Publication Date:
2013-07-18
Description:
Nanocrystalline CaF2powder specimens were produced both by co-precipitation of CaCl2and NH4F and by ball milling of a coarse powder. The specimen homogeneity and a detailed picture of the lattice defects can be assessed by the simultaneous analysis of the powder diffraction pattern and of the solid-state19F magic angle spinning NMRT1relaxometry data. While diffraction line profiles provide information on domain size distribution and the content of dislocations,T1relaxometry is more sensitive to inhomogeneity of the powder (large defect-free grainsversusdefective small ones). After extensive milling it is possible to obtain fluorite domains of comparable size to the chemically synthesized CaF2(circa10–12 nm), but with a marked difference in the lattice defect types and content. It is then proved that surface defects (related to domain size), line defects (dislocations) and point (Frenkel) defects have a quite different effect on the powder pattern as well as on theT1spin-lattice relaxation time.
Print ISSN:
0021-8898
Electronic ISSN:
1600-5767
Topics:
Geosciences
,
Physics
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