Abstract
Natural fluorite is used for growing CaF2 boules from melt by an improved technique. Chemical treatment of the starting ore decomposes the accessory minerals, thus producing small amounts of the oxides of Si, Al, and Fe insoluble in the melt, whereas the overall content of rare earth elements (REEs) of hundreds of μg g−1, remains unchanged. Analytical techniques and optical measurements provide for assessing the concentration range and trends in the distribution of residual metal impurities along the height of the boules. Solid sampling electrothermal atomic absorption spectrometry (SS-ETAAS) gives good reproducibility for impurities’ distribution within a large concentration range of 0.1–10 μg g−1. The concentrations of Zn and Cu determined were found to vary within the lowest tenths of μg g−1 range in the starting portions of chemically treated fluorspar and a batch of boules produced subsequently. The concentrations of both elements show a decreasing trend towards the top section within the confidential interval, the width of which confirms the definite in homogeneities in their distribution at those concentration levels. The Fe occurs in the boules below the detection limit, while the content of lead diminishes rapidly towards their upper section, probably due to a shorter path in the liquid phase before any vapour phase transition proceeds. A satisfactory correlation is found between the Pb concentration in ng g−1-range and light-absorption peak intensity at 204 nm, the precise determination of which is impeded due to the overlapping bands and the light-scattering effect. Reliable determination of impurities enables optimisation of the basic purification — growing stages for the production of high grade crystals.
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© 2011 Institute of Chemistry, Slovak Academy of Sciences
Articles in the same Issue
- Determination of impurities for controllable growth of high quality optical fluorite
- Microbial and enzymatic hydrolysis of tannic acid: influence of substrate chemical quality
- Characterisation and performance of three promising heterogeneous catalysts in transesterification of palm oil
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Articles in the same Issue
- Determination of impurities for controllable growth of high quality optical fluorite
- Microbial and enzymatic hydrolysis of tannic acid: influence of substrate chemical quality
- Characterisation and performance of three promising heterogeneous catalysts in transesterification of palm oil
- Synthesis of rare earth ternary complexes using tryptophan and sodium citrate and their anticoagulant action
- A new bis(azine) tetradentate ligand and its transition metal complexes: Synthesis, characterisation, and extraction properties
- Bicontinuous nanodisc and nanospherical titania materials prepared by sol-gel process in reverse microemulsion
- Oxidation of 3,5-di-tert-butylcatechol in the presence of V-polyoxometalate
- A new convenient synthesis of 5-aryl-2-(arylamino)-1,3,4-oxadiazole derivatives
- From a Tb3+ chelated compound to a hybrid material: selective emission responses to anions
- Doping level of Mn in high temperature grown Zn1−x MnxO studied through electronic charge distribution, magnetization, and local structure
- Thermal analysis of (NaF/AlF3)-FeF3 and (NaF/AlF3)-FeO systems