scholarly journals Permittivity and modulus spectroscopic study of BaFe0.5Nb0.5O3 ceramics

2013 ◽  
Vol 7 (4) ◽  
pp. 181-187 ◽  
Author(s):  
Subrat Kar ◽  
Pawan Kumar
Keyword(s):  
Activation Energy ◽  
Room Temperature ◽  
Perovskite Phase ◽  
Space Charge Polarization ◽  
Reaction Route ◽  
Conventional Solid State Reaction ◽  
Polarization Model ◽  
Single Perovskite Phase ◽  
Solid State Reaction Route ◽  
C Complex

Ba(Fe0.5Nb0.5)O3 (BFN) powder was synthesized in single perovskite phase by conventional solid state reaction route and BFN ceramic was obtained by uniaxial pressing and sintering at 1350?C. Complex immittance like: permittivity and modulus spectroscopic formalism were simultaneously used to explain dielectric behaviour of the ceramics. The activation energy calculated from dielectric relaxation below 100?C was found to be ~ 0.19 eV. The activation energy obtained from modulus spectra above 100?C was ~0.59 eV. The space charge polarization model was used to explain the origin of relaxation and ?giant? permittivity of BFN ceramics near room temperature.

Effect of Technological Parameters on the Microstructure and Electrical Properties of ZnO Varistors

2013 ◽  
Vol 820 ◽  
pp. 208-211
Author(s):  
Li Li ◽  
Qi Bin Liu
Keyword(s):  
Solid State ◽  
Electrical Properties ◽  
Leakage Current ◽  
Sintering Temperature ◽  
Voltage Gradient ◽  
Technological Parameters ◽  
Reaction Route ◽  
Conventional Solid State Reaction ◽  
Zno Varistors ◽  
Solid State Reaction Route

To improve voltage-gradient and to reduce the sintering temperature of ZnO varistors, high voltage-gradient ZnO varistors were synthesized with a conventional solid state reaction route. By means of SEM and DC parameter instrument for varistor, the influence of different technological parameters on microstructure, voltage-gradient and leakage current of ZnO varistors was investigated. The experimental results show that by using the process that presintering the additives at 850°C, the density is improved, the voltage-gradient is increased, and the leakage current is decreased. The optimum voltage-gradient and leakage current are 371V/mm and 3μA, respectively.

scholarly journals Influence of Nd Substitution by La in on Structural and Transport Properties for Sensing Applications

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Sudarshan Vadnala ◽  
Saket Asthana ◽  
Prem Pal ◽  
S. Srinath
Keyword(s):  
Transport Properties ◽  
Room Temperature ◽  
Parent Compound ◽  
Theoretical Models ◽  
Maximum Temperature ◽  
Structural Form ◽  
Reaction Route ◽  
Temperature Coefficients ◽  
Sensing Applications ◽  
Solid State Reaction Route

The structural and transport properties of manganites with and 0.2 prepared by solid state reaction route are studied. These compounds are found to be crystallized in orthorhombic structural form. A shift in the metal-semiconductor/insulator transition temperature () towards room temperature (289 K) with the substitution of Nd by La, as the value of is varied in the sequence (0, 0.1, and 0.2), has been provided. The shift in the , from 239 K (for ) to near the room temperature 289 K (for ), is attributed to the fact that the average radius of site-A increases with the percentage of La. The maximum temperature coefficients of resistance (TCR) of ( and 0.2) are found to be higher compared to its parent compound which is almost independent of . The electrical resistivity of the experimental results is explored by various theoretical models below and above . An appropriate enlightenment for the observed behavior is discussed in detail.

Molten Salt Synthesis of Nanocrystalline Phase of High Dielectric Constant Material CaCu3Ti4O12

2008 ◽  
Vol 8 (11) ◽  
pp. 5762-5769 ◽  
Author(s):  
B. Shri Prakash ◽  
K. B. R. Varma
Keyword(s):  
Dielectric Constant ◽  
Grain Size ◽  
Solid State ◽  
Molten Salt ◽  
Solid State Reaction ◽  
Molten Salt Synthesis ◽  
Reaction Route ◽  
Conventional Solid State Reaction ◽  
Phase Pure ◽  
Solid State Reaction Route

Nanocrystalline powders of giant dielectric constant material, CaCu3Ti4O12 (CCTO), have been prepared successfully by the molten salt synthesis (MSS) using KCl at 750 °C/10 h, which is significantly lower than the calcination temperature (∼1000 °C) that is employed to obtain phase pure CCTO in the conventional solid-state reaction route. The water washed molten salt synthesized powder, characterized by X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), and Transmission electron microscopy (TEM) confirmed to be a phase pure CCTO associated with ∼150 nm sized crystallites of nearly spherical shape. The decrease in the formation temperature/duration of CCTO in MSS method was attributed to an increase in the diffusion rate or a decrease in the diffusion length of reacting ions in the molten salt medium. As a consequence of liquid phase sintering, pellets of as-synthesized KCl containing CCTO powder exhibited higher sinterability and grain size than that of KCl free CCTO samples prepared by both MSS method and conventional solid-state reaction route. The grain size and the dielectric constant of KCl containing CCTO ceramics increased with increasing sintering temperature (900 °C–1050 °C). Indeed the dielectric constants of these ceramics were higher than that of KCl free CCTO samples prepared by both MSS method and those obtained via the solid-state reaction route and sintered at the same temperature. Internal barrier layer capacitance (IBLC) model was invoked to correlate the observed dielectric constant with the grain size in these samples.

