Synthesis, Structure Of A Serials Metal Oxides Nanocrystals And Their Catalytic Behavior On NH₄CIO₄

In the past decades, the synthesis and application of novel nanomaterials have been studied extensively. The manipulation of combustion properties composes the core part in the technology of powders and explosives. Catalyzed combustion provides a most popular approach to improve the properties of powder and explosives, in particular for solid propellants. According to the thermal decomposition of the predominant components in composite propellants, the behavior of the catalysts can be derived. In this dissertation, a series of nanometer-sized catalysts including NiO, CuO, LaFeO₃, LaCoO₃, etc have been prepared, and their effects on ammonium perchlorate (AP) thermal decomposition and propellants combustion were investigated. The dissertation is mainly focused on:1. A solid state reaction method is employed to synthesis nanometer-sized NiO and the overall procedure was monitored by FTIR, XRD, and EDS. The impacts of dispersant and thermal treatment temperature were also discussed. In compared with bulk, infrared absorption band of NiO nanoparticles shifts to low wave number (red-shift) and UV-vis optical absorption is blue-shift 0.55eV. We attribute such phenomenon to the size growth of the obtained products and decrement of the lattice distortion at elevated temperature. Furthermore, oxides such as CuO, Fe₂O₃, CuO-Fe₂O₃, and CuFe₂O₄ were prepared in the same way.2. The glycine combustion method was used to synthesis LaFeO₃, LaCoO₃, LaNiO₃, LaFe_0.2Co_0.8O₃, LaFe_0.5Co_0.5O₃ LaFe_0.8Co_0.2O₃, and NdFeO₃ nanocrystals. Based on the XRD results, the Fullprof software were used to index the XRD data and calculate the crystal parameter. As the same time, the products were characterized by TEM, HERTEM, SEM, EDS. The activation energy of LaFeO₃ and LaNiO₃ nanocrystals formation during calcination were calculated. Compared with solid state method, the products of combustion method are more dispersed. Addition of ammonia improves the dispersity of the products.3. The catalysis of prepared products on AP thermal decomposition was investigated, by DTA and TG. The experimental results indicated that all prepared catalysts work for AP thermal decomposition in some degree:(1). Addition of 2% of NiO nanoparticles in AP decreases the peak temperature of high temperature decomposition by 93℃ and increases the exothermic quantity of decomposition from 590J·g^-1 to 1.4kJ·g^-1. The activation energy of AP high temperature decomposition decreased from 188J·mol^-1 to 120J·mol^-1. The catalytic mechanism was...