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Thermal expansion of manganese dioxide using high‐temperature in situ X‐ray diffraction
Author(s) -
Dose Wesley M.,
Donne Scott W.
Publication year - 2013
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889813017846
Subject(s) - manganese , thermal expansion , atmospheric temperature range , thermal decomposition , analytical chemistry (journal) , diffraction , materials science , chemistry , thermodynamics , composite material , metallurgy , optics , physics , organic chemistry , chromatography
High‐temperature in situ X‐ray diffraction is used to determine the thermal expansion behaviour of manganese dioxide in air at temperatures between 298 and 673 K, the range accessible prior to material decomposition. Two manganese dioxide samples of different origins are investigated to observe the effect of synthesis conditions and resultant material properties on the thermal response. β‐MnO 2 prepared by a chemical pathway is found to expand linearly over the temperature window with thermal expansion coefficients (in units of K −1 ) of α a = 9.3 (4) × 10 −6 , α c = 7.0 (2) × 10 −6 and β = 25.6 (8) × 10 −6 . Conversely, the thermal expansion of heat‐treated electrolytic manganese dioxide is disjointed about 473 K in the a direction and for the overall unit‐cell volume, and about 523 K in the c direction. Coefficients are therefore given (in units of K −1 ) as α a = 23 (4) × 10 −6 (298–473 K), 10 (3) × 10 −6 (473–673 K); α c = 0.2 (9) × 10 −6 (298–523 K), 10 (1) × 10 −6 (523–673 K); and β = 49 (9) × 10 −6 (298–473 K), 26 (5) × 10 −6 (473–673 K).