Oxygen vacancies induced variations in structural, optical and dielectric properties of SnO2/graphite nanocomposite

2021 ◽  
Author(s):  
Zulfiqar ◽  
Sardar Ali Khan ◽  
Nasir Rahman ◽  
Tahirzeb Khan ◽  
RajWali Khan ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Oxygen Vacancies

Size Dependent Dielectric Properties of TiO2 Nanoparticles

2020 ◽  
Vol 833 ◽  
pp. 147-151
Author(s):  
K.K. Anjali ◽  
A. Uma Maheswari ◽  
Manickam Sivakumar
Keyword(s):  
Dielectric Properties ◽  
Oxygen Vacancies ◽  
Surface Defects ◽  
Peak Shift ◽  
Chemical Precipitation ◽  
Space Charge Polarization ◽  
Precipitation Method ◽  
Bandgap Energy ◽  
Size Dependent ◽  
Mobility Of Charge Carriers

In this study, influence of nanoparticles size on optical and dielectric properties of TiO2 nanoparticles is investigated through thermal treatment of hydrous amorphous titania synthesized by chemical precipitation method at temperatures 300 °C and 600 °C. The average sizes of nanoparticles estimated respectively are ~ 8 nm and ~ 22 nm. Although the optical bandgap energy of both samples remains the same the Eg Raman mode observed at 144 cm-1 for bulk TiO2 is shifted to 150 cm-1 only for nanoparticles calcined at 300 °C. The shift is ascribed to the size as well as higher density of surface defects. Moreover, the presence of surface defects like oxygen vacancies which provide effective sites for catalytic reaction are confirmed by EPR and photoluminescence studies. The oxygen vacancies enhances space charge polarization and consequently results in higher dielectric constant. In addition, the peak shift of loss tangent which determines the mobility of charge carriers is found to be size dependent. Hence calcination temperature has significant influence on defect levels which in turn determine the optical and dielectric properties of TiO2 nanoparticles.

Microwave dielectric properties of (Zr0.8Sn0.2)TiO4 ceramics with pentavalent additives

1995 ◽  
Vol 10 (8) ◽  
pp. 2085-2090 ◽  
Author(s):  
Ki Hyun Yoon ◽  
Young Sol Kim ◽  
Eung Soo Kim
Keyword(s):  
Dielectric Properties ◽  
Resonant Frequency ◽  
Temperature Coefficient ◽  
Electron Concentration ◽  
Oxygen Vacancies ◽  
Microwave Dielectric Properties ◽  
Temperature Range ◽  
Microwave Dielectric ◽  
Ionic Size

The microwave dielectric properties of (Zr0.8Sn0.2)TiO4 were investigated as a function of the amount of additives such as Nb2O5 Ta2O5 and Sb2O5 in the temperature range of 20 °C to 80 °C at 7 GHz. As the amount of additives increased up to 1.0 mol %, the unloaded Q increased due to the decrease of oxygen vacancies in the (Zr0.8Sn0.2)TiO4 lattice and then decreased with further addition of additives because the electron concentration was increased. The temperature coefficient of the resonant frequency turned more negative with increasing additives. Although the Nb+5, Ta+5, and Sb+5 ions have a similar ionic size and the same valence electronics, each resulted in different microwave dielectric properties.

Influence of Ti additions on the Texture and Dielectric Properties of LSBN-BST Complex Ceramics

1998 ◽  
Vol 541 ◽  
Author(s):  
J. Portelles ◽  
H. Amorín ◽  
J. M. Siqueiros ◽  
F.F. Castilión ◽  
E. Martínez ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Oxygen Vacancies ◽  
Tungsten Bronze ◽  
Material Structure ◽  
X Ray Diffraction ◽  
Strontium Barium ◽  
Tetragonal Tungsten Bronze ◽  
X Ray ◽  
First Results

