Nonlinear Electrical Properties Research Articles

Microstructure and Electrical Properties of Nd<sub>2</sub>O<sub>3</sub>-Doped TiO<sub>2</sub>-Ta<sub>2</sub>O<sub>5</sub>-Based Capacitor-Varistor Ceramics

A low-voltage TiO2 capacitor-varistor ceramics doped with Ta2O5 and Nd2O3 was systematically researched. The effect of Nd2O3 on the microstructure, nonlinear electrical properties, and dielectric properties of TiO2-based ceramics was investigated. It was found that an optimal doping composition of 99.20 mol% TiO2-0.10 mol%Ta2O5-0.7 mol% Nd2O3 was obtained with low breakdown voltage of 8.5 v/mm, high nonlinear constant of 4.0, ultrahigh electrical permittivity of 1.07× 105 and low tanδ of 0.39. In view of these electrical characteristics, the ceramics of 99.20 mol% TiO2-0.10 mol%Ta2O5-0.7 mol% Nd2O3 is a viable candidate for capacitor-varistor functional devices. The theory of defects in the crystal lattice was introduced to explain the nonlinear electrical behavior of the Nd2O3-doped TiO2-based varistor ceramics.

Structure and properties of polymer core-shell systems: Helium ion microscopy and electrical conductivity studies

Peculiarities of the structural organization and electrical properties of two core-shell polymer systems under different fabrication protocols have been studied with a combination of helium ion microscopy (HIM) and current-voltage characterization. The systems under study included a submicrometer core of a ferroelectric polymer polyvinylidene fluoride and a shell of intrinsically conducting or semiconducting polymer polyaniline (PANI) or poly(3-methylthiophene) (P3MT). Application of HIM allowed identification of the polymer components, visualization of the electrically conductive percolation network of PANI or P3MT, and its variation due to thermal annealing and/or interaction with the environment. HIM is proved to be a powerful tool for characterization of not only the morphology but also of the charge distribution and conductivity properties on the nanoscale. The specific contrast formation in HIM imaging is due to differences in local electrical conductivity of the components. The authors have demonstrated that the polymer core-shell systems under study can serve as a universal platform for development of nanostructured multifunctional materials. Specifically, it is shown that they can be used for preparation of conducting and semiconducting polymer films or layers having promising nonlinear electrical and sensor properties.

Linear and nonlinear electric properties of spatially confined LiH molecule, studied with the finite field method

The influence of spatial confinement on the electric properties: dipole moment ( μ), dipole polarizability ( α), first hyperpolarizability ( β) and second hyperpolarizability ( γ) of the LiH molecule was studied. The confining model potential is assumed in the form of a penetrable spherical box. The properties in question were calculated within the finite field approach, with an accurate, explicitly correlated wave function. We found all studied properties diminished under confinement.

Influence of Fe 2O 3 doping on microstructural and electrical properties of ZnO–Pr 6O 11 based varistor ceramic materials

The doping effect of Fe 2O 3 on the microstructural and electrical properties of ZnO–Pr 6O 11 based varistor ceramic materials was investigated. Fe 2O 3 doping would inhibit the growth of ZnO grains, whose average sizes were found to decrease from 3.0 to 2.7 μm with the doping level of Fe 2O 3 increased from 0 to 1 mol%. When the doping level of Fe 2O 3 was 0.005 mol%, the varistors exhibited the optimum nonlinear electrical characteristics with nonlinear coefficient of about 26, breakdown voltage of approximately 571 V/mm and leakage current of less than 65 μA. With higher doping level of Fe 2O 3, more Fe atoms would segregate at grain boundaries, providing more extra electrical carriers, decreasing the resistances of the grain boundaries, and PrFeO 3 would be formed, destroying the construction of grain boundaries. Therefore, the nonlinear electrical properties of the resultant varistor materials were deteriorated.

Rectification in three-terminal graphene junctions

Nonlinear electrical properties of graphene-based three-terminal nanojunctions are presented. Intrinsic rectification of voltage is observed up to room temperature. The sign and the efficiency of the rectification can be tuned by a gate. Changing the charge carrier type from holes to electrons results in a change in the rectification sign. At a bias <20 mV and at a temperature below 4.2 K the sign and the efficiency of the rectification are governed by universal conductance fluctuations.

