Dielectric behavior and complex impedance analysis of Ti-doped Mg0.5Cu0.5Mn0.4Fe1.6O4 ferrites

The multiferroic magnetoelectric materials have gained intensive research interest in the recent years due to their prospective applications. In this perspective, the thermally tunable complex impedance, dielectric behavior and room-temperature magnetoelectric coupling of xCo[Formula: see text]Ni[Formula: see text]Fe2O4–(1 - x)PbZr[Formula: see text]Ti[Formula: see text]O3 (x = 0.2, 0.3 and 0.5) nanocomposites have been investigated. A series of samples have been prepared by chemical pyrophoric reaction process. The structural characterization confirms the coexistence of two different types of phases, there is no phase segregation. The temperature-controlled complex impedance analysis reveals that grain boundaries and grain of the nanocomposites are playing a dominating role. The existence of Maxwell–Wagner interfacial polarization of the nanocomposites causes a high dielectric constant at low frequency. The calculated AC conductivity values with frequency at different temperatures follow the Jonscher’s power-law. A small polaronic hopping contributes largely to the conduction process of the decorated composite. The magnetostriction properties lead to the AC and DC magnetic field-dependent magnetoelectric coupling of the nanocomposites. The magnetoelectric coupling coefficient depends on the concentration of the piezomagnetic phase of the composites.

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Grain boundary effects in NTC-PTC composite thermistor materials

Journal of Materials Research ◽

10.1557/jmr.1999.0019 ◽

1999 ◽

Vol 14 (1) ◽

pp. 120-123 ◽

Cited By ~ 10

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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Upshot of Concentration of Zirconium (IV) Oxynitrate Hexa Hydrate on Preparation and Analyses of Zirconium Oxide (ZrO2) Nanoparticles by Modified Co-Precipitation Method

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2021.19488 ◽

2021 ◽

Vol 21 (11) ◽

pp. 5707-5713

Author(s):

M. Ramachandran ◽

R. Subadevi ◽

P. Rajkumar ◽

R. Muthupradeepa ◽

R. Yuvakkumar ◽

...

Keyword(s):

Ionic Conductivity ◽

Complex Impedance ◽

Impedance Analysis ◽

Raw Material ◽

Precipitation Method ◽

Zro2 Nanoparticles ◽

Fixed Amount ◽

Complex Impedance Analysis ◽

Dta Analysis ◽

Co Precipitation

In the present work, pure nanocrystalline monoclinic Zirconia (ZrO2) has been successfully synthesized and optimized by the modified co-precipitation method. The concentration of raw material has been optimized with the fixed amount of precipitation agent (Potassium hydroxide KOH). The thermal history of the precursor has been examined through TG/DTA analysis. All the samples are subjected to study the structure, fingerprints of the molecular vibrations, and morphology analyses. The representative sample has been analyzed through Transmission Electron Microscope (TEM) and X-ray Photo Electron Spectroscopy (XPS) analyses. The as-prepared sample exhibits the better crystallinity and surface morphology with lesser particle size (190 nm) when the raw material concentration is 0.2 M. The as-prepared ZrO2 filler (0, 3, 6, 9, and 12 wt.%) is spread through the enhanced polymer electrolyte P(S-MMA) (27 Wt.%)-LiClO4 (8 wt.%)-EC + PC (1;1 of 65 wt.%) complex system via solution casting method. The as-synthesized electrolyte films are examined via complex impedance analysis. P(S-MMA) (27 wt.%)-LiCIO4 (8 wt.%)-EC + PC (1 ;1 of 65 wt.%)-6 wt.% of ZrO2 shows the high ionic conductivity 2.35 × 10–3 Scm–1. Temperature-dependent ionic conductivity studies obey the non-linear behavior. The enhanced ZrO2 has been expected to enhance the other electrochemical properties of the lithium secondary battery.

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The effects of calcination and doping on structural and dielectric properties of CaCu3-xCoxTi4O12 ceramic

Mediterranean Journal of Chemistry ◽

10.13171/10.13171/mjc8319052011nh ◽

2019 ◽

Vol 8 (3) ◽

pp. 234

Author(s):

Nasr Hadi ◽

Tajdine Lamcharfi ◽

Farid Abdi ◽

Nor-Said Echtoui ◽

Ahmed Harrach ◽

...

Keyword(s):

Dielectric Constant ◽

Dielectric Properties ◽

Complex Impedance ◽

Impedance Analysis ◽

Xrd Analysis ◽

Secondary Phases ◽

Solid State Method ◽

Complex Impedance Analysis ◽

Oxide Powders ◽

Increasing Temperature

The influences of calcination temperature and doping with cobalt in A–site on structural and dielectric properties of CaCu3-xCoxTi4O12 (CCCxTO, x = 0.00, 0.02 and 0.10) ceramics sintered at 1050 0C for 8h were investigated. The ceramic samples are prepared by the conventional solid-state method using high purity oxide powders, and they are calcined at 850 °C, 950 °C and 1050 0C for 4h. The X-ray diffraction (XRD) analysis of pure and doped CCTO samples calcined at 950 °C and 1050 0C showed no traces of any other secondary phases, while impurity phases alongside CCTO phase in the x=0.00 sample calcined at 850 0C was observed. Scanning electron microscopy (SEM) investigation showed an increase in grain size with increasing of Co content and calcining temperature. Dielectric measurements indicated that the dielectric constant of the pure CCTO calcined at 1050 0C/4h has a low value in the frequency range of 1kHz up to 1MHz, whereas the substitution of Co up to x = 0.10 into CCTO caused a huge increase in the dielectric constant value of the calcined samples which is equal to 153419 and 18957 at 950 °C and 1050 0C respectively. The complex impedance analysis of all samples shows a decrease in resistance with an increasing temperature, which suggests a semiconductor nature of the samples.

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