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Electrical conductivity and conduction mechanisms in (Na <sub/>0.5</sub> Bi <sub/>0.5</sub> TiO <sub/>3</sub> ) <sub/>1?x</sub> (BiScO <sub/>3</sub> ) <sub/>x</sub> (0.00 ≤ <i>x</i> ≤ 0.25) solid solutions
摘要： 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, Sc'Ti, and oxygen vacancies, V??O, 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.
关键词： transport number,electrical conductivity,solid solutions,sodium bismuth titanate,oxide-ion conduction,conduction mechanisms,impedance spectroscopy,BiScO3
更新于2025-11-14 17:28:48
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Electric field dependence of dc conductivity in As2Te3 (in) thin films
摘要： The time evolutions of transient current data for As2Te3(In) thin films were measured at different electric fields for the dc voltages of 0.001 V, 0.002 V, 0.005 V, 0.01 V, 0.1 V, 0.5 V and 1 V at room temperature (296 K). Transient current was analyzed by means of time series analysis in order to identify different conduction regimes. The maximal Lyapunov exponents for the transient currents were calculated. Positive maximal Lyapunov exponents reflected electric field dependence with positive Lyapunov exponents. Existence of a positive Lyapunov exponent means sensitive dependence on initial conditions and As2Te3(In) is known to have memory effects hence different initial conditions for each dc current measurement. Detrended Fluctuation Analysis was utilized to characterize the behavior of dc current time series which is invariant to initial conditions. Detrended Fluctuation Analysis identified three different conduction regimes with multiple conduction mechanisms.
关键词： Weak chaotic systems,Conduction mechanisms,Time Series Analysis,Detrended Fluctuation Analysis,Scaling exponent
更新于2025-09-10 09:29:36
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[IEEE 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Budapest (2018.7.1-2018.7.5)] 2018 IEEE 2nd International Conference on Dielectrics (ICD) - High Voltage Electrical Properties of Epoxy / h-BN Microcomposites
摘要： Two high voltage properties – DC conductivity and AC breakdown strength – of epoxy composites filled with 30 wt% of micron sized hexagonal boron nitride (h-BN) are discussed in comparison to neat epoxy. The influence of h-BN upon the field dependence of DC conductivity has been studied up to 18 kV/mm. The addition of h-BN does not lead to a modification of conduction mechanisms: the J-V characteristics show an ohmic behavior at low fields and a space charge limited current (SCLC) at higher fields for both neat epoxy and composite. However, the addition of 30 wt% h-BN reduces the overall electrical conductivity and increases the threshold voltage between ohmic and SCLC regions, leading to a significant modification of electrical conductivity within the field range compared to neat epoxy. AC breakdown strength is enhanced for epoxy – h-BN composites while generally speaking the addition of micro fillers in an epoxy matrix tends to decrease it.
关键词： DC conductivity,electrical conduction mechanisms,epoxy composites,hexagonal boron nitride,AC breakdown strength
更新于2025-09-09 09:28:46