Summary
The principal coefficients of expansion and the orientation of the ellipsoid of expansion have been determined for orthoboric acid, a triclinic crystal, for the range of temperatures 30 to 80° C. by an X-ray method. The anisotropy of expansion is extremely large, the maximum expansion being 256 and the minimum −4, ×10−6. The direction of the maximum expansion coefficient is close to the normal to thec plane, to which all the O3 groups are closely parallel. The occurrence of a negative expansion is a special feature of this crystal, the direction of which is found to be parallel to the shortest hydrogen bonds. This is the first time that the thermal expansion of a triclinic crystal has been fully studied by an X-ray method.
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References
Bell, R. J. T.Co-ordinate Geometry of Three Dimensions, Macmillan and Co., London, 1931, p. 208.
Cohen, E. and Bredee, H. L.Proc. K. Akad. Amsterdam, 1936,39, 358.
Fizeau, H.Pogg. Ann., 1867,132, 292.
Groth, P.Chemische Kristallographie, 1910,1, 121.
Jones, G. and Jelen, F. C.Journ. Am. Chem. Soc., 1935,57, 2532.
Lonappan, M. A.Proc. Phy. Soc., 1955a,68B, 75.
—Proc. Ind. Acad. Sci., 1955b,41A, 239.
Megaw, H. D.Proc. Roy. Soc., 1933,142A, 198.
Partington, J. R.Text-Book of Inorganic Chemistry, Macmillan and Co., London, 1946, p. 717.
Sreedhar, A. K.J. Ind. Inst. Sci., 1953,35A, 17.
Ubbelohde, A. R. and Woodward, I.Proc. Roy. Soc., 1942–43,181A, 415.
Zachariasen, W. H.Zeits. f. Krist, 1934,88, 150.
—Acta. Cryst., 1954,7, 305.
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(Communicated by Prof. G. N. Ramachandran,F.A.Sc.)
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Lonappan, M.A. Thermal expansion of boric acid. Proc. Indian Acad. Sci. 42, 10–21 (1955). https://doi.org/10.1007/BF03053556
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DOI: https://doi.org/10.1007/BF03053556