IMPEDANCE SPECTROSCOPY STUDY OF NaCa2Nb5O15 CERAMICS

2009 ◽  
Vol 23 (01) ◽  
pp. 97-109 ◽  
Author(s):  
BANARJI BEHERA ◽  
P. NAYAK ◽  
R. N. P. CHOUDHARY
Keyword(s):  
Electrical Transport ◽  
Complex Modulus ◽  
Complex Impedance ◽  
Tungsten Bronze ◽  
Polycrystalline Sample ◽  
Transport Processes ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Wide Range ◽  
Increasing Temperature

Polycrystalline sample of NaCa 2 Nb 5 O 15 was prepared by a high-temperature solid-state reaction technique. Preliminary X-ray structural analysis exhibits the orthorhombic crystal structure of the compound at room temperature. Detailed dielectric studies of NaCa 2 Nb 5 O 15 over a wide range of temperature (31–500°C) and frequency (102–106 Hz) did not show any dielectric anomaly (or ferroelectric phase transition) as observed in other members of the tungsten bronze structural family. However, the low loss tangent and dielectric constant increase with increasing temperature. Complex impedance and modulus plots (at different temperature and frequency) show the existence of non-Debye type of relaxation process in the compound. Complex modulus spectrum shows only grain contribution in the compound. Electric modulus analysis suggests that a possible hopping mechanism is evident for electrical transport processes in the system. Studies of AC conductivity with frequency suggest that the material obeys Jonscher's universal power law.

Structural and electrical properties of KCa2Nb5O15 ceramics

Open Physics ◽  
2008 ◽  
Vol 6 (2) ◽  
Author(s):  
Banarji Behera ◽  
Pratibindhya Nayak ◽  
Ram Choudhary
Keyword(s):  
Electrical Properties ◽  
Temperature Variation ◽  
Electrical Transport ◽  
Room Temperature ◽  
Complex Impedance ◽  
Tungsten Bronze ◽  
Transport Processes ◽  
Relaxation Processes ◽  
Orthorhombic Crystal Structure ◽  
Grain Distribution

AbstractA polycrystalline sample of KCa2Nb5O15 with tungsten bronze structure was prepared by a mixed oxide method at high temperature. A preliminary structural analysis of the compound showed an orthorhombic crystal structure at room temperature. Surface morphology of the compound shows a uniform grain distribution throughout the surface of the sample. Studies of temperature variation on dielectric response at various frequencies show that the compound has a transition temperature well above the room temperature (i.e., 105°C), which was confirmed by the polarization measurement. Electrical properties of the material have been studied using a complex impedance spectroscopy (CIS) technique in a wide temperature (31–500°C) and frequency (102–106 Hz) range that showed only bulk contribution and non-Debye type relaxation processes in the material. The activation energy of the compound (calculated from both the loss and modulus spectrum) is same, and hence the relaxation process may be attributed to the same type of charge carriers. A possible ‘hopping’ mechanism for electrical transport processes in the system is evident from the modulus analysis. A plot of dc conductivity (bulk) with temperature variation demonstrates that the compound exhibits Arrhenius type of electrical conductivity.

STRUCTURAL AND IMPEDANCE CHARACTERISTICS OF KPb2V5O15

2011 ◽  
Vol 25 (28) ◽  
pp. 3745-3753
Author(s):  
P. S. DAS ◽  
P. K. CHAKRABORTY ◽  
BANARJI BEHERA ◽  
R. N. P. CHOUDHARY
Keyword(s):  
Boundary Effect ◽  
Complex Impedance ◽  
Negative Temperature ◽  
Polycrystalline Sample ◽  
Homogeneous Distribution ◽  
Orthorhombic Crystal ◽  
Ac Electrical Conductivity ◽  
Orthorhombic Crystal Structure ◽  
Impedance Characteristics ◽  
Sem Micrograph

