Polyamorphism and frustrated crystallization in the acid-base reaction of magnesium potassium phosphate cements

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68378297%3A_____%2F18%3A00491029" target="_blank" >RIV/68378297:_____/18:00491029 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1039/C8CE00670A" target="_blank" >http://dx.doi.org/10.1039/C8CE00670A</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1039/c8ce00670a" target="_blank" >10.1039/c8ce00670a</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Polyamorphism and frustrated crystallization in the acid-base reaction of magnesium potassium phosphate cements

Popis výsledku v původním jazyce

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.

Název v anglickém jazyce

Polyamorphism and frustrated crystallization in the acid-base reaction of magnesium potassium phosphate cements

Popis výsledku anglicky

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.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10403 - Physical chemistry

Projekt

<a href="/cs/project/LO1219" target="_blank" >LO1219: Udržitelný pokročilý rozvoj CET</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2018

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

CrystEngComm

ISSN

1466-8033

e-ISSN

—

Svazek periodika

20

Číslo periodika v rámci svazku

32

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

13

Strana od-do

4600-4613

Kód UT WoS článku

000442612000011

EID výsledku v databázi Scopus

2-s2.0-85051475594