Conductivity studies of Ni and Gd substituted BiCoO3

2014 ◽  
Vol 28 (05) ◽  
pp. 1450034 ◽  
Author(s):  
T. Ramachandran ◽  
N. E. Rajeevan ◽  
P. P. Pradyumnan
Keyword(s):  
Thermal Conductivity ◽  
Room Temperature ◽  
Structural Studies ◽  
Reaction Route ◽  
Low Thermal Conductivity ◽  
Sem Micrograph ◽  
New Material ◽  
Cubic Structure ◽  
Solid State Reaction Route ◽  
Room Temperature Raman Spectrum

In this paper, we report the synthesis, thermal and electrical property studies of Ni 0.5 Gd 0.2 Bi 0.3 CoO 3, a new material for thermoelectric applications. The material was synthesized by solid state reaction route taking BiCoO 3 as basic matrix by substituting bismuth with nickel and gadolinium. Structural studies using room temperature XRD and room temperature Raman spectrum established cubic structure for Ni 0.5 Bi 0.5 CoO 3 and tetragonal structure for Ni 0.5 Gd 0.2 Bi 0.3 CoO 3. The SEM micrograph of the samples revealed crystallites of micrometer dimension with varying grain size. The sample showed interestingly low thermal conductivity and VRH mechanism was found to dominate in the electrical conduction at low temperature regime. The low thermal conductivity and moderate electrical conductivity is suggestive of strong candidature of the material for thermoelectric applications.

scholarly journals Normal and abnormal dielectric relaxation behavior in KTaO3 ceramics

RSC Advances ◽  
2017 ◽  
Vol 7 (80) ◽  
pp. 50680-50687 ◽  
Author(s):  
Lei Tong ◽  
Jie Sun ◽  
Shuting Wang ◽  
Youmin Guo ◽  
Qiuju Li ◽  
...  
Keyword(s):  
Solid State ◽  
Dielectric Relaxation ◽  
Solid State Reaction ◽  
Relaxation Behavior ◽  
Reaction Route ◽  
Conventional Solid State Reaction ◽  
Ceramic Samples ◽  
Solid State Reaction Route ◽  
Dielectric Relaxation Behavior

KTaO3 ceramic samples were prepared via a conventional solid state reaction route.

scholarly journals Magnetic ion oxidation state dependent magnetoelectric coupling strength in Fe doped BCT ceramics

RSC Advances ◽  
2020 ◽  
Vol 10 (35) ◽  
pp. 21019-21027
Author(s):  
Aanchal Chawla ◽  
Anupinder Singh ◽  
P. D. Babu ◽  
Mandeep Singh
Keyword(s):  
Solid State ◽  
Coupling Strength ◽  
Solid State Reaction ◽  
Ferroelectric Properties ◽  
Reaction Route ◽  
Conventional Solid State Reaction ◽  
State Dependent ◽  
Significant Difference ◽  
Solid State Reaction Route ◽  
Magnetic Ion

Polycrystalline samples of Ba0.96Ca0.04Ti0.91Fe0.09O3 were prepared using a conventional solid state reaction route with different Fe starting precursors (Fe2O3, Fe3O4). A significant difference in the magnetic and ferroelectric properties was observed.

Dielectric and Piezoelectric Properties of Na0.42K0.08Bi0.5 TiO3 and Na0.45K0.05Bi0.5TiO3 Ceramics

2007 ◽  
Vol 280-283 ◽  
pp. 251-254 ◽  
Author(s):  
Su Chuan Zhao ◽  
Lina Zhang ◽  
Guo Rong Li ◽  
Liao Ying Zheng ◽  
Ai Li Ding
Keyword(s):  
Room Temperature ◽  
Piezoelectric Properties ◽  
Perovskite Phase ◽  
X Ray Diffraction ◽  
Depolarization Temperature ◽  
X Ray ◽  
Single Perovskite Phase ◽  
Dielectric And Piezoelectric Properties ◽  
Rhombohedral Symmetry ◽  
Ferroelectric And Piezoelectric Properties

Na0.42K0.08Bi0.5TiO3 and Na0.45K0.05Bi0.5TiO3 ceramics were fabricated by the solid-state reaction. The structures were determined by X-ray diffraction. Dielectric, ferroelectric and piezoelectric properties of the ceramics were measured and discussed. The ceramics have a single perovskite phase with rhombohedral symmetry at room temperature. The thermal variations of the permittivity follow the law 1/ e − 1/ em = C(T − Tm)2 which is the character of typical relax ferroelectrics, when temperature is higher than the temperature of the maximum of dielectric constant (Tm). The depolarization temperature (Td) of spontaneous polarization is 215oC for Na0.45K0.05Bi0.5TiO3 and 152oC for Na0.42K0.08Bi0.5TiO3 respectively. There exist two different dielectric behaviors of the Na0.42K0.08Bi0.5TiO3 ceramic, without and after poling. Na0.45K0.05Bi0.5TiO3 possesses relatively high kt and Td. The use for device application has been indicated.

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