scholarly journals Effect of Microwave Sintering on Electrical Properties of Sr-deficient and Bi-rich Strontium Bismuth Niobate (Sr0.8Bi2.2Nb2O9) Ferroelectric Ceramic

2016 ◽  
Vol 1 (1) ◽  
pp. 35-45 ◽  
Author(s):  
RAJVEER SINGH ◽  
Vandna Luthra ◽  
Ram Pal Tandon
Keyword(s):  
Conduction Mechanism ◽  
Microwave Sintering ◽  
Complex Impedance ◽  
Negative Temperature ◽  
Ferroelectric Ceramic ◽  
Relaxation Mechanism ◽  
Bulk Resistance ◽  
Conventional Solid State Reaction ◽  
Debye Relaxation ◽  
Bismuth Niobate

Nonstoichiometric strontium bismuth niobate (Sr0.8Bi2.2Nb2O9: SBN) ceramic was prepared using conventional solid-state reaction and microwave sintering methods. Complex impedance spectroscopy (CIS) has been used to investigate the intra and intergranular contribution to the impedance SBN ceramics as a function of temperature and frequency. Complex impedance Cole‑Cole plots were used to interpret the relaxation mechanism in SBN ceramic which showed a non-Debye relaxation. The grain and grain boundary contribution to conductivity have been estimated from the Cole‑Cole plots. The bulk (grain) resistance of both samples was found to decrease with rise in temperature indicating negative temperature coefficient of resistance (NTCR) type behavior like that of semiconductors. The microwave sintered SBN was found to have low value of bulk resistance indicating more increase in conductivity as compared to conventionally sintered SBN. The temperature dependence of the relaxation time was found to obey the Arrhenius law. Studies of electrical modulus show the presence of hoping conduction mechanism in SBN.

scholarly journals Dielectric relaxation and modulus spectroscopy analysis of (Na0.47 K0.47 Li0.06) NbO3 ceramics

2017 ◽  
Vol 07 (03) ◽  
pp. 1750020 ◽  
Author(s):  
Md Kashif Shamim ◽  
Seema Sharma ◽  
Sangeeta Sinha ◽  
Eqra Nasreen
Keyword(s):  
Dielectric Relaxation ◽  
Spectroscopic Analysis ◽  
Microwave Sintering ◽  
Complex Impedance ◽  
Tungsten Bronze ◽  
Negative Temperature ◽  
Nyquist Plot ◽  
Orthorhombic Symmetry ◽  
Modulus Spectroscopy ◽  
C Complex

We have investigated the structure, dielectric and electrical properties of lead-free polycrystalline (Na[Formula: see text] K[Formula: see text] Li[Formula: see text]) NbO3 ceramics as a function of temperature and frequency in order to understand the intrinsic contribution of grain/bulk and grain boundary effects toward the dielectric response as well as the electrical conduction mechanism in the samples fabricated by microwave sintering method. X-ray diffraction analysis exhibits perovskite structure with orthorhombic symmetry, which is well supported by the Raman spectroscopic analysis. A minor secondary impurity phase of tungsten bronze structure was observed for samples sintered at 1050[Formula: see text]C, which gets weaker for samples sintered at 1150[Formula: see text]C. Dielectric permittivity was enhanced by 50%, although there was a reduction in the dielectric loss by about 50% at Curie temperature (450[Formula: see text]C) for samples sintered at 1150[Formula: see text]C. Complex impedance spectroscopic analysis indicated non-Debye-type dielectric relaxation present in the samples, and this phenomenon followed thermally activated process related to hopping mechanism. Nyquist plot showed the negative temperature coefficient of resistance, characteristic of the samples.

scholarly journals Dielectric and ac conductivity of ilmenite-type CdTiO3 ceramic

2019 ◽  
Vol 8 (3) ◽  
pp. 255
Author(s):  
Radouane Bahloul ◽  
Salaeddine Sayouri ◽  
TajEddine Lamcharfi
Keyword(s):  
Loss Tangent ◽  
Ac Conductivity ◽  
Conduction Mechanism ◽  
Sol Gel ◽  
Complex Impedance ◽  
Powder Sample ◽  
Hopping Conduction ◽  
Bulk Resistance ◽  
Tan Δ

<p class="Abstracttitle">Cadmium titanate CdTiO3 powder sample was prepared using the sol-gel route and calcined at 900°C. The dependence of the permittivity, loss tangent (tan δ) on the temperature in the range 40–600°C, and frequency in the range 103–2.106 Hz for the pure hexagonal ilmenite is reported. The ln(σac) versus T plots suggest that the conduction mechanism is of ionic hopping nature. The evolution of ln(σac) as a function of frequency suggests that the ionic hopping conduction decreases with the rise in temperature. The complex impedance plots revealed two depressed semicircular arcs indicating the bulk and interface contributions. The bulk resistance was found to increase with a decrease in temperature exhibiting typical semiconductor-like behavior.</p>

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.

scholarly journals Dielectric and ac conductivity of ilmenite-type CdTiO3 ceramic

