Počet záznamů: 1
Polyamorphism and frustrated crystallization in the acid-base reaction of magnesium potassium phosphate cements
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SYSNO ASEP 0491029 Druh ASEP J - Článek v odborném periodiku Zařazení RIV J - Článek v odborném periodiku Poddruh J Článek ve WOS Název Polyamorphism and frustrated crystallization in the acid-base reaction of magnesium potassium phosphate cements Tvůrce(i) Viani, Alberto (UTAM-F) RID, ORCID, SAI
Mácová, Petra (UTAM-F) RID, SAI, ORCIDCelkový počet autorů 2 Zdroj.dok. CrystEngComm. - : Royal Society of Chemistry - ISSN 1466-8033
Roč. 20, č. 32 (2018), s. 4600-4613Poč.str. 13 s. Forma vydání Tištěná - P Jazyk dok. eng - angličtina Země vyd. GB - Velká Británie Klíč. slova cement ; potassium compounds ; crystalline materials ; reaction intermediates Vědní obor RIV CF - Fyzikální chemie a teoretická chemie Obor OECD Physical chemistry CEP LO1219 GA MŠMT - Ministerstvo školství, mládeže a tělovýchovy UT WOS 000442612000011 EID SCOPUS 85051475594 DOI 10.1039/c8ce00670a Anotace Magnesium potassium phosphate cements are a class of acid−base cements for bioengineering and civil engineering applications. The kinetics of the chemical reaction was investigated in-situ with isothermal conduction calorimetry and with powder X-ray diffraction, quantifying amorphous and crystalline products. The first reaction step, dissolution of MgO, with apparent activation energy of 71 kJ/mol, dictates the time-evolution of two amorphous intermediate precursors and of the crystalline product. The early crystallization of the latter has been described with an Avrami equation with apparent activation energy of 81 kJ/mol, pointing to a mechanism of deceleratory nucleation and growth in one direction, compatible with the acicular crystal habit observed with electron microscopy. The observed polyamorph transformation is controlled by a complex interplay between kinetic and thermodynamic factors, in which the changes in chemical environment (increase in pH) driven by the MgO dissolution, play a crucial role. It is proposed that the onset of the amorphous-amorphous transformation hinders crystallization by decreasing ion mobility, raising the energy barriers to structural reorganization. The rate of MgO dissolution depends on the reactivity of the powder and parameters of the mix (such as the amount of liquid) and influences the reaction pathways, impacting on material performance. Pracoviště Ústav teoretické a aplikované mechaniky Kontakt Kulawiecová Kateřina, kulawiecova@itam.cas.cz, Tel.: 225 443 285 Rok sběru 2019 Elektronická adresa http://dx.doi.org/10.1039/C8CE00670A
Počet záznamů: 1