Hostname: page-component-77c89778f8-sh8wx Total loading time: 0 Render date: 2024-07-22T23:26:44.648Z Has data issue: false hasContentIssue false
  • English
  • Français

An X-ray investigation of the thermal decomposition of portlandite

Published online by Cambridge University Press:  05 July 2018

N. H. Brett
N. H. Brett*
Affiliation:
Department of Ceramics with Refractories Technology, University of Sheffield
Get access Rights & Permissions [Opens in a new window]

Summary

The thermal decomposition of portlandite, Ca(OH)2, has been studied in air and in vacuum using X-ray single-crystal techniques. In air, the crystals were decomposed in situ on the goniometer arcs whilst X-ray reflections were simultaneously recorded. The transformation to CaO was not accompanied by topotaxy; this is attributed to the high nucleation rate of CaO crystallites in air. When Ca(OH)2 single crystals were decomposed under vacuum (and subsequently exposed to X-rays), some orientation of the CaO crystallites occurred. These results are compared with those of previous workers using electron-diffraction techniques. Decomposition of Ca(OH)2 single crystals commences at ∼ 450 °C in air and at ∼ 230 °C in a vacuum of 10−6 mmHg; reaction commences at crystal edges and surface defects, the reaction boundary moving inwards to the centre of the crystal. This observation is consistent with a homogeneous mechanism of decomposition.

Type
Research Article
Information
Mineralogical Magazine , Volume 37 , Issue 286 , June 1969 , pp. 244 - 249
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1969

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Anderson, (P. J.), Horlock, (R. F.), and Avery, (R. G.), 1965. Proc. Brit. Ceram. Soc., 3 33.Google Scholar
Ashton, (F. N.) and Wilson, (R.), 1927. Amer. Journ. Sci. ser. 5, 13, 209.10.2475/ajs.s5-13.75.209CrossRefGoogle Scholar
Balmbra, (R. R.), Clunie, (J. S.), and Goodman, (J. F.), 1966. Nature, 209, 1083.10.1038/2091083a0CrossRefGoogle Scholar
Barclay, (A.) and Donaldson, (J. D.), 1961. Journ. Sci. Instr. 38, 286.10.1088/0950-7671/38/7/304CrossRefGoogle Scholar
Brett, (N. H.), 1968. Ibid., ser. 2, 1, 1254.Google Scholar
Chatterji, (S.) and Jeffery, (J. W.), 1966. Min. Mag. 35, 867.Google Scholar
Dent, (L. S.), 1957. Ph.D. Thesis. Univ. of Aberdeen.Google Scholar
Dent Glasser, (L. S.), Glasser, (F. P.), and Taylor, (H. F. W.), 1962. Quart. Rev. 16, 343.10.1039/qr9621600343CrossRefGoogle Scholar
Garrido, (J.), 1951. Ion. Rev. Españ. Quire. Aplic. 11, 206, 220, and 453.Google Scholar
Goodman, (J. F.), 1958. Proe. Roy. Soc., ser. A, 247, 346.10.1098/rspa.1958.0188CrossRefGoogle Scholar
Gordon, (R. S.) and Kingery, (W. O.), 1966. Journ. Amer. Ceram. Soc. 49, 654.10.1111/j.1151-2916.1966.tb13194.xCrossRefGoogle Scholar
Shannon, (R. D.) and Rossi, (R. C.), 1964. Nature, 202, 1000.10.1038/2021000a0CrossRefGoogle Scholar
West, (C. D.), 1934. Amer. Min. 17, 316.Google Scholar