Synthesis and Spectral Characterizations of Nano-Sized Lithium Niobate (LiNbO3) Ceramic

2020 ◽  
Vol 12 (2) ◽  
pp. 81-86 ◽  
Author(s):  
Rajanigandha Barik ◽  
Santosh K. Satpathy ◽  
Banarji Behera ◽  
Susanta K. Biswal ◽  
Ranjan K. Mohapatra
Keyword(s):  
Dielectric Constant ◽  
High Temperature ◽  
Dielectric Loss ◽  
Lithium Niobate ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Negative Temperature ◽  
Solid State Reaction Method ◽  
Ferroelectric Material ◽  
Dc Conductivity

Background: Lithium Niobate (LiNbO3) is a ferroelectric material suitable for a variety of applications. Its versatilityis made possible by the excellent electro-optic, nonlinear, and piezoelectric properties of the intrinsic material. Objective: Study of structural, microstructural and electrical propertiesare to understand the structure and topography of the composites. Methods: The sample of LiNbO3 was prepared by solid state reaction method at high temperature using high purity ingredients. Results: The analysis of the X-ray diffraction at room temperature confirmed the trigonal structure. The grains are more or less homogeneously distributed throughout the surface. The dielectric constant and dielectric loss are decreases with increase in frequency. The material has high dielectric constant and low dielectric loss at room temperature. The magnitude of real impedance decreases with rise in temperature which shows negative temperature coefficient of resistance behavior.The nature of the conductivity in solids is analyzed which obeyed Jonscher’s power law. The temperature-dependence of dc conductivity indicates that the electrical conduction in the material is a thermally activated process. Conclusion: The compound exhibits a dielectric anomaly at high temperature suggesting ferroelectric–paraelectric phase transition. The activation energy of the material is found to be 0.00184 eV in the high temperature region of Arrhenius plot for electrical conductivity. The nature of temperature dependence of the dc conductivity exhibited the NTCR behaviour of the material.

Effect of Gd Substitution on the Dielectric Properties and Magnetoelectric Effect of BiFeO3

2010 ◽  
Vol 150-151 ◽  
pp. 1470-1475
Author(s):  
Gui Lin Song ◽  
Tian Xing Wang ◽  
Cun Jun Xia ◽  
Chao Li ◽  
Fang Gao Chang
Keyword(s):  
Dielectric Constant ◽  
Rare Earth ◽  
Dielectric Loss ◽  
Room Temperature ◽  
Magnetoelectric Effect ◽  
Solid State Reaction Method ◽  
Impurity Phase ◽  
Conventional Solid State Reaction ◽  
Reaction Method ◽  
Dielectric Relaxation Process

Multiferroic Bi1-xGdxFeO3(x=0, 0.05, 0.1, 0.15, 0.2) ceramics were prepared by conventional solid state reaction method. For all the samples prepared, they exhibit magnetoelectric effect at room temperature, and the dielectric constant and dielectric loss decrease with increasing frequency in the range from 10000Hz to 1 MHz from a typical orientational dielectric relaxation process. It has been found that both dielectric constant and dielectric loss are strongly dependent on the Gd3+ content. And substitution of Bi with rare earth Gd helps to eliminate the impurity phase in BiFeO3 ceramics.,

ABOUT HEAT CAPACITY OF TITANIUM CARBIDE TiCx

2019 ◽  
pp. 56-66
Author(s):  
I. Khidirov ◽  
V. V. Getmanskiy ◽  
A. S. Parpiev ◽  
Sh. A. Makhmudov
Keyword(s):  
Heat Capacity ◽  
High Temperature ◽  
Titanium Carbide ◽  
Temperature Dependence ◽  
Carbon Concentration ◽  
Room Temperature ◽  
Thermodynamic Characteristics ◽  
Liquid Nitrogen Temperature ◽  
Analysis Data ◽  
Thermal Excitation

This work relates to the field of thermophysical parameters of refractory interstitial alloys. The isochoric heat capacity of cubic titanium carbide TiCx has been calculated within the Debye approximation in the carbon concentration  range x = 0.70–0.97 at room temperature (300 K) and at liquid nitrogen temperature (80 K) through the Debye temperature established on the basis of neutron diffraction analysis data. It has been found out that at room temperature with decrease of carbon concentration the heat capacity significantly increases from 29.40 J/mol·K to 34.20 J/mol·K, and at T = 80 K – from 3.08 J/mol·K to 8.20 J/mol·K. The work analyzes the literature data and gives the results of the evaluation of the high-temperature dependence of the heat capacity СV of the cubic titanium carbide TiC0.97 based on the data of neutron structural analysis. It has been proposed to amend in the Neumann–Kopp formula to describe the high-temperature dependence of the titanium carbide heat capacity. After the amendment, the Neumann–Kopp formula describes the results of well-known experiments on the high-temperature dependence of the heat capacity of the titanium carbide TiCx. The proposed formula takes into account the degree of thermal excitation (a quantized number) that increases in steps with increasing temperature.The results allow us to predict the thermodynamic characteristics of titanium carbide in the temperature range of 300–3000 K and can be useful for materials scientists.

