Thermal expansion of select Mn+1AXn(M=early transition metal, A=A group element, X=C or N) phases measured by high temperature x-ray diffraction and dilatometry

T. H. Scabarozi, S. Amini, O. Leaffer, A. Ganguly, S. Gupta, W. Tambussi, S. Clipper, J. E. Spanier, M. W. Barsoum, J. D. Hettinger, S. E. Lofland

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Abstract

Herein we report on a systematic investigation of the thermal expansion of select Mn+1AXn phases. The bulk dilatometric thermal expansion coefficient αdil was measured in the 25-1200 °C temperature range and the thermal expansion of more than 15 of these phases was studied by x-ray diffraction in the 25-800 °C temperature range. The coefficient of thermal expansion for the a axis αa ranged between (2.9±0.1) × 10-6 ° C-1(Nb2 AsC) and (12.9±0.1) × 10-6 ° C-1 (Cr2 GeC) while the coefficient for the c axis (αc) ranged between (6.4±0.2) × 10-6 ° C-1 (Ta2 AlC) and (17.6±0.2) × 10-6 ° C-1 (Cr 2 GeC). Weak anisotropy in the thermal expansion was seen in most phases, with the largest value of αc / αa belonging to Nb2 AsC. The Grüneisen parameters along the a and c directions were calculated from ab initio values for the elastic compliances and were relatively isotropic. A good correlation was found between the thermal expansion anisotropy and the elastic constant c13 and we conclude that the anisotropy in thermal expansion is related to the bonding between the M-A elements.

Original languageEnglish (US)
Article number013543
JournalJournal of Applied Physics
Volume105
Issue number1
DOIs
StatePublished - 2009

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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