Crystallization kinetics of Ni-doped Ca2Al2SiO7 glass microspheres

• Published in: Journal of thermal analysis and calorimetry 2020, Vol.142 (5), p.2111-2121
• Main Authors: Majerová, Melinda, Prnová, Anna, Plško, Alfonz, Hruška, Branislav, Valúchová, Jana, Kraxner, Jozef, Bruneel, Els, De Buysser, Klaartje, Galusek, Dušan
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Chemical synthesis; Chemistry; Chemistry and Materials Science; Crystal growth; Crystal structure; Crystallinity; Crystallization; Crystals; Diameters; Exothermic reactions; Gehlenite; Glass; Inorganic Chemistry; Measurement Science and Instrumentation; Microspheres; Morphology; Nanoparticles; Nickel; Nucleation; Phase composition; Physical Chemistry; Polymer Sciences; Temperature dependence; Thermodynamic properties
• ISSN: 1388-6150; 1588-2926
• DOI: 10.1007/s10973-020-10154-7

The Ni-doped Ca 2 Al 2 SiO 7 glass systems were prepared by flame synthesis. Solid-state reaction was used to prepare the powder precursors. The concentration of Ni was 0.5, 1 and 3 mol%. Polydisperse systems were prepared with diameters between 5 and 140 μm. Detailed examination of morphology of the glass microbeads by SEM revealed no features indicating the presence of crystalline phases. However, X-ray diffraction analysis showed that the samples GNi0.5 (0.5 mol% of Ni) and GNi1.0 (1.0 mol% of Ni) contained traces of crystalline gehlenite. HT-XRD was used to determine the temperature dependence of phase composition. For all prepared compositions, only one crystalline phase (Ca 2 Al 2 SiO 7 ) was observed. DSC measurements in the temperature range 30–1200 °C at five different heating rates were carried out to study the thermal behavior. The DSC curves of all glasses contained one exothermic peak, which was attributed to crystallization of the gehlenite. The maximum of the peak decreased with increasing Ni content in the microspheres. The kinetic parameters (frequency factor A , apparent activation energy E app and the Avrami coefficient m ) of the crystallization were determined using the Johnson–Mehl–Avrami–Kolgomorov model. In case of GNi0.5 and GNi1.0 glasses, the nucleation’s rate had linear temperature dependence, the crystal growth interface is controlled by chemical boundary and the crystal growth is one-dimensional. The rate of nucleation is linear, the crystal interface growth is controlled by diffusion and one-dimensional crystal growth prevails in crystallization of the GNi3.0 (3.0 mol% of Ni).