Citation link:
https://doi.org/10.26092/elib/13
Thermal behavior of mullite between 4 K and 1320 K
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Authors: | Murshed, Mohammad Mangir ![]() Šehović, Malik Fischer, Michael ![]() Senyshyn, Anatoliy ![]() Schneider, Hartmut ![]() Gesing, Thorsten M. ![]() |
Abstract: | The evolution of metric parameters of 2:1 and 3:2 mullites have been measured between 4 K and 1320 K using neutron and X‐ray powder diffraction. Negative thermal expansion was observed at low temperature for the a‐cell parameter and consequently for the cell‐volume, which is more pronounced for 2:1 mullite than those for 3:2 mullite. Each parameter is simulated using Grüneisen first‐order approximation for the zero pressure equation of state at 0 K, where the vibrational energy was calculated using microscopic approach. While the b‐ and c‐cell parameters require only one Debye term, a second Debye spectrum with negative Grüneisen parameter was required to fit the a‐cell parameter as well as the cell volume. At 4 K, 300 K and 1320 K the model, respectively, calculates the volume thermal expansion coefficients of 0.09x10−6 K−1, 9x10−6 K−1, and 17.3x10−6 K−1 for 2:1 mullite, and 0.09x10−6 K−1, 8.7x10−6 K−1, and 17.3x10−6 K−1 for 3:2 mullite. Temperature‐dependent Raman spectra and phonon density of states hint for the possible microscopic sources of the cell contraction at low temperature. A simple polynomial approach is presented to calculate the elastic stiffness coefficients of the 3:2 mullite, which are not available from experiments. |
Keywords: | neutron diffraction; thermal expansion; X‐ray diffraction; mullite; phonon | Issue Date: | 26-Jun-2017 | Project: | Chemische Kristallographie fester Stoffe | Journal/Edited collection: | Journal of the American Ceramic Society | Start page: | 5259 | End page: | 5273 | Type: | Artikel/Aufsatz | ISSN: | 00027820 | Secondary publication: | no | DOI: | 10.26092/elib/13 | URN: | urn:nbn:de:gbv:46-elib42289 | Institution: | Universität Bremen | Faculty: | Fachbereich 02: Biologie/Chemie (FB 02) |
Appears in Collections: | Forschungsdokumente |
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