HIGH DIELECTRIC CONSTANT AND NONLINEAR ELECTRIC RESPONSE IN Bi2Sr2SmCu2Oy

1996 ◽  
Vol 10 (27) ◽  
pp. 1365-1377 ◽  
Author(s):  
M. CHANDRA SEKHAR ◽  
B. GOPALA KRISHNA ◽  
M. MAHESH KUMAR ◽  
S.V. SURYANARAYANA
Keyword(s):  
Dielectric Constant ◽  
Temperature Region ◽  
Localization Length ◽  
Solid State Reaction Method ◽  
Physical Parameters ◽  
Nominal Composition ◽  
Electric Response ◽  
Metallic Behavior ◽  
High Dielectric ◽  
Semiconducting Behavior

Samples with the nominal composition Bi 2 Sr 2 SmCu 2 O y were prepared by solid state reaction method. From the room temperature X-ray diffraction data, it was found that the sample is similar to the Bi-2212 structure. DC electrical resistivity was done from 80 K to 573 K and the impedance measurements were performed from 80 K to 573 K at different frequencies in the range of 10 kHz to 800 kHz. The sample Bi 2 Sr 2 SmCu 2O y has exhibited semiconducting behavior in the low temperature region (80 K to 343 K), metallic behavior in the temperature range of 343 K to 443 K and again semiconducting behavior above 443 K. The sample has exhibited the phenomenon of variable rangehopping mechanism (VRH). The physical parameters related to VRH such as localization length (a), hopping distance (R) and hopping energy (W) have been evaluated and discussed. The activation energy in the high temperature region (above 300 K) decreases with increasing frequency. Tan δ increases with increase in temperature (303 K-573 K), which is attributed to increased conductivity. The dielectric constant increases with increase in temperature. For a given temperature the value of ε is found to decrease with increase in frequency.

Microstructure and Electrical Properties of CeO2-Doped WO3 Ceramics Prepared by Nanopowders

2007 ◽  
Vol 280-283 ◽  
pp. 381-384
Author(s):  
Xin Sheng Yang ◽  
Yu Wang ◽  
Liang Dong
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Constant ◽  
Electrical Properties ◽  
High Dielectric Constant ◽  
Raw Materials ◽  
Nonlinear Coefficient ◽  
Metallic Behavior ◽  
High Dielectric ◽  
Increasing Temperature ◽  
Semiconducting Behavior

CeO2-doped WO3 ceramics were fabricated by using nanometer WO3 and CeO2 powders as raw materials. The microstructure and electrical properties were studied. The ceramics have relatively low breakdown voltage and high dielectric constant. The nonlinear coefficient does not decrease with the increase of the ambient temperature. The electrical conductivity decreases with increasing temperature, indicating that the ceramics have metallic behavior instead of semiconducting behavior.

scholarly journals Nb Substitution Effects on Superconducting Properties ofRu1−xNbxSr2Eu1.4Ce0.6Cu2O10−δ

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
J. L. Maldonado-Mejía ◽  
J. D. Quiz-Celestino ◽  
M. E. Botello-Zubiate ◽  
S. A. Palomares-Sánchez ◽  
J. A. Matutes-Aquino
Keyword(s):  
Solid State Reaction Method ◽  
Substitution Effects ◽  
Superconducting Transition ◽  
Metallic Behavior ◽  
Resistivity Measurements ◽  
Niobium Doping ◽  
Method Substitution ◽  
Insight Into ◽  
Semiconducting Behavior