Low‐Temperature Sintering and Electrical Properties of ZnO–Bi2O3–TiO2–Co2O3–MnCO3‐Based Varistor with Bi2O3–B2O3 Frit for Multilayer Chip Varistor Applications

The effects of a Bi2O3–B2O3 frit (denoted as BiBF) on the densification, phase transformation, microstructure, and nonlinear electrical properties of ZnO–Bi2O3–TiO2–Co2O3–MnCO3 (ZBTCM)‐based varistors have been investigated. The varistor ceramic with the addition of >2 wt% BiBF can be sintered at 900°C and 96.3% of the theoretical density was achieved. SEM revealed that the microstructure of the varistor ceramics with 2 wt% BiBF is uniform, with an average grain size of 13.5 μm. No porosity is observed. The typical ZnO–Bi2O3–TiO2‐based varistor phase compositions were detected for all varistor ceramics but the formation of a secondary phase, Bi4B2O9, became apparent when 4 wt% BiBF was added. The Bi4B2O9 phase crystallized from the Bi2O3–B2O3 frit, acting as a potential barrier at the grain boundary, increases the density of interface states Ns, barrier height Φb, and plays an important role in improving the electrical properties of the varistor ceramics. However, a large amount will be detrimental. Optimum properties were exhibited for the varistor ceramics with 2 wt% BiBF sintered at 900°C, with E1 mA=124.9 V/mm, α=46.2, and JL=0.2 μA/cm2. The reactivity of the varistor ceramic with Ag was also studied. The excellent electrical properties and low sintering temperature, coupled with chemical compatibility with Ag, suggest that Bi2O3–B2O3 frit sintering aids for ZnO–Bi2O3–TiO2–Co2O3–MnCO3 (ZBTCM)‐based varistors have great potential for using the base metal Ag as inner electrodes for low‐voltage MLV fabrication.

Nonlinear electrical transport via grain boundary tunneling in La-deficient compound La0.9Mn0.9Co0.1O3

Nonlinear electrical transport properties in La-deficient compound La0.9Mn0.9Co0.1O3 have been investigated as a function of temperature (T) and magnetic field (H). The experiment was carried out through temperature range 20–293 K and in magnetic field up to 5 kOe. The nonlinear electrical transport was studied in low temperature region below the paramagnetic to ferromagnetic transition temperature (TC) at 195 K. The analysis of current–voltage (I–V) characteristic shows that the transport through grain boundary (GB) is dominated by multi-step inelastic tunneling in low temperature. This transport is also effected by magnetic field. Zero bias conductance [G0=(dI/dV)V=0] is enhanced in the presence of magnetic field. The electrical transport properties have been interpreted in terms of tunneling through the GB region where substitution of Mn by Co introduces more disorder in GB.

Electrical Properties and Kinetic of Crystalline Grain Growth of Low-voltage ZnO Varistor Doped with Zn-B Glass

The effects of Zn-B glass additive on microstructure and electrical properties of low-voltage ZnO varistor were studied.The results show that ZnO varistor with x=0.1wt% obtains the optimal nonlinear electrical properties: E1mA=36.7V/mm,α=30.4,IL=0.1μA.The grain growth mechanism of low-voltage ZnO varistor doped with Zn-B glass is also investigated in terms of the phenomenological kinetic of crystalline grain growth.Based on the theory,the grain growth kinetic exponent n and apparent activation energy Q are calculated as 4.54 and 316.5kJ/mol for ZnO ceramics varistor sintered at the temperature below 1000℃.The grain growth mechanism is that non-melting Zn-B glass pins the ZnO grain boundaries,which inhibits the grain growth of ZnO varistor.However,n and Q value are 2.92 and 187kJ/mol at the temperature higher than 1000℃.It indicates that melting Zn-B glass wetting the ZnO grain boundaries creates a liquid phase sintering mechanism,which accelerates the grain growth of ZnO varistor.

