A nonlinear optical single crystal of potassium pentaborate tetrahydrate (KB5O8? 4H2O) has been grown from aqueous solution by using unidirectional crystal growth method of Sankaranarayanan-Ramasamy (SR) with a due modification in the growth assembly. Potassium pentaborate crystal of 60 mm length and 10 mm diameter has been grown along (100) plane with a growth rate of 3 mm per day within a period of 20 days. The grown crystal was subjected to single crystal X-ray diffraction analysis to confirm that the crystal belongs to the orthorhombic system. Some fundamental data such as valance electron plasma energy, Penn gap, Fermi energy and electronic polarizability of the grown crystal were calculated. The presence of borate in the grown crystal was confirmed by Fourier transform infrared (FTIR) spectroscopy. The optical transmission property of the grown crystal was analyzed using ultra violet (UV) visible spectral analysis. Surface morphology of the growth plane was observed using scanning electron microscopy (SEM). The mechanical strength of the crystals was found out using Vickers microhardness test along the growth axis. Frequency dependent dielectric constant of the grown crystal was studied for various temperatures along (100) plane.
Bilayered FTO/AZO (fluorine doped tin oxide/aluminium doped zinc oxide) films were fabricated using a simple, cost effective spray pyrolysis technique. X-ray diffraction (XRD) profiles of bilayered films showed that in the case of lower thickness FTO over layers, (002) plane of ZnO phase had the highest intensity, whereas the predominance was changed in favour of (200) plane of SnO2 phase for higher thickness FTO over layer. UV studies showed that bilayered FTO/AZO films exhibited a sharp absorption edge as that of AZO film. The decrease in the photoluminescence (PL) peak at 420 nm with increasing FTO over layer thickness indicated a reduction in the zinc vacancies which caused a reduction in the sheet resistance (Rsh). Electrical studies revealed that, eventhough the Rsh value (916 Ω/?) of bilayered FTO (313 nm)/AZO (314 nm) film was found to be higher than that of FTO single layer film (72 Ω/?), it was much lower than that of AZO single layer film (5661 Ω/?). The atomic force microscopy (AFM) images reflect the characteristic features of both
zinc oxide and tin oxide films.
Flower-like Cu2SnS3 nanostructures composed of nano-flakes were successfully synthesized by solvothermal technique at 180 oC for 16 h. In the preparation process, CuCl2·2H2O, SnCl2·2H2O and thiourea were used as raw materials, and ethylene glycol were used as solvent. The results showed that the obtained product was pure phase Cu2SnS3. The average diameter of Cu2SnS3 flowers and the thickness of the nano-flakes were about 1e1.5 mm and 10 nm, respectively. The influence of reaction time and solvents on the morphology, size and structure of the products was investigated by powder X-ray diffraction and field-emission scan electron microscopy (FESEM). The ultraviolet-visible absorption spectrum measurement indicated that the band gap of the sample was about 1.26 eV and could be applied to the absorbing layer of thin solar cell. The possible formation mechanism of flower-like Cu2SnS3 was also proposed and discussed.