Electrical Properties in Large Frequency and Temperature Ranges of Sr0.6Ca0.4TiO3 Ceramics

2020 ◽  
Vol 13 (3) ◽  
pp. 201-210
Keyword(s):  
Dielectric Permittivity ◽  
High Temperatures ◽  
Complex Impedance ◽  
Impedance Measurement ◽  
Conductivity Measurement ◽  
Calcium Titanate ◽  
Lead Free ◽  
Dielectric Losses ◽  
Low Frequencies ◽  
Wide Range

Abstract: Lead-free Sr0.6Ca0.4TiO3 (SCT) ceramic was prepared by the solid state reaction route. X-Ray diffraction technique showed the phase purity and identified the orthorhombic perovskite structure of the material. Scanning Electronic Microscopy observation evidenced homogeneous morphology and dense microstructure for the ceramic. The dielectric and conductivity properties of the sample were studied using complex impedance measurement technique in a wide range of frequencies and temperatures: from 100 Hz to 1.8 GHz and from 25°C to 550°C. The ceramic exhibits a stable dielectric permittivity and low dielectric losses in frequency and temperature up to 200°C. This is very interesting in view of developing high-quality lead-free ceramic capacitors for applications requiring high temperatures; for example, in cars. The increase in dielectric permittivity for temperatures higher than 200°C may be related to oxygen vacancies that are heat-activated in the material. Dielectric losses show the existence of a dielectric relaxation at low temperatures and low frequencies. Conductivity measurement investigated at high temperatures show on one hand high AC conductivity values attributed to the high temperature jumping process and on the other hand two electrical conductivity mechanisms above 400° C in the material. Keywords: Strontium calcium titanate, Ceramic, Structure, Dielectric properties, Conductivity.

Relaxation mechanism and conductivity studies of lead-free ceramics: Fe1/2(NaLi)1/4TiO3

2020 ◽  
Vol 34 (06) ◽  
pp. 2050081
Author(s):  
Subrat Kumar Barik ◽  
A. R. Atique Ulla
Keyword(s):  
Complex Impedance ◽  
Negative Temperature ◽  
Relaxation Mechanism ◽  
Lead Free ◽  
X Ray Diffraction ◽  
Prepared Sample ◽  
Lead Free Ceramics ◽  
Wide Range ◽  
Different Temperatures ◽  
Energy Formula

A single-phase lead-free ferroelectric compound, Fe[Formula: see text](NaLi)[Formula: see text]TiO3, is found at room temperature. The solid state reaction technique helps to process the sample at the calcination and sintering temperatures of 900 and 950[Formula: see text][Formula: see text]C for 4 h respectively. The desired phase and crystal structure formation of the prepared sample are confirmed by analysis of X-ray diffraction (XRD) data and are found to be in orthorhombic structure. The correlation among phase formation and physical properties has been established by using complex impedance spectroscopy (CIS) method over a wide range of frequencies (from 100 Hz to 1 MHz) and different temperatures (25–280[Formula: see text][Formula: see text]C). The overlap depressed semicircular arcs represent the association of grain and grain boundary effects in the material. Activation energy [Formula: see text] is noted to be 1 eV for the prepared sample. The frequency dependent ac conductivity is followed by Jonscher’s universal power law. DC conductivity versus temperature graph also indicates the negative temperature coefficient of resistance (NTCR) behavior of the material.

Complex Impedance Measurement System for the Frequency Range from 5 kHz to 100 kHz

2015 ◽  
Vol 644 ◽  
pp. 133-136 ◽  
Author(s):  
Mitar Simić
Keyword(s):  
Measurement System ◽  
Integrated Circuit ◽  
Complex Impedance ◽  
Impedance Measurement ◽  
Wide Range ◽  
Measurement Results ◽  
Improved Design ◽  
Sd Card ◽  
Complex Impedance Measurement ◽  
Line Analysis

