Preparation Technique for Reference Samples of REO and REX/REO in RExOy Controlled by Matrix Dilution Method
With the development of science and technology,investigators had more stringent requirements for rare earth standard sample preparation methods.This article investigated a method for the preparation of rare earth standard samples using diluents to con-trol the standard values of total rare earths,and the preparation of rare earth standard samples with standard values for total rare earths(REO).Diluents selectedwere stable and did not react chemically with the candidate materials,the candidate materials were designed for composition according to the proportional requirements of the actual product;they were then batched,mixed and ground,and NaCl was added according to the configuration of the designed REO values;and the final standard values representing the properties of the standard samples were obtained.The content of said REO standard values ranged from 28％to 42％.This standard sample prepara-tion method enabled quality control and instrument calibration for the testing process of rare earth products such as carbonated rare earths and chlorinated rare earths,mainly as an evaluation and calibration of the standard methods for the determination of REO by weight and inductively coupled plasma emission spectrometer(ICP-OES)methods.To meet the problem that products such as carbon-ate and chloride rare earths were inherently unstable and could not be directly prepared as standard samples,the research into the use of matrix doping techniques was performed to achieve a controlled component content of REO and rare earth fractions(REX/REO)in rare earth oxides.NaCl crystals were selected as the doping matrix and a mixture consisting of single rare earth oxides such as La2O3,CeO2,Pr6O11 and Nd2O3 was diluted to prepare a standard sample candidate.The homogeneity and stability of the standard sample can-didates were investigated by using the particle size and scanning electron microscope(SEM)data of the mixed rare earth oxide stan-dard sample(GSB 04-3064-2013)as a reference,and effectively controlled REO and REX/REO of the candidates in agreement with the standard values of the independent design.The physical and chemical properties of Na2SO4,Na2CO3,NaHCO3 and NaCl were theo-retically analyzed,and NaCl crystals were finally identified as diluents for the study,combining the melting points of the four sodium salts,their toxicity and the stability of the four sodium salts when mixed with rare earth oxides.Through the comparative verification of the particle size and SEM images of the rare-earth oxide standard samples and standard sample candidates and the stability study of in-ductively coupled plasma emission spectrometer(GD-MS)data,and it was clarified that the rare-earth oxides and NaCl crystals were uniformly distributed in chemical composition and coexist as rare-earth oxides wrapped and adsorbed on the surface of sodium chloride crystals.The analysis of thermogravimetric analyzer(TG)and differential scanning calorimetry(DSC)curves of the standard sample candidates showed that there was no mass or reaction change in the range of 30～60 ℃ and the stability requirements of the standard samples could be met.In this study,a method was developed for the preparation of standard samples of REO and REX/REO compo-nents in RExOy.The prepared standard samples contained 38.80％and 29.58％of REO respectively,which was applicable to the de-velopment of similar standard samples and had reference significance for the development of standard samples of controlled compo-nents.
NETL
NSTL
万方数据
