A High Sensitivity Isopropanol Vapor Sensor Based on Cr2O3-SnO2 Heterojunction Nanocomposites via Chemical Precipitation Route.

Cr2O3-SnO2 heterojunction nanocomposites were prepared via chemical precipitation method. The prepared samples were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectra and Field Emission Electron Microscopy (FESEM). The XRD spectrum confirms the presence of both tetragonal rutile SnO2 and rhombohedral corundum Cr2O3 structure. Further investigation into the gas sensing performances of the prepared Cr2O3-SnO2 nanocomposites exhibited an enhanced sensitivity towards VOPs such as isopropanol, acetone, ethanol and formaldehyde. Especially, isopropanol vapor sensor shows excellent sensitivity at an operating temperature of 100 °C. The highest sensitivity for Cr2O3-SnO2 heterojunction nanocomposites indicate that these materials can be a good candidate for the production of high-performance isopropanol sensors.

Unidirectional growth of benzil crystal from solution by Sankaranarayanan-Ramasamy method and its characterization.

Good quality <100> benzil single crystal with a diameter 18 mm and length 75 mm was successfully grown from solution by the unidirectional growth method of Sankaranarayanan-Ramasamy (SR) for the first time in the literature. The seed crystals have been harvested from conventional solution growth technique and subsequently used for unidirectional growth. The grown crystal was subjected to various characterization studies. The results of UV-vis spectral analysis, photoluminescence, etching and microhardness studies were compared with conventional solution grown crystal to that of SR method grown crystal. The quality of SR method grown benzil crystal is better than conventional solution grown crystal.

Synthesis, growth, thermal, optical and mechanical properties of 2-Aminopyridinium 4-methylbenzoate Dihydrate.

Organic NLO material of 2-Aminopyridinium 4-methylbenzoate Dihydrate (2A4M) was synthesized using 2-Aminopyridinium and 4-methylbenzoic acid as starting materials. Single crystals of 2A4M were grown by the slow evaporation solution growth technique at room temperature using water as a solvent. The grown crystal was characterized by single crystal XRD to confirm the crystal system and lattice parameters. From the optical studies the optical band gap and the refractive index of the material are found to be 2.9 eV and 1.40 at 1200 nm. Functional groups of the crystallised material were confirmed by FTIR vibrational spectrum. Thermal behaviour of the title compound was studied using thermogravimetric (TG) and differential thermal analyses (DTA). The initial weight loss is found up to 125°C, which corresponds to 13.2% i.e. presence of 2 mole of water in the lattice. The grown crystal was subjected to Vickers hardness test and the brittleness index, fracture toughness, yield strength were estimated. The etching studies reveal the growth pattern and dislocations present in the grown crystal. The second harmonic generation (SHG) behaviour of 2A4M was tested by Kurtz-Perry powder technique. The relative SHG efficiency of 2A4M is found to be 3.03 times that of the reference material KDP.

Bis(tetra-ethyl-ammonium) bis-(hydrogen l-tartrate) l-tartaric acid monohydrate.

In the title compound, 2C(8)H(20)N(+)·2C(4)H(5)O(6) (-)·C(4)H(6)O(6)·H(2)O, the presence of the two tetra-ethyl-ammonium cations is balanced by two hydrogen l-tartrate anions. Also present in the asymmetric unit are a mol-ecule of l-tartaric acid and a water mol-ecule. The various components are linked by O-H⋯O hydrogen bonds. In the crystal, two-dimensional networks are formed via O-H⋯O hydrogen bonds and C-H⋯O inter-actions involving the water mol-ecule, the hydrogen l-tartrate anions and the l-tartaric acid mol-ecules. These layers, which stack along [001], are separated by tetra-ethyl-ammonium cations. The latter are also involved in C-H⋯O inter-actions with the anions and the l-tartaric acid and water mol-ecules participating in the two-dimensional network.