In order to gain further insight into the role of substitution of Ru by Nb on superconductivity, polycrystalline samples of Ru1−xNbxSr2Eu1.4Ce0.6Cu2O10−δ  (0.0 ≤x≤ 1.0) have been synthesized by solid-state reaction method. Substitution of Nb at the Ru site in the system takes place isostructurally in the tetragonal structure (space groupI4/mmm) with full solubility (x= 1.0). Superconductivity exists for all compositions. Resistivity measurements in function of temperature from 0 to 300 K were done using the four-probe technique. It is found that the substitution of Ru5+for Nb5+depresses the superconductivity of samples fromTc = 29 K forx= 0.0 toTc = 5 K forx= 1.0 (whereTcis the critical temperature, when resistivity becomes equal to zero). In the normal state, the dependence of resistivity with temperature, for compositions withx = 0.0 and 0.2, shows a metallic behavior, while for compositions betweenx= 0.4 andx= 1 it shows a semiconducting behavior. In that way, the density of charge carriers is reduced with niobium doping, leading to the semiconducting behavior. The resistive transition to the superconducting state of all samples is found to be affected by granularity. Samples undergo double superconducting transition.

High dielectric constant and nonlinear electric response in nonmetallicYBa2Cu3O6+δ

1992 ◽  
Vol 45 (18) ◽  
pp. 10639-10646 ◽  
Author(s):  
C. M. Rey ◽  
H. Mathias ◽  
L. R. Testardi ◽  
S. Skirius
Keyword(s):  
Dielectric Constant ◽  
High Dielectric Constant ◽  
Electric Response ◽  
High Dielectric

Preparation and Microwave Dielectric Properties of xBaZn2Ti4O11-(1-x)BaNd2Ti4O12 Ceramics

2017 ◽  
Vol 726 ◽  
pp. 210-214
Author(s):  
Xu Wang ◽  
Ren Li Fu ◽  
Yue Xu ◽  
Yang Yang ◽  
Jun De Cai ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Microwave Dielectric Properties ◽  
Solid State Reaction Method ◽  
Phase System ◽  
Microwave Ceramics ◽  
Two Phase ◽  
Microwave Dielectric ◽  
X Band ◽  
High Dielectric

xBaZn2Ti4O11–(1-x)BaNd2Ti4O12 (x = 0.18–0.30) ceramics were prepared by solid-state reaction method and their microwave dielectric properties were investigated with the purpose of finding a microwave ceramics with high dielectric constant (εr), high quality factor (Q×f ) and zero temperature coefficient of resonant frequency (τf).The two phase system BaZn2Ti4O11–BaNd2Ti4O12 affected the unit cell volume and the microstructure, the microwave dielectric properties (εr, Q×f, τf). As increasing x from 0.18 to 0.30, the main phase composition was BaNd2Ti4O12. Therefore, the εr decreased from 64.9 to 60.3 and the Q×f values raised from 11,350GHz to 13,210GHz, and the τf values decreased from 7ppm/° to -5ppm/°.The 0.22BaZn2Ti4O11–0.78BaNd2Ti4O12 ceramics sintered at 1250°C for 4 h displayed the best dielectric constant εr,Q×f and τf, as 63.9, 12380 GHz and-0.1 ppm/° respectively.

Dielectric Behavior and Impedance Spectroscopy of Bi2Sr2GdCu2Oy

2003 ◽  
Vol 17 (21) ◽  
pp. 3847-3856 ◽  
Author(s):  
M. Chandrasekhar
Keyword(s):  
Activation Energy ◽  
Temperature Region ◽  
Ac Conductivity ◽  
Room Temperature ◽  
Complex Impedance ◽  
Frequency Dispersion ◽  
Solid State Reaction Method ◽  
Dielectric Behavior ◽  
Nominal Composition ◽  
Present System

Samples with the nominal composition Bi 2 Sr 2 GdCu 2 O y in Bi -2212 where Gd replaces Ca as well as samples without Gd were prepared by solid-state reaction method. From the room temperature X-ray diffraction data, the samples were found to be similar to the single phase Bi -2212 structure. Impedance studies were performed from room temperature to 423 K at different frequencies in the range of 10 to 700 KHz. The AC conductivity increases with temperature and frequency, exhibiting frequency dispersion at low temperature region. The activation energy from AC conductivity in the high temperature region is found to be 0.432 eV. The permitivity increases with the increase in temperature and at 373 K it shows a maximum value exhibiting a dielectric loss. Complex impedance spectra are analyzed in terms of bulk relaxation and interfacial effects. The activation energy of the dipoles involved in the relaxation was estimated to be 0.482 eV. The universal power law of Jonscher is verified in the present system.

