Unravelling the Effects of Calcium Substitution in BaGd2CoO5 Haldane Gap 1D Material and Its Thermoelectric Performance

authors	Narendar, N; Kovalevsky, AV; Xie, WJ; Rasekh, S; Constantinescu, G; Weidenkaff, A; Pukazhselvan, D; Fagg, DP
nationality	International
journal	JOURNAL OF PHYSICAL CHEMISTRY C
keywords	DEFECT CHEMISTRY; OXIDE; CA3CO4O9; ENHANCEMENT; POWER; GLASS
abstract	Ecobenign and high-temperature-stable oxides are considered a promising alternative to traditional Bi2Te3-, Bi2Se3-, and PbTe-based thermoelectric materials. The quest for highperforming thermoelectric oxides is still open and, among other challenges, includes the screening of various materials systems for potentially promising electrical and thermal transport properties. In this work, a new family of acceptor-substituted Haldane gap 1D BaGd2CoO5 dense ceramic materials was characterized in this respect. The substitution of this material with calcium results in a general improvement of the electrical performance, contributed by an interplay between the charge carrier concentration and their mobility. Nevertheless, a relatively low electrical conductivity was measured, reaching similar to 5 S/cm at 1175 K, resulting in a maximum power factor of similar to 25 mu W/(K x m(2)) at 1173 K for BaGd1.80Ca0.20CoO5. On the other hand, the unique anisotropic 1D structure of the prepared materials promotes efficient phonon scattering, leading to low thermal conductivities, rarely observed in oxide electroceramics. While the BaGd2-xCaxCoO5 materials show attractive Seebeck coefficient values in the range 210-440 mu V/K, the resulting dimensionless figure of merit is still relatively low, reaching similar to 0.02 at 1173 K. The substituted BaGd2-xCaxCoO5 ceramics show comparable thermoelectric performance in both inert and air atmospheres. These features highlight the potential relevance of this structure type for thermoelectric applications, with future emphasis placed on methods to improve conductivity.
publisher	AMER CHEMICAL SOC
issn	1932-7447
isbn	1932-7455
year published	2020
volume	124
issue	24
beginning page	13017
ending page	13025
digital object identifier (doi)	10.1021/acs.jpcc.0c03149
web of science category	Chemistry, Physical; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary
subject category	Chemistry; Science & Technology - Other Topics; Materials Science
unique article identifier	WOS:000549942500015