The polycrystalline sample of KPb 2 V 5 O 15 was prepared by a mixed-oxide method relatively at low temperature (i.e., 550°C). X-ray diffraction studies of the compound showed the formation of single phase orthorhombic crystal structure at room temperature. SEM micrograph showed the homogeneous distribution of grains throughout the sample. Electric properties were analyzed using the complex impedance spectroscopy. The modulus plot showed the presence of both the grain and grain boundary effect. The bulk impedance evaluated from the Nyquist plots was observed to decrease with the rise in temperature, showing a negative temperature coefficient of resistance. The variation of AC electrical conductivity (σ AC ) was measured in a wide temperature (30–500°C) and frequency (102–106 Hz) range. The activation energy of the compound calculated from both the impedance and modulus spectrum was found to be the same.

scholarly journals Complex Impedance Spectroscopic Properties of Ceramics

2008 ◽  
Vol 2008 ◽  
pp. 1-5 ◽  
Author(s):  
Praveen Khatri ◽  
Banarji Behera ◽  
V. Srinivas ◽  
R. N. P. Choudhary
Keyword(s):  
Electrical Transport ◽  
Complex Impedance ◽  
Negative Temperature ◽  
Polycrystalline Sample ◽  
Spectroscopic Properties ◽  
Wide Frequency Range ◽  
Transport Processes ◽  
Effect Of Temperature ◽  
Temperature Dependent ◽  
Impedance Parameters

The polycrystalline sample of was prepared by a high-temperature solid-state reaction technique. The effect of temperature on impedance parameters was studied using an impedance analyzer in a wide frequency range (  Hz). The real and imaginary parts of complex impedance trace semicircles in the complex plane. The temperature-dependent plots reveal the presence of both bulk and grain boundary effects above C. The bulk resistance of the material decreases with rise in temperature. This exhibits a typical negative temperature coefficient of resistance (NTCR) behavior of the material. The modulus analysis suggests a possible hopping mechanism for electrical transport processes of the material. The nature of variation of dc conductivity suggests the Arrhenius type of electrical conductivity.

Dielectric properties of Ba3Sr2DyTi3V7O30 ceramics

Open Physics ◽  
2010 ◽  
Vol 8 (4) ◽  
Author(s):  
Priyadarshini Sahoo ◽  
Anuradha Panigrahi ◽  
Sunanda Patri ◽  
Rasm Choudhary
Keyword(s):  
Room Temperature ◽  
Paraelectric Phase ◽  
Tungsten Bronze ◽  
Polycrystalline Sample ◽  
Dielectric Anomaly ◽  
Tungsten Bronze Structure ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Oxygen Ion ◽  
Temperature Surface

AbstractA polycrystalline sample, Ba3Sr2DyTi3V7O30, with tungsten bronze structure was prepared by a mixed-oxide method at high temperature (950°C). Preliminary structural analysis of the compound showed an orthorhombic crystal structure at room temperature. Surface morphology of the compound was studied by scanning electron microscopy. The dielectric anomaly at 321°C may be attributed to the ferro-paraelectric phase transitions. This was also confirmed from the appearance of a hysteresis loop. The nature of variation of the ac conductivity and value of activation energy at different temperature regions, suggest that the conduction process is of mixed-type (i.e., ionic-polaronic and space charge generated from the oxygen ion vacancies).

Structural, Dielectric and Electrical Studies of Ba4CaRTi3Nb7O30 (R = Eu, Dy) Ferroelectric System

2013 ◽  
Vol 547 ◽  
pp. 41-48 ◽  
Author(s):  
Prasun Ganguly ◽  
A.M. Biradar ◽  
A.K. Jha
Keyword(s):  
Single Phase ◽  
Microstructural Analysis ◽  
Tungsten Bronze ◽  
Negative Temperature ◽  
Xrd Analysis ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Orthorhombic Crystal ◽  
Paraelectric Phase Transition ◽  
Orthorhombic Crystal Structure

