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Hardness Alternation in alpha,omega-Alkanedicarboxylic Acids

Mishra, Manish Kumar and Ramamurty, Upadrasta and Desiraju, Gautam R (2015) Hardness Alternation in alpha,omega-Alkanedicarboxylic Acids. In: CHEMISTRY-AN ASIAN JOURNAL, 10 (10, SI). pp. 2176-2181.

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Official URL: http://dx.doi.org/10.1002/asia.201500322


The variation of hardness as a function of the number of carbon atoms in alpha,omega-alkanedicarboxylic acids, CNH2N-2O4 (4 <= N <= 9), was examined by recourse to nanoindentation on the major faces of single crystals. Hardness exhibits odd-even alternation, with the odd acids being softer and the even ones harder; the differences decrease with increasing chain length. These variations are similar to those seen for other mechanical, physical, and thermal properties of these diacids. The softness of odd acids is rationalized due to strained molecular conformations in them, which facilitate easier plastic deformation. Relationships between structural features, such as interplanar spacing, interlayer separation distance, molecular chain length, and signatures of the nanoindentation responses, namely, discrete displacement bursts, were also examined. Shear sliding of molecular layers past each other during indentation is key to the mechanism for plastic deformation in these organic crystals.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the WILEY-V C H VERLAG GMBH, POSTFACH 101161, 69451 WEINHEIM, GERMANY
Keywords: carboxylic acids; crystal engineering; hardness; mechanical properties; nanoindentation
Department/Centre: Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited: 12 Nov 2015 05:08
Last Modified: 12 Nov 2015 05:08
URI: http://eprints.iisc.ac.in/id/eprint/52720

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