skip to main content

SciTech ConnectSciTech Connect

Title: Anisotropic small-polaron hopping in W:BiVO{sub 4} single crystals

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.
Authors:
 [1] ; ;  [2] ;  [3] ;  [4] ;  [5] ;  [2] ;  [5] ;  [6] ;  [1] ;  [5] ;  [5]
  1. McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States)
  2. Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712 (United States)
  3. Lake Shore Cryotronics, Westerville, Ohio 43081 (United States)
  4. School of Mechanical and Materials Engineering, Washington State University, Pullman, Washington 99164 (United States)
  5. (United States)
  6. Department of Physics and Astronomy, The University of New Mexico, Albuquerque, New Mexico 87131 (United States)
Publication Date:
OSTI Identifier:
22399106
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; Journal Issue: 2; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ACTIVATION ENERGY; ANISOTROPY; BISMUTH COMPOUNDS; DOPED MATERIALS; ELECTRIC CONDUCTIVITY; HALL EFFECT; MONOCLINIC LATTICES; MONOCRYSTALS; N-TYPE CONDUCTORS; POLARONS; SEEBECK EFFECT; TEMPERATURE DEPENDENCE; TUNGSTEN; VANADATES