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.

IMPEDANCE CHARACTERISTICS OF La3/2Bi3/2Fe5O12 CERAMICS

2009 ◽  
Vol 23 (26) ◽  
pp. 5179-5189
Author(s):  
K. JAWAHAR ◽  
BANARJI BEHERA ◽  
R. N. P. CHOUDHARY
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Solid State ◽  
Room Temperature ◽  
Complex Impedance ◽  
Conductivity Spectrum ◽  
High Temperature Region ◽  
Solid State Reaction Technique ◽  
Impedance Characteristics ◽  
Universal Power Law

Polycrystalline La 3/2 Bi 3/2 Fe 5 O 12 (LBIO) compound was prepared by a high-temperature solid-state reaction technique. The complex impedance of LBIO was measured over a wide temperature (i.e., room temperature to 500°C) and frequencies (i.e., 102–106 Hz) ranges. This study takes advantage of plotting ac data simultaneously in the form of impedance and modulus spectroscopic plots and obey non-Debye type of relaxation process. The Nyquist's plot showed the presence of grain effects in the material at high temperature. The ac conductivity spectrum was found to obey Jonscher's universal power law. The dc conductivity was found to increase with rise in temperature. The activation energy of the compound was found to be 0.24 and 0.51 eV in the low and high-temperature region, respectively, for conduction process.

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.

scholarly journals Structure, dielectric and electrical properties of relaxor lead-free double perovskite: Nd2NiMnO6

2019 ◽  
Vol 13 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Rutuparna Das ◽  
Ram Choudhary
Keyword(s):  
Ac Conductivity ◽  
Negative Temperature Coefficient ◽  
Complex Impedance ◽  
Double Perovskite ◽  
Negative Temperature ◽  
Solid State Reaction Method ◽  
Temperature Coefficient Of Resistance ◽  
X Ray ◽  
Impedance Data ◽  
Nyquist Plots

In this paper, dielectric relaxor, impedance, AC conductivity and electrical modulus of double perovskite Nd2NiMnO6, prepared by a solid state reaction method and sintered at 1250?C, have been reported in the wide temperature (25-150?C) and frequency (1 kHz-1MHz) ranges. From the preliminary X-ray structural analysis, it is found that the structure of the material is monoclinic. In the study of the temperature dependence of the dielectric constant, the relaxor behaviour of the material is observed. Such type of behaviour is explained by a modified Curie-Weiss and a Vogel-Fulcher law. By analysing Nyquist plots, the existence of grain and grain boundary effects is established. The non-Debye type of relaxation is investigated by the analysis of complex impedance and the modulus data. From the study of impedance data, it is found that the grain resistance is reduced with the increase in temperature indicating the existence of negative temperature coefficient of resistance (NTCR) behaviour in the material which also matches with temperature versus AC conductivity plots. From these results, it may be concluded that this compound may have extreme potential for different high temperature applications.

scholarly journals Nickel Manganite-Sodium Alginate Nano-Biocomposite for Temperature Sensing

Chemosensors ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 241
Author(s):  
Milena P. Dojcinovic ◽  
Zorka Z. Vasiljevic ◽  
Janez Kovac ◽  
Nenad B. Tadic ◽  
Maria Vesna Nikolic
Keyword(s):  
Activation Energy ◽  
Sodium Alginate ◽  
Room Temperature ◽  
Small Polaron ◽  
Spinel Phase ◽  
Sol Gel ◽  
Complex Impedance ◽  
Relaxation Frequency ◽  
Polaron Hopping ◽  
Ft Ir

Nanocrystalline nickel manganite (NiMn2O4) powder with a pure cubic spinel phase structure was synthesized via sol-gel combustion and characterized with XRD, FT-IR, XPS and SEM. The powder was mixed with sodium alginate gel to form a nano-biocomposite gel, dried at room temperature to form a thick film and characterized with FT-IR and SEM. DC resistance and AC impedance of sensor test structures obtained by drop casting the nano-biocomposite gel onto test interdigitated PdAg electrodes on an alumina substrate were measured in the temperature range of 20–50 °C at a constant relative humidity (RH) of 50% and at room temperature (25 °C) in the RH range of 40–90%. The material constant obtained from the measured decrease in resistance with temperature was determined to be 4523 K, while the temperature sensitivity at room temperature (25 °C) was −5.09%/K. Analysis of the complex impedance plots showed a dominant influence of grains. The decrease in complex impedance with increase in temperature confirmed the negative temperature coefficient effect. The grain resistance and grain relaxation frequency were determined using an equivalent circuit. The activation energy for conduction was determined as 0.45 eV from the temperature dependence of the grain resistance according to the small polaron hopping model, while the activation energy for relaxation was 0.43 eV determined from the Arrhenius dependence of the grain relaxation frequency on temperature.

