低温溶剂热法合成圆饼状球霰石碳酸钙

Synthesis of Cake-like Vaterite CaCO_3 by Low-temperature Solvothermal Method

以醋酸钙和尿素为原料,乙醇-水为溶剂,添加羟基乙叉二膦酸(HEDP),采用低温溶剂热法制备出由纳米粒子团聚而成的圆饼状球霰石型碳酸钙,利用X射线衍射(XRD)、傅立叶红外光谱(FTIR)、扫描电镜(SEM)、高分辨透射电镜(HRTEM)、选区电子衍射(SAED)分别对产品的结构、形貌进行表征。初步探讨了圆饼状球霰石型碳酸钙的形成机理,研究了HEDP的浓度、反应时间对产物的影响。结果表明,HEDP的浓度对碳酸钙的结构、形貌起着至关重要的作用,适量的HEDP可以抑制产物球霰石相向文石相的转化,稳定存在的球霰石型纳米颗粒团聚生长形成圆饼状球霰石型碳酸钙;未添加以及加入过量的羟基乙叉二膦酸时得到由纳米棒组装而成的捆束状文石相结构。

Cake-like vaterite CaCO3 composed of nanoparticles is synthesized via the low-temperature solvother- real method in the presence of hydroxy ethylidene 1, 1-diphosphonic acid（HEDP） using calcium acetate and urea as raw materials and ethanol as the solvent. The structure and morphologies of the samples are characterized by X-ray diffrac tion（XRD）, Fourier transform infrared spectroscopy （F-FIR）, scanning electron microscopy（SEM）, high resolution transmission electron microscopy（TEM） and selected area electron diffraction（SAED）. The formation mechanism of cake-like vateri-te CaCOa, as well as the effects of HEDP and reaction time on the products are also studied. Results show that the concentration of HEDP plays an important role in controlling the structure and morphologies of calcium carbonate. The use of HEDP in the appropriate proportion can suppress the transformation from vaterite to aragonite and allows synthesis of cake-like vaterite CaCOa, which are grown by self-assembly of small primary nanparticles. Without or more addition of HEDP, bundle-like aragonite composed of nonorods are obtained.