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.

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.

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.

scholarly journals Dielectric relaxation and modulus spectroscopy analysis of (Na0.47 K0.47 Li0.06) NbO3 ceramics

2017 ◽  
Vol 07 (03) ◽  
pp. 1750020 ◽  
Author(s):  
Md Kashif Shamim ◽  
Seema Sharma ◽  
Sangeeta Sinha ◽  
Eqra Nasreen
Keyword(s):  
Dielectric Relaxation ◽  
Spectroscopic Analysis ◽  
Microwave Sintering ◽  
Complex Impedance ◽  
Tungsten Bronze ◽  
Negative Temperature ◽  
Nyquist Plot ◽  
Orthorhombic Symmetry ◽  
Modulus Spectroscopy ◽  
C Complex

We have investigated the structure, dielectric and electrical properties of lead-free polycrystalline (Na[Formula: see text] K[Formula: see text] Li[Formula: see text]) NbO3 ceramics as a function of temperature and frequency in order to understand the intrinsic contribution of grain/bulk and grain boundary effects toward the dielectric response as well as the electrical conduction mechanism in the samples fabricated by microwave sintering method. X-ray diffraction analysis exhibits perovskite structure with orthorhombic symmetry, which is well supported by the Raman spectroscopic analysis. A minor secondary impurity phase of tungsten bronze structure was observed for samples sintered at 1050[Formula: see text]C, which gets weaker for samples sintered at 1150[Formula: see text]C. Dielectric permittivity was enhanced by 50%, although there was a reduction in the dielectric loss by about 50% at Curie temperature (450[Formula: see text]C) for samples sintered at 1150[Formula: see text]C. Complex impedance spectroscopic analysis indicated non-Debye-type dielectric relaxation present in the samples, and this phenomenon followed thermally activated process related to hopping mechanism. Nyquist plot showed the negative temperature coefficient of resistance, characteristic of the samples.

scholarly journals Effect of Gate Dielectrics on the Performance of P-Type Cu2O TFTs Processed at Room Temperature

2013 ◽  
Vol 856 ◽  
pp. 215-219 ◽  
Author(s):  
H.A. Al-Jawhari ◽  
J.A. Caraveo-Frescsa
Keyword(s):  
Indium Tin Oxide ◽  
Room Temperature ◽  
Single Phase ◽  
Gate Dielectric ◽  
Gate Dielectrics ◽  
Operating Voltage ◽  
Dc Magnetron Sputtering ◽  
Post Annealing ◽  
Semiconducting Properties ◽  
P Type

Single-phase Cu2O films with p-type semiconducting properties were successfully deposited by reactive DC magnetron sputtering at room temperature followed by post annealing process at 200°C. Subsequently, such films were used to fabricate bottom gate p-channel Cu2O thin film transistors (TFTs). The effect of using high-κ SrTiO3 (STO) as a gate dielectric on the Cu2O TFT performance was investigated. The results were then compared to our baseline process which uses a 220 nm aluminum titanium oxide (ATO) dielectric deposited on a glass substrate coated with a 200 nm indium tin oxide (ITO) gate electrode. We found that with a 150 nm thick STO, the Cu2O TFTs exhibited a p-type behavior with a field-effect mobility of 0.54 cm2.V-1.s-1, an on/off ratio of around 44, threshold voltage equaling-0.62 V and a sub threshold swing of 1.64 V/dec. These values were obtained at a low operating voltage of-2V. The advantages of using STO as a gate dielectric relative to ATO are discussed.

