Investigation of Structural and Dielectric Properties of Polycrystalline PbMg1∕3 Ti1∕3W1∕3O3 Tungsten Perovskite

SPIN ◽  
2020 ◽  
Vol 10 (03) ◽  
pp. 2050021
Author(s):  
P. Ganga Raju Achary ◽  
R. N. P. Choudhary ◽  
S. K. Parida
Keyword(s):  
Activation Energy ◽  
Conduction Mechanism ◽  
Complex Impedance ◽  
Interfacial Polarization ◽  
Average Crystallite Size ◽  
Solid State Reaction Method ◽  
Tetragonal Crystal ◽  
Average Grain Size ◽  
Temperature Ranges ◽  
Lead Magnesium

Lead magnesium tungsten titanate PbMg[Formula: see text] Ti[Formula: see text]W[Formula: see text]O3 was prepared by adopting a high-temperature solid-state reaction method. The sample has tetragonal crystal structure having average crystallite size 45.1325[Formula: see text]nm calculated using Scherer’s relation and the average grain size is about 40[Formula: see text]nm from Scanning Electron Microscope (SEM) measurement. Measurements of dielectric permittivity ([Formula: see text]) and loss ([Formula: see text]) have been investigated, both as a function of frequency (1[Formula: see text]kHz to 5[Formula: see text]MHz) and temperature (25–[Formula: see text]C) and the results showed the presence of interfacial polarization of the material. The dielectric spectra with frequency and temperature suggest that the prepared sample is semiconducting in nature following the NTCR behavior. The complex impedance results showed the contribution of grain and grain boundaries in the conduction mechanism. The activation energies were determined from the ac conductivity data in the temperature ranges of 200–[Formula: see text]C and 360–[Formula: see text]C. It has been observed that with the rise of frequency and temperature, the activation energy increases in the sample. The greater value of the activation energy always supports the conduction mechanism due to hopping of the charge carriers. The semicircular arcs of Cole–Cole plots confirm that the sample is semiconducting in nature which supports our dielectric results.

scholarly journals Structural, Dielectric and Impedance Spectroscopy of Cerium Doped Bamno3 Single Perovskite

2020 ◽  
Author(s):  
P.G.R. Achary ◽  
Soumakanta Khandai ◽  
Priyabrata Sahoo ◽  
R.K. Bhuyan ◽  
R.N.P. Choudhary ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Dominant Role ◽  
Complex Impedance ◽  
Average Crystallite Size ◽  
Thermally Activated ◽  
Host Materials ◽  
Average Grain Size ◽  
High Temperature Oxide ◽  
Sem Micrograph ◽  
Mixing Method

Abstract The synthesis of barium cerium manganite (BaMn0.9Ce0.1O3) perovskite compound by using a high-temperature oxide mixing method is reported. Structural analysis suggests a hexagonal crystal structure with space group P63/mmc. The average crystallite size and micro-lattice strain of the sample are about 74.4 nm and 0.107% respectively. The SEM micrograph suggests the uniform distribution of grains through well-defined grain boundaries and average grain size is about 11.9 μm. The relaxation time of the electrical process is calculated using the analysis of the real and imaginary parts of the complex impedance data, which suggests that the grain plays a dominant role compare to grain boundaries in defining the conductivity in the sample. Increase of activation energy from 96.8 meV to 689.9 meV with rise of temperature supports thermally activated conduction process. The modulus study suggests the relaxation process is controlled by the immobile charge carriers in the host materials at low-temperature range while controlled by defects at higher temperatures. The presence of semicircular arcs in both Nyquist and Cole-Cole plots confirms the semiconducting nature of the sample and find applications in solid oxide fuel cells and scintillators.

Dielectric Behavior and Impedance Spectroscopy of Bi2Sr2GdCu2Oy

2003 ◽  
Vol 17 (21) ◽  
pp. 3847-3856 ◽  
Author(s):  
M. Chandrasekhar
Keyword(s):  
Activation Energy ◽  
Temperature Region ◽  
Ac Conductivity ◽  
Room Temperature ◽  
Complex Impedance ◽  
Frequency Dispersion ◽  
Solid State Reaction Method ◽  
Dielectric Behavior ◽  
Nominal Composition ◽  
Present System