The improved design of previously developed complex impedance measurement system is described. Realized system for measurement of complex impedance is based on integrated circuit AD5933 which is controlled by microcontroller ATmega128. Device has full standalone capabilities with LCD for displaying of results and keyboard for configuration on the field. Created report with measured values of impedance magnitude and phase angle is stored on micro SD card in format compatible with MS Excel which ensures easy off-line analysis on PC. Realized device is equipped with self-calibration system which ensures high accuracy in wide range of impedance and frequency. In the aim of the verification of developed system, the measurement results are plotted and compared with theoretical impedance values. Realized system can be used for complex impedance measurement, impedance spectrometry, biomedical and automotive sensors, proximity sensors, FFT processing, structural health monitoring, etc.

scholarly journals A Study on the Dielectric Behaviour of Epoxy/Hafnium Oxide Nanopowder Composites

2011 ◽  
Vol 20 (5) ◽  
pp. 096369351102000 ◽  
Author(s):  
S.N. Georga
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Permittivity ◽  
High Temperatures ◽  
High Frequency ◽  
Dielectric Response ◽  
Hafnium Oxide ◽  
Filler Concentration ◽  
High Frequency Range ◽  
Frequency Range ◽  
Low Frequencies

The dielectric response of 10 and 15phr epoxy/HfO2 nanocomposite systems has been studied in a wide frequency and temperature range. The experimental results show an enhancement of the dielectric permittivity with increasing filler concentration. The dielectric spectra reveal the presence of α-relaxation and a weak MWS effect. In the high frequency range the real part of the electrical conductivity obeys the Universal Dielectric Response (UDR), whereas at low frequencies and high temperatures DC conductivity is observed. VFT (Vogel-Fulcher-Tamann) parameters are calculated for all measured specimens.

scholarly journals Very Low Resource Digital Implementation of Bioimpedance Analysis

Sensors ◽  
2019 ◽  
Vol 19 (15) ◽  
pp. 3381 ◽  
Author(s):  
Fabien Soulier ◽  
Achraf Lamlih ◽  
Vincent Kerzérho ◽  
Serge Bernard ◽  
Tristan Rouyer
Keyword(s):  
Integrated Circuit ◽  
Complex Analysis ◽  
Complex Impedance ◽  
Impedance Measurement ◽  
Biological Tissues ◽  
Frequency Range ◽  
Digital Implementation ◽  
Analysis Algorithm ◽  
Low Resource ◽  
Wide Range

Bioimpedance spectroscopy consists of measuring the complex impedance of biological tissues over a large frequency domain. This method is particularly convenient for physiological studies or health monitoring systems. For a wide range of applications, devices need to be portable, wearable or even implantable. Next generation of bioimpedance sensing systems thus require to be implemented with power and resource savings in mind. Impedance measurement methods are divided into two main categories. Some are based on “single-tone” signals while the others use “multi-tone” signals. The firsts benefit from a very simple analysis that may consist of synchronous demodulation. However, due to necessary frequency sweep, the total measurement may take a long time. On the other hand, generating a multi-frequency signal allows the seconds to cover the whole frequency range simultaneously. This is at the cost of a more complex analysis algorithm. This makes both approaches hardly suitable for embedded applications. In this paper, we propose an intermediate approach that combines the speed of multi-tone systems with a low-resource analysis algorithm. This results in a minimal implementation using only adders and synchronous adc. For optimal performances, this small footprint digital processing can be synthesized and embedded on a mixed-mode integrated circuit together with the analog front-end. Moreover, the proposed implementation is easily scalable to fit an arbitrary frequency range. We also show that the resulting impact on noise sensitivity can be mitigated.