Relaxation mechanism and conductivity studies of lead-free ceramics: Fe1/2(NaLi)1/4TiO3

2020 ◽  
Vol 34 (06) ◽  
pp. 2050081
Author(s):  
Subrat Kumar Barik ◽  
A. R. Atique Ulla
Keyword(s):  
Complex Impedance ◽  
Negative Temperature ◽  
Relaxation Mechanism ◽  
Lead Free ◽  
X Ray Diffraction ◽  
Prepared Sample ◽  
Lead Free Ceramics ◽  
Wide Range ◽  
Different Temperatures ◽  
Energy Formula

A single-phase lead-free ferroelectric compound, Fe[Formula: see text](NaLi)[Formula: see text]TiO3, is found at room temperature. The solid state reaction technique helps to process the sample at the calcination and sintering temperatures of 900 and 950[Formula: see text][Formula: see text]C for 4 h respectively. The desired phase and crystal structure formation of the prepared sample are confirmed by analysis of X-ray diffraction (XRD) data and are found to be in orthorhombic structure. The correlation among phase formation and physical properties has been established by using complex impedance spectroscopy (CIS) method over a wide range of frequencies (from 100 Hz to 1 MHz) and different temperatures (25–280[Formula: see text][Formula: see text]C). The overlap depressed semicircular arcs represent the association of grain and grain boundary effects in the material. Activation energy [Formula: see text] is noted to be 1 eV for the prepared sample. The frequency dependent ac conductivity is followed by Jonscher’s universal power law. DC conductivity versus temperature graph also indicates the negative temperature coefficient of resistance (NTCR) behavior of the material.

scholarly journals Ferroelectric Properties ofNa2Pb2R2W2Ti4V4O30(R = Dy, Pr) Ceramics

2007 ◽  
Vol 2007 ◽  
pp. 1-5 ◽  
Author(s):  
Piyush R. Das ◽  
Banarji Behera ◽  
R. N. P. Choudhary ◽  
B. K. Samantray
Keyword(s):  
Room Temperature ◽  
Single Phase ◽  
Ferroelectric Properties ◽  
X Ray Diffraction ◽  
Orthorhombic Crystal ◽  
Solid State Reaction Technique ◽  
Orthorhombic Crystal Structure ◽  
Preparation Conditions ◽  
Polarization Study ◽  
Ferroelectric Phase Transitions

The polycrystalline samples ofNa2Pb2R2W2Ti4V4O30(R = Dy, Pr) were prepared by low-temperature, (i.e., at650∘C) solid-state reaction technique. The preparation conditions have been optimized using thermogravimetry analysis (TGA) technique. X-ray diffraction (XRD) studies of the compounds showed the formation of a single-phase orthorhombic crystal structure at room temperature. Studies of dielectric properties (ɛrand tanδ) of the compounds at frequencies 10, 100, and 1000 kHz in a wide temperature range (room temperature–500∘C) exhibit ferroelectric phase transitions at132∘Cfor NPDWTV and at122∘Cfor NPPWTV of diffuse type. Ferroelectric properties of the materials are confirmed by polarization study.

Growth of CuInGaSe2 Films by RF Sputtering Using CuInGaSe2 Single Phase Target

2013 ◽  
Vol 372 ◽  
pp. 571-574
Author(s):  
Kenji Yoshino ◽  
Takahiro Tokuda ◽  
Akira Nagaoka ◽  
Kenichiro Miseki ◽  
Rie Mori ◽  
...  
Keyword(s):  
Room Temperature ◽  
Single Phase ◽  
Rf Sputtering ◽  
Diffraction Peak ◽  
Secondary Phases ◽  
X Ray Diffraction ◽  
High Quality ◽  
Homogeneous Surface ◽  
X Ray

CuIn0.8Ga0.2Se2 thin film is grown at room temperature by RF sputtering using high quality of CuIn0.8Ga0.2Se2 single phase target. A (112) diffraction peak is dominant with no secondary phases such as selenide materials in the X-ray diffraction pattern. A flat and homogeneous surface can be obtained in the sample.

scholarly journals Evaluation of structure, dielectric and electrical properties of (Li/Ta/Sb) modified (Na, K) NbO3 lead-free ceramics with excess Na concentration

2017 ◽  
Vol 07 (06) ◽  
pp. 1750037 ◽  
Author(s):  
Md. Kashif Shamim ◽  
Arpana Singh ◽  
Seema Sharma
Keyword(s):  
Single Phase ◽  
Ferroelectric Properties ◽  
Structural Phase ◽  
Complex Impedance ◽  
Negative Temperature ◽  
X Ray Diffraction ◽  
Electrical Measurements ◽  
Lead Free Ceramics ◽  
Raman Modes

