48.8, 52.6, and 57.8, with peak positions well-matched with the powder diffraction data reported for the wurtzite structure [19,20].…”

Nano‐Sized Quaternary CuGa2In3S8 as an Efficient Photocatalyst for Solar Hydrogen Production

“…Through this strategy, CuGa 2 In 3 S 8 (CGIS) visible‐light‐driven photocatalysts, which can absorb light up to ≈700 nm, have been prepared successfully using the solid‐state method by heat treatment at a high temperature in an evacuated sealed quartz glass tube 10b. 11…”