Samples with the nominal composition Bi 2 Sr 2 GdCu 2 O y in Bi -2212 where Gd replaces Ca as well as samples without Gd were prepared by solid-state reaction method. From the room temperature X-ray diffraction data, the samples were found to be similar to the single phase Bi -2212 structure. Impedance studies were performed from room temperature to 423 K at different frequencies in the range of 10 to 700 KHz. The AC conductivity increases with temperature and frequency, exhibiting frequency dispersion at low temperature region. The activation energy from AC conductivity in the high temperature region is found to be 0.432 eV. The permitivity increases with the increase in temperature and at 373 K it shows a maximum value exhibiting a dielectric loss. Complex impedance spectra are analyzed in terms of bulk relaxation and interfacial effects. The activation energy of the dipoles involved in the relaxation was estimated to be 0.482 eV. The universal power law of Jonscher is verified in the present system.

Effect of La2O3 Additions on Microstructure, Morphology and Pressure Sensing Behaviour of PZT Based Ceramics Sintered in Al2O3 Environment

2010 ◽  
Vol 173 ◽  
pp. 96-101
Author(s):  
Mohammad Hafizuddin Haji Jumali ◽  
Ying Ying Tio ◽  
Ramli Norhashimah ◽  
Mat Salleh Muhammad ◽  
Muhammad Yahaya
Keyword(s):  
Structural Investigation ◽  
Solid State Reaction Method ◽  
Conventional Solid State Reaction ◽  
Pressure Sensing ◽  
Novel Approach ◽  
Tetragonal Crystal ◽  
Tetragonal Crystal Structure ◽  
Average Grain Size ◽  
Custom Made ◽  
Microstructure Morphology

Effect of La2O3 addition on microstructure, morphology and pressure sensing behaviour of (Pb1-x, Lax)(Zr0.52, Ti0.48)O3 based ceramics was studied in three different compositions of La2O3, namely x = 0.10, 0.12 and 0.15. The samples were prepared through a conventional solid-state reaction method using high purity metal oxides powders. In order to control the PbO losses due to high sintering temperature, a novel approach was explored whereby the samples were sintered in Al2O3 environment. Structural investigation using XRD revealed that all samples exhibited a tetragonal crystal structure. However the c/a ratios exhibited a decreasing trend as the La2O3 content increased, indicating that (Pb1-x, Lax)(Zr0.52, Ti0.48)O3 crystals gradually evolved towards pseudocubic structure. SEM micrographs showed that in all samples the grains have uniform pebble stone morphology. The average grain size reduced from ~ 4.5 µm to ~ 3.0 µm with the increment of La¬2O3 content. The performance of pressure sensing behaviour which was investigated using custom-made pressure chamber showed that sample with composition of x = 0.10 exhibited the best piezoelectric properties with high pressure sensitivity, good stability and repeatability.

Transformation of Structure, Magnetic Properties and Microwave Absorption Capability in Nd-Doped Strontium Hexaferrite

2020 ◽  
Vol 855 ◽  
pp. 255-260
Author(s):  
Mukhtar Effendi ◽  
Efi Solihah ◽  
Candra Kurniawan ◽  
Wahyu Tri Cahyanto ◽  
Wahyu Widanarto
Keyword(s):  
Magnetic Properties ◽  
Microwave Absorption ◽  
Solid State Reaction Method ◽  
Strontium Hexaferrite ◽  
Basic Material ◽  
X Ray Diffraction ◽  
Cell Parameters ◽  
Tetragonal Crystal ◽  
Capability Analysis ◽  
Natural Iron

The synthesize of Nd3+-strontium hexaferrite magnetic material by the solid-state reaction method has been successfully carried out. This study aims to determine the effect of Nd3+ on the structure, magnetic properties, and microwave absorption capability of the material. Preparation of (1-x)SrO:xNd2O3:6Fe2O3 where x = 0, 10, 20, and 30 mol% using basic material in the form of SrCO3 powder, Nd2O3 powder and Fe3O4 from natural iron sand. The characterization includes the X-Ray Diffraction (XRD) examination to determine the crystal structure, the Scanning Electron Microscope (SEM) for exploring the surface morphology, Vibrating Sample Magnetometer (VSM) for the magnetic properties investigation of material, and Vector Network Analyzer (VNA) for microwave absorption capability analysis. The XRD results show that the addition of Nd3+ doping increases the number of SrNdFeO4 phases. The phase has a tetragonal crystal system that has cell parameters a = b = 3.846 Å, and c = 12.594 Å. The magnetic properties of the material showed that the addition of Nd3+ decreased the saturation and remanence magnetization values, whereas the value of the coercivity field increased. Meanwhile, the best microwave absorption occurs in samples with the addition of Nd3+ as much as 0.3 mol, which results in a reflection loss value of -18.9 dB with a frequency bandwidth of 3.9 GHz.

