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Influence of a Second Cation ( M = Ca 2+ , Mg 2+ ) on the Phase Evolution of (Ba x M 1– x )F 2 Starting from Amorphous Deposits
Author(s) -
Mu Xiaoke,
Sigle Wilfried,
Bach Andreas,
Fischer Dieter,
Jansen Martin,
van Aken Peter A.
Publication year - 2014
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201400099
Subject(s) - amorphous solid , rutile , annealing (glass) , crystallization , crystallography , metastability , ternary operation , analytical chemistry (journal) , fluorite , materials science , solid solution , x ray crystallography , transmission electron microscopy , phase (matter) , diffraction , chemistry , nanotechnology , physics , organic chemistry , optics , chromatography , computer science , programming language , metallurgy , composite material
A second type of cation (Mg 2+ , Ca 2+ ) was introduced into BaF 2 by low‐temperature atomic beam deposition. The structure evolution from low‐temperature (–150 °C) amorphous deposits to high‐temperature (< 1000 °C) annealed crystalline phases was studied by in‐situ transmission electron microscopy and X‐ray diffraction. Amorphous (Ba 0.5 , Ca 0.5 )F 2 crystallizes in a first step to metastable solid solution phase (fluorite‐type), which then decomposes into the pure phases of CaF 2 and BaF 2 at higher temperature. The crystallization behavior of amorphous (Ba x Mg 1– x )F 2 is completely different. When the Mg/Ba atomic ratio is around 1:1, the mixture transforms to the ternary compound BaMgF 4 at annealing, and no decomposition occurs by further heating up to 1000 °C. When the Ba concentration is below 15 % in atomic ratio ( x < 0.15), the mixture forms a solid solution phase (rutile type) with the lattice expanded by +1 % compared to rutile type MgF 2 . The difference between the phase evolutions of the two mixture systems is discussed.