Electrical conductivity and conduction mechanisms in (Na0.5Bi0.5TiO3)1−x(BiScO3)x (0.00 ≤ x ≤ 0.25) solid solutions

The electrical properties of (Na0.5Bi0.5TiO3)1−x(BiScO3)x (NBT-BS, 0.00 ≤ x ≤ 0.25) solid solutions are established by ac impedance spectroscopy and electromotive force transport number measurements. The bulk conductivity decreases with increasing BS incorporation but the oxide-ion transport number remains high (>0.85) over a wide compositional range 0.00 ≤ x ≤ 0.15 and drops to ∼0.7 for x ≥ 0.20. NBT-BS solid solutions can only present either predominant oxide-ion conduction or mixed ionic-electronic conduction behaviour, indicating that oxide-ion conduction cannot be fully eliminated by incorporation of BS. This is in contrast from our previous study where incorporation of ∼7% BiAlO3 (BA) can fully suppress the oxide-ion conduction in NBT. The conductivity–composition relationships of NBT-BS solid solutions are attributed to a competing effect from lattice expansion, which enlarges the channel for oxygen ion migration, with trapping between B-site acceptor ions, , and oxygen vacancies, , which decreases oxygen ion migration. Comparisons between NBT-BS, NBT-BA and NBT-BiGaO3 (BG) solid solutions suggest that small acceptor ions on the B-site are more effective in trapping oxygen vacancies and consequently more effective to suppress the oxide-ion conduction and thus reduce dielectric loss at elevated temperatures.

[1]  D. Sinclair,et al.  Use of the time constant related parameter fmax to calculate the activation energy of bulk conduction in ferroelectrics , 2018 .

[2]  H. Yan,et al.  Perovskite Srx(Bi1−xNa0.97−xLi0.03)0.5TiO3 ceramics with polar nano regions for high power energy storage , 2018, Nano Energy.

[3]  Fei Li,et al.  Multilayer Lead‐Free Ceramic Capacitors with Ultrahigh Energy Density and Efficiency , 2018, Advanced materials.

[4]  D. Sinclair,et al.  Defect chemistry and electrical properties of sodium bismuth titanate perovskite , 2018 .

[5]  K. Albe,et al.  Ionic conductivity of acceptor doped sodium bismuth titanate: influence of dopants, phase transitions and defect associates , 2017 .

[6]  D. Sinclair,et al.  Suppression of electrical conductivity and switching of conduction mechanisms in ‘stoichiometric’ (Na0.5Bi0.5TiO3)1−x(BiAlO3)x (0 ≤ x ≤ 0.08) solid solutions , 2017 .

[7]  H. Yan,et al.  Effect of Phase Transitions on Thermal Depoling in Lead-Free 0.94(Bi0.5Na0.5TiO3)–0.06(BaTiO3) Based Piezoelectrics , 2017 .

[8]  K. Albe,et al.  Influence of phase transitions and defect associates on the oxygen migration in the ion conductor Na1/2Bi1/2TiO3 , 2017 .

[9]  D. Sinclair,et al.  Controlling mixed conductivity in Na1/2Bi1/2TiO3 using A-site non-stoichiometry and Nb-donor doping , 2016 .

[10]  I. Tanaka,et al.  Crystal structure, defect chemistry and oxygen ion transport of the ferroelectric perovskite, Na0.5Bi0.5TiO3: insights from first-principles calculations , 2015 .

[11]  Yifei Mo,et al.  Accelerated materials design of Na0.5Bi0.5TiO3 oxygen ionic conductors based on first principles calculations. , 2015, Physical chemistry chemical physics : PCCP.

[12]  Zhao Pan,et al.  Semiconductor/relaxor 0–3 type composites without thermal depolarization in Bi0.5Na0.5TiO3-based lead-free piezoceramics , 2015, Nature Communications.

[13]  D. Sinclair,et al.  Donor-doping and reduced leakage current in Nb-doped Na0.5Bi0.5TiO3 , 2015 .

[14]  C. Kwak,et al.  Sr2(Mg1−xGax)Ge2O7+0.5x: Melilite-type oxygen ionic conductor associated with fivefold coordinated germanium and gallium , 2015 .

[15]  D. Sinclair,et al.  Dramatic Influence of A-Site Nonstoichiometry on the Electrical Conductivity and Conduction Mechanisms in the Perovskite Oxide Na0.5Bi0.5TiO3 , 2015 .

[16]  Jacob L. Jones,et al.  Crystal Structure–Ionic Conductivity Relationships in Doped Ceria Systems , 2009 .

[17]  Yun Sun,et al.  Synthesis and characterization of (Mg, Al)-doped apatite-type lanthanum germanate , 2008 .

[18]  B. Johansson,et al.  Optimization of ionic conductivity in doped ceria. , 2006, Proceedings of the National Academy of Sciences of the United States of America.

[19]  E. Boucher,et al.  Structural and ferroelectric study of Na$_{0.5}$Bi$_{0.5}$TiO$_{3}$-BiScO$_{3}$ system , 2005 .

[20]  Pam A. Thomas,et al.  Investigation of the structure and phase transitions in the novel A-site substituted distorted perovskite compound Na(0.5)Bi(0.5)TiO(3). , 2002, Acta crystallographica. Section B, Structural science.

[21]  Brian H. Toby,et al.  EXPGUI, a graphical user interface for GSAS , 2001 .

[22]  H. Inaba,et al.  Structural consideration on the ionic conductivity of perovskite-type oxides , 1999 .

[23]  K. Clausen,et al.  Defect structure of yttria-stabilized zirconia and its influence on the ionic conductivity at elevated temperatures , 1999 .

[24]  N. Imanishi,et al.  Zirconia based oxide ion conductors for solid oxide fuel cells , 1998 .

[25]  R. Grimes,et al.  Dielectric polarizability of ions and the corresponding effective number of electrons , 1998 .

[26]  H. Nagata,et al.  Lead-Free Piezoelectric Ceramics of (Bi1/2Na1/2)TiO3–KNbO3–1/2(Bi2O3·Sc2O3) System , 1997 .

[27]  R. Brook,et al.  A study of oxygen ion conductivity in doped non-stoichiometric oxides , 1982 .

[28]  R. D. Shannon.  Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides , 1976 .

[29]  Ming Li,et al.  A family of oxide ion conductors based on the ferroelectric perovskite Na1/2Bi1/2TiO3 , 2013 .

[30]  E. Boucher,et al.  Dielectric properties of some low-lead or lead-free perovskite-derived materials: Na0.5Bi0.5TiO3–PbZrO3, Na0.5Bi0.5TiO3–BiScO3 and Na0.5Bi0.5TiO3–BiFeO3 ceramics , 2006 .

[31]  M. Islam.  Ionic transport in ABO3 perovskite oxides: a computer modelling tour , 2000 .