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Chemical models of molybdenum-calcium phosphate glasses
Authors: Holubová Jana | Chládková Monika | Brázdová Simona | Černošek Zdeněk
Year: 2023
Type of publication: článek v odborném periodiku
Name of source: Journal of Non-Crystalline Solids
Publisher name: Elsevier Science BV
Place: Amsterdam
Page from-to: 122222
Titles:
Language Name Abstract Keywords
cze Chemický model fosfátových skel s molybdenem Byl studován vliv molybdenu na měnící se fosfátovou síť. Ukázalo se, že skutečné chemické složení skel je komplikovaná směs chemických sloučenin. Chemický model umožnil také vysvětlení kompozičních závislostí teploty skelného přechodu a koeficientu tepelné roztažnosti skel. Fosfátová skla; chemický model; Molybden; 31P MAS NMR; ESR
eng Chemical models of molybdenum-calcium phosphate glasses The influence of molybdenum at varying phosphate network was studied. Three series of MoO3-CaO-P2O5 glasses starting with calcium metaphosphate and ending with chemical compositions formally corresponding to molybdenyl metaphosphate(2+), molybdenyl pyrophosphate(2+) and their equimolar mixture were prepared. Molybdenum is incorporated as molybdenyls, which to a significantly predominant extent form the divalent colorless two-oxygen diamagnetic cation MoVIO22+ accompanied in low concentration by colored paramagnetic MoVO2+. Molybdenyls are bound in the structure by four donor-acceptor bonds with non-bridging phosphate oxygens and form a distiorted tetragonal bipyramid. A chemical model of glasses describing their actual chemical compositions and compositional dependencies was created. It has been shown that the actual chemical composition of glasses is a complicated mixture of chemical compounds. The chemical model also made it possible to have an explanation of the compositional dependences of the glass transition temperature and the coefficient of the thermal expansion of glasses. Phosphate glasses; Molybdenum; Chemical model; 31 P MAS NMR; ESR