The crystal structure of Cu2GeSe3 and the structure-types of the I2-IV-VI3 family of semiconducting compounds

Almost 50 years after the initial report, the crystal structure of Cu2GeSe3, a I2-IV-VI3 semiconductor, has been revised using modern single-crystal X-ray diffraction data. The structure of this material can be properly described in the monoclinic space group Cc (No. 9) with unit-cell parameters a = 6.7703 (4) Å, b = 11.8624 (5) Å, c = 6.7705 (4) Å, β = 108.512 (6)°, V = 515.62 (5) Å3, Z = 4, rather than in the orthorhombic space group Imm2 (No. 44) with unit-cell parameters a = 11.860 (3), b = 3.960 (1), c = 5.485 (2) Å, V = 257.61 Å3, Z = 2, as originally proposed [Parthé & Garín (1971). Monatsh. Chem. 102, 1197–1208]. Contrary to what was observed in the orthorhombic structure, the distortions of the tetrahedra in the monoclinic structure are consistent with the distortions expected from considerations derived from the bond valence model. A brief revision of the structures reported for the I2-IV-VI3 family of semiconducting compounds (I: Cu, Ag; IV: Si, Ge, Sn; and VI: S, Se, Te) is also presented.

Surface micromorphology characterization of PDI8-CN2 thin films on H-Si by AFM analysis

A nanoscale investigation of three-dimensional (3-D) surface micromorphology of archetypical N, N0- bis (n-etyl) x:y, dicyanoperylene- 3, 4:9, 10 bis (dicarboximide) (PDI8-CN2) thin films on H-Si substrates, which are applicable in n-type semiconducting compounds, has been performed by using fractal analysis. In addition, surface texture characteristics of the PDI8-CN2 thin films have been characterized by using atomic force microscopy (AFM) operated in tapping-mode in the air. These analyses revealed that all samples can be described well as fractal structures at nanometer scale and their three dimensional surface texture could be implemented in both graphical models and computer simulations.

A carbazole functionalized semiconducting compound as a heavy atom free photosensitizer for phototherapy against lung cancer

Semiconducting compounds with high photostability and excellent photothermal ability are potential candidates for phototheranostics.

Synthesis of Composite Zn2SnO4/SnO2 as Photocatalyst Materials by Means of Sonochemical Treatment and Its Electronic Structure

Metal oxide semiconducting compounds have potential application as photocatalyst materials to decompose many types of dyes and pollutants in the water. Zn2SnO4 and SnO2 are semiconducting materials that have photocatalytic properties and the properties of those two semiconducting materials in the composite form have been studied. Metal oxide compounds of Zn2SnO4 and SnO2 have been prepared through sonochemical methods using ZnCl2 and SnCl4.5H2O as precursors. After sonication and heat treatment at 1000 °C, we could obtain Zn2SnO4 and SnO2 compound in the sample as confirmed by x-ray diffraction measurement. The volume fraction of Zn2SnO4 and SnO2 phases in the sample were found to be at 60 % and 40 %, respectively. The absorption spectra revealed that the band gap of the composite materials is 3.7 eV. This material could degrade all of the methylene blue with concentration of 6.0 x 10-6 M in 120 minutes. The band structure calculation revealed that the comparable band gap values are found for Zn2SnO4 and SnO2 compounds. However, the absorption edges for those compounds are slightly different, with absorption edge at 3.2 eV for SnO2 and 3.6 eV for Zn2SnO4, respectively.

Surface Oxidation of TiNiSn (Half-Heusler) Alloy by Oxygen and Water Vapor

TiNiSn-based half-Heusler semiconducting compounds have the highest potential as n-type thermoelectric materials for the use at elevated temperatures. In order to use these compounds in a thermoelectric module, it is crucial to examine their behaviour at a working temperature (approximately 1000 K) under oxygen and a humid atmosphere. Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) were utilized to study the surface composition and oxidation of the TiNiSn alloy at elevated temperatures. It was found that during heating in vacuum, Sn segregates to the surface. Exposing the alloy to oxygen at room temperature will cause surface oxidation of Ti to TiO2 and Ti2O3 and some minor oxidation of Sn. Oxidation at 1000 K induces Ti segregation to the surface, creating a titanium oxide layer composed of mainly TiO2 as well as Ti2O3 and TiO. Water vapor was found to be a weaker oxidative gas medium compared to oxygen.

The structure-directing amine changes everything: structures and optical properties of two-dimensional thiostannates

Two different two-dimensional thiostannates (SnS) were synthesized using tris(2-aminoethyl)amine (tren) or 1-(2-aminoethyl)piperidine (1AEP) as structure-directing agents. Both structures consist of negatively charged thiostannate layers with charge stabilizing cations sandwiched in-between. The fundamental building units are Sn3S4broken-cube clusters connected by double sulfur bridges to form polymeric (Sn3S72−)nhoneycomb hexagonal layers. The compounds are members of theR-SnS-1 family of structures, whereRindicates the type of cation. Despite consisting of identical structural units, the band gaps of the two semiconducting compounds were found to differ substantially at 2.96 eV (violet–blue light) and 3.21 eV (UV light) for tren–SnS-1 and 1AEP–SnS-1, respectively. Aiming to explain the observed differences in optical properties, the structures of the two thiostannates were investigated in detail based on combined X-ray diffraction, solid-state13C and119Sn MAS NMR spectroscopy and scanning electron microscopy studies. The compound tren–SnS-1 has a hexagonal structure consisting of planar SnS layers with regular hexagonal pores and disordered cations, whereas 1AEP–SnS-1 has an orthorhombic unit cell with ordered cations, distorted hexagonal pores and non-planar SnS layers. In the formation of 1AEP–SnS-1, an intramolecular reaction of the structure-directing piperidine takes place to form anN-heterobicyclic cation throughin situC—H activation. Hirshfeld surface analysis was used to investigate the interaction between the SnS layers and cations in 1AEP–SnS-1 and revealed that the most nucleophilic part of the SnS sheets is one of the two crystallographically distinct double sulfur bridges.