Electronic Parameters of Diode Based Organometallic Semiconductor Dyes Centered Ruthenium Complexes with Active COOH Terminals

In this study, the ruthenium complexes, which is an organometallic N-3 and C-106 semiconductor material, was coated on indium tin oxide (ITO) by using the self-assembled technique and thus a diode containing an organometallic interface was produced. The effects of this interface on the electronic parameters of the diode were investigated. It is aimed to improve the heterogeneity problem of the inorganic/organic interface by chemically bonding these materials from COOH active parts to the ITO surface. In order to understand how the electronic parameters of the diode change with this modification, the Schottky diode electrical characterization approach has been used. The charge mobility of the diode was calculated using the current density-voltage curve (J–V) characteristic with Space Charge Limited Current (SCLC) technique. When the electrical field is applied to the diode, it can be said that the ruthenium complexes molecules create an electrical dipole and the tunneling current is transferred to the anode contact ITO through the ruthenium molecule through the charge carrier, thus contributing to the hole injection. The morphology of these interface modifications was examined by Atomic Force Microscope (AFM) and surface potential energy by KelvinProbe Force Microscope (KPFM). To investigate local conductivity of bare ITO and modified ITO surface, Scanning Spreading Resistance Microscopy (SSRM) that is a conductive AFM analyzing technique were performed by applying voltage to the conductive tip and to the sample. According to the results of this work the diode containing N-3 material shows the best performance in terms of charge injection to the ITO due to possess the lowest barrier height Φb as 0.43 eV.

Piezoelectric Nonlinearity and Hysteresis Arising from Dynamics of Electrically Conducting Domain Walls

Macroscopic nonlinearity and hysteresis observed in the piezoelectric and dielectric responses of ferroelectric materials to external stimuli are commonly attributed to localized displacements of domain walls (DWs). The link between the macroscopic response and microscopic DW dynamics is provided by the well-known Rayleigh relations, extensively used to quantify the electrical and electromechanical behavior of ferroelectric ceramics and thin films under subswitching conditions. In this chapter, I will present an intriguing case where DWs exhibit enhanced electrical conductivity with respect to the bulk conductivity. By combining experimental data and modeling, it will be shown that the local conductivity, related to accumulation of charged points defect at DWs, does not only affect DW dynamics through DW-defect pinning interactions, as we may expect, but goes beyond it by affecting the macroscopic nonlinearity and hysteresis in a more complex manner. The major characteristics and implications of the underlying nonlinear Maxwell-Wagner piezoelectric relaxation, triggered by the presence and dynamics of conducting DWs, will be presented, reviewed and discussed in the framework of systematic multiscale analyses on BiFeO3 ceramics. The result may have implications in the development of promising BiFeO3-based compositions for high-temperature piezoelectric applications.

HYBRID 3D PRINTER FOR LAYER-BY-LAYER FORMATION OF STRUCTURES WITH CONDUCTIVE TOPOLOGY

The paper presents the main characteristics and functionality of a hybrid 3D-printer created at the Institute of Automation and Electrometry SB RAS, containing a portal recording system with dispenser heads for digital inkjet printing and a laser scanning system for subsequent post-processing with precise alignment software. The formation zone is located on a mobile platform moving along the Z coordinate. This design makes it possible, by layer-by-layer additive synthesis, to form three-dimensional structures with given local conductivity.

Исследование диэлектрического отклика, проводимости и тока термостимулированной деполяризации в релаксорном сегнетоэлектрике PbNi-=SUB=-1/3-=/SUB=-Nb-=SUB=-2/3-=/SUB=-O-=SUB=-3-=/SUB=-

This paper presents results of a study of temperature dependences of dielectric response and DC and AC - conductivity in single crystals of the relaxor ferroelectric PbNi1/3Nb2/3O3 (PNN) in a wide range of frequencies (10 Hz - 100 kHz) and temperatures (80 - 750 K). Anomalies in the dielectric response in the form of broad frequency-dependent maxima in the vicinity of 153 and 730 K are observed. The thermal activation character of DC conductivity has been obtained, and activation energies determined as Ea = 770 meV (T > 310 K) and Ea = 23 meV (T <310 K). The analysis of conductivity gives reason to assume the existence of local conductivity in the low-temperature region. It is shown that the conductivity character changes above 350 K from the local to the bulk one. Measurement by thermally stimulated depolarization has shown the presence of a residual polarization below 130 K.