The polycrystalline samples of Ba4CaRTi3Nb7O30 (R = Eu, Dy), members of tungsten-bronze family, were prepared by high-temperature solid state reaction method and studied for their dielectric and electrical properties. X-ray diffraction (XRD) analysis reveals the formation of single-phase compounds having orthorhombic crystal structure at room temperature. Microstructural analysis by scanning electron microscope (SEM) shows that the compounds have well defined grains, which are distributed uniformly throughout the sample. Detailed dielectric properties of the compounds as a function of frequency and temperature show that the compounds undergo non-relaxor kind of ferroelectric-paraelectric phase transition of diffuse nature. Ferroelectric, piezoelectric and pyroelectric studies of the compounds have been discussed in this paper. The temperature dependence of dc conductivity of the compounds have been investigated. The conductivity study over a wide temperature range suggests that the compounds have negative temperature coefficient of resistance (NTCR) behaviour.

Effect of Sintering on Structural and Transport Properties on Nanosized Pr0.85Na0.15MnO3

2015 ◽  
Vol 1107 ◽  
pp. 272-277 ◽  
Author(s):  
Siau Wei Ng ◽  
Kean Pah Lim ◽  
S.A. Halim ◽  
Hassan Jumiah ◽  
Albert H.M. Gan ◽  
...  
Keyword(s):  
Grain Size ◽  
Transport Properties ◽  
Electrical Transport ◽  
Boundary Effect ◽  
Sol Gel ◽  
Magnetic Layer ◽  
Electrical Transport Properties ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Semiconductor Behavior

We have investigated the structural, microstructure and electrical transport properties of nanosized Pr0.85Na0.15MnO3 (PNMO) synthesized by sol-gel technique and sinter from 600°C to 1000°C. The grain size increases from 67 nm (S600) up to 284 nm (S1000) due to the grain growth during heat treatment. XRD showed that single phase orthorhombic crystal structure of PNMO is fully forms started at 600°C. The resistivity decreased with the increased of grain size and crystallite size due to the reduction of grain boundary effect (dead magnetic layer) which improved their grain conductivity.All samples showed semiconductor behavior where their metal insulator transition temperatures (TMIT) were estimated to be lower than 80K.

Structural, dielectric, electrical and piezoelectric properties of Ba4SrRTi3V7O30 (R=Sm, Dy) ceramics

Open Physics ◽  
2008 ◽  
Vol 6 (4) ◽  
Author(s):  
Priyadarshini Sahoo ◽  
Anuradha Panigrahi ◽  
Sunanda Patri ◽  
Ram Choudhary
Keyword(s):  
Room Temperature ◽  
Single Phase ◽  
Complex Impedance ◽  
Tungsten Bronze ◽  
Negative Temperature ◽  
Scanning Electron Micrographs ◽  
Polarization Study ◽  
Semiconducting Properties ◽  
Wide Range

AbstractPolycrystalline samples of Ba4SrRTi3V7O30 (R=Sm and Dy), members of the tungsten-bronze family, were prepared using a high-temperature, solid-state reaction technique and studied their electrical properties (using complex impedance spectroscopy) in a wide range of temperature (31–500°C) and frequency (1 kHz-1 MHz). Preliminary structural (XRD) analyses of these compounds show the formation of single-phase, orthorhombic structures at room temperature. The scanning electron micrographs (SEM) provided information on the quality of the samples and uniform distribution of grains over the entire surface of the samples. Detailed studies of the dielectric properties suggest that they have undergone ferroelectric-paraelectric phase transition well above the room temperatures (i.e., 432 and 355°C for R= Sm and Dy, respectively, at frequency 100 kHz). Measurements of electrical conductivity (ac and dc) as a function of temperature suggest that the compounds have semiconducting properties much above the room temperature, with negative temperature coefficient of resistance (NTCR) behavior. The existence of ferroelectricity in these compounds was confirmed from a polarization study.

