Research On Mechanism Of The Special Morphology Rare Earth Carbonate By PAH

Rare earth carbonates regulated and compounded by template has attracted more andmore attention because of its special morphology. In this paper, macromolecule organicpoly allylamine hydrochloride (PAH) is used as template. By using Ce(NO3)3as rawmaterial and (NH4)2CO3as precipitant, the six arrises flake Ce2(CO3)38H2O is producedby the method of Liquid template method, and controlling technological condition at thesame time to produce petaliform product assembled and stacked by Six arrises piece. Andlow temperature sintering makes it easier for morphology to hand down by heredity. Tofigure out the whole regulation and control mechanism of PAH, this paper expounds thecontrol mechanism of template PAH in three different stages on the basis of Cerium’sdifferent morphology in every stage. Meanwhile, the discovery of the amorphous ceriumcarbonate clusters also brings non-classical homogeneous nucleation theory to this field.Because the induction, nucleation and growth period are highly interrelated and Surfaceenergy, solid liquid interface and system space’s reaction environment are complex, PAH’sstructural morphology, amorphous cerium carbonate clusters and Solid phase andamorphous rare earth carbonate can have different regulation-induced types with thechange of reaction systems’ acidity and salinity. The experiment is studied in two parts;this thesis reaches some conclusions as following:1. The research about what influence PAH can have on Cerium carbonate in differentperiod (focus on the induction and nucleation period), and mainly studies the change ofCerium carbonate in different phases. pH recorder, DM4500P Professional reflectivemicroscopic, SEM, XRD, laser particle, BET and some other testing method andmathematic model and relevant software are used to analyze the forming process ofCerium carbonate with template PAH. This paper interprets the phenomenon in theory andhopefully this can reflect the influence of pH value on the amorphous cerium carbonateclusters’s forming process. Meanwhile, using mathematic model and relevant software toexplain how PAH can influence nucleation in different stage from molecule and unit cell. 2. The research about the regulation mechanism of PAH controlling regulation ofCerium carbonate.(Focus on the induction and nucleation period), mainly studies onsolving the identificatioin problem about regulating crystal faces growth. AsPolyelectrolyte self-assembled film, PAH is used to regulate Cerium carbonate’smorphology and size. By IR analysis, PAH and Ce3+coordinate and are in sp2hybridization,producing π-allyl complex: meanwhile, the N and Ce Atomic models in the PAH areComplexation bonding. This Complexation exists in the form of trimer and induces theform of crystal nucleus. Because PAH is electrified body, using this electrostatic interaction,lattice geometrical matching and stereochemical complimentary, the crystal can groworiented and finally compound petal shaped Ce2(CO3)3. By XRD, SEM, TEM analysis,PAH has inhibiting effect on (160),(022) face of crystal, while promote the growth of (242)face and have little effect on (202) face. It can also confirm the oriented growth trend ofCe2(CO3)3.