Conduction mechanism, impedance spectroscopic investigation and dielectric behavior of La0.5Ca0.5−xAgxMnO3 manganites with compositions below the concentration limit of silver solubility in perovskites (0 ≤ x ≤ 0.2)

2015 ◽  
Vol 44 (22) ◽  
pp. 10457-10466 ◽  
Author(s):  
H. Rahmouni ◽  
M. Smari ◽  
B. Cherif ◽  
E. Dhahri ◽  
K. Khirouni

This study presents the electrical properties, complex impedance analysis and dielectrical behavior of La0.5Ca0.5−xAgxMnO3 manganites.

2015 ◽  
Vol 1094 ◽  
pp. 155-159
Author(s):  
Li Peng Tian ◽  
Zhi Hua Ren

Apatite-type lanthanum silicates doped with Pr3+ at the La site, La10-xPrxSi6O27 (x = 0, 1, 2, 3, 4, 4.5), were synthesized via sol-gel process. Thermal behavior of the dried gel of La10-xPrxSi6O27 sample was studied using TG/DTA. X-ray diffraction, SEM and complex impedance analysis were used to investigate the microstructure and electrical properties of La10-xPrxSi6O27 ceramics. The XRD results indicated the maximum doping quantity of Pr3+ is x = 4.5. Lanthanum silicates doped with Pr3+ cations have a higher total conductivity than that of undoped lanthanum silicates. The enhanced total conductivity depends on the improved density of La10-xPrxSi6O27 (x = 0, 1, 2, 3, 4, 4.5). At 973K, the highest total conductivity is 1.36×10-3S.cm-1 for La9PrSi6O27 ceramic.


2021 ◽  
Vol 13 ◽  
Author(s):  
Jayanta Kumar Mishra ◽  
Khusboo Agrawal ◽  
Banarji Behera

Background: Since (1-x)[Pb(Mg1/3Nb2/3)O3]-(x)PbTiO3 (PMN-PT) ceramic has high dielectric constant and piezoelectric coefficient, it has been widely investigated for profound applications in electro-optical devices, sensors, multilayer capacitors and actuators. Objectives: The aim is to study the structural and electrical properties of 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (0.7PMN-0.3PT) ceramic to understand the biphasic structural nature using Rietveld Refinement. Also, it characterises on the basis of electrical properties such as impedance and modulus to understand the relaxation process, type of conduction process as well as the role of grain and grain boundary resistance in the material. Methods: 0.7PMN-0.3PT is synthesised by mixed oxide method using PbO, MgO, Nb2O5 and TiO2 as precursor materials. Results: The XRD data reveals the biphasic structure of tetragonal phase with the space group of P4mm and monoclinic phase with the space group of Pm. The complex impedance analysis clearly represents the effect of grain on the overall resistance and departs from normal Debye type behaviour. Also, the resistance is found to decrease with temperature, thereby confirming the semiconducting nature of the sample. The presence of long as well as short-range mobility of charge carriers is confirmed from the modulus and impedance analysis. The influence of long-range motion is observed at high temperature and of short-range motion at low temperatures. Conclusion: XRD analysis confirmed the biphasic structure of M+T phase. The frequency-dependent modulus and impedance spectroscopy show the presence of a relaxation effect in the ceramic which is found to increase with temperature. The Nyquist plot shows that the resistance is decreased with temperature, thereby confirming the NTCR behaviour in the studied sample.


2019 ◽  
Vol 33 (05) ◽  
pp. 1950022 ◽  
Author(s):  
Sarit Chakraborty ◽  
S. K. Mandal ◽  
B. Saha

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.


2018 ◽  
Vol 08 (03) ◽  
pp. 1850022 ◽  
Author(s):  
Bibhuti B. Sahu ◽  
S. K. Patri ◽  
Banarji Behera ◽  
B. Maharana

The polycrystalline sample of Ba2Mg2Fe[Formula: see text]O[Formula: see text] was prepared by solid-state reaction technique. Room-temperature X-ray diffraction (XRD) has confirmed the formation of rhombohedral structure. The electrical properties of the sample were studied in wide ranges of temperatures and frequencies. The impedance analysis indicates the presence of bulk effect. The bulk resistance of the material decreases with rise in temperature and exhibits NTCR behavior. This compound also exhibits the temperature-dependent non-Debye type of relaxation phenomena. The presence of non-Debye type of relaxation has been confirmed by the complex impedance analysis. The variation of DC conductivity (bulk) with temperature demonstrates that the compound exhibits Arrhenius type of electrical conductivity. The activation energy of the compound is found to be 0.55[Formula: see text]eV in high-temperature region.


2014 ◽  
Vol 88 (12) ◽  
pp. 1251-1256 ◽  
Author(s):  
F. Sallemi ◽  
M. Megdiche ◽  
B. Louati ◽  
K. Guidara

1999 ◽  
Vol 14 (1) ◽  
pp. 120-123 ◽  
Author(s):  
D. J. Wang ◽  
J. Qiu ◽  
Y. C. Guo ◽  
Z. L. Gui ◽  
L. T. Li

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.


2021 ◽  
Vol 21 (11) ◽  
pp. 5707-5713
Author(s):  
M. Ramachandran ◽  
R. Subadevi ◽  
P. Rajkumar ◽  
R. Muthupradeepa ◽  
R. Yuvakkumar ◽  
...  

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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