Vinayak M Adimule; Debdas Bhowmik; Adarsha Haramballi Jagadeesha
Abstract
Gadolinium (Gd) doped titanate nanostructures (NS) with a new set of 10-50 wt. % of Gd were synthesized by microwave-assisted hydrothermal and reduction using hydrazine hydrate. The crystal structure has been evaluated with SEM (scanning electron microscopy) analysis exhibited rod like geometry of nanoparticles ...
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Gadolinium (Gd) doped titanate nanostructures (NS) with a new set of 10-50 wt. % of Gd were synthesized by microwave-assisted hydrothermal and reduction using hydrazine hydrate. The crystal structure has been evaluated with SEM (scanning electron microscopy) analysis exhibited rod like geometry of nanoparticles (NPs). XRD (X-ray diffraction spectroscopy) analysis of GdTiO3 and undoped titanate nanostructure (NS) intense peak exhibited crystal tetragonal structure. CV (cyclic voltammetry) exhibited an oxidation potential of 50 wt. % of GdTiO3 was found to be - 0.54 eV. UV-Visible spectroscopic revealed absorptivity of 50 wt. % of GdTiO3 was found to be 650 nm (visible region) and undoped titanate absorptivity at 320 nm (UV region). The pelletized nanostructures of GdTiO3 were investigated for current-voltage (I-V), capacitance-voltage (C-V), resistance-voltage (R-V) measurements, which showed frequency range in between 1 kHz to 2 MHz and 50 wt. % GdTiO3 NS showed a decreasing trend in admittance value with an increase in frequency. However, an increase in the conductance, power dissipation values with a decrease in resistivity, and increase in the frequency has been noticed which embark considerable variation in conductivity and power dissipation in GdTiO3 NS. The results from the plots of current-voltage (I-V), capacitance-voltage (C-V), and bias voltage with an applied frequency of the GdTiO3 NS has been discussed.
Mrinal Kanti Adak; Prasanta Dhak; Atreyee Kundu; Debasis Dhak
Abstract
In this present work, nanocrystalline Co 2+ and Ta 5+ substituted barium bismuth niobate Ba0.5Co0.5Bi2NbTaO9 was synthesized by chemical process. Room temperature single phase, tetragonal structure was confirmed using X-ray diffraction (XRD) study. Average crystallite and particle sizes were found to ...
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In this present work, nanocrystalline Co 2+ and Ta 5+ substituted barium bismuth niobate Ba0.5Co0.5Bi2NbTaO9 was synthesized by chemical process. Room temperature single phase, tetragonal structure was confirmed using X-ray diffraction (XRD) study. Average crystallite and particle sizes were found to be 33 nm and 40 nm, when analyzed through XRD and transmission electron microscopy (TEM) respectively. Field emission scanning electron microscopy (FESEM) was used for micro-structural investigation of samples sintered at 950?C for 4h. The investigation revealed that the material was exhibiting high dielectric constant value of 1017 at Curie temperature (Tc), 500?C when measured at 10 kHz. Impedance spectroscopy analysis showed that above 425?C, the material exhibited both bulk and grain boundary conductivities which were evidenced from FESEM studies. Density of states, minimum hoping distance, binding energy etc. were studied along with other electrical properties from impedance analysis. Hysteresis behavior was also investigated using polarization study.
M. Ramar; S. S. Rawat; R. Srivastava; S. K. Dhawan; C. K. Suman
Abstract
The impact of cross linking chain of N, N’-bis (napthalen-|-y|)-N, N’-bis(phenyl)-benzidine (NPB) was studied for opto-electrical properties having focus on temperature dependent transport properties. The Spiro structured NPB compound is closed in itself and the thin film surface roughness ...
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The impact of cross linking chain of N, N’-bis (napthalen-|-y|)-N, N’-bis(phenyl)-benzidine (NPB) was studied for opto-electrical properties having focus on temperature dependent transport properties. The Spiro structured NPB compound is closed in itself and the thin film surface roughness is less in comparison to NTNPB compounds. Both absorptions and photoluminence shows a shift of 10 nm towards higher wavelength in case of cross linked spiro structured compound. The mobility calculated in SCLC region for NT and Spiro NPB was 1.32×10 -7 and 3.3x10 -7 cm 2 V -1 s -1 , respectively. Both the compounds show single relaxations and can be modeled as an RC equivalent circuits. The dc conductivity for both the compounds was explained by Mott’s VRH models showing 3D transport mechanism. The hopping distance for NT and Spiro NPB compounds is 0.8 and 0.5 nm, respectively. The hopping conduction process can be explained clearly using correlated barrier hopping model. The cross linking of the compounds shows two orders of less density of states.
Fathy Salman; Reda Khalil;Hany Hazaa
Abstract
Impedance measurements of (50-x)P < sub>2O5-xAgI-40Ag2O-10Fe2O3, [where x = 0, 15, 20, 25, 30, 35, 40 and 45 mol %] superionic glasses have been studied in the frequency range (500 Hz - 5 MHz) and in the temperature range 303-413 K. The frequency dependence of the total conductivity (σt) for the ...