2019 ◽  
Vol 8 (3) ◽  
pp. 255-260
Author(s):  
Radouane Bahloul ◽  
Salaeddine Sayouri ◽  
TajEddine Lamcharfi
Keyword(s):  
Loss Tangent ◽  
Ac Conductivity ◽  
Conduction Mechanism ◽  
Sol Gel ◽  
Complex Impedance ◽  
Powder Sample ◽  
Hopping Conduction ◽  
Bulk Resistance ◽  
Tan Δ

Cadmium titanate CdTiO3 powder sample was prepared using the sol-gel route and calcined at 900°C. The dependence of the permittivity, loss tangent (tan δ) on the temperature in the range 40–600°C, and frequency in the range 103–2.106 Hz for the pure hexagonal ilmenite is reported. The ln(σac) versus T plots suggest that the conduction mechanism is of ionic hopping nature. The evolution of ln(σac) as a function of frequency suggests that the ionic hopping conduction decreases with the rise in temperature. The complex impedance plots revealed two depressed semicircular arcs indicating the bulk and interface contributions. The bulk resistance was found to increase with a decrease in temperature exhibiting typical semiconductor-like behavior

scholarly journals Dielectric Relaxation and Hopping Conduction in La2NiO4+δ

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Woo-Hwan Jung
Keyword(s):  
Dielectric Relaxation ◽  
Ac Conductivity ◽  
Conduction Mechanism ◽  
Complex Impedance ◽  
Relaxation Property ◽  
Relaxation Mechanism ◽  
Angular Frequency ◽  
Limited Temperature ◽  
Electrical Data ◽  
Bulk Effect

An ac conductivity as well as dielectric relaxation property of La2NiO4.1 is reported in the temperature range of 77 K–130 K and in the frequency range of 20 Hz–1 MHz. Complex impedance plane plots show that the relaxation (conduction) mechanism in this material is purely a bulk effect arising from the semiconductive grain. The relaxation mechanism has been discussed in the frame of electric modulus spectra. The scaling behavior of the modulus suggests that the relaxation mechanism describes the same mechanism at various temperatures. The logarithmic angular frequency dependence of the loss peak is found to obey the Arrhenius law with the activation energy of ~0.09 eV. The frequency-dependent electrical data are also analyzed in the frame of ac conductivity formalism. The ac conductivity has been found to follow a power-law behavior at a limited temperature and frequency region where Anderson localization plays a significant role in the transport mechanism for La2NiO4.1.

Studies of relaxation mechanism and conductivity property of lead-free electronic material: Ba0.7Sr0.3TiO3

2019 ◽  
Vol 33 (29) ◽  
pp. 1950352
Author(s):  
Subrat Kumar Barik ◽  
Susmita Nath ◽  
Sugato Hajra ◽  
R. N. P. Choudhary
Keyword(s):  
Conduction Mechanism ◽  
Single Phase ◽  
Complex Impedance ◽  
Relaxation Mechanism ◽  
Nyquist Plot ◽  
X Ray Diffraction ◽  
Reaction Route ◽  
Conductivity Property ◽  
Universal Power Law ◽  
Phase Compound

The strontium-modified barium titanate [Formula: see text] ceramic was fabricated by high temperature compound reaction route. The pattern of X-ray diffraction confirms a single-phase compound with better crystallization. The dielectric properties (permittivity/loss) are investigated as a function of temperature and frequency. The relaxation mechanism and correlation with the physical properties are studied using complex impedance spectroscopy. The Nyquist plot shows the association of various effects (grain and grain boundary) by fitting electrical circuits at various temperature regions. This study tells the nature and conduction mechanism of the prepared sample. The Jonscher’s universal power law is being followed by the frequency-dependent ac conductivity.

scholarly journals Frequency and temperature dependence behaviour of impedance, modulus and conductivity of BaBi4Ti4O15 aurivillius ceramic

2014 ◽  
Vol 8 (3) ◽  
pp. 145-153 ◽  
Author(s):  
Tanmaya Badapanda ◽  
Ranjan Harichandan ◽  
Sudhasu Nayak ◽  
Avinna Mishra ◽  
Sahid Anwar
Keyword(s):  
Relaxation Times ◽  
Complex Impedance ◽  
Negative Temperature ◽  
Impedance Spectrum ◽  
Nyquist Plot ◽  
Dielectric Study ◽  
Complex Impedance Spectrum ◽  
Debye Relaxation ◽  
Positive Side ◽  
Different Temperatures

In this work, we report the dielectric, impedance, modulus and conductivity study of BaBi4Ti4O15 ceramic synthesized by solid state reaction. X-ray diffraction (XRD) pattern showed orthorhombic structure with space group A21am confirming it to be an m=4 member of the Aurivillius oxide. The frequency dependence dielectric study shows that the value of dielectric constant is high at lower frequencies and decreases with increase in frequency. Impedance spectroscopy analyses reveal a non-Debye relaxation phenomenon since relaxation frequency moves towards the positive side with increase in temperature. The shift in impedance peaks towards higher frequency side indicates conduction in material and favouring of the long rangemotion of mobile charge carriers. The Nyquist plot from complex impedance spectrum shows only one semicircular arc representing the grain effect in the electrical conduction. The modulus mechanism indicates the non-Debye type of conductivity relaxation in the material, which is supported by impedance data. Relaxation times extracted using imaginary part of complex impedance (Z??) and modulus (M??) were also found to follow Arrhenius law. The frequency dependent AC conductivity at different temperatures indicates that the conduction process is thermally activated. The variation of DC conductivity exhibits a negative temperature coefficient of resistance behaviour.

