Grain boundary blocking and segregation effects in yttrium-doped polycrystalline titanium dioxide

Abstract Impedance spectroscopy was used to investigate the electrical behavior of undoped, 0.025 mol% and 0.1 mol% yttrium-doped polycrystalline TiO 2 . In the doped samples, distinct contributions from the bulk and grain boundaries to the electronic conduction were evident, while no grain boundary blocking effect was observed in pure titania samples. The activation energy for grain boundary electronic conduction increased with increasing dopant concentration, which implied an increasing barrier height in these regions introduced by the solute interfacial excess. The impedance behavior was correlated with grain boundary solute segregation measurements and rationalized in terms of the local grain boundary defect chemistry in the grain boundary cores and space-charge layers.

[1]  Donald Morgan Smyth,et al.  The Defect Chemistry of Metal Oxides , 2000 .

[2]  L. M. Kukreja,et al.  Pulsed laser deposition of TiO 2 for MOS gate dielectric , 2002 .

[3]  R. M. Cannon,et al.  Space charge, elastic field, and dipole contributions to equilibrium solute segregation at interfaces , 1983 .

[4]  W. Heywang,et al.  Resistivity Anomaly in Doped Barium Titanate , 1964 .

[5]  J. Baumard,et al.  A study of TiO system between Ti3O5 and TiO2 at high temperature by means of electrical resistivity , 1977 .

[6]  Rainer Waser,et al.  Grain boundaries in dielectric and mixed-conducting ceramics , 2000 .

[7]  David B. Williams,et al.  Transmission Electron Microscopy , 1996 .

[8]  S. Chan,et al.  Electrical Conductivities of (CeO2)1−x(Y2O3)x Thin Films , 2002 .

[9]  H. Tuller,et al.  Electrical and defect thermodynamic properties of nanocrystalline titanium dioxide , 1999 .

[10]  A. Hippel,et al.  Dielectric Materials and Applications , 1995 .

[11]  Yasuhiro Shimamoto,et al.  Rutile-type TiO2 thin film for high-k gate insulator , 2003 .

[12]  Y. Chiang,et al.  Solute Segregation and Grain‐Boundary Impedance in High‐Purity Stabilized Zirconia , 1996 .

[13]  D. D. Armstrong,et al.  (He 3 , d) Reaction on the N=28 Nuclei , 1965 .

[14]  E. Greener,et al.  Electrical Conductivity of Single and Polycrystalline Near‐Stoichiometric Rutile in the Range 600° to 1400°C , 1965 .

[15]  Y. Chiang,et al.  Space Charge Segregation at Grain Boundaries in Titanium Dioxide: I, Relationship between Lattice Defect Chemistry and Space Charge Potential , 1993 .

[16]  M. Rȩkas,et al.  Electrical surface versus bulk properties of Fe-doped TiO2 single crystals , 1994 .

[17]  R. Waser,et al.  Influence of temperature and interface charge on the grain-boundary conductivity in acceptor-doped SrTiO3 ceramics , 1998 .

[18]  R. Wallace,et al.  High-κ gate dielectrics: Current status and materials properties considerations , 2001 .

[19]  Xin Guo,et al.  Determination of electronic and ionic partial conductivities of a grain boundary: method and application to acceptor-doped SrTiO3 , 2002 .

[20]  W. W. Rhodes,et al.  Preparation and properties of TiO2 varistors , 1982 .

[21]  J. Baumard,et al.  Electrical conductivity and charge compensation in Nb doped TiO2 rutile , 1977 .

[22]  Y. Chiang,et al.  Space Charge Segregation at Grain Boundaries in Titanium Dioxide: II, Model Experiments , 1993 .

[23]  M. Grätzel,et al.  A low-cost, high-efficiency solar cell based on dye-sensitized colloidal TiO2 films , 1991, Nature.

[24]  I. Lauermann,et al.  Temperature- and oxygen partial pressure-dependent electrical conductivity in nanoporous rutile and anatase , 1999 .

[25]  Y. Chiang,et al.  Size-dependent solute segregation and total solubility in ultrafine polycrystals: Ca in TiO2 , 1995 .

[26]  G. Rohrer,et al.  Grain boundary segregation in oxide ceramics , 2003 .

[27]  W. Kenan,et al.  Impedance Spectroscopy: Emphasizing Solid Materials and Systems , 1987 .

[28]  C. J. Chen,et al.  The abnormal grain growth and dielectric properties of (Nb, Ba) doped TiO2 ceramics , 1989 .

[29]  Craig A. Grimes,et al.  Unprecedented ultra-high hydrogen gas sensitivity in undoped titania nanotubes , 2006 .

[30]  C. Demetry,et al.  Grain size-dependent electrical properties of rutile (TiO2) , 1999 .

[31]  Rainer Waser,et al.  Modeling of electroceramics—Applications and prospects , 1999 .

[32]  W. Sigle,et al.  Electrical and structural characterization of a low-angle tilt grain boundary in iron-doped strontium titanate , 2003 .

[33]  E. Dickey,et al.  Grain boundary segregation in yttrium-doped polycrystalline TiO2 , 2004 .

[34]  Tadao Watanabe,et al.  Misorientation dependence of grain boundary segregation , 1978 .

[35]  J. Baukus,et al.  Electrical conductivity of nonstoichiometric rutile single crystals from 1000° to 1500°C , 1966 .