Anisotropic small-polaron hopping in W:BiVO{sub 4} single crystals
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States)
- Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712 (United States)
- Lake Shore Cryotronics, Westerville, Ohio 43081 (United States)
- School of Mechanical and Materials Engineering, Washington State University, Pullman, Washington 99164 (United States)
- Department of Physics and Astronomy, The University of New Mexico, Albuquerque, New Mexico 87131 (United States)
DC electrical conductivity, Seebeck and Hall coefficients are measured between 300 and 450 K on single crystals of monoclinic bismuth vanadate that are doped n-type with 0.3% tungsten donors (W:BiVO{sub 4}). Strongly activated small-polaron hopping is implied by the activation energies of the Arrhenius conductivities (about 300 meV) greatly exceeding the energies characterizing the falls of the Seebeck coefficients' magnitudes with increasing temperature (about 50 meV). Small-polaron hopping is further evidenced by the measured Hall mobility in the ab-plane (10{sup −1 }cm{sup 2 }V{sup −1 }s{sup −1} at 300 K) being larger and much less strongly activated than the deduced drift mobility (about 5 × 10{sup −5 }cm{sup 2 }V{sup −1 }s{sup −1} at 300 K). The conductivity and n-type Seebeck coefficient is found to be anisotropic with the conductivity larger and the Seebeck coefficient's magnitude smaller and less temperature dependent for motion within the ab-plane than that in the c-direction. These anisotropies are addressed by considering highly anisotropic next-nearest-neighbor (≈5 Å) transfers in addition to the somewhat shorter (≈4 Å), nearly isotropic nearest-neighbor transfers.
- OSTI ID:
- 22399106
- Journal Information:
- Applied Physics Letters, Vol. 106, Issue 2; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
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