Dielectric Properties of Li2CO3 Doped Nio Measured at High Frequency

2015 ◽  
Vol 1087 ◽  
pp. 246-250
Author(s):  
C.T. Ping ◽  
Sharifah Aishah Syed Salim ◽  
Julie Juliewatty Mohamed ◽  
Zainal Arifin Ahmad
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
High Frequency ◽  
Single Phase ◽  
High Dielectric Constant ◽  
Lithium Carbonate ◽  
Solid State Reaction Method ◽  
High Dielectric Loss ◽  
High Dielectric ◽  
Single Phase Formation

NiO-based ceramic has shown high dielectric constant with 103-105, as well as high dielectric loss. Previous studies showed that doping with monovalent cations can cause a considerable decrease in dielectric loss. In this research, the effect of Lithium carbonate (Li2CO3) dopant on NiO was investigated. The electroceramic of LixNi1-xO were prepared by using solid state reaction method. The mixture of Li+ and NiO were ball milled for 24 hours. The samples were calcined at 800oC for 6 hours, pressed into pellet shape at 750 MPa and sintered at 1200°C for 10 hours. The sintered pellets were subjected to XRD, SEM, density testing and Impedance analyzer. XRD result shows the single phase formation of LixNi1-xO. The grain becomes larger with the increament of Li+ mole %. The dielectric constant of LixNi1-xO decrease with the increasing frequency. The highest dielectric constant was observed in x= 0.03 with 5210 at frequency range of 1GHz to 1MHz.

scholarly journals The influence of the partially europium substitution on the AC electrical properties of BiSr2CaCu2O6.5 ceramics

2019 ◽  
Vol 13 (4) ◽  
pp. 323-332 ◽  
Author(s):  
Zeynep Özdemir ◽  
Mehmet Kılıç ◽  
Yaşar Karabul ◽  
Seda Erdönmez ◽  
Orhan İçelli
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
High Dielectric Constant ◽  
Earth Metal ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Low Dielectric ◽  
Fourier Transformed Infrared Spectroscopy ◽  
High Dielectric

In this work, EuxBi1-xSr2CaCu2O6.5 (where x = 0, 0.3, 0.5) samples were prepared by solid-state reaction method and sintered at 950?C for 24 h. The structural characterizations were done by X-ray diffraction, X-ray fluorescence, scanning electron microscope and Fourier transformed infrared spectroscopy. The thermal stability of the samples was also analysed by thermogravimetric TG and DTA measurements. It was shown that Eu0.5Bi0.5Sr2CaCu2O6.5 sample exhibited high dielectric constant and low dielectric loss relative to BiSr2CaCu2O6.5 material. Thus, the dielectric loss was lowered by heavy rare earth metal substitution on Bi-Sr-Ca-Cu-O ceramics while the dielectric constant still remained high. Temperature-dependent complex electrical modulus spectra obtained between 296 and 433K also revealed the temperature-activated relaxation process in the materials which can be attributed to the Maxwell-Wagner type polarization effect. Ultimately, it was suggested that the Eu0.5Bi0.5Sr2CaCu2O6.5 ceramics may have a promising potential for applications which require high dielectric constant with a low dielectric loss.

scholarly journals Effect of Average Ionic Radius of A-site, B-site in Ba0.85X0.15TiO3, BaY0.15Ti 0.85O3 Systems Respectively (X = Pb, Ca, Co), (Y = Zr, Mn, Si) as a Perovskite Structure Ceramics (ABO3) on Crystal Structure, Curie Temperature

2021 ◽  
Author(s):  
Jasim Yaseen
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Barium Titanate ◽  
Curie Temperature ◽  
Ionic Radius ◽  
Structural Parameters ◽  
Solid State Reaction Method ◽  
Average Ionic Radius ◽  
High Dielectric ◽  
A Site