Growth, Structural, NLO and Impedance Properties of Cu2+ doped Lithium Sulphate Monohydrate Single Crystals

2021 ◽  
Author(s):  
A Annalakshmi ◽  
K. Balasubramanian
Keyword(s):  
Single Crystals ◽  
Complex Impedance ◽  
Relative Dielectric Constant ◽  
Relaxation Mechanism ◽  
Tangent Loss ◽  
Monoclinic Crystal ◽  
Debye Relaxation ◽  
Nlo Property ◽  
Lithium Sulphate ◽  
Evaporation Technique

Abstract Single crystals of 2.5 mole% of Cu 2+ doped Lithium sulphate monohydrate (LSMH) have been grown using slow evaporation technique at room temperature. Powder X-ray diffraction (PXRD) analysis ensures that the crystal belongs to monoclinic crystal system. The variation of relative dielectric constant, dielectric loss and tangent loss with frequency have been discussed. The conductivity and dielectric relaxation mechanism involved in the grown crystals have been carried out by using complex impedance spectroscopy in the temperature range (343K and 353K) and in the frequency range from 20Hz to 2MHz. The frequency dependent ac conductivity obeys the Jonscher’s power law. The imaginary part Mʺ of electrical modulus of grown crystals shows the formation of asymmetric dispersion peak and indicating non- Debye relaxation behaviour. Morphology properties of the grown crystals have been studied using atomic force microscopy and hence the roughness of the grown crystals has been calculated. The NLO property and LDT values of the grown crystals are analysed using Nd:YAG laser operating at 1064 nm and 532 nm respectively.

scholarly journals Phase Transition, Dielectric Relaxation and Impedance Spectroscopy of Perovskite xBa0.95Sr0.05Tio3-(1‒X)BiFe0.9Sm0.1O3 Ceramics

2020 ◽  
Vol 27 (1) ◽  
pp. 23-42
Author(s):  
MJ Miah ◽  
SC Mazumder ◽  
AKM Akther Hossain
Keyword(s):  
Conduction Mechanism ◽  
Negative Temperature Coefficient ◽  
Boundary Effect ◽  
Structural Phase ◽  
Complex Impedance ◽  
Negative Temperature ◽  
Cubic Phase ◽  
Structural Phase Transitions ◽  
Impedance Data ◽  
Grain Boundary Effect

Polycrystalline xBa0.95Sr0.05TiO3-(1‒x)BiFe0.9Sm0.1O3[xBST-(1‒x)BFSO] ceramics were synthesized. The structural phase transitions were studied and it was found that structure of the compound transformed from rhombohedral to cubic phase. The compound exhibited a dielectric anomaly in the vicinity of Néel temperature of BiFeO3 except for x = 0.25. Enhanced dielectric properties were noticed and this might be attributed to the reduction of oxygen vacancies. Studies of electrical conductivity over a wide temperature range showed that the ceramics behaved like a semiconductor with the negative temperature coefficient of resistance. Contribution of grains in conduction mechanism of the materials dominated and the grain resistance was found to be decreased with the increase in temperature. A Non-Debye type relaxation was seen in the material. The impedance data were re-plotted using the modulus formulae to avoid the ambiguity arising out of the presence of grain/grain boundary effect. Activation energy was found to be 0.18 to 0.33 eV in modulus study which was very close to complex impedance observation and it was implied that the charge carrier had the same energy barrier during the relaxation. Bangladesh Journal of Physics, 27(1), 23-42, June 2020

Grain boundary effects in NTC-PTC composite thermistor materials

1999 ◽  
Vol 14 (1) ◽  
pp. 120-123 ◽  
Author(s):  
D. J. Wang ◽  
J. Qiu ◽  
Y. C. Guo ◽  
Z. L. Gui ◽  
L. T. Li
Keyword(s):  
Energy Level ◽  
Grain Boundary ◽  
Boundary Effect ◽  
Complex Impedance ◽  
Negative Temperature ◽  
Impedance Analysis ◽  
Composite Effect ◽  
Complex Impedance Analysis ◽  
Temperature Coefficient Of Resistivity ◽  
Grain Boundary Effect

Yttrium-doped (Sr0.45Pb0.55)TiO3 ceramics have been studied by complex impedance analysis. As a sort of NTC-PTC composite thermistor, it exhibited a significantly large negative temperature coefficient of resistivity below Tc in addition to the ordinary PTC characteristics above Tc. It is found that the NTC effect in NTC-PTC materials was not originated from the deep energy level of donor (bulk behavior), but from the electrical behavior of the grain boundary. Therefore, the NTC-PTC composite effect was assumed to be a grain boundary effect, and yttrium was a donor at shallow energy level. The NTC-PTC ceramics were grain boundary controlled materials.

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