Charge Transport in Metal Oxides: A Theoretical Study of Hematite α-Fe2O3

Transport of conduction electrons and holes through the lattice of α-Fe2O3 (hematite) is modeled as a valence alternation of iron cations using ab initio electronic structure calculations and electron transfer theory. Experimental studies have shown that the conductivity along the (001) basal plane is four orders of magnitude larger than the conductivity along the [001] direction. In the context of the small polaron model, a cluster approach was used to compute quantities controlling the mobility of localized electrons and holes, i.e., the reorganization energy and the electronic coupling matrix element that enter Marcus’ theory. The calculation of the electronic coupling followed the generalized Mulliken–Hush approach using the complete active space self-consistent field method. Our findings demonstrate an approximately three orders of magnitude anisotropy in both electron and hole mobility between directions perpendicular and parallel to the c axis, in good accord with experimental data. The anisotropy ...

[1]  R. K. Nesbet,et al.  Self‐Consistent Orbitals for Radicals , 1954 .

[2]  M. Rȩkas,et al.  Surface and bulk electrical properties of the hematite phase Fe2O3 , 1991 .

[3]  J. Ulstrup.  Charge Transfer Processes in Condensed Media , 1979 .

[4]  J. Nowotny,et al.  Electrical Properties of Oxide Materials , 1996, Key Engineering Materials.

[5]  V. Farmer.  The Infrared spectra of minerals , 1974 .

[6]  Clarence Zener,et al.  Dissociation of Excited Diatomic Molecules by External Perturbations , 1933 .

[7]  P. A. Cox.  The Electronic Structure And Chemistry Of Solids , 1987 .

[8]  Robert J. Cave,et al.  Generalization of the Mulliken-Hush treatment for the calculation of electron transfer matrix elements , 1996 .

[9]  P. Hagenmuller,et al.  Anisotropie des proprietes electriques de l'oxyde de fer Fe2O3α , 1984 .

[10]  Joshua Jortner,et al.  Electron transfer : from isolated molecules to biomolecules , 2007 .

[11]  M. A. Henderson,et al.  The photon-driven hydrophilicity of titania: A model study using TiO2(110) and adsorbed trimethyl acetate , 2003 .

[12]  R. Marcus,et al.  Electron transfers in chemistry and biology , 1985 .

[13]  S. Elliott,et al.  The Physics and Chemistry of Solids , 1956, Nature.

[14]  M. Dupuis,et al.  An ab initio model of electron transport in hematite (α-Fe2O3) basal planes , 2003 .

[15]  H. Shechter,et al.  The antiferromagnetic curie point in α-Fe2O3☆ , 1962 .

[16]  D. Sherman.  Cluster molecular orbital description of the electronic structures of mixed-valence iron oxides and silicates , 1986 .

[17]  Mark S. Gordon,et al.  General atomic and molecular electronic structure system , 1993, J. Comput. Chem..

[18]  Rudolph A. Marcus,et al.  Chemical and Electrochemical Electron-Transfer Theory , 1964 .

[19]  J. Pople,et al.  Self‐consistent molecular orbital methods. XX. A basis set for correlated wave functions , 1980 .

[20]  R. S. Mulliken.  Molecular Compounds and their Spectra. II , 1952 .

[21]  J. Lielmezs,et al.  Reversible Thermal Effect in α‐Fe2O3 at 690°±5°C , 1965 .

[22]  J. White,et al.  Photoinduced Redox Reaction Coupled with Limited Electron Mobility at Metal Oxide Surface , 2004 .

[23]  M. Dupuis,et al.  Reorganization energy associated with small polaron mobility in iron oxide. , 2004, The Journal of chemical physics.

[24]  E. Clementi,et al.  Electric-field induced intramolecular electron transfer in spiro .pi.-electron systems and their suitability as molecular electronic devices. A theoretical study , 1990 .

[25]  B. Roos,et al.  A complete active space SCF method (CASSCF) using a density matrix formulated super-CI approach , 1980 .

[26]  A. J. Bosman,et al.  Small-polaron versus band conduction in some transition-metal oxides , 1970 .

[27]  Harold Basch,et al.  Relativistic compact effective potentials and efficient, shared-exponent basis sets for the third-, fourth-, and fifth-row atoms , 1992 .

[28]  T. Nakau.  Electrical Conductivity of α-Fe2O3 , 1960 .

[29]  L. Sandratskii,et al.  First-principles LSDF study of weak ferromagnetism in Fe2O3 , 1996 .

[30]  M. Catti,et al.  Ab initio study of corundum-like Me2O3oxides (Me=Ti, V, Cr, Fe, Co, Ni) , 1997 .

[31]  M. Dupuis,et al.  First-principles study of noncommutative band offsets at [alpha]-Cr2O3/[alpha]-Fe2O3(0001) interfaces , 2004 .

[32]  Bruce S. Brunschwig,et al.  A semiclassical treatment of electron-exchange reactions. Application to the hexaaquoiron(II)-hexaaquoiron(III) system , 1980 .

[33]  H. L. Dryden,et al.  Investigations on the Theory of the Brownian Movement , 1957 .

[34]  L. Sandratskii,et al.  Band theory for electronic and magnetic properties of , 1996 .

[35]  P. Durand,et al.  A theoretical method to determine atomic pseudopotentials for electronic structure calculations of molecules and solids , 1975 .

[36]  Valerio,et al.  Theoretical study of electronic, magnetic, and structural properties of alpha -Fe2O3 (hematite). , 1995, Physical review. B, Condensed matter.

[37]  D. Sherman.  The electronic structures of Fe3+ coordination sites in iron oxides: Applications to spectra, bonding, and magnetism , 1985 .

[38]  R. Chang,et al.  Direct‐Current Conductivity and Iron Tracer Diffusion in Hematite at High Temperatures , 1972 .

[39]  J. White,et al.  Thermal Chemistry of Trimethyl Acetic Acid on TiO2(110) , 2004 .