scholarly journals Structure and electric properties of cerium substituted SrBi1.8Ce0.2Nb2O9 and SrBi1.8Ce0.2Ta2O9 ceramics

2016 ◽  
Vol 10 (3) ◽  
pp. 183-188 ◽  
Author(s):  
Mohamed Afqir ◽  
Amina Tachafine ◽  
Didier Fasquelle ◽  
Mohamed Elaatmani ◽  
Jean-Claude Carru ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Solid State ◽  
Room Temperature ◽  
Single Phase ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Reaction Method ◽  
X Ray ◽  
Lcr Meter ◽  
Curie Temperature Tc

SrBi1.8Ce0.2Nb2O9 (SBCN) and SrBi1.8Ce0.2Ta2O9 (SBCT) powders were prepared via solid-state reaction method. X-ray diffraction analysis reveals that the SBCN and SBCT powders have the single phase orthorhom-bic Aurivillius structure at room temperature. The contribution of Raman scattering and FTIR spectroscopy of these samples were relatively smooth and resemble each other. The calcined powders were uniaxially pressed and sintered at 1250?C for 8 h to obtaine dense ceramics. Dielectric constant, loss tangent and AC conductivity of the sintered Ce-doped SrBi2Nb2O9 and SrBi2Ta2O9 ceramics were measured by LCR meter. The Ce-doped SBN (SBCN) ceramics have a higher Curie temperature (TC) and dielectric constant at TC (380?C and ?? ~3510) compared to the Ce-doped SBT (SBCT) ceramics (330?C and ?? ~115) when measured at 100Hz. However, the Ce-doped SBT (SBCT) ceramics have lower conductivity and dielectric loss.

Microwave and Electrical Properties of Zr-Doped SrTiO3 for Dielectric Resonator Antenna Application

2018 ◽  
Vol 280 ◽  
pp. 142-148 ◽  
Author(s):  
Norhizatol Fashren Muhamad ◽  
Rozana Aina Maulat Osman ◽  
Mohd Sobri Idris ◽  
Faizal Jamlos ◽  
Nor Azura Malini Ahmad Hambali
Keyword(s):  
Dielectric Constant ◽  
Electrical Properties ◽  
Dielectric Loss ◽  
Dielectric Resonator ◽  
Ceramic Powder ◽  
Experimental Studies ◽  
Orthorhombic Phase ◽  
Solid State Reaction Method ◽  
Dielectric Resonator Antenna ◽  
Conventional Solid State Reaction

Present investigation provides experimental studies on cylindrical dielectric resonator antennas (CDRAs) fabricated from SrTi1-xZrxO3ceramic with different substitution of Zr in place of Ti for (0 ≤ x ≤1). Ceramic powder were prepared using conventional solid state reaction method. X-ray Diffraction exposes physical properties Zr-doped SrTiO3which exhibit phase transition from cubic, tetragonal to orthorhombic phase. The electrical properties such as dielectric constant (εr) and dielectric loss (tan δ) were studied in variation of temperatures and frequencies. At room temperature the dielectric constant decreased from 240 to 21 with increase of Zr content however the amazing result was obtained for multiband antenna by Zr content. The dielectric loss obtain shows very low loss value roughly below 0.07 for all samples. The variations of return loss, resonance frequency and bandwidth of CDRAs at their respective resonant frequencies are studied experimentally.

scholarly journals Resistivity and Carrier Mobility of the SmBa2 Cu3 O6+x Superconductor with Different Oxygen Doping Levels

1999 ◽  
Vol 54 (2) ◽  
pp. 95-100 ◽  
Author(s):  
G. Spinolo ◽  
P. Ghigna ◽  
G. Chiodelli ◽  
M. Ferretti ◽  
G. Flor
Keyword(s):  
High Temperature ◽  
Temperature Dependence ◽  
Oxygen Pressure ◽  
Anderson Localization ◽  
Carrier Mobility ◽  
Hole Mobility ◽  
Dc Conductivity ◽  
Sudden Increase ◽  
Conductivity Measurements ◽  
Oxygen Doping