AbstractThe stoichiometric La-Ti doped strontium-barium niobate ceramic system was obtained for different concentrations of Titanium ions (Ti=1,3,5,10,30,50 %), where the Nb5− was substituted by Ti4+ according to the following expression Sr0.255 La0.03Bao0.7Nb2−yTiyO6−y/2 (LSBN-BST). The oxygen vacancies thus created which, together with the vacancies in the A sites of the tetragonal tungsten-bronze (TTB) material structure, have an important influence on their texture and dielectric properties, due to the crucial role of the occupancy of the crystallographic sites. X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy and thermoelectric analyses are reported. We report the first results for thin films of LSBNT- 7 % obtained by the PLD technique. The diffraction pattern reveals the presence of the LSBNT structure without annealing.

scholarly journals Anisotropic Ferro- and Dielectric Properties of Textured Bi4Ti3O12Ceramics Prepared by the Solid-State Reaction Based on Multiple Calcination

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
Xiangyu Mao ◽  
Wei Wang ◽  
Hui Sun ◽  
Xiaobing Chen
Keyword(s):  
Activation Energy ◽  
Dielectric Properties ◽  
Solid State ◽  
Solid State Reaction ◽  
Oxygen Vacancies ◽  
Remanent Polarization ◽  
Domain Walls ◽  
Solid State Reaction Method ◽  
Dielectric Anomaly ◽  
Reaction Method

The grain-oriented Bi4Ti3O12(BIT) samples were prepared by the solid-state reaction method with a multicalcination process. The grain-oriented BIT samples exhibit anisotropic structural, ferroelectric, piezoelectric, and dielectric properties. The remanent polarization (2Pr) and the piezoelectric constant (d33) ofa/b- andc-direction BIT ceramics are 49.5 μC cm−2, 22.2 pC N−1and 6.7 μC cm−26.9 pC N−1, respectively. The dielectric anomalies of samples are observed around 157 K and 232 K. The dielectric anomalies at around 157 K are related to oxygen vacancies. The activation energy of the dielectric relaxation of this anomaly is estimated to be 1.36 eV. Another dielectric anomaly at around 232 K is related to polarizable domains and the viscous motion of domain walls.

Structure Refinement and Dielectric Properties of Bismuth-Based Pyrochlores Containing Titanium

2014 ◽  
Vol 809-810 ◽  
pp. 770-777
Author(s):  
Bing Jie Zhang ◽  
Hui Ling Du ◽  
Cen Zhao
Keyword(s):  
Dielectric Properties ◽  
Oxygen Vacancies ◽  
Single Phase ◽  
Structure Refinement ◽  
Structural Defects ◽  
Free Oxygen ◽  
Oxygen Ions ◽  
Thermally Activated ◽  
Three Samples ◽  
Xrd Patterns

Bismuth-based pyrochlore dielectrics with the formula (Bi1.5Zn0.5)(Ti1.5M0.5)O7 (M = Nb, Ta and Sb) have been synthesized to investigate the influence of M between the dielectric properties and crystal structure. The XRD patterns show that all of the three samples give single phase. The refined data by GSAS program and the bond valence theory were used to analyze the differences in dielectric properties with occupation of different ions in B site. The dielectric constant of BZTS is the smallest in the BZTM, which is due to the polarizability and the contribution of BO6octahedra which has weak correlation when Sb placed into the center of the octahedra would also result in small αε. When it comes to the moderate temperature range, oxygen vacancies migration was thermally activated as the carriers mechanism, and the different activation energies is related to the association and the disassociation of massive complex defects. The Rietveld refinement data pointed that with the respectively change of B ions, more oxygen vacancies and free oxygen ions are provided by structural defects to participate in the conduction which can lead to the σ increase gradually.

