Premium
Linear Thermal Expansion of Lead‐Free Piezoelectric K 0.5 Na 0.5 NbO 3 Ceramics in a Wide Temperature Range
Author(s) -
Malič Barbara,
Razpotnik Helena,
Koruza Jurij,
Kokalj Samo,
Cilenšek Jena,
Kosec Marija
Publication year - 2011
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.1551-2916.2011.04628.x
Subject(s) - thermal expansion , materials science , tetragonal crystal system , monoclinic crystal system , ceramic , atmospheric temperature range , classification of discontinuities , microstructure , piezoelectricity , phase (matter) , phase transition , composite material , mineralogy , thermodynamics , crystal structure , crystallography , chemistry , mathematical analysis , physics , mathematics , organic chemistry
The objective of this work was to examine linear thermal expansion of K 0.5 Na 0.5 NbO 3 ceramics between room temperature and 790°C by contact dilatometry. The material was single phase with 95.5% relative density and with a uniform microstructure. Three distinct regions of thermal expansion could be discerned, corresponding to the three phases of K 0.5 Na 0.5 NbO 3 : monoclinic (assuming a single perovskite unit cell), tetragonal, and cubic, separated by discontinuities as typical for the first‐order phase transitions. The linear coefficient of thermal expansion between 30° and 195°C is 2.96 × 10 −6 K −1 , between 208° and 364°C is 4.35 × 10 −6 K −1 , and between 434° and 790°C is 7.52 × 10 −6 K −1 .