Investigation of Structural and Dielectric Properties of Polycrystalline PbMg1∕3 Ti1∕3W1∕3O3 Tungsten Perovskite

SPIN ◽  
2020 ◽  
Vol 10 (03) ◽  
pp. 2050021
Author(s):  
P. Ganga Raju Achary ◽  
R. N. P. Choudhary ◽  
S. K. Parida
Keyword(s):  
Activation Energy ◽  
Conduction Mechanism ◽  
Complex Impedance ◽  
Interfacial Polarization ◽  
Average Crystallite Size ◽  
Solid State Reaction Method ◽  
Tetragonal Crystal ◽  
Average Grain Size ◽  
Temperature Ranges ◽  
Lead Magnesium

Lead magnesium tungsten titanate PbMg[Formula: see text] Ti[Formula: see text]W[Formula: see text]O3 was prepared by adopting a high-temperature solid-state reaction method. The sample has tetragonal crystal structure having average crystallite size 45.1325[Formula: see text]nm calculated using Scherer’s relation and the average grain size is about 40[Formula: see text]nm from Scanning Electron Microscope (SEM) measurement. Measurements of dielectric permittivity ([Formula: see text]) and loss ([Formula: see text]) have been investigated, both as a function of frequency (1[Formula: see text]kHz to 5[Formula: see text]MHz) and temperature (25–[Formula: see text]C) and the results showed the presence of interfacial polarization of the material. The dielectric spectra with frequency and temperature suggest that the prepared sample is semiconducting in nature following the NTCR behavior. The complex impedance results showed the contribution of grain and grain boundaries in the conduction mechanism. The activation energies were determined from the ac conductivity data in the temperature ranges of 200–[Formula: see text]C and 360–[Formula: see text]C. It has been observed that with the rise of frequency and temperature, the activation energy increases in the sample. The greater value of the activation energy always supports the conduction mechanism due to hopping of the charge carriers. The semicircular arcs of Cole–Cole plots confirm that the sample is semiconducting in nature which supports our dielectric results.

STUDIES OF STRUCTURAL AND ELECTRICAL BEHAVIOR OF SAMARIUM BARIUM TUNGSTATE CERAMICS

2011 ◽  
Vol 01 (04) ◽  
pp. 465-470 ◽  
Author(s):  
N. K. SINGH ◽  
PRITAM KUMAR ◽  
O. P. ROY ◽  
R. N. P. CHOUDHARY
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Temperature Region ◽  
Room Temperature ◽  
Pyrochlore Structure ◽  
Structure Type ◽  
High Temperature Region ◽  
Phase Compound ◽  
Barium Tungstate ◽  
Xrd Patterns

Polycrystalline samples of samarium barium tungstate [ Sm2(Ba0.5W0.5)2O7 : (SBW)] pyrochlore structure type oxides have been prepared by a solid-state reaction technique. X-ray diffraction (XRD) patterns of this compound at room temperature suggest the formation of a single phase compound with orthorhombic structure. Studies of the dielectric constant and dielectric loss of compound as a function of frequency (4 kHz–1 MHz) at room temperature, and as a function of temperature (23–350°C) at 20 and 50 kHz frequencies suggest that the compound does not have dielectric anomaly. The variation of dc resistivity suggests the semiconductor characteristics of the material. The value of activation energy (E a ~ 0.43 at 20 kHz and E a ~ 0.29 at 50 kHz) of the above mentioned compound has been calculated from the slope of the ln σac versus 1/T graph in the high temperature region (> 240°C). The low value of activation energy supports the superionic nature of the compounds in the high temperature region.

scholarly journals Spectroscopic analysis and temperature-dependent dielectric properties of bulk Ni–Zn ceramics

2019 ◽  
Vol 09 (02) ◽  
pp. 1950014
Author(s):  
Anand Yadav ◽  
Pankaj Choudhary ◽  
P. Saxena ◽  
V. N. Rai ◽  
A. Mishra
Keyword(s):  
Dielectric Constant ◽  
Ac Conductivity ◽  
Room Temperature ◽  
Lattice Structure ◽  
Dielectric Behavior ◽  
Tangent Loss ◽  
Temperature Dependent ◽  
Dielectric Parameters ◽  
Increase With Increase ◽  
Ion Substitution

In the present work, series of Zn ion-doped Ni[Formula: see text]ZnxFe2O4 ([Formula: see text]) ceramics were prepared by the double sintered solid-state reaction route to find out the influence of Zn[Formula: see text] ions on the crystal structure, lattice structure and dielectric behavior of parent NiFe2O4. X-ray diffraction (XRD) study favors that all the prepared compounds belong to the cubic spinel structure. Lattice parameters found to have increasing value with increased Zn[Formula: see text] ion substitution. The Raman scattering measurement discerns optical-active modes with blue shift as the doping increases. The dielectric constant ([Formula: see text] and dielectric tangent loss (tan [Formula: see text] decrease with an increase in frequency and at higher frequency, both become constant. Dielectric parameters observe nonlinear behavior with increasing Zn[Formula: see text] ion substitution. Room temperature dielectric constant of 10% Zn ion-doped NiFe2O4 [Ni[Formula: see text]Zn[Formula: see text]Fe2O4] is much higher as compared to other prepared ceramics. The room temperature ac conductivity is found to increase with increase in frequency and temperature-dependent ac conductivity increases with increase in temperature.