SYNTHESIS AND CHARACTERIZATION OF COMPLEX FERROELECTRIC OXIDE

2012 ◽  
Vol 02 (04) ◽  
pp. 1250024 ◽  
Author(s):  
PIYUSH R. DAS ◽  
B. N. PARIDA ◽  
R. PADHEE ◽  
R. N. P. CHOUDHARY
Keyword(s):  
Temperature Dependence ◽  
Electrical Transport ◽  
Room Temperature ◽  
Structural Characteristics ◽  
Ferroelectric Properties ◽  
Complex Impedance ◽  
Electrical Transport Properties ◽  
Arrhenius Behavior ◽  
Orthorhombic Crystal ◽  
Grain Distribution

The polycrystalline sample of Li2Pb2Pr2W2Ti4V4O30 was prepared by a solid-state reaction technique. The preparation conditions of the compound have been optimized using thermal analysis (DTA and TGA) technique. Room temperature structural analysis confirms the formation of single phase compound in orthorhombic crystal system. The surface morphology of the sample, recorded by scanning electron microscope, shows uniform grain distribution on the surface of the sample. The observation of hysteresis loop confirmed that the material has ferroelectric properties at room temperature. Electrical properties of the material were studied by complex impedance spectroscopic technique. Temperature dependence of electrical parameters (impedance, modulus, etc.) is strongly correlated to the micro-structural characteristics (bulk, grain boundary, etc.) of the sample. A typical temperature-dependent resistive characteristic of the sample (i.e., negative temperature coefficient of resistance (NTCR)) exhibits its semiconducting properties. The temperature dependence of dc conductivity shows a typical Arrhenius behavior. A signature of ionic conductivity in the system was observed in ac conductivity spectrum. The sample obeys Jonscher's universal power law. The hopping mechanism for electrical transport properties of the system with nonexponential-type conductivity relaxation was suggested from the electrical modulus analysis.

IMPEDANCE SPECTROSCOPY AND MAGNETIC PROPERTIES OF AURIVILLIUS STRUCTURES

2012 ◽  
Vol 02 (03) ◽  
pp. 1250015
Author(s):  
S. K. PATRI ◽  
R. N. P. CHOUDHARY ◽  
C. RINALDI
Keyword(s):  
Electrical Properties ◽  
Impedance Spectroscopy ◽  
Complex Impedance ◽  
Hysteresis Loops ◽  
Solid State Reaction Method ◽  
Layered Perovskite ◽  
X Ray Diffraction ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Layered Perovskite Structure

Bi 9-x Fe 5+x Ti 3 O 27 (x = 0-3) compounds of bismuth layered perovskite structure have been successfully prepared by solid-state reaction method. X-ray diffraction (XRD) studies revealed the orthorhombic crystal structure of all the compounds. Impedance spectroscopy has been studied to characterize the electrical properties of polycrystalline Bi 9-x Fe 5+x Ti 3 O 27 (x = 0-3) compounds. The shape of complex impedance curves inferred the contribution of bulk and grain boundary effects on the electrical properties of the compounds. Temperature dependent magnetization measurements were made from 2 K to 300 K. Narrow hysteresis loops observed at room temperature indicate antiferromagnetic behavior of the compounds.

Rietveld Refinement and DC Conductivity of Na0.5K0.5NbO3 Ceramics

2012 ◽  
Vol 585 ◽  
pp. 210-213 ◽  
Author(s):  
Monica Sindhu ◽  
N. Ahlawat ◽  
Sujata Sanghi ◽  
Ashish Agarwal ◽  
A. Ashima ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Rietveld Refinement ◽  
Base Material ◽  
Polycrystalline Sample ◽  
Solid State Reaction Method ◽  
Dc Conductivity ◽  
Potassium Sodium Niobate ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Refinement Method

Potassium Sodium Niobate, Na0.5K0.5NbO3 is a promising base material for lead free piezoceramics. The polycrystalline sample Na0.5K0.5NbO3 was synthesized using solid state reaction method. The crystal structure and phase purity was studied by XRD and analysed using Rietveld refinement method. Good agreement was observed between the observed and calculated patterns in Rietveld refinement. The refinement inferred orthorhombic crystal structure with Amm2 space group. The impedance spectroscopy of the sample was performed in frequency range 10 Hz to 7 MHz in temperature range 573K to 703K. The activation energy was obtained to be 0.67eV from the reciprocal temperature variation of dc conductivity which follows the Arrhenius law.

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