scholarly journals Studies of Structural, Dielectric and Electrical Characteristics of Complex Perovskite: Pb(Co1/3Mn1/3W1/3)O3

2020 ◽  
Vol 64 (2) ◽  
Author(s):  
P.Ganga Raju Achary ◽  
Deeptimayee Khatua ◽  
Santosh Parida ◽  
Sujit Dehury ◽  
R.N.P. Choudhary
Keyword(s):  
Complex Impedance ◽  
Orthorhombic Crystal ◽  
Solid State Reaction Technique ◽  
Dielectric Parameters ◽  
Orthorhombic Crystal Structure ◽  
Sem Image ◽  
Multiple Phase ◽  
Nyquist Plots ◽  
Diffusivity Parameter ◽  
Frequency Temperature

A lead-based multiferroic, Pb(Co1/3Mn1/3W1/3)O3, was synthesized by using a high-temperature solid-state reaction technique. Based on X-ray structural analysis, an orthorhombic crystal structure has been suggested for the material. The scanning electron microscopy (SEM) image exhibits a morphology with and uniform grains distribution. A detailed study of variation of dielectric parameters with frequency and temperature exhibits that Pb(Co1/3Mn1/3W1/3)O3 undergoes multiple phase transitions; first transition (Tc1) appeared at 436K (ferroelastic to ferroelectric) whereas second transition ( Tc2) appeared at 504K ( ferroelectric to paraelectric). Since the peaks of dielectric constant are broader and diffused, a diffusivity parameter (γ) has been estimated to the amount of disordering in the material structure.The contribution of grain,grain boundaries and electrode effect in electrical conduction mechanisim can be understood by frequency-temperature dependence of resistive characterestics using CIS spectroscopy (complex impedance spectroscopy). Impedance or Nyquist plots were modeled with an equivalent circuit having capacitance, resistance and related parameters. Studies of transport properties, ac conductivity, electrical modulus and magneto-electric (ME) effect of the materialis reported in this communication.

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.

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.

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.

IMPEDANCE SPECTROSCOPIC STUDIES OF BiFeO3-Pb(ZrTi)O3 NANOCOMPOSITES

2009 ◽  
Vol 23 (22) ◽  
pp. 2655-2664 ◽  
Author(s):  
R. N. P. CHOUDHARY ◽  
SUBRAT K. BARIK ◽  
R. S. KATIYAR
Keyword(s):  
Complex Impedance ◽  
Signal Amplitude ◽  
Dissipation Factor ◽  
Spectroscopic Studies ◽  
Solid State Reaction Technique ◽  
Dielectric Parameters ◽  
Air Atmosphere ◽  
Universal Power Law ◽  
Wide Range ◽  
Electrical Data

BiFeO 3- Pb ( ZrTi ) O 3 [i.e., ( Bi 1-x Pb x)( Fe 1-x Zr 0.6x Ti 0.4x) O 3 (x = 0.15, 0.25, 0.40, 0.50)] nanocomposites were synthesized using mechanical activation followed by a solid-state reaction technique. The dielectric parameters (capacitance, dissipation factor D, impedance Z and phase angle Φ) of all the samples were measured in a wide range of frequencies (1 kHz–1 MHz) and temperatures (300–630 K) in air atmosphere using an impedance analyzer with low signal amplitude of 500 mV. Electrical properties of the compounds were studied using a complex impedance spectroscopy (CIS) technique. The frequency dependence of electrical data was analyzed in the framework of conductivity and modulus formalisms. AC conductivity spectrum obeys Jonscher's universal power law.

Modification in structural, functional, thermal, dielectric, impedance and nonlinear optical properties of ammonium pentaborate crystal by addition of di-sodium sulphide nanoparticles

2019 ◽  
Vol 33 (07) ◽  
pp. 1950084
Author(s):  
A. P. Kochuparampil ◽  
J. H. Joshi ◽  
H. O. Jethva ◽  
M. J. Joshi
Keyword(s):  
Nonlinear Optical ◽  
Complex Impedance ◽  
Precipitation Method ◽  
Dielectric Study ◽  
Sodium Sulphide ◽  
Frequency Range ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Nlo Properties ◽  
Co Precipitation

Ammonium penataborate (APB) crystals are well known for their nonlinear optical (NLO) properties. Attempt is made to study the changes produced by addition of chalcogenide compound sodium sulphide in APB crystals. Di-sodium sulphide (Na2S) is soluble in water and its solubility is further increased for Na2S nanoparticles. The Na2S nanoparticles are synthesized by using co-precipitation method followed by microwave irradiation. The slow solvent evaporation method is used to grow pure and Na2S added APB crystals. Pure and Na2S added APB crystals possess orthorhombic crystal structure with the mixed phase nature for the Na2S added APB. The presence of sodium in APB is confirmed by AAS study. In FTIR spectra the absorption peak of S–H asymmetric stretching is observed for Na2S added APB indicating the presence of sulphur. The thermal stability of APB crystal is enhanced on doping the Na2S in it. The dielectric study is also carried out within this frequency range. The Jonscher’s power law is applied to AC conductivity data. The impedance spectroscopy study is carried out at room temperature within 100 Hz to 1 MHz frequency range. The complex impedance and modulus plots are drawn. The complex impedance plots indicate only the grain contribution. The Kurtz and Perry powder study indicates that all the crystals are exhibiting NLO properties with varying SHG efficiency.

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.