Abstract DC conductivity measurements between 15 and 300 K are reported for SmBa2 Cu3O6+x samples with different oxygen doping amounts (x) produced by annealing under appropriate high temperature and oxygen pressure conditions and quenching. Samples with x≥0.5 are superconductors: Tc ~60 K at x=0.7, Tc >80 K at ; x=0.9. The transition from superconduction to non-superconduction corresponds to the tetragonal to orthorhombic structural tran-sition and to the transition from semiconducting to metallic temperature dependence of the resistivity. Oxygen doping causes a sudden increase of hole mobility near x=0.5. Below this threshold, the be-havior of the carrier mobility is in agreement with an Anderson localization.

scholarly journals Dielectric properties and conductivity of PVdF-co-HFP/LiClO4 polymer electrolytes

2018 ◽  
Vol 96 (7) ◽  
pp. 786-791 ◽  
Author(s):  
Kemal Ulutaş ◽  
Ugur Yahsi ◽  
Hüseyin Deligöz ◽  
Cumali Tav ◽  
Serpil Yılmaztürk ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Polymer Electrolytes ◽  
Room Temperature ◽  
Solid Polymer Electrolytes ◽  
Solid Polymer ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Maximum Conductivity

In this study, it was aimed to prepare a series of PVdF-co-HFP based electrolytes with different LiClO4 loadings and to investigate their chemical and electrical properties in detail. For this purpose, PVdF-co-HFP based electrolytes with different LiClO4 loadings (1–20 weight %) were prepared using solution casting method. X-ray diffraction (XRD), differential scanning calorimetry, and thermogravimetric (TGA) –differential thermal and dielectric spectroscopy analysis of PVdF-co-HFP/LiClO4 were performed to characterize their structural, thermal, and dielectric properties, respectively. XRD results showed that the diffraction peaks of PVdF-co-HFP/LiClO4 electrolytes broadened and decreased with LiClO4. TGA patterns exhibited that PVdF-co-HFP/LiClO4 electrolytes with 20 wt % of LiClO4 had the lowest thermal stability and it degraded above 473 K, which is highly applicable for solid polymer electrolytes. Dielectric constant, dielectric loss, and conductivities were calculated by measuring capacitance and dielectric loss factor of PVdF-co-HFP/LiClO4 in the range from 10 mHz to 20 MHz frequencies at room temperature. In consequence, conductivities of PVdF-co-HFP/LiClO4 increased significantly with frequency for low loading of LiClO4 while they only slightly changed with higher LiClO4 addition. On the other hand, dielectric constant values of PVdF-co-HFP/LiClO4 films decreased with frequency whereas they rose with LiClO4 addition. The dielectric studies showed an increase in dielectric constant and dielectric loss with decreasing frequency. This result was attributed to high contribution of charge accumulation at the electrode–electrolyte interface. The electrolyte showed the maximum conductivity of 8 × 10−2 S/cm at room temperature.

Silicon Carbide Vertical JFET Operating at High Temperature

2008 ◽  
Vol 600-603 ◽  
pp. 1063-1066 ◽  
Author(s):  
Konstantin Vassilevski ◽  
Keith P. Hilton ◽  
Nicolas G. Wright ◽  
Michael J. Uren ◽  
A.G. Munday ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
High Temperature ◽  
Temperature Dependence ◽  
Power Law ◽  
Current Density ◽  
Electron Mobility ◽  
Room Temperature ◽  
Protective Atmosphere ◽  
State Resistance ◽  
A Current

Trenched and implanted vertical JFETs (TI-VJFETs) with blocking voltages of 700 V were fabricated on commercial 4H-SiC epitaxial wafers. Vertical p+-n junctions were formed by aluminium implantation in sidewalls of strip-like mesa structures. Normally-on 4H-SiC TI-VJFETs had specific on-state resistance (RO-S ) of 8 mW×cm2 measured at room temperature. These devices operated reversibly at a current density of 100 A/cm2 whilst placed on a hot stage at temperature of 500 °C and without any protective atmosphere. The change of RO-S with temperature rising from 20 to 500 °C followed a power law (~ T 2.4) which is close to the temperature dependence of electron mobility in 4H-SiC.