scholarly journals IMPEDANCE AND MODULUS SPECTROSCOPY CHARACTERIZATION OF SODIUM-BISMUTH TITANATE-BASED LEAD-FREE FERROELECTRIC MATERIALS

2012 ◽  
Vol 02 (01) ◽  
pp. 1250002 ◽  
Author(s):  
DHANANJAY K. SHARMA ◽  
RAJU KUMAR ◽  
RADHESHYAM RAI ◽  
SEEMA SHARMA ◽  
ANDREI L. KHOLKIN
Keyword(s):  
Bismuth Titanate ◽  
Complex Impedance ◽  
Polycrystalline Sample ◽  
Solid State Reaction Method ◽  
Dielectric Behavior ◽  
Ferroelectric Materials ◽  
Impedance Plot ◽  
Sodium Bismuth Titanate ◽  
Modulus Spectroscopy ◽  
Wide Range

In this paper, we present impedance spectroscopy of Sodium Bismuth Titanate-based materials belonging to (1-x) Na 1/2 Bi 1/2 TiO 3-x BaTiO 3(x = 0.04) (NBT–BT) system. NBT–BT ceramics are prepared by high temperature solid-state reaction method. X-ray diffraction technique showed single-phase polycrystalline sample with an ABO3 perovskite structure. Dielectric behavior and the impedance relaxation were investigated in a wide range of temperature (room temperature (RT) –500°C) and frequency (1 kHz–1 MHz). A broad dielectric constant peak was observed over a wide temperature range around the phase transition temperature. The complex impedance plot exhibited one impedance semicircle identified over the frequency range of 1 kHz–1 MHz, which is explained by the grain effect of the bulk. The centers of the impedance semicircles lie below the real axis, which indicates that the impedance response is a Cole–Cole type relaxation.

IMPEDANCE SPECTROSCOPIC STUDIES ON GdBi5Fe2Ti3O18 CERAMIC

2001 ◽  
Vol 15 (14) ◽  
pp. 2053-2065 ◽  
Author(s):  
N. V. PRASAD ◽  
G. PRASAD ◽  
T. BHIMASANKARAM ◽  
S. V. SURYANARAYANA ◽  
G. S. KUMAR
Keyword(s):  
Solid State ◽  
Room Temperature ◽  
Complex Impedance ◽  
Impedance Measurement ◽  
Solid State Reaction Method ◽  
Spectroscopic Studies ◽  
Conductivity Measurements ◽  
Frequency Range ◽  
Reaction Method ◽  
Complex Impedance Measurement

GdBi 5 Fe 2 Ti 3 O 18 (GBFT), a compound of Aurivillius family, was prepared by solid state reaction method. Complex impedance measurement was made on these samples from room temperature to 500°C in the frequency range of 1 kHz–1 MHz. Cole–Cole plots were found to become very broad near 400°C. Dielectric and dc conductivity measurements were made on these samples. The results are analysed to understand the conductivity mechanism.

Preparation, Structural, Optical, Electrical, and Magnetic Characterisation of Orthorhombic GdCr0.3Mn0.7O3 Multiferroic Nanoparticles

2017 ◽  
Vol 72 (1) ◽  
pp. 87-95
Author(s):  
Deepa Singh ◽  
K.K. Bamzai
Keyword(s):  
Activation Energy ◽  
Ac Conductivity ◽  
Room Temperature ◽  
Magnetic Behaviour ◽  
X Ray Diffraction ◽  
Orthorhombic Crystal ◽  
Sem Images ◽  
Chemical Route ◽  
Orthorhombic Crystal Structure ◽  
Universal Power Law

AbstractIn this article, chromium-doped gadolinium manganate (GdCr0.3Mn0.7O3) nanoparticles has been prepared by wet-chemical route in order to investigate their structural, optical, electrical, and room temperature magnetic properties. Microstructural and compositional analyses have been carried out by X-ray diffraction and scanning electron microscopy (SEM). Synthesised material is found to be in orthorhombic crystal structure with Pbnm space group. The spherical morphology of the nanoparticles has been examined from the SEM images. Functional groups have been identified using Fourier transform infrared spectroscopy. Dielectric constant, dielectric loss, AC conductivity (σac), and activation energy in the range of 1 kHz–1 MHz from room temperature to high temperature (400°C) have been investigated. The frequency dependence of AC conductivity obeys the universal power law. The value of activation energy depends on increase in frequency. Room temperature magnetic behaviour suggests the material to be paramagnetic in nature.

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