Abstract Barium titanate BaTiO3 is one of the most ferroelectrics. Its commonly used in capacitors due to its high dielectric constant. In this study, our goal is to determine the extent to which the change in the average ionic radius of A, B sites affects the structural, dielectric properties of this ceramic. In this study, barium titanate (Ba0.85X0.15TiO3, BaY0.15Ti0.85O3) (X = Pb, Ca, Co, Y= Zr, Si, Mn) was prepared by solid state reaction method in which the calcination temperature was 1200 °C for 2 hours. Structural characterization and dielectric properties were determined and calculated by using x-ray diffractometer, RCL-Meter (PM6303) at frequency 20 Hz using different temperature respectively. The results of the work showed that the average ionic radius at the A, B sites plays a large and clear role in determining the values of the dielectric constant and Curie temperature in perovskites in addition to the structural parameters.

High Dielectric Constant and Variable Range Hopping in Bi2Sr2YCu2Oy

1997 ◽  
Vol 11 (16n17) ◽  
pp. 727-738 ◽  
Author(s):  
M. Chandra Sekhar ◽  
B. Gopala Krishna ◽  
M. Maheshkumar ◽  
S. V. Suryanarayana
Keyword(s):  
Dielectric Constant ◽  
Single Phase ◽  
High Dielectric Constant ◽  
Solid State Reaction Method ◽  
Variable Range Hopping ◽  
Conductivity Measurements ◽  
Variable Range ◽  
Temperature Range ◽  
High Dielectric ◽  
Very High

The sample Bi2Sr2YCu2O y prepared by solid state reaction method showed a single phase Bi-2212. DC resistivity measured in the temperature range 77.5–300 K showed M–I like transition. AC conductivity measurements were performed in the temperature range 80–473 K at different frequencies. The conduction is by Mott's Variable Range Hopping. Various parameters pertaining to the conduction process are evaluated. The value of dielectric constant ε increases with temperature and shows a very high value. For a given temperature the value is found to decrease with increase in frequency.

Microstructural characterization of YBaCuO Films on LaAlO3 substrates

1989 ◽  
Vol 47 ◽  
pp. 180-181
Author(s):  
E. L. Hall ◽  
A. Mogro-Campero ◽  
N. Lewis ◽  
L. G. Turner
Keyword(s):  
Dielectric Constant ◽  
Single Crystal ◽  
Film Growth ◽  
Microstructural Characterization ◽  
Lattice Parameter ◽  
Film Plane ◽  
Substrate Material ◽  
High Loss ◽  
Amorphous Substrates ◽  
High Dielectric

There have been a large number of recent studies of the growth of Y-Ba-Cu-O thin films, and these studies have employed a variety of substrates and growth techniques. To date, the highest values of Tc and Jc have been found for films grown by sputtering or coevaporation on single-crystal SrTiO3 substrates, which produces a uniaxially-aligned film with the YBa2Cu3Ox c-axis normal to the film plane. Multilayer growth of films on the same substrate produces a triaxially-aligned film (regions of the film have their c-axis parallel to each of the three substrate <100> directions) with lower values of Jc. Growth of films on a variety of other polycrystalline or amorphous substrates produces randomly-oriented polycrystalline films with low Jc. Although single-crystal SrTiO3 thus produces the best results, this substrate material has a number of undesireable characteristics relative to electronic applications, including very high dielectric constant and a high loss tangent at microwave frequencies. Recently, Simon et al. have shown that LaAlO3 could be used as a substrate for YBaCuO film growth. This substrate is essentially a cubic perovskite with a lattice parameter of 0.3792nm (it has a slight rhombohedral distortion at room temperature) and this material exhibits much lower dielectric constant and microwave loss tangents than SrTiO3. It is also interesting from a film growth standpoint since it has a slightly smaller lattice parameter than YBa2Cu3Ox (a=0.382nm, b=c/3=0.389nm), while SrTiO3 is slightly larger (a=0.3905nm).

Sign in / Sign up

Export Citation Format

Share Document