Improvement of grain alignment in Bi2Sr2Co1.8Oy thermoelectric through the electrically assisted laser floating zone
authors Ferreira, NM; Madre, MA; Torres, MA; Davarpanah, A; Amaral, V; Costa, FM; Sotelo, A
nationality International
journal MATERIALS RESEARCH BULLETIN
author keywords Bi-Sr-Co-O; oxide thermoelectric; Electrically Assisted Laser Floating Zone; thermoelectric performance; figure of merit; texture; thermal conductivity
keywords PERFORMANCE; GROWTH; MICROSTRUCTURE; ENHANCEMENT; FABRICATION; CA3CO4O9
abstract Thermoelectric performances of cobaltite ceramics were improved by increasing grain sizes and alignment through the Electrically Assisted Laser Floating Zone method. Bi2Sr2Co1.8Oy, ceramics were directionally grown at 30 mm/h, applying external DC (0-500 mA) during the growth process. Microstructure and thermoelectric properties are significantly influenced by the external current direction and intensity. Negative currents/pole on the seed rod prevent the formation of thermoelectric phase, while positive pole on the seed rod, decreases the amount of secondary phases and increase grain orientation when compared to samples grown without current. Annealing procedure decreases secondary phases content, without modifying grain alignment. The best thermoelectric performances were obtained for samples grown with + 300 mA, reaching the highest ZT values of 0.09 at 650 degrees C. Moreover, it should be highlighted that these processed samples can be directly applied in thermoelectric modules, avoiding the long and expensive steps necessary when other preparation processes are used.
publisher PERGAMON-ELSEVIER SCIENCE LTD
issn 0025-5408
isbn 1873-4227
year published 2020
volume 130
digital object identifier (doi) 10.1016/j.materresbull.2020.110933
web of science category Materials Science, Multidisciplinary
subject category Materials Science
unique article identifier WOS:000551881500006
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5 year journal impact factor 3.139
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