Low-temperature Solid State Reaction - Symbiotic Sublimation Of Ammonium Chloride Prepared By Nano-materials And Applications

Characteristics of solid-state reaction at low temperature and the common methods for preparing nanometer materials were reviewed. The probality of preparing nanometer Co₃O₄,NiO, MgO, ZnO by sublimating NH₄Cl and solid-state reaction at low temperature was studied by thermodynamics method.Nanometer CO₃O₄ was obtained by solid-state reaction at low temperature combining with sublimating NH₄Cl. Influence of reactant ratio, milling, desiccation, sintering and dispersant on solid-state reaction and properties of Co₃O₄ were investigated. The optimized synthesis conditions were obtained. Ratio of CoCl₂ · 6H₂O and (NH₄)₂C₂O₄·H₂O is 1:1.2 TEA with the concentration of 40μL/g was added into the reactants. The mixture was dried at 120℃ for 10h after 30min's whetting. The synthesized nanometer Co₃O₄ has a narrow particle size distribution with an average diameter of about 8nm..Nanometer NiO, MgO and ZnO were synthesized by solid-state reaction at low temperature combining with sublimating NH₄Cl, and the synthesis conditions were optimized. Diameters of synthesized NiO, MgO and ZnO are 25nm, 20nm and 50nm, respectively.Layed LiCoO₂ was synthesized by the reaction of nanometer CO₃O₄ with Li₂CO₃ at 800℃ in air. Discharge capacity of the first cycle is 182mAh/g in the range of 2.75-4.2V. It remains 147.1mAh/g after 30 charge-discharge cycles at 0.1C rate.The results show that the new method of sublimating NH₄Cl in solid state reaction at low heating temperature is simple and environment-friendly. It is attractive in high yields, clear distinction in reaction and low expense in synthesis, No solvent is needed for the reaction and agglomeration can be avoided effectively. Therefore, it is a promising adoptable technic in industry application.The main influence factors include the reactants proportion, whetting time, and the decomposing temperature. Decomposingtemperature is the most influential factor and heating time is the next. Products are only obtained at the strictly controlled reaction temperature.