溶剂和溶液酸碱性对碳酸钙晶型和形状影响研究

Morphology and shape of calcium carbona influenced by solvents and pH

CaCO3主要有三种晶型：方解石,文石和球霰石,方解石是CaCO3晶体最稳定的晶型,球霰石是最不稳定的,文石的稳定性介于两者之间。在生物矿物中经常发现有文石和方解石的存在,具有结构功能和光学等性能,是生物体硬组织中的主要无机成份之一。在珍珠、贝壳、甲壳、动物骨骼等生物组织中CaCO3与少量有机基质（生物大分子）结合,形成具有特定性质的有机/无机杂化材料,例如,方解石存在于骨头,牙齿等硬组织中,另外还具有在神经束中的光聚焦功能;

In this paper,calcium carbonate particles were prepared by a precipitation reaction of urea with calcium acetate from mixed solution of organic solvents and water or organic solvents in the presence of potassium hydrogen phthalate at 120 °C.The asprepared products were characterized with X-ray diffraction and FT-IR.The shapes are observed by scanning electron microscopy.The effects of different solvents and pH on the crystal shape and morphology of the as-prepared CaCO3were investigated and discussed.The results show that pure vaterite crystals were obtained in the absense of K2 CO3,while a mixture of vaterite and aragonite with a molar ratio of 0.217,0.783（vaterite ： aragonite） in the prescence of K2CO3.In CH3OH and DMF/H2O（DMF： N,N-dimtthylformamide,v/v： 3： 2）,pure aragonite and pure vaterite are obtained,respectively.In CH3CH2OH/H2O（CH3CH2OH/ H2O,v/v： 3： 2） and CH3 CH2 OH,the mixtures of vaterite and aragonite obtained with ratio of 0.791： 0.209 and 0.709,0.307（vaterite ： aragonite） respectively.The results show that solvents and pH can have great influence on the shapes and morphology of CaCO3.