Physics and Chemistry of Minerals

, Volume 43, Issue 1, pp 59–68 | Cite as

Evolution of nanostructure and specific surface area during thermally driven dehydration of Mg(OH)2

Original Paper

Abstract

The thermally induced dehydration of micrometer-sized particles of Mg(OH)2 was investigated experimentally at ambient pressure and temperatures ranging from 350 to 1300 °C. Reaction progress is correlated with the evolution of the specific surface area and of the particle internal nanostructure. The maximum specific surface area of about 320 m2/g corresponding to a 70-fold increase relative to the starting material is obtained after heat treatment at 350 °C for about 2 h. This is due to the formation of a highly porous, particle-internal nanostructure comprised of newly crystallized strictly aligned, cube-shaped and nanometer-sized crystals of MgO and about 50 vol% porosity. Associated with the dehydration, intensive fracturing and defoliation occurs parallel to the (0001) plane of the original Mg(OH)2 or (111) of the topotaxially grown MgO. After heat treatment at increasingly higher temperatures, enhanced coarsening and sintering of the MgO crystals and healing of cracks leads to a successive decrease of the specific surface area. After heat treatment at 1300 °C for 2.5 h, the specific surface area has decreased to 5 m2/g close to the value typical for the original Mg(OH)2.

Keywords

Mg(OH)2 Dehydration experiment Nanostructure Specific surface area Orientation relations 

Notes

Acknowledgments

We thank two anonymous reviewers for constructive critique and helpful comments. We thank Mrs. Hrabe and Mrs. Beybel for their support in sample preparation. Fruitful discussions with R. Nilica and G. Gelbmann are gratefully acknowledged.

Supplementary material

269_2015_774_MOESM1_ESM.pdf (84 kb)
Supplementary material 1 (pdf 83 KB)

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Copyright information

© Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  • H. Pimminger
    • 1
  • G. Habler
    • 1
  • N. Freiberger
    • 2
  • R. Abart
    • 1
  1. 1.Department of Lithospheric ResearchUniversity of ViennaViennaAustria
  2. 2.RHI AG, Technology CenterLeobenAustria

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