Anomalous Broad Dielectric Dispersion of 0.4PZN-0.3PSN-0.3PZN Relaxor Ceramics at Lower Temperatures

2006 ◽  
Vol 514-516 ◽  
pp. 216-220
Author(s):  
Juras Banys ◽  
Jan Macutkevic ◽  
Algirdas Brilingas ◽  
Vytautas Samulionis ◽  
K. Bormanis ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
Bias Field ◽  
Dielectric Dispersion ◽  
Dielectric Losses ◽  
Low Frequencies ◽  
External Bias ◽  
Very High ◽  
Maximum Permittivity

Dielectric properties of 0.4PbZn1/3Nb2/3O3-0.3PbSc1/2Nb1/2O3-0.3PbMg1/3Nb2/3O3- (0.4PZN- 0.3PSN-0.3PMN) ceramics are presented for 200 < T < 500 K and 20 Hz < ν < 1 MHz. Dielectric constant is very high (more 14000) in the vicinity of the peak. Anomalous broad dielectric relaxation have been observed near the temperature of the maximum permittivity, Tm (at 1 kHz). External bias field considerably lowers the value of dielectric losses at low frequencies due to decrease of polar nano regions contribution to the dielectric permittivity.

scholarly journals Study of Phase Transition in Bi3TiNbO9-BaBi2Nb2O9 Ceramics

2016 ◽  
Vol 61 (3) ◽  
pp. 1503-1510 ◽  
Author(s):  
M. Adamczyk ◽  
J. Kusz ◽  
W. Hofmeister ◽  
M. Zubko ◽  
L. Kozielski ◽  
...  
Keyword(s):  
Phase Transition ◽  
Grain Size ◽  
Dielectric Permittivity ◽  
Layer Structure ◽  
Lead Free ◽  
Maximum Value ◽  
Average Grain Size ◽  
Wide Range ◽  
The Subject ◽  
And Shifts

Abstract The subject of the paper is lead free bismuth layer structure oxides (1-x)Bi3TiNbO9-xBaBi2Nb2O9 (x=0; 1; 2; 3 mol). The influence of Bi3TiNbO9/BaBi2Nb2O9 ratio on dielectric and structural properties was studied in a wide range of temperatures. Change in the ratio causes a decrease in the maximum value of dielectric permittivity and shifts the temperature of ε’max to low values, leading to linear decreasing of average grain size and linear increasing of ceramics density. These results indicate an augment of the packing degree and the participation of pores are significantly decreased with the increase of BaBi2Nb2O9 compound intake. Moreover, for 0.7Bi3TiNbO9-0.3BaBi2Nb2O9 ceramics the dielectric phase transition is broadened and the properties characteristic for the ferroelectric relaxor appear.

scholarly journals Extending In-Plane Impedance Measurements from 2D to 3D Cultures: Design Considerations

2021 ◽  
Vol 8 (1) ◽  
pp. 11
Author(s):  
Sorel E. De Leon ◽  
Lana Cleuren ◽  
Zay Yar Oo ◽  
Paul R. Stoddart ◽  
Sally L. McArthur
Keyword(s):  
Three Dimensional ◽  
3D Culture ◽  
Collagen Gel ◽  
Impedance Measurement ◽  
Impedance Spectrum ◽  
3D Models ◽  
Low Frequencies ◽  
3D Cell Cultures ◽  
3D Collagen ◽  
2D And 3D

Three-dimensional (3D) cell cultures have recently emerged as tools for biologically modelling the human body. As 3D models make their way into laboratories there is a need to develop characterisation techniques that are sensitive enough to monitor the cells in real time and without the need for chemical labels. Impedance spectroscopy has been shown to address both of these challenges, but there has been little research into the full impedance spectrum and how the different components of the system affect the impedance signal. Here we investigate the impedance of human fibroblast cells in 2D and 3D collagen gel cultures across a broad range of frequencies (10 Hz to 5 MHz) using a commercial well with in-plane electrodes. At low frequencies in both 2D and 3D models it was observed that protein adsorption influences the magnitude of the impedance for the cell-free samples. This effect was eliminated once cells were introduced to the systems. Cell proliferation could be monitored in 2D at intermediate frequencies (30 kHz). However, the in-plane electrodes were unable to detect any changes in the impedance at any frequency when the cells were cultured in the 3D collagen gel. The results suggest that in designing impedance measurement devices, both the nature and distribution of the cells within the 3D culture as well as the architecture of the electrodes are key variables.

