Ab initio study of single-crystalline and polycrystalline elastic properties of Mg-substituted calcite crystals

We employ ab initio calculations and investigate the single-crystalline elastic properties of (Ca,Mg)CO3 crystals covering the whole range of concentrations from pure calcite CaCO3 to pure magnesite MgCO3. Studying different distributions of Ca and Mg atoms within 30-atom supercells, our theoretical...

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Bibliographic Details
Published inJournal of the mechanical behavior of biomedical materials Vol. 20; pp. 296 - 304
Main Authors Zhu, L.-F., Friák, M., Lymperakis, L., Titrian, H., Aydin, U., Janus, A.M., Fabritius, H.-O., Ziegler, A., Nikolov, S., Hemzalová, P., Raabe, D., Neugebauer, J.
Format Journal Article
LanguageEnglish
Published Netherlands Elsevier Ltd 01.04.2013
Subjects
Ab initio
Biocompatible Materials - chemistry
Calcite
Calcium Carbonate - chemistry
Computer Simulation
Crystallization - methods
Crystals
Elastic anisotropy
Elastic constants
Elastic Modulus
Elasticity
Homogenizing
Magnesite
Magnesium
Magnesium - chemistry
Mg-substitution
Models, Chemical
Models, Molecular
Molecular Conformation
Single crystals
Stiffening
Elasticity
Mg-substitution
Ab initio
Stiffening
Calcite
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Summary:We employ ab initio calculations and investigate the single-crystalline elastic properties of (Ca,Mg)CO3 crystals covering the whole range of concentrations from pure calcite CaCO3 to pure magnesite MgCO3. Studying different distributions of Ca and Mg atoms within 30-atom supercells, our theoretical results show that the energetically most favorable configurations are characterized by elastic constants that nearly monotonously increase with the Mg content. Based on the first principles-derived single-crystalline elastic anisotropy, the integral elastic response of (Ca,Mg)CO3 polycrystals is determined employing a mean-field self-consistent homogenization method. As in case of single-crystalline elastic properties, the computed polycrystalline elastic parameters sensitively depend on the chemical composition and show a significant stiffening impact of Mg atoms on calcite crystals in agreement with the experimental findings. Our analysis also shows that it is not advantageous to use a higher-scale two-phase mix of stoichiometric calcite and magnesite instead of substituting Ca atoms by Mg ones on the atomic scale. Such two-phase composites are not significantly thermodynamically favorable and do not provide any strong additional stiffening effect.
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ISSN:1751-6161
1878-0180
DOI:10.1016/j.jmbbm.2013.01.030