Densification and grain growth of CuO-doped Pr 6O 11 varistors

The effect of CuO doping on the microstructure and electrical properties of Pr 6O 11 varistors was investigated. Samples were prepared by conventional ceramic techniques, and were sintered at 1150 °C in air for 2 h. The microstructure was investigated by scanning electron microscopy (SEM). The phases and chemical composition were analyzed by X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). The results indicated that CuO can promote the densification of the Pr 6O 11-based varistors to 95.8% of the theoretical density. CuO forms a solid solution with Pr 6O 11 up to 0.5 mol%, above which Pr 2CuO 4 precipitates in the grain boundary. From the I– V measurements, minor CuO doping can improve the nonlinear electrical properties. A further increase in CuO content induces a reduction in the nonlinear electrical properties due to the consumption of absorbed oxygen on the grain surfaces.

Interaction-induced electric properties and cooperative effects in model systems

A detailed analysis of the interaction-induced linear and non-linear axial static electric dipole properties and the interaction energy of the model HCHO(HF)(n) (n = 1, 2) complexes is carried out using the HF SCF, MP2, CCSD and CCSD(T) levels of approximation combined with a wide range of basis sets, namely the correlation-consistent basis sets of Dunning and co-workers, the polarization-consistent basis sets of Jensen, and the recently reported polarized LPol sets. The results of this study show that even the smallest among the LPol sets, the LPol-ds and LPol-dl sets, yield interaction induced axial static electric dipole properties of an accuracy comparable to that obtained with the aug-cc-pVQZ basis set. Using the LPol-ds, the LPol-dl, and the LPol-fl sets we have estimated the induced electric properties and the interaction energy of the HCHO(HF)(n) (n = 1-9) complexes, the cooperative effects in these systems, and the two-body effects. The many-body analysis shows that the two-body contributions to the induced first hyperpolarizability are not sufficient to correctly reproduce the general tendency for the changes in the property with the elongation of the polymer chain, since already for the n = 4 complex the more-than-two-body terms become dominant.

Influence of soaking time on nonlinear electrical behavior and dielectric properties of TiO2-based varistor ceramics

The influence of soaking time on the nonlinear electrical behavior and dielectric properties of TiO2-based varistor ceramics was investigated. Based on single sintering process, six disk samples of (Sr, Bi, Si, Ta)-doped TiO2-based varistor ceramics were fabricated by sintering at 1250 ℃ for 0.5−5.0 h. The samples were characterized by X-ray diffraction, voltage-current characteristics, energy spectra, metallographs, breakdown voltages, and apparent dielectric constant. It is found that the breakdown electrical field intensity at a current density of 10 mA/cm2 decreases from 5.5 to 4.1 V/mm first and then increases to 7.0 V/mm, the nonlinear coefficient increases from 2.39 to 2.62 first and then decreases to 2.42, and the apparent dielectric constant increases from 98 200 to 115 049 first and then decreases to 73 865 with the soaking time increasing from 0.5 to 5.0 h. These indicate that the optimal soaking time is 2.0−3.0 h considering both nonlinear electrical behavior and dielectric properties.

Preparation and varistor properties of new quaternary Zn–V–Mn–(La, Dy) ceramics

The La and Dy doping effects on microstructures, nonlinear electrical properties, and its stability of ZVM (Zn–V–Mn)-based ceramics were investigated. The microstructure of the quaternary ZVML (Zn–V–Mn–La)-based ceramics doped with La and quaternary ZVMD (Zn–V–Mn–Dy)-based ceramics doped with Dy commonly consisted of mainly ZnO grains and Zn 3(VO 4) 2 as a secondary phase. In addition, the quaternary ZVML- and ZVMD-based ceramics revealed the secondary phases, such as LaVO 4 and DyVO 4, respectively, in addition to Zn 3(VO 4) 2. It seems that all secondary phases act as a liquid-phase sintering aid because it has a significant effect on the sintered density and average grain size. The incorporation of La and Dy into the ZVM-based ceramics increased the breakdown field, and improved the nonlinear electrical properties, in which the nonlinear coefficient was close to 33. The ZVML-based ceramics exhibited the best stability, where the variation of breakdown field (%Δ E B) against DC accelerated aging stress is −9.7%.

