The Growth Mechanism Of Cerium Carbonate With Special Morphology Has Been Studied

The different morphology,size,dispersibility and other physical and chemical properties of cerium carbonate crystals determine its application in related fields such as ultraviolet absorption,glass polishing,glass additives and catalysis.In the early stage,the research group used experiments and computer simulation methods to study the influence of different electrical polymers on the morphology of cerium carbonate crystals and the mechanism of polymer control morphology,but experimental support is needed.The purpose of this paper is to find a computer simulation method,and directly use simulation calculation methods to study the influence of different electrical polymers on the nucleation and growth of cerium carbonate crystals,so as to achieve the purpose of controlling its morphology.The main research results are as follows:Without polymer participation,use the ab initio quantum chemistry software VASP and first-principles to study the electronic structure inside the unit cell of Ce₂（CO₃）·8H₂O,and combine the symmetry of the crystal itself to explore The stability of the internal bonding of the crystal to explain its crystal morphology.The study found that the whole crystal is divided into Part 1 and Part 2 based on symmetry.Both primitives surround the center Ce³⁺along the a-axis and b-axis directions,and form ab flat.In the ab plane,whether it is Part 1 or Part 2,the DOS and-COHP of the center Ce³⁺are basically the same as those of CO₃^2-,and the integral bond is stable in the unit cell.The sex is basically the same.In the unit cell along the c-axis,the two ab planes are connected by hydrogen bonds formed by H₂O and H₂O,CO₃^2-and H₂O without charge transfer.The stability of the bond formation It is much smaller than the ionic bond formed in the ab plane,resulting in a greater possibility of the ab plane in the system,thus forming an irregular sheet structure.Under the condition of polymer polyvinylpyrrolidone（PVP）,it can be divided into two parts:nucleation and growth.At the nucleation stage,by calculating the bond changes of atoms in the system before and after the addition of CO₃^2-,it is found that the ketone group in PVP will preferentially combine with Ce³⁺to form a complex and provide heterogeneous nucleation sites for the system.In the growth stage,the relative growth rate between the crystal planes is determined by studying the energy change between the easily exposed crystal planes and the adsorption energy between the crystal planes and PVP.The study found that when there is no PVP adsorption on the crystal plane,the surface energy difference between the three crystal planes（120）,（010）,（001）is huge,and when PVP simulated adsorption is added,the order of the adsorption energy is（120）>（010）>（001）,and there is only a 2e V error between the（010）and（001）crystal planes,indicating that the growth of the（120）crystal plane due to the adsorption of PVP during the growth of heterogeneous nucleation points The obstacles are the greatest,which increases the probability of the（120）crystal plane appearing in the equilibrium state,and the final morphology of the cerium carbonate crystal will form a hexagonal plate with the（120）crystal plane as the hypotenuse.