NDLI: The impact of charge transfer and structural disorder on the thermoelectric properties of cobalt intercalated TiS<sub>2</sub>

Content Provider	Royal Society of Chemistry (RSC)
Author	Guélou, Gabin Powell, Anthony V. Kockelmann, Winfried Guilmeau, Emmanuel Vaqueiro, Paz Hébert, Sylvie Barbier, Tristan Prado-Gonjal, Jesús
Copyright Year	2016
Abstract	A family of phases, CoxTiS2 (0 ≤ x ≤ 0.75) has been prepared and characterised by powder X-ray and neutron diffraction, electrical and thermal transport property measurements, thermal analysis and SQUID magnetometry. With increasing cobalt content, the structure evolves from a disordered arrangement of cobalt ions in octahedral sites located in the van der Waals' gap (x ≤ 0.2), through three different ordered vacancy phases, to a second disordered phase at x ≥ 0.67. Powder neutron diffraction reveals that both octahedral and tetrahedral inter-layer sites are occupied in Co0.67TiS2. Charge transfer from the cobalt guest to the TiS2 host affords a systematic tuning of the electrical and thermal transport properties. At low levels of cobalt intercalation (x < 0.1), the charge transfer increases the electrical conductivity sufficiently to offset the concomitant reduction in \|S\|. This, together with a reduction in the overall thermal conductivity leads to thermoelectric figures of merit that are 25% higher than that of TiS2, ZT reaching 0.30 at 573 K for CoxTiS2 with 0.04 ≤ x ≤ 0.08. Whilst the electrical conductivity is further increased at higher cobalt contents, the reduction in \|S\| is more marked due to the higher charge carrier concentration. Furthermore both the charge carrier and lattice contributions to the thermal conductivity are increased in the electrically conductive ordered-vacancy phases, with the result that the thermoelectric performance is significantly degraded. These results illustrate the competition between the effects of charge transfer from guest to host and the disorder generated when cobalt cations are incorporated in the inter-layer space.
Starting Page	1871
Ending Page	1880
Page Count	10
File Format	HTM / HTML PDF
ISSN	20507526
Volume Number	4
Issue Number	9
Journal	Journal of Materials Chemistry C
DOI	10.1039/c5tc04217h
Language	English
Publisher	Royal Society of Chemistry
Access Restriction	Subscribed
Subject Keyword	X-ray crystallography Neutron diffraction Thermal analysis SQUID Magnetometer Cobalt Van der Waals force Electrical resistivity and conductivity Thermal conductivity Thermoelectric effect Charge carrier Crystal structure Thermoelectric materials
Content Type	Text
Resource Type	Article
Subject	Chemistry Materials Chemistry

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The impact of charge transfer and structural disorder on the thermoelectric properties of cobalt intercalated TiS2

The impact of charge transfer and structural disorder on the thermoelectric properties of cobalt intercalated TiS₂