镧石型碳酸镨钕向碱式碳酸镨钕的相转变反应特征及其应用  

Characterization and Application of Phase Transformation from(PrNd)_2(CO_3)_3·8H_2O to(PrNd)(OH)(CO_3)

作　　者：丁龙[1] 周新木[1] 周雪珍[1] 李静[1] 刘艳珠[1] 李东平[1] 李永绣[1] 

机构地区：[1]南昌大学稀土与微纳功能材料研究中心,南昌330031

出　　处：《无机化学学报》2014年第7期1518-1524,共7页Chinese Journal of Inorganic Chemistry

基　　金：科技部支撑计划(No.2012BAE01B02)资助项目

摘　　要：镧石型碳酸镨钕[(PrNd)2(CO3)3·8H2O,LPN]在95℃的不同起始pH值的溶液中陈化不同时间所得样品的XRD衍射图证明了LPN向碱式碳酸镨钕[(PrNd)(OH)(CO3),BPN]的相态转变。为此,详细研究了这一相态转变的反应条件以及粒子特征变化。结果表明:LPN是由片状或条状结晶连生而成的聚集体,具有大的粒度和小的堆密度。当在热的水溶液中陈化时,由于水解反应而发生由LPN向BPN的相转变。这一相转变可以在95℃下pH=7以上的溶液中发生,其转化率随起始溶液pH值的升高和陈化时间的延长而增大。随着相转变的进行,溶液的pH值开始下降明显,而后趋于平缓。相应地,大的团聚体颗粒解散成小的单个粒子,导致粒度减小,分布变窄,氯根含量降低和堆密度的增大。而且,这些变化直接与溶液pH值和陈化时间相关。据此,发展了一种新的制备具有高堆密度、低氯根含量、细粒度和窄分布的新方法,而且通过改变相转变条件可以方便地调谐颗粒特征。In this paper, the crystalline phases of samples obtained by aging lanthanide type carbonate of praseodymium and neodymium [（PrNd）z（CO3）3· 8H2O, LPN] in aqueous solution with different initiate pH values for different times at 95℃ were determined to be basic carbonate of praseodymium and neodymium [（PrNd）（OH） （CO3）, BPN] by their XRD patterns. Therefore, the transformation reaction conditions and the particle characterization were investigated in detail. The results showed that the powders of LPN show low bulk density and large particle size because they are aggregates formed by the linking growth of crystals with plate or strip shape. When aging in hot aqueous solution, LPN transfers to BPN due to the hydrolysis reactions of carbonate group. This crystalline phase transformation can occur at 95℃ when the initiate pH of aqueous solution over 7, and the transfer percentages are increased with initiate pH increase and aging time extension. With the phase transformation conducting, the pH of solution falls significantly at first and then reaches a stable value finally. Correspondingly, the large aggregates are dispersed into many single particles, which results in the decrease of particle size D50, particle size distribution D90-D10, the chloride content, and the increase of bulk density of powders. Moreover, these variations are directly related to the pH value of solution and the aging time. Therefore, a novel method to prepare rare earth basic carbonates with high bulk density, low chloride content, fine particle characterization is developed, with which the particle characterization of final products can be easily tuned by changing the crystalline phase transformation conditions.

关 键 词：相转化 镧石型碳酸镨钕 碱式碳酸镨钕 水解反应 粒度特征 

分 类 号：O614.334[理学—无机化学] O614.335[理学—化学]