Spherulitic crystal growth in the prodissoconch larval of Crassostrea virginica

1983 ◽  
Vol 41 ◽  
pp. 518-519
Author(s):  
George G. Cocks ◽  
Louis Leibovitz ◽  
DoSuk D. Lee
Keyword(s):  
Crystal Structure ◽  
Crassostrea Virginica ◽  
Crystal Orientation ◽  
Developmental Changes ◽  
Gastrula Stage ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Stages Of Growth ◽  
Early Stages ◽  
Initial Deposition

Our understanding of the structure and the formation of inorganic minerals in the bivalve shells has been considerably advanced by the use of electron microscope. However, very little is known about the ultrastructure of valves in the larval stage of the oysters. The present study examines the developmental changes which occur between the time of conception to the early stages of Dissoconch in the Crassostrea virginica(Gmelin), focusing on the initial deposition of inorganic crystals by the oysters.The spawning was induced by elevating the temperature of the seawater where the adult oysters were conditioned. The eggs and sperm were collected separately, then immediately mixed for the fertilizations to occur. Fertilized animals were kept in the incubator where various stages of development were stopped and observed. The detailed analysis of the early stages of growth showed that CaCO3 crystals(aragonite), with orthorhombic crystal structure, are deposited as early as gastrula stage(Figuresla-b). The next stage in development, the prodissoconch, revealed that the crystal orientation is in the form of spherulites.

A New Phase of the Na+ Ion Conductor Na3PS4

2019 ◽  
Author(s):  
Theodosios Famprikis ◽  
James Dawson ◽  
François Fauth ◽  
Emmanuelle Suard ◽  
Benoit Fleutot ◽  
...  
Keyword(s):  
Solid Electrolytes ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Ion Conductor ◽  
Solid State Batteries ◽  
Density Analysis ◽  
Two Phases ◽  
Dynamics Simulations

<div> <p>Solid electrolytes are crucial for next‑generation solid‑state batteries and Na<sub>3</sub>PS<sub>4</sub> is one of the most promising Na<sup>+</sup> conductors for such applications. At present, two phases of Na<sub>3</sub>PS<sub>4</sub> have been identified and it had been thought to melt above 500 °C. In contrast, we show that it remains solid above this temperature and transforms into a third polymorph, γ, exhibiting superionic behavior. We propose an orthorhombic crystal structure for γ‑Na<sub>3</sub>PS<sub>4</sub> based on scattering density analysis of diffraction data and density functional theory calculations. We show that the Na<sup>+</sup> superionic behavior is associated with rotational motion of the thiophosphate polyanions pointing to a rotor phase, based on <i>ab initio</i> molecular dynamics simulations and supported by high‑temperature synchrotron and neutron diffraction, thermal analysis and impedance spectroscopy. These findings are of importance for the development of new polyanion‑based solid electrolytes.</p> </div>

scholarly journals Crystal Structures of New Ivermectin Pseudopolymorphs

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 172
Author(s):  
Kirill Shubin ◽  
Agris Bērziņš ◽  
Sergey Belyakov
Keyword(s):  
Crystal Structure ◽  
Molecular Conformation ◽  
Methyl Tert Butyl Ether ◽  
Minor Role ◽  
Scanning Calorimetry ◽  
Orthorhombic Crystal ◽  
Monoclinic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Space Group ◽  
Structure Space

New pseudopolymorphs of ivermectin (IVM), a potential anti-COVID-19 drug, were prepared. The crystal structure for three pseudopolymorphic crystalline forms of IVM has been determined using single-crystal X-ray crystallographic analysis. The molecular conformation of IVM in crystals has been compared with the conformation of isolated molecules modeled by DFT calculations. In a solvent with relatively small molecules (ethanol), IVM forms monoclinic crystal structure (space group I2), which contains two types of voids. When crystallized from solvents with larger molecules, like γ-valerolactone (GVL) and methyl tert-butyl ether (MTBE), IVM forms orthorhombic crystal structure (space group P212121). Calculations of the lattice energy indicate that interactions between IVM and solvents play a minor role; the main contribution to energy is made by the interactions between the molecules of IVM itself, which form a framework in the crystal structure. Interactions between IVM and molecules of solvents were evaluated using Hirshfeld surface analysis. Thermal analysis of the new pseudopolymorphs of IVM was performed by differential scanning calorimetry and thermogravimetric analysis.

Flame Retardant Polyamide 6 Composites Using NMH or NMH/MCA/APP

2011 ◽  
Vol 189-193 ◽  
pp. 1208-1211 ◽  
Author(s):  
Yan Shen ◽  
Shao Guo Wen ◽  
Ji Hu Wang ◽  
Hong Bo Liu ◽  
Hai Liang Qi ◽  
...  
Keyword(s):  
Flame Retardant ◽  
Magnesium Hydroxide ◽  
Flame Retardants ◽  
Polyamide 6 ◽  
X Ray Diffraction ◽  
Upward Trend ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Orthogonal Experiments ◽  
Nitrogen Phosphorus

In this paper, flame retardant Polyamide 6 (PA6) composites were prepared by nano-magnesium hydroxide (NMH) or its composites with melamine cyanurate(MCA) and ammonium polyphosphate(APP). Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to analyze the structure of nano-magnesium hydroxide. The properties including tensile properties, molten index (MFI), rockwell hardness and density of flame retardant PA6 were analyzed. Orthogonal experiments were used to study flame retardancy of PA6 with NMH, MCA and APP. The results showed NMH had hexagonal orthorhombic crystal structure with size of 300×200×100nm. Density of polyamide 6 showed an upward trend when the content of NMH was increasing, the mechanical properties and hardness changed little while processing performance serious declined. The flame retardance of nitrogen-phosphorus -inorganic flame retardants was not desirable.

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