Charge Transport by Polyatomic Anion Diffusion in SC2(WO4)(3) / Zhou Yongkai,Adams Stefan,Rao R. Prasada,Edwards Doreen D.,Neiman Arkady,Pestereva N. // CHEMISTRY OF MATERIALS. - 2008. - V. 20, l. 20. - P. 6335-6345.

ISSN/EISSN:

0897-4756 / 1520-5002

Type:

Article

Abstract:

Discussions about the nature of the charge carriers in the scandium tungstate and other isostructural tungstates and molybdates have persisted in the literature since a variety of experimental indications pointed toward trivalent cations as the mobile species. Here variations of the structure over a wide temperature range are analyzed by XRD and computational methods, demonstrating that the negative thermal expansion persists throughout the range of 11-1300 K. Over a limited temperature range (<500 K) molecular dynamics simulations with an optimized forcefield reproduce this negative thermal expansion. Likewise, charge transport is monitored both experimentally by impedance spectroscopy and Tubandt experiments and computationally based oil the molecular dynamics simulation trajectories. Extended isothermal-isobaric simulations suggest a complex migration of polyatomic tungstate anions as the energetically most favorable transport mechanism in SC2(WO4)(3)). A bond valence analysis depicts possible diffusion pathways for WO4, although there is no indication of a pathway for Sc. The hopping mechanism of tungstate ions from one equilibrium site to another one follows the instantaneous diffusion pathways. A long-range transport still requires the rare formation Of WO42- Frenkel defects limiting the accuracy of the simulated absolute conductivity. Both MD simulations and bond valence analysis suggest WO42- be the mobile species, which follow the interstitialcy diffusion mechanism. Our 3-section Tubandt-type experiments qualitatively show that the transfer of W occurs in the form of a negatively charged complex. This should be the first example of polyatomic diffusion species and opens a new field in the search for new ionic conductors.

Author keywords:

NEGATIVE THERMAL-EXPANSION; MOLECULAR-DYNAMICS SIMULATIONS; CONDUCTING SOLID ELECTROLYTES; TRIVALENT ION CONDUCTION; PADDLE-WHEEL MECHANISM; SC-2(WO4)(3)-TYPE STRUCTURE; SULFATE PHASES; BOND VALENCE; TUNGSTATE; MODELS

DOI:

10.1021/cm800466y

Web of Science ID:

ISI:000260254400013

Соавторы в МНС:

Другие поля

Поле	Значение
Month	OCT 28
Publisher	AMER CHEMICAL SOC
Address	1155 16TH ST, NW, WASHINGTON, DC 20036 USA
Language	English
EISSN	1520-5002
Keywords-Plus	NEGATIVE THERMAL-EXPANSION; MOLECULAR-DYNAMICS SIMULATIONS; CONDUCTING SOLID ELECTROLYTES; TRIVALENT ION CONDUCTION; PADDLE-WHEEL MECHANISM; SC-2(WO4)(3)-TYPE STRUCTURE; SULFATE PHASES; BOND VALENCE; TUNGSTATE; MODELS
Research-Areas	Chemistry; Materials Science
Web-of-Science-Categories	Chemistry, Physical; Materials Science, Multidisciplinary
Author-Email	mseasn@nus.edu.sg
ResearcherID-Numbers	Adams, Stefan/G-9146-2011
ORCID-Numbers	Adams, Stefan/0000-0003-0710-135X Rayavarapu, Prasada Rao/0000-0002-4022-2340
Funding-Acknowledgement	SERC {[}NSF-MWN 062 119 0009]; NSF {[}DMR-060288]; RFBR {[}06-03-90170-NSF]
Funding-Text	Acknowledgment. This Materials World Network project was cofunded by A-Star SERC (NSF-MWN 062 119 0009), NSF (DMR-060288), and RFBR (06-03-90170-NSF).
Number-of-Cited-References	40
Usage-Count-Last-180-days	1
Usage-Count-Since-2013	26
Journal-ISO	Chem. Mat.
Doc-Delivery-Number	363FY