Year: 2014
Type: article
Abstract: We have grown single crystals of ${\mathrm{Na}}_{x}{\mathrm{Ca}}_{y}\mathrm{Co}{\mathrm{O}}_{2}$ and determined their superstructures as a function of composition using neutron and x-ray diffraction. Inclusion of ${\mathrm{Ca}}^{2+}$ stabilizes a single superstructure across a wide range of temperatures and concentrations. The superstructure in the ${\mathrm{Na}}^{+}$ layers is based on arrays of divacancy clusters with ${\mathrm{Ca}}^{2+}$ ions occupying the central site, and it has an ideal concentration ${\mathrm{Na}}_{4/7}{\mathrm{Ca}}_{1/7}\mathrm{Co}{\mathrm{O}}_{2}$. Previous measurements of the thermoelectric properties on this system are discussed in light of this superstructure. ${\mathrm{Na}}_{4/7}{\mathrm{Ca}}_{1/7}\mathrm{Co}{\mathrm{O}}_{2}$ corresponds to the maximum in thermoelectric performance of this system.
Source: Physical Review B
Institutions: Royal Holloway University of London, Centre National de la Recherche Scientifique, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Service de Physique de l'État Condensé, CEA Paris-Saclay, Rutherford Appleton Laboratory, Science and Technology Facilities Council, University of Oxford
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W1993633050