Polarized basis sets for accurate calculations of static and dynamic electric properties of molecules

We report on the development and testing of large polarized basis sets (LPolX, where X is the element symbol) for accurate calculations of linear and nonlinear electric properties of molecules. The method used to generate LPolX sets is based on our studies of the analytic dependence of Gaussian functions on external time-independent and time-dependent electric fields. At variance with the earlier investigations of small, highly compact (ZPolX) basis sets for moderately accurate calculations of electric properties of large molecules, the present goal is to obtain basis sets that are nearly saturated with respect to the selected class of electric properties and can be used for accurate studies of interaction-induced properties. This saturation makes the LPolX sets also useful in calculations of optical properties for chiral molecules. In this article, the LPolX sets are generated for X = H, C, N, O, and F, and examined in calculations of linear and nonlinear electric properties of four standard test systems: HF, N(2), CO, and HCN. The study of the performance of LPolX basis sets has been carried out at different levels of approximation ranging from the SCF HF method to highly correlated CCSD(T) approach. The results obtained in this study compare favorably with accurate reference data and show a high level of saturation of LPolX basis sets with respect to the polarization effect due to external electric fields.

Effect of Nd<sub>2</sub>O<sub>3</sub> and Sm<sub>2</sub>O<sub>3</sub> on the Microstructure and Electrical Properties of WO<sub>3</sub> Capacitor-Varistor Ceramics

The effect of Nd2O3 and Sm2O3 on the microstructure, nonlinear electrical properties, and dielectric properties of WO3-based ceramics was investigated. The dopant Nd2O3 and Sm2O3 can promote the grain growth of WO3 grains. It was also found that Nd2O3 and Sm2O3 can reduce the breakdown voltages values of WO3-based ceramics effectively, but do not strongly influence the nonlinear values. The nonlinear coefficient of doped samples was 2-3 and the barrier voltage was very low with the value of 0.04-0.08 V. Through impedance analysis, it can be found that those rare earth ions have a great influence on the dielectric properties. The dielectric constant of doped samples was higher than that of undoped samples, and the high dielectric constant makes them suitable as capacitor-varistor materials. The theory of defects in the crystal lattice was introduced to explain the nonlinear electrical behavior of the WO3-based varistor ceramics.

Linear and Non-Linear Electrical Properties in Peptidergic Neurons of Crayfish Procambarus Clarkii and Cherax Quadricarinatus

Abstract This work presents a comparative study of the electrophysiological properties of the peptidergic neurons in crayfish Procambarus clarkii and Cherax quadricarinatus. Recordings were made in order to determine the linear and non-linear properties of electrical activity in these neurons. Charge curves were obtained in order to carry out measurements of the input resistance and the determination of the electrotonic length as part of the linear properties of these cells. Different recordings of the action potentials and the ionic currents are presented as part of their non-linear properties. The electrotonic length in P. clarkii was 0.8253 ± 0.1311 and 1.7616 ± 0.4726 in C. quadricarinatus. The input resistance in P. clarkii was 92.4 ± 23.2 MΩ and 56.46 ± 17.2 MΩ in C. quadricarinatus. Silent neurons were recorded (53% in P. clarkii and 60 % in C. quadricarinatus) as well as tonic neurons (35% and 28% in each species respectively) and neurons responding with action potential bursts (12% for both speci...

Analytic calculations of nonlinear mixed electric and magnetic frequency-dependent molecular properties using London atomic orbitals: Buckingham birefringence

We present the results of the first gauge-origin independent calculations, carried out at Hartree-Fock level, of the molecular parameters that describe the electric-field-induced linear birefringence, also known as Buckingham birefringence. Focus is in particular on the temperature-independent contribution to the observable. We employ a recently developed analytical scheme for calculating frequency-dependent molecular properties of arbitrary order for self-consistent field methods using basis sets that depend explicitly on the frequency and on the external perturbations. The method is applied to naphthalene, fluorobenzene and furan, three systems for which the Buckingham birefringence has been studied experimentally. It is demonstrated that LAOs lead to significant improvements in the basis set convergence of the temperature-independent contribution to the Buckingham birefringence, and that the results obtained on the basis of aug-cc-pVDZ quality London atomic orbital calculations are closer to the basis set limit than the results obtained on the basis of conventional aug-cc-pVQZ quality calculations. The computed values can be used to correct for the neglect of the temperature-independent higher-order contribution often implied in the derivation of the effective quadrupole moments from experimental measurements of the induced birefringence at a single temperature.

