Crystallization of amorphous silicates far from equilibrium part I: A versatile nitrate-based sol–gel synthesis of amorphous porous Ca,Mg-rich silicates

Fine-grained amorphous calcium silicate CaSiO3 from vacuum dried sol–gel – Production, characterisation and thermal behaviour

“…The use of sol-gel procedures for synthesising non-crystalline Casilicate has attracted increasing attention in recent years, driven in part by the potential scalability for industrial manufacture and by the often more desirable properties of the final product over other methods for certain applications [20][21][22][23][24][25][26][27]. For example, one of the main properties required of bioactive materials is their bonebonding ability through the formation of a biologically active apatite layer on the surface of ceramic implants.…”

“…Indeed, the study of sol-gel derived amorphous silicates has a long history in this field in respect of Mg-rich silicates [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47] where the resulting materials exhibit properties similar to those of dust grains expected to be formed in the environments of certain types of oxygen rich stars [42]. In this context also, the production of mixed Mg and Ca silicate compositions using sol-gel methods is beginning to receive interest [26] due to the possibility of controlling the Ca:Mg composition.…”

Crystallization of amorphous silicates far from equilibrium part II: Experimental insight into the key role of decoupled cation mobilities

“…This last feature is crucial since preexisting nuclei could affect the mineralogy and the kinetics of crystal growth. As demonstrated in the companion paper [25], the samples were completely amorphous at the TEM scale. The hygroscopic behaviour of such precursors was not a problem in this study since the phase transformations occurred above 700°C and therefore occurred after heating of the material through the dehydration temperature interval.…”

“…The hygroscopic behaviour of such precursors was not a problem in this study since the phase transformations occurred above 700°C and therefore occurred after heating of the material through the dehydration temperature interval. A detailed protocol and an extensive characterization can be found in [25].…”

“…The sample powders (~100 μm in diameter) prepared in an agate mortar were aggregates of amorphous and homogeneous nanometersized particles as described and imaged in [25]. Isothermal annealing and slow temperature ramping were used for experimental testing.…”