Polycrystalline perovskite structured (Li[Formula: see text] (Na[Formula: see text] K[Formula: see text])[Formula: see text] (Nb[Formula: see text]Ta[Formula: see text] Sb[Formula: see text] O3 ceramics with [Formula: see text], 0.005 and 0.01 mole excess Na concentration were prepared by solid state sintering method. The present study relates the role of excess Na addition with the stoichiometry, density, structure, dielectric and ferroelectric properties of the samples. X-ray diffraction (XRD) pattern exhibits single phase orthorhombic structure. The characteristic Raman modes were observed due to translational modes of cations and vibrational modes of NbO6 octahedra and no structural phase transition were observed. This confirms the formation of single phase perovskite structure and is consistent with XRD results. The dielectric permittivity increases about two times, while dielectric loss decreases by four times for [Formula: see text] composition. The electrical measurements carried by Complex Impedance spectroscopic analysis suggest negative temperature coefficient of resistance (NTCR) behavior.

Temperature-Dependent Structural Disintegration of Delafossite CuFeO2

2009 ◽  
Vol 1183 ◽  
Author(s):  
Shojan P Pavunny ◽  
Ashok Kumar ◽  
Reji Thomas ◽  
Nishit M Murari ◽  
Ram S Katiyar
Keyword(s):  
Raman Spectra ◽  
Room Temperature ◽  
Single Phase ◽  
Significant Shift ◽  
Gravimetric Analysis ◽  
Temperature Dependent ◽  
Thermo Gravimetric ◽  
Xps Spectra ◽  
X Ray ◽  
Wide Range

AbstractSingle phase delafossite p-type CuFeO2 (CFO) semiconductor was synthesized in bulk by modified solid state reaction technique. X-ray diffraction (XRD) and X-ray photo spectroscopy (XPS) studies suggest single phase CFO at room temperature. The energy dispersive X-ray spectroscopy (EDX) revealed that the atomic ratio of Cu and Fe is 1:1. The XPS spectra showed two intense Cu 2p3/2 and 2p1/2 peaks at 932.5 eV and 952 eV suggesting Cu is in +1 state. The temperature dependent Raman spectra of CFO displayed two intense modes at 349 cm-1 and 690 cm-1 at room temperature that matched with other delaffosite structures. The temperature dependent Raman spectra showed significant shift in both Raman active modes to lower frequency side. We observed the disappearance of pure CFO Raman active modes above 750 K and the appearance of new peaks related to CuO compounds, indicating disintegration of CFO starting above 750 K which almost completed above 1100 K. The temperature dependent thermo-gravimetric analysis indicates change in CFO mass above 750 K with wide range of differential thermo-gravimetric slope suggests disintegration started above 750 K and completed at 1100 K. Raman spectra, XPS, and XRD of disintegrated CFO matched well with the Raman spectra, XPS and XRD of CuO and CuFe2O4 confirmed its disintegration above 750 K in air.

Electron Paramagnetic Resonance in Cu2O Compared with Other Semiconducting Properties

1971 ◽  
Vol 49 (10) ◽  
pp. 1275-1283 ◽  
Author(s):  
J. C. W. Taylor ◽  
F. L. Weichman ◽  
R. E. D. McClung
Keyword(s):  
Activation Energy ◽  
Electron Paramagnetic Resonance ◽  
Single Crystals ◽  
Room Temperature ◽  
Starting Material ◽  
Paramagnetic Resonance ◽  
Semiconducting Properties ◽  
Wide Range ◽  
Temperature Activation ◽  
Electron Paramagnetic

Electron paramagnetic resonance spectra have been observed in single crystals of Cu2O at 4.2 °K. Six samples cut from the same starting material were individually heated under a wide range of vacuum conditions and comparison was made between the observed e.p.r. spectrum and the luminescence, activation energy, and photoconductivity in the same sample. No direct relationships between e.p.r. spectra and the luminescence and photoconductivity were found although a good correlation between the complexity of the e.p.r. spectra and the room temperature activation energy was observed.

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