Advanced Modelling Techniques for Resonator Based Dielectric and Semiconductor Materials Characterization

This article reports recent developments in modelling based on Finite Difference Time Domain (FDTD) and Finite Element Method (FEM) for dielectric resonator material measurement setups. In contrast to the methods of the dielectric resonator design, where analytical expansion into Bessel functions is used to solve the Maxwell equations, here the analytical information is used only to ensure the fixed angular variation of the fields, while in the longitudinal and radial direction space discretization is applied, that reduced the problem to 2D. Moreover, when the discretization is performed in time domain, full-wave electromagnetic solvers can be directly coupled to semiconductor drift-diffusion solvers to better understand and predict the behavior of the resonator with semiconductor-based samples. Herein, FDTD and frequency domain FEM approaches are applied to the modelling of dielectric samples and validated against the measurements within the 0.3% margin dictated by the IEC norm. Then a coupled in-house developed multiphysics time-domain FEM solver is employed in order to take the local conductivity changes under electromagnetic illumination into account. New methodologies are thereby demonstrated that open the way to new applications of the dielectric resonator measurements.

Quantitative evaluation of electrical conductivity inside stress corrosion crack with electromagnetic NDE methods

This paper presents a comparison of studies on the local distributed electrical conductivity in stress corrosion crack (SCC) from signals of eddy current testing (ECT) and direct current potential drop (DCPD) aiming to improve SCC sizing accuracy when using electromagnetic non-destructive testing (NDT) methods. Experimental setups of ECT and DCPD were established, respectively, to collect measurement signals due to artificial SCCs in a plate of austenitic stainless steel. The local conductivity in the SCC region was reconstructed from the feature parameters extracted from the measured ECT and DCPD signals through inverse analyses. The inversion strategies for ECT and DCPD, each including an efficient forward simulation and an optimization scheme, were introduced from the viewpoint of conductivity reconstruction. Inversion results obtained from the measured ECT and DCPD signals showed the consistent trend which proved the validity of the predicted electrical conductivity indirectly. It is clarified that the electrical conductivity in a SCC is relatively high at the crack tip area and may become as high as 17% of that of the base material. These results provide a good reference to enhance the sizing accuracy of SCC with an electromagnetic NDT method such as ECT by updating the conductive crack model based on the results of this work. This article is part of the theme issue ‘Advanced electromagnetic non-destructive evaluation and smart monitoring’.

Feasibility of in vivo Magnetic Induction Tomography in Rabbits

Background: As a non-contact, non-invasive medical imaging technique, magnetic induction tomography (MIT) can measure the conductivity distribution inside the human body. Numerical calculation and physical phantom tests have showed the accuracy of MIT in principle. However, very few human studies have limited the development and application. At the key stage before clinical trials, animal experiment will be an effective method to verify the feasibility of in vivo detection the conductivity variation inside of biological body. Methods: An abdominal subcutaneous injection rabbit model was used to simulate the local conductivity perturbation by injecting a 0.9% NaCl solution along with in vitro heparinized blood step by step. An insulated and sliding operation console was built to carry out the animal tests. An improved 16-channel MIT data acquisition system was used to record the data at 13.56 MHz and 4 seconds per frame. A series of time-difference reconstructed images, relative to non-injection, were obtained by the regularized Newton-Raphson algorithm for every 3 mL of injection. Results: 15 rabbits were divided by two groups. Six rabbits were injected with 0.9% NaCl solution and nine rabbits were injected with the in vitro heparinized blood. The target with an increased conductivity distribution can clearly be observed in all the reconstructed images. The maximum target value in each image increased with the injection dosage. The slopes of the regressive line for the mean of maximum target value in two groups were statistically different. Conclusion: Local conductivity perturbation inside of the rabbits is able to be reconstructed. The position and conductivity difference relative to the surrounding tissue of the target can be reflected correctly. This preliminary rabbit test shows the feasibility of the in vivo application for MIT and will be the basis for further animal tests and clinical trials in the future.