Open AccessThe Change in Physical Properties of Bi2Ca2Co2O8 Thermoelectric Materials Induced by Pb and Rare-Earth Dopings
Author(s) -
Inge Magdalena Sutjahja
Publication year - 2016
Publication title -
kontribusi fisika indonesia
Language(s) - English
Resource type - Journals
ISSN - 0854-6878
DOI - 10.5614/itb.ijp.2011.22.3.6
Subject(s) - thermoelectric effect , dopant , materials science , doping , seebeck coefficient , electrical resistivity and conductivity , condensed matter physics , magnetism , analytical chemistry (journal) , chemistry , thermodynamics , optoelectronics , physics , quantum mechanics , chromatography
We report in this paper the change in the physical properties due to dopant effect in Bi2Sr2Co2O8 parent compound system. The doped samples consists of Pb-doped samples (Bi2Sr2Co2O8, x = 0, 0.5, 1.0, 1.5, and 2.0) and RE-doped samples (Bi2-xPbxCa1.9RE0.1Co2O8, RE = Y, La, Pr, Sm, Eu, Gd, and Ho). The structure of this layered oxide system consist of an alternate stack of CoO2 layer and Bi2Sr2O4 block along the c-axis with misfit structure along b-direction. From the analysis of XRD data it is found that the c-axis parameter reduced significantly in the RE-doped samples compared with those of Pb-doped samples, while the value of misfit degree almost the same. The changes in these lattice structures are accompanied by variation in the spin-state of Co-ions and electrical conductivity. We argue that these structural changes and its effect on the electrical transport properties as well as control of the magnetism plays a pivotal role in determining the thermopower in this class of magnetic thermoelectric materials through the entropy of the charge carriers. This, in turn, will determine the thermoelectric performance for application.