Free Volumes Associated with Sintering in Gadolinium Doped Ceria Solid Solutions

Gadolinium-doped ceria (GDC) solid solution prepared by the oxalate coprecipitation method is investigated by X-ray diffraction (XRD), complex impedance analysis, and positron lifetime spectroscopy. XRD reveals an expansion of GDC lattice constant by doping gadolinium into a ceria host crystal, in agreement with an oxygen vacancy model. The ionic conductivity of GDC measured at 773 K in air is two orders of magnitude higher than that of undoped ceria. Positron lifetime spectroscopy reveals the presence of vacancy-sized free volumes and nanovoids in interfaces among crystallites. It is found that the vacancy-sized free volumes shrink with increasing sintering temperatures. In the present paper, recent advances in the studies of GDC by XRD, complex impedance measurement, and positron lifetime spectroscopy are reviewed to gain an insight into the sintering mechanism.

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Synthesis, Structure and Electrical Properties of Pr-Doped Apatite-Type Lanthanum Silicates

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1094.155 ◽

2015 ◽

Vol 1094 ◽

pp. 155-159

Author(s):

Li Peng Tian ◽

Zhi Hua Ren

Keyword(s):

Electrical Properties ◽

Sol Gel ◽

Complex Impedance ◽

Impedance Analysis ◽

Total Conductivity ◽

X Ray Diffraction ◽

Complex Impedance Analysis ◽

Sol Gel Process ◽

Lanthanum Silicates ◽

Apatite Type

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.

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An intensive study on the AC impedance mechanism of (AgPO3)1-x(Ag2SO4)x ionic glass systems under various conditions

World Journal of Engineering ◽

10.1108/wje-01-2019-0001 ◽

2019 ◽

Vol 16 (4) ◽

pp. 477-486

Author(s):

Atif Alkhazali ◽

Morad Etier ◽

Mohammad Aljarrah ◽

Akram Alsukker ◽

Fathy Salman

Keyword(s):

Complex Impedance ◽

Entropy Change ◽

Impedance Analysis ◽

Cole Plot ◽

X Ray Diffraction ◽

Content Type ◽

Activation Free Energy ◽

Complex Impedance Analysis ◽

Different Temperatures ◽

Increasing Temperature

Purpose The purpose of this study is to investigate the effect of the considerable Ag2SO4 content on the electrical and dielectric properties of (AgPO3)1−x(Ag2SO4)x ion glass system as well as to extract thermodynamic parameters. Design/methodology/approach Glass samples of (AgPO3)1-x(Ag2SO4)x with different mole ratios of Ag2SO4 [x = 0.00, 0.10,0.15,0.20 and 0.25] have been synthesized and used. X-ray diffraction and differential thermal analysis were used to investigate structural and thermal properties, and then the electrical characterizations of the bulk glasses were performed in different frequency and temperature range. Findings For different ratios of Ag2SO4 on AgPO3, the bulk conductivity is enhanced with increasing the amount of Ag2SO4 until the composition of x = 0.20, after which the conductivity decreases. The general behavior of both ε’ and ε” decreases with increasing frequency and increases with increasing temperature. Complex impedance analysis studied by Z‘−Z’ and Cole–Cole plot at different temperatures revealed that bulk resistance decreases with temperature. Originality/value The calculated values of activation free energy, enthalpy and entropy change for different compositions of (AgPO3)1-x(Ag2SO4)x showed an increase in activation energy and enthalpy when Ag2SO4 ratio is increased in (AgPO3)1-x(Ag2SO4)x composition up to 20%, and then there is a decrease in their values at x = 25%, which may be explained based on non-bridging oxygen.

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Dielectric, ferroelectrics properties and impedance spectroscopy analysis of the [(Na0.535K0.480)0.966Li0.058](Nb0.90Ta0.10)O3-based lead-free ceramics

Journal of Advanced Dielectrics ◽

10.1142/s2010135x15500071 ◽

2015 ◽

Vol 05 (01) ◽

pp. 1550007 ◽

Cited By ~ 2

Author(s):

M. Saidi ◽

A. Chaouchi ◽

S. D'Astorg ◽

M. Rguiti ◽

C. Courtois

Keyword(s):

Complex Impedance ◽

Negative Temperature ◽

Impedance Analysis ◽

Xrd Analysis ◽

Ac Impedance ◽

Nyquist Plot ◽

X Ray Diffraction ◽

Complex Impedance Analysis ◽

Lead Free Ceramics ◽

Different Temperatures

Polycrystalline of [( Na 0.535 K 0.480)0.966 Li 0.058] (Nb 0.90 Ta 0.10) O 3 samples were prepared using the high-temperature solid-state reaction technique. X-ray diffraction (XRD) analysis indicates the formation of a single-phase with orthorhombic structure. AC impedance plots were used as tool to analyze the electrical behavior of the sample as a function of frequency at different temperatures. The AC impedance studies revealed the presence of grain effect, from 425°C onwards. Complex impedance analysis indicated non-Debye type dielectric relaxation. The Nyquist plot showed the negative temperature coefficient of resistance (NTCR) characteristic of NKLNT. The AC conductivity results were used to correlate with the barrier hopping (CBH) model to evaluate the binding energy (Wm), the minimum hopping distance (R min ), the density of states at Fermi level (N(Ef)), and the activation energy of the compound.

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Electrical properties of Y-type hexaferrite

Journal of Advanced Dielectrics ◽

10.1142/s2010135x18500224 ◽

2018 ◽

Vol 08 (03) ◽

pp. 1850022 ◽

Cited By ~ 1

Author(s):

Bibhuti B. Sahu ◽

S. K. Patri ◽

Banarji Behera ◽

B. Maharana

Keyword(s):

Electrical Properties ◽

Complex Impedance ◽

Polycrystalline Sample ◽

Impedance Analysis ◽

Rhombohedral Structure ◽

X Ray Diffraction ◽

Temperature Dependent ◽

Solid State Reaction Technique ◽

Complex Impedance Analysis ◽

Bulk Effect

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.

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TiO2 Nanoparticles Thin Film Prepared by Electrostatic Spray Deposition Technique for Humidity-Sensing Device

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1131.153 ◽

2015 ◽

Vol 1131 ◽

pp. 153-156 ◽

Cited By ~ 1

Author(s):

Direklit Chantarawong ◽

Korakot Onlaor ◽

Thutiyaporn Thiwawong ◽

Benchapol Tunhoo

Keyword(s):

Thin Film ◽

Thin Films ◽

Spray Deposition ◽

Complex Impedance ◽

Impedance Analysis ◽

Deposition Technique ◽

X Ray Diffraction ◽

Electrostatic Spray Deposition ◽

Complex Impedance Analysis ◽

Electrostatic Spray

Titanium dioxide (TiO2) nanoparticles thin films were prepared by electrostatic spray deposition technique. The effect of the deposition times on properties of TiO2 films was investigated. The characteristics of TiO2 thin films were performed by X-ray diffraction, and Raman spectroscopy. In addition, the TiO2 nanoparticles thin film was deposited onto the interdigited electrodes to fabricate the humidity sensor device. The humidity adsorption and desorption properties of the sensor were studies. The sensing mechanism of the humidity device can be explained by complex impedance analysis.

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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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