Nonlinear electrical properties and aging characteristics of (NiO, MgO, Cr2O3)-doped Zn-Pr-Co-R (R = Y, Er) oxide-based varistors

The electrical properties and stability of the varistors, which composed of (NiO, MgO, Cr2O3)-doped Zn-Pr-Co-R (Y, Er) oxide-based ceramics, were investigated for different additives. The breakdown voltage of the varistors increased in order of NiO→undoped→MgO→Cr2O3: 1200→1551→1691→1959 V/cm for ZPCY system and undoped→NiO→MgO→Cr2O3: 1024→1041→1500→1668 V/cm for ZPCE system, respectively. The nonlinear coefficient value increased in order of undoped→NiO→MgO→Cr2O3: 21→25→38→50 in ZPCY system and NiO→undoped→MgO→Cr2O3: 27→32→35→38 in ZPCE system, respectively. In ZPCY and ZPCE systems, the Cr2O3-additives most greatly improved the nonlinear properties. In Cr2O3-doped system, ZPCY system exhibited higher nonlinear properties than that of ZPCE system. The stability against d.c. accelerated aging stress was higher in Cr2O3-additives than in NiO- and MgO-additives for ZPCY system and was higher in NiO-additives than in MgO- and Cr2O3-additives for ZPCE system.

Memory effect in semiconductor gas discharge electronic devices

The memory effect in the planar semiconductor gas discharge system at different pressures (15–760 Torr) and interelectrode distances (60–445 µm) was experimentally studied. The study was performed on the basis of current–voltage characteristic (CVC) measurements with a time lag of several hours of afterglow periods. The influence of the active space charge remaining from the previous discharge on the breakdown voltage (UB) has been analysed using the CVC method for different conductivities of semiconductor GaAs photocathode. CVC showed that even a measurement taken 96 h after the first breakdown was influenced by accumulated active particles deposited from the previous discharge. Such phenomena based on metastable atoms surviving from the previous discharge and recombined on the cathode to create initial electrons in the avalanche mechanism are shown to be fully consistent with CVC data for both pre-breakdown and post-breakdown regions. However, in the post-breakdown region pronounced negative differential conductivity was observed. Such nonlinear electrical property of GaAs is attributed to the existence of deep electronic defect called EL2 in the semiconductor cathode material. On the other hand, the CVC data for subsequent dates present a correlation of memory effect and hysteresis behaviour. The explanation for such a relation is based on the influence of long lived active charges on the electronic transport mechanism of semiconductor material.

On the origin of the large electron correlation contribution to the hyperpolarizabilities of some diacetylene rare gas compounds

A comprehensive study of the linear and nonlinear molecular optical properties of HRgC(4)H, where Rg = Ar,Kr,Xe, has been performed. Dynamical electron correlation effects were computed by employing the coupled cluster methodology. A large electron correlation contribution to the nonlinear properties of HArC(4)H has been revealed. This contribution decreases by increasing the atomic number of the inserted rare gas atom. In order to interpret the origin of this noteworthy property, the complete active space self-consistent field method was employed. We have performed a systematic study of the linear and nonlinear electric properties by modifying the active space. The calculations have shown the significant contribution of the doubly excited sigma(*2) configuration and a negligible contribution of pi(*2). A quite remarkable discrepancy between numerically and analytically evaluated hyperpolarizabilities has also been observed for HArC(4)H. This was attributed to the contribution of near degenerate states.

Transport properties of three-terminal ballistic junctions realized by focused ion beam enhanced etching in InGaAs/InP

Three-terminal junction devices are realized in an InGaAs/InP quantum well by focused ion beam (FIB) implantation and selective wet etching. Room temperature electrical measurements show that the fabricated devices exhibit strong nonlinear electrical properties. The results are discussed in terms of ballistic electron transport. It is demonstrated that FIB-enhanced etching processing can be exploited as a maskless, resist-free technique for fabrication of high-quality and functional nanoelectronic devices.