关键词: 固相反应, ZnCO3, 自晶化

Abstract: The nano-crystals of ZnCO3 were synthesized via solid state reaction at room temperature, when ZnSO4×7H2O reacted with NH4HCO3 containing PEG-400 as template, the average particle size of the crystals was about 25 nm. The experimental results showed that the crystals with ideal crystallization were obtained, while keeping NH4HCO3 excessive all the time to keep from impurity forming under optimal mixing of reactants. It was not necessary to let the reaction mixtures deposit for crystallization, for the product of zinc carbonate had spontaneously crystallized into ideal crystals within 20 min grinding time. On the contrary , the byproduct would form in long depositing time, resulting in formation of basic zinc carbonate. The template reagent played a key role for controlling composition of the product. The product was nano-crystals of zinc carbonate with the template, and leaving the rest mixture without the template, which contained basic zinc carbonate in majority and zinc carbonate. Comparing the product with that from microemulsion synthesis method reported in the literature, it was supposed that the controlling role of the template was played via forming microemulsion with water releasing from crystallized water in the reactants during the grinding process.

Key words: solid state reaction, ZnCO3, spontaneous crystallization