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Impedance measurements of (50-x)P < sub>2O5-xAgI-40Ag2O-10Fe2O3, [where x = 0, 15, 20, 25, 30, 35, 40 and 45 mol %] superionic glasses have been studied in the frequency range (500 Hz - 5 MHz) and in the temperature range 303-413 K. The frequency dependence of the total conductivity (σt) for the investigated samples was carried out at different ambient temperatures. The temperature dependence of ac conductivity σac(ω) and dc conductivity (σdc) were studied, where Arrhenius behavior has been observed for all the samples glass, and the corresponding activation energies ΔEac and ΔEdc, respectively have been obtained. The bulk conductivity (σb) of the samples has been carried out at different temperatures, from impedance plots, where the activation energy ΔEb can be obtained. From the frequency dependence of the ac conductivity of the investigated samples, σac(ω)=Aωs, the frequency exponent s and the maximum barrier height Wm have been deduced at different compositions. The results are interpreted in terms of the correlated barrier hopping (CBH), Funke, and Minami models.
Momin Hossain Khan;Sudipta Pal
Abstract
We report the impedance spectroscopy (IS) behavior of the ferroelectric- ferromagnetic (50% BaTi O3-50% La0.7Sr0.3MnO3) nano-composite prepared by sol-gel method. Frequency and temperature dependence of the complex impedance and conductivity has been measured over the temperature range 310 K-430 K. A ...
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We report the impedance spectroscopy (IS) behavior of the ferroelectric- ferromagnetic (50% BaTi O3-50% La0.7Sr0.3MnO3) nano-composite prepared by sol-gel method. Frequency and temperature dependence of the complex impedance and conductivity has been measured over the temperature range 310 K-430 K. A distribution of relaxation times and decentralization of the semicircle has been observed from the Cole–Cole plots of real and imaginary parts of the complex impedance. Non-Debye type relaxation has been observed in the investigated composite system. An equivalent circuit has been constructed to describe the IS. Interestingly, a typical universal dielectric response in the frequency-dependent conductivity at different temperature has been found. The frequency dependent ac conductivity at different temperature indicates that the conduction process is thermally activated. The activation energy has been obtained from the Arrhenius fitting. The obtained dc conductivity showed that the system undergoes a positive temperature coefficient resistance (PTCR) to negative temperature coefficient resistance (NTCR) near 350 K. The results would help to understand deeply the relaxation process in these types of materials.
Rajiv Ranjan; Nawnit Kumar; Banarji Behera; R. N. P.Choudhary
Abstract
Pb1-xSmx(Zr0.45Ti0.55)1-x/4O3 (PSZT; x = 0.00, 0.03 and 0.06) ceramic samples were prepared by high temperature mixed oxide method. Using complex impedance spectroscopy (CIS) technique, the complex impedance (Z*) and modulus (M*) properties of the materials were analyzed within a wide range of temperature ...
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Pb1-xSmx(Zr0.45Ti0.55)1-x/4O3 (PSZT; x = 0.00, 0.03 and 0.06) ceramic samples were prepared by high temperature mixed oxide method. Using complex impedance spectroscopy (CIS) technique, the complex impedance (Z*) and modulus (M*) properties of the materials were analyzed within a wide range of temperature and frequency. Impedance analysis indicates the presence of mostly bulk resistive (grain) contributions which is found to decrease with the increase in temperature. It suggests about the negative temperature coefficient of resistance (NTCR) type behaviour of the materials. Complex modulus plots exhibit the presence of grain (bulk) as well as grain boundary contributions in the materials and also support their NTCR type behaviour. Both the complex impedance and complex modulus plots confirm the presence of non-Debye type of relaxation in the materials. At higher temperatures, bulk resistance is found to increase with the increase in Sm 3+ concentration in PSZT along with the increase in relaxation phenomenon.
B. N. Parida; R. Padhee;R. N. P. Choudhary; Piyush R. Das
Abstract
A new ferroelectric oxide (Li2Pb2Gd2W2Ti4Nb4O30) of the tungsten bronze structural family was synthesized using a high temperature solid-state reaction (i.e., mixed-oxide) method at 1100 o C. Room temperature structural analysis (XRD) shows the formation of a new compound in single phase. The ferroelectric ...
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A new ferroelectric oxide (Li2Pb2Gd2W2Ti4Nb4O30) of the tungsten bronze structural family was synthesized using a high temperature solid-state reaction (i.e., mixed-oxide) method at 1100 o C. Room temperature structural analysis (XRD) shows the formation of a new compound in single phase. The ferroelectric phase transition temperature (much above the room temperature) was determined by the dielectric and polarization measurements. Impedance, modulus and electrical conductivity of the material exhibit a strong correlation between its micro-structure and electrical parameters. The existence of non-exponential-type of conductivity relaxation in the compound was confirmed by detailed studies of its transport properties.
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