Premium
Anisotropic Thermal Expansion of β‐Ca 2 SiO 4 Monoclinic Crystal
Author(s) -
Fukuda Koichiro,
Maki Iwao,
Ito Suketoshi
Publication year - 1997
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1997.tb03023.x
Subject(s) - thermal expansion , monoclinic crystal system , anisotropy , materials science , crystallography , negative thermal expansion , diffusionless transformation , volume expansion , crystal structure , mineralogy , condensed matter physics , martensite , chemistry , composite material , optics , physics , microstructure , medicine
Crystals of β‐Ca 2 SiO 4 (space group P 12 1 / n 1) were examined by high‐temperature powder X‐ray diffractometry to determine the change in unit‐cell dimensions with temperature up to 645°C. The temperature dependence of the principal expansion coefficients (α i ) found from the matrix algebra analysis was as follows: α 1 = 20.492 × 10 −6 + 16.490 × 10 −9 ( T ‐ 25)°C −1 , α 2 = 7.494 × 10 −6 + 5.168 × 10 −9 ( T ‐ 25)°C −1 , α 3 =−0.842 × 10 −6 − 1.497 × 10 −9 ( T ‐ 25)°C −1 . The expansion coefficient α 1 , nearly along [302] was approximately 3 times α 2 along the b ‐axis. Very small contraction (α 3 ) occurred nearly along [01]. The volume changes upon martensitic transformations of β↔α L ′ were very small, and the strain accommodation would be almost complete. This is consistent with the thermoelasticity.