Solution-based Synthesis And Characterization Of Inorganic Nanomaterials

Nanostructured materials, due to its unusual mechanical, optical, electrical, and magnetic properties and potential applications in many fields, have attracted considerable attention in the recent years. And then, a number of methods and technologies to synthesize nanostructured materials have appeared. Meanwhile, a great many of materials with new nanostructures have been fabricated.The present thesis is aimed at exploring novel hydrothermal and solvothermal methods to synthesize inorganic nanomaterials with novel structures and morphologies. The main works achieved are summed up as follows:1. Strontium carbonate as an efficient precursor was derived from the reaction of K2CrO4 and SrCl2 based on microemulsion system at room temperature by hydrotheraml trreatment. And then the final products were obtained through redox reaction at a reaction temperature as low as 160℃for 12 h. After that, the final products were obstained by HAc pickling and 600℃annealing for 3 h. The influence of the reaction temperature and time on the size and morphology of the products were investigated. X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy were used to characterize the Cr2O3 nanocrystallites. The internal magnetic order and magnetic properties of the as-prepared Cr2O3 nanotubes were also studied. In addition, a possible growth mechanism for the Cr2O3 nanotubes was also proposed.2. In this section, MnCO3 nanowires were successfully derived from the solvothermal reaction of MnCl2 and urea based on a novel detached system using N,N-dimethylformamide as the solvent and cetyltrimethylammonium bromide as the surfactant. The as-prepared MnCO3 nanocrystals can act as an efficient precursor for production of homomorphous Mn3O4 andα-Mn2O3 nanostructures by calcination at 400℃under the atmosphere of argon and air, respectively. X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy were employed to study the crystal structure and morphologies of the products. The influence of the detached system, solvent, surfactant and reaction time on the formation of the MnCO3 nanowires was invertigated and the thermal characterization was studied by differential scanning calorimetric analysis and thermogravimetric analysis measurements. Meanwhile, a possible growth mechanism for the MnCO3 nanowires was also studies.3. Various hierarchical architectures of SrMoO4 nanosheets (thickness of 8-9 nm) have been successfully derived from the reaction of SrCl2 and (NH4)6Mo7O24 in nonaqueous system by a surfactant-assisted solvothermal method. X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy were employed to study the crystal structure and morphologies of the products. Experiments showed that the solvent, surfactant, reaction temperature and reaction time were crucial for the oriented aggregation of the SrMoO4 nanosheets. A possible growth mechanism for these hierarchical architectures has also been proposed according to the morphological evolution with the reaction time. The optical properties of the products were also examined by means of photoluminescence and excitation spectroscopy. Photoluminescence studies revealed that these SrMoO4 nanocrystals exhibited a greatly strong blue emission under 325-nm excitation with different intensities but centered at the same position of 474 nm.