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ASAXS study of CaF 2 nanoparticles embedded in a silicate glass matrix
Author(s) -
Hoell Armin,
Varga Zoltan,
Raghuwanshi Vikram Singh,
Krumrey Michael,
Bocker Christian,
Rüssel Christian
Publication year - 2014
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s1600576713030100
Subject(s) - crystallite , materials science , nanoparticle , silicate , scattering , analytical chemistry (journal) , crystallography , optics , chemistry , nanotechnology , physics , metallurgy , organic chemistry , chromatography
The formation and growth of nanosized CaF 2 crystallites by heat treatment of an oxyfluoride glass of composition 7.65Na 2 O–7.69K 2 O–10.58CaO–12.5CaF 2 –5.77Al 2 O 3 –55.8SiO 2 (wt%) was investigated using anomalous small‐angle X‐ray scattering (ASAXS). A recently developed vacuum version of the hybrid pixel detector Pilatus 1M was used for the ASAXS measurements below the Ca K ‐edge of 4038 eV down to 3800 eV. ASAXS investigation allows the determination of structural parameters such as size and size distribution of nanoparticles and characterizes the spatial distribution of the resonant element, Ca. The method reveals quantitatively that the growing CaF 2 crystallites are surrounded by a shell of lower electron density. This depletion shell of growing thickness hinders and finally limits the growth of CaF 2 crystallites. Moreover, in samples that were annealed for 10 h and more, additional very small heterogeneities (1.6 nm diameter) were found.