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Aplikace metody sol-gel na synt©zu dikalciumsiliktu a jeho tuhch roztok / Application of Sol-Gel Method for Preparation of Dicalcium Silicate and its Solid Solutions

The subject of this doctoral thesis was to elucidate the mechanism of reaction leading to the formation of dicalcium silicate (C2S), its solid solutions and other phosphatic calcium silicate phases using the sol-gel method of synthesis. SiO2 (Tosil A), CaO (calcium nitrate tetra-hydrate) and H3PO4 (as a source of P2O5) were used as starting materials. Series of samples with different content of P2O5 were synthesized. The characterization of Tosil A and samples was based on the following methods: DTA/TGA and EGA, XRD and SEM and EDS analy-ses. It is known, that phosphorous oxide can enter the structure of C2S and possibly form solid solutions and different phosphatic calcium silicate phases in C2SâC3P system. Depending on the P2O5 concentration in mixtures, three distinct phases are formed: larnite (2CaOâSiO2), Ca14,92(PO4)2,35(SiO4)5,65 and 5CaOâSiO2âP2O5, as detected by XRD. Local microanalysis de-monstrated the presence of calcium phosphate epicenters (C3P) containing SiO2, calcium sili-cate (C2S) zones with minimum content of P2O5 and intermediary areas of various phosphatic calcium silicates. The formation of two distinct islets of C2S and C3P is due the affinity of acid oxides (SiO2, P2O5) towards the basic one (CaO) during the sol-gel process. Then, the formation of various phosphatic calcium silicates results from the diffusion of P2O5 and SiO2 towards calcium silicate and calcium phosphate, respectively.

Identiferoai:union.ndltd.org:nusl.cz/oai:invenio.nusl.cz:233387
Date January 2014
CreatorsBarÄek, Jan
ContributorsŽivica, Vladimír, Rovnaníková, Markéta, Palou, Martin
PublisherVysoké učení technické v Brně. Fakulta chemická
Source SetsCzech ETDs
LanguageCzech
Detected LanguageEnglish
Typeinfo:eu-repo/semantics/doctoralThesis
Rightsinfo:eu-repo/semantics/restrictedAccess

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