Study of Method for Determination of Thermal Conductivity of Automotive Interior Materials

2014 ◽  
Vol 526 ◽  
pp. 46-51
Author(s):  
Li Xiong Zhang ◽  
Rong Gang Gao
Keyword(s):  
Thermal Conductivity ◽  
Conductivity Measurement ◽  
Transient Heat Conduction ◽  
Traditional Theory ◽  
Infinite Plane ◽  
Plane Source ◽  
Transient Plane Source ◽  
Wide Range ◽  
Automotive Interior

Based on the traditional theory of transient plane source for thermal conductivity measurement, this paper designed and developed a new pattern of heating and temperature sensing probe, presented the study of transient heat conduction of half-infinite plane while being heated, established a modified mathematical model of transient plane source method, and achieved the measurement of thermal conductivity of automotive interior material sample by the data processing method of mathematical iteration and liner regression using the modified transient plane source probe. According to the data of experiments, the instrument which this paper designed has a high precision of 5% and a wide range of 0.003-1W/(mK).This paper provides a practicable way for heat capacity determination of automotive interior materials.

scholarly journals Deformation of Ordered Mesoporous Silica Structures on Exposure to High Temperatures

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
John B. Lowe ◽  
Richard T. Baker
Keyword(s):  
Mesoporous Silica ◽  
Pore Structure ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Ordered Mesoporous Silica ◽  
Large Cage ◽  
Pore Structures ◽  
Ordered Mesoporous ◽  
Pore Size Distributions ◽  
Wide Range

Ordered mesoporous silica materials are of interest for a wide range of applications. In many of these, elevated temperatures are used either in the preparation of the material or during its use. Therefore, an understanding of the effect of high temperature treatments on these materials is desirable. In this work, a detailed structural study is performed on silicas with three representative pore structures: a 2-D hexagonal pore arrangement (SBA-15), a continuous 3D cubic bimodal pore structure (KIT-6), and a 3D large cage pore structure (FDU-12). Each silica is studied as prepared and after treatment at a series of temperatures between 300 and 900°C. Pore structures are imaged using Transmission Electron Microscopy. This technique is used in conjunction with Small-Angle X-ray Diffraction, gas physisorption, and29Si solid state Nuclear Magnetic Resonance. Using these techniques, the pore size distributions, the unit cell dimensions of the mesoporous structures, and the relative occupancy of the distinct chemical environments of Si within them are cross correlated for the three silicas and their evolution with treatment temperature is elucidated. The physical and chemical properties before, during, and after collapse of these structures at high temperatures are described as are the differences in behavior between the three silica structures.

Dielectric Behavior of Mechano-chemically Synthesized [(CH3NH3)3Bi2Br9]: A Lead Free Hybrid Perovskite

2021 ◽  
Author(s):  
Swagatalaxmi Pujaru ◽  
Priyabrata Sadhukhan ◽  
Basudev Ghosh ◽  
Arup Dhara ◽  
Sachindranath Das
Keyword(s):  
Impedance Spectroscopy ◽  
Complex Impedance ◽  
Negative Temperature ◽  
Dielectric Behavior ◽  
Lead Free ◽  
Published Data ◽  
Temperature Dependent ◽  
Microstructural Parameters ◽  
Hybrid Perovskite ◽  
Refinement Method

Abstract Lead free hybrid halide perovskite (CH3NH3)3Bi2Br9 has been successfully synthesized by mechano-chemical method. The microstructure analysis by Rietveld’s refinement method revealed that the crystal belongs to trigonal system with space group P3 ̅m1. The obtained microstructural parameters are well in agreement with the previously published data. Temperature-dependent ac conductivity, impedance spectroscopy, and complex dielectric properties have been investigated in detail. The negative temperature coefficient of resistance behaviour reveals the semiconducting nature of the materials. The complex impedance spectroscopy also supports the semiconducting nature of the sample with activation energy for conduction ~0.38 eV.

Sign in / Sign up

Export Citation Format

Share Document