Dielectric Properties of BiFeO3 Ceramics with Equal and Unequal Substitutions of Ti for Fe

2010 ◽  
Vol 434-435 ◽  
pp. 278-280
Author(s):  
Yan Hong Gu ◽  
Wan Ping Chen ◽  
Ming Jian Ding ◽  
Jian Quan Qi
Keyword(s):  
Dielectric Properties ◽  
Solid State ◽  
Dielectric Loss ◽  
Oxygen Vacancies ◽  
Solid State Reactions ◽  
Defect Complexes ◽  
Electrical And Dielectric Properties

BiFeO3, BiFe0.9Ti0.1O3 and BiFe0.9Ti0.05O3 ceramics were prepared by solid state reactions and were compared in electrical and dielectric properties. The resistivity of BiFe0.9Ti0.05O3 was 1.3×1012 Ω cm, which was about two and a half orders of magnitude higher than that of BiFeO3. and three times higher than that of BiFe0.9Ti0.1O3. The dielectric loss of BiFe0.9Ti0.05O3 was 0.1 and 0.02 at 100Hz and 1MHz, respectively. These phenomena can be explained base on the decrease of oxygen vacancies VO•• and defect complexes between the ferrum vacancies VFe and oxygen vacancies VO•• in the ceramics.

DIELECTRIC PROPERTIES OF Ca2CuO3–CaCu2O3–CuO COMPOSITE CERAMICS

2013 ◽  
Vol 27 (06) ◽  
pp. 1350042 ◽  
Author(s):  
QING-SHOU LI ◽  
YUN-QIANG ZHANG ◽  
LI-BEN LI ◽  
GUO-ZHONG ZANG
Keyword(s):  
Dielectric Properties ◽  
Schottky Barrier ◽  
Dielectric Response ◽  
Oxygen Vacancies ◽  
Arrhenius Equation ◽  
Composite Ceramics ◽  
High Dielectric ◽  
Sintering Method ◽  
Very High ◽  
Barrier Model

The Ca 2 CuO 3– CaCu 2 O 3– CuO ceramics were synthesized by traditional solid-state sintering method. The complex dielectric response of the samples measured from 102–106 Hz and from 300–500 K reveals very high real part of ε > 104. The activation energy (being about 0.63 eV) calculated by the Arrhenius equation indicates that the oxygen vacancies may contribute to the high dielectric response. And the fitting to a Schottky barrier model of capacitance versus applied voltage suggests that the existence of Schottky barrier at the grain boundaries may be another important reason for the origination of good dielectric properties.

scholarly journals Effects of Oxygen Vacancies on Dielectric Properties and Relaxor Behavior of Ba(ZrxTi1-x)O3 Ceramics

2021 ◽  
Vol 2101 (1) ◽  
pp. 012050
Author(s):  
Xiang Li ◽  
Zheng Sun ◽  
Yuan Zhang ◽  
Dianchen Huang ◽  
Jitao Hu
Keyword(s):  
Activation Energy ◽  
Dielectric Properties ◽  
Oxygen Vacancies ◽  
Annealing Treatment ◽  
Dielectric Materials ◽  
Ferroelectric Materials ◽  
Relaxor Behavior ◽  
Long Distance ◽  
Long Distance Movement ◽  
The Impact

Abstract By comparing the structure, dielectric and electrical conduction properties of sintered Ba(Zr0.15Ti0.85)O3 ceramics (short as BZT15) annealed in air and oxygen atmosphere was conducted to explore the impact of oxygen vacancies (OVs) on them. The dielectric properties of the samples were studied as changing with temperature (260–400K) in the scope of frequency from 100 Hz to 100 kHz. A typical relaxor behavior was observed in BZT15 and the relaxor behavior was enhanced after oxygen annealing treatment, which confirmed that the relaxation process was connected with the OVs inside ceramics. The value of activation energy was calculated to be 1.76 eV, 1.79eV, and 1.85 eV for as-prepared, air and oxygen annealed samples, respectively. Besides, the dielectric relaxor behavior was found to be associated with the conductivity originated from the dipolar conduction and long-distance movement of doubly ionized OVs. More interestingly, compared with other ferroelectric materials, the higher activation energy of BZT15 ceramics revealed a weaker concentration of OVs for such dielectric materials.

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