Dielectric Properties of Sintered AIN

1989 ◽  
Vol 167 ◽  
Author(s):  
R. D. Harris ◽  
R. C. Enck ◽  
J. L. Fields
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
Room Temperature ◽  
Dc Resistivity ◽  
Thermally Activated ◽  
Exponential Factors ◽  
Ac Electrical Properties ◽  
Different Sources ◽  
Room Temperature Dielectric Constant ◽  
Product Literature

AbstractWe have initiated a study of the ac electrical properties (dielectric constant and dielectric loss) and the dc resistivity of sintered AIN. For this study, we have used samples purchased commercially as well as samples made by the Carborundum Company, a member of the BP Group. Variations are observed in the room temperature dielectric constant for AIN substrates obtained from different sources. The source-to-source range is from 8.5 to 8.7. This range is lower than the 8.8 to 9.2 that is generally reported in the product literature. Similar source-tosource variations in the room temperature dielectric loss are observed. All of the samples show thermally activated behavior in the dc resistivity. The activation energy observed for all of the samples is similar, EA ∼0.47 eV; however, different pre-exponential factors are apparent. As a result, there are large variations in the measured room temperature resistivities for samples from different sources.

Effects of Mg2SiO4 Addition on the Microstructure and Dielectric Properties of MgTiO3-CaTiO3 Ceramics

2013 ◽  
Vol 675 ◽  
pp. 200-204
Author(s):  
Fei Shi ◽  
Peng Cheng Du ◽  
Jing Xiao Liu ◽  
Ji Wei Wu ◽  
De Qing Chen ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Solid State ◽  
Dielectric Loss ◽  
Solid State Reaction ◽  
Sintering Temperature ◽  
Solid State Reaction Method ◽  
Composite Ceramics ◽  
Reaction Method ◽  
Dielectric Ceramics

The Mg2SiO4-MgTiO3-CaTiO3 composite dielectric ceramics with different Mg2SiO4 addition amounts were prepared by solid state reaction method. The effects of Mg2SiO4 addition amounts on the microstructure and dielectric properties as well as sintering temperature of xMg2SiO4-(0.95-x)MgTiO3-0.05CaTiO3 (abbreviated as xMSTC, 0.25≦x≦0.75) composite ceramics were investigated. The results indicated that the sintering temperature of MgTiO3-CaTiO3 based ceramics with Mg2SiO4 addition could be lowered effectively to 1320~1340°C, and the dielectric constant decreased and dielectric loss increased gradually with the increase of Mg2SiO4 content. The 0.45MSTC ceramics containing 45 wt% Mg2SiO4 and sintered at 1340°C showed desirable dielectric properties with dielectric constant εr=13.3，dielectric loss tanδ=4.5×10-4 and temperature coefficient of relative permittivity τε =10 ppm/°C.

Effect of MnO2 Impurity on the PZT-PMN System Ceramics for Piezoelectric Transformer

2008 ◽  
Vol 55-57 ◽  
pp. 189-192
Author(s):  
Y. Suwan ◽  
Anuson Niyompan ◽  
Rungnapa Tipakontitikul ◽  
Pitak Laoratanakul
Keyword(s):  
Dielectric Constant ◽  
Grain Size ◽  
Phase Transformation ◽  
Physical Properties ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Piezoelectric Properties ◽  
Relative Dielectric Constant ◽  
Linear Shrinkage ◽  
Poling Process

The PZT-PMN ceramics system was derived from Pb(Zr0.5Ti0.5)O3 and Pb(Mg2/3Nb1/3)O3 based compositions those obtained via the columbite method. The effect of MnO2 addition on microstructure, physical properties and piezoelectric properties were investigated. In this study, the composition with PZT/PMN ratio of 1:1 was selected. To observe the effect of MnO2 adding, its concentration was varied in range 0-10 mol%. Green pellets were sintered at temperature 1250oC for 4 hours. For piezoelectric investigation, the ceramics pellets were subjected to a poling process. The XRD results show that there is no phase transformation observed for all sintered PZT-PMN samples with presence of MnO2. The SEM micrographs reveal that MnO2 can enhance sinterability as evidenced by lowering of porosity and increasing of grain size with increasing of MnO2 content. Increasing of linear shrinkage and apparent densities also confirmed such effect. Improvement of d33 from 28 to 114 pC/N could only found for MnO2 in range 0 to 4 mol%. For higher MnO2 content, there is only slightly increased. However, increasing of kp with increasing of MnO2 is clearly observed. While dielectric constant measured at room temperature and at frequency 1 kHz is higher for ceramics without MnO2 doping and it decreases with increasing MnO2 concentration. The temperature dependence of relative dielectric constant go to peak of value about 6000 at temperature around 180oC and shifting of these peaks with frequency can only be observed for samples with higher MnO2 content. This indicates a normal ferroelectric behavior for sample with lower MnO2 and there are converted to relaxor after MnO2 increased.

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