Influence of Excess Bi2O3 and Na2Co3 on Crystal Structure and Microstructure of Bismuth Sodium Titanate Ceramics

2011 ◽  
Vol 474-476 ◽  
pp. 1711-1714 ◽  
Author(s):  
Panadda Sittiketkron ◽  
Arrak Klinbumrung ◽  
Theerachai Bongkarn
Keyword(s):  
Crystal Structure ◽  
Dielectric Properties ◽  
Perovskite Phase ◽  
Average Particle Size ◽  
Sodium Titanate ◽  
Solid State Reaction Method ◽  
Lattice Parameter ◽  
Rhombohedral Structure ◽  
Average Particle ◽  
Average Grain Size

This study investigated the influence of excess Bi2O3 and Na2CO3 on the crystal structure, microstructure and dielectric properties of (Bi0.5Na0.5)TiO3 (BNT) ceramics. The BNT ceramics were synthesized using the solid-state reaction method with various excess Bi2O3 and Na2CO3 levels (0, 1, 2, 3 and 4 mol%). The X-ray characterization revealed that all samples had a rhombohedral structure. A pure perovskite phase was obtained in all samples. The lattice parameter a tended to increase with increased excess Bi2O3 and Na2CO3 content in the calcined powders and sintered ceramics. The average particle size increased while, the average grain size tended to decreased with increased of excess Bi2O3 and Na2CO3 content. The depolarization temperature (Td) and the Curie temperature (Tc) were slightly decreased with the increase of excess Bi2O3 and Na2CO3 content. The dielectric properties were related to the density.

High Tc Oxide Solid State Reaction Kinetics Via Complex Impedance Spectroscopy

1989 ◽  
Vol 169 ◽  
Author(s):  
E. A. Cooper ◽  
T. O. Mason ◽  
U. Balachandran ◽  
M. L. Kullberg
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Solid State ◽  
Solid State Reaction ◽  
Complex Impedance ◽  
Particle Size Effect ◽  
Large Temperature ◽  
Impedance Spectra ◽  
High Tc ◽  
Solid State Reaction Kinetics

AbstractImpedance spectra (5Hz ‐ 13MHz) were collected during the solid state reaction of Yba2Cu2O6+y from large monosized CuO particles imbedded in a finely divided Y2 O3 /BaCO3 matrix. No particle size effect was observed, but a large temperature effect was observed corresponding to an activation energy of approximately 1.8eV (175kJ/mol) over the range 700‐900°C.

Thermal Stability of Ultrafine-Grained Pure Titanium Processed by High-Pressure Torsion

2021 ◽  
Vol 1016 ◽  
pp. 338-344
Author(s):  
Wan Ji Chen ◽  
Jie Xu ◽  
De Tong Liu ◽  
De Bin Shan ◽  
Bin Guo ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Grain Size ◽  
High Pressure ◽  
Annealing Temperature ◽  
High Pressure Torsion ◽  
Stored Energy ◽  
Ultrafine Grained ◽  
Average Grain Size ◽  
Thermal Stability Of

High-pressure torsion (HPT) was conducted under 6.0 GPa on commercial purity titanium up to 10 turns. An ultrafine-grained (UFG) pure Ti with an average grain size of ~96 nm was obtained. The thermal properties of these samples were studied by using differential scanning calorimeter (DSC) which allowed the quantitative determination of the evolution of stored energy, the recrystallization temperatures, the activation energy involved in the recrystallization of the material and the evolution of the recrystallized fraction with temperature. The results show that the stored energy increases, beyond which the stored energy seems to level off to a saturated value with increase of HPT up to 5 turns. An average activation energy of about 101 kJ/mol for the recrystallization of 5 turns samples was determined. Also, the thermal stability of the grains of the 5 turns samples with subsequent heat treatments were investigated by microstructural analysis and Vickers microhardness measurements. It is shown that the average grain size remains below 246 nm when the annealing temperature is below 500 °C, and the size of the grains increases significantly for samples at the annealing temperature of 600 °C.

Effect of Ni Substitution to Structure and Morphology of Ca0.9La0.05Bi0.05Mn1-xNixO3 by Sol-Gel Method

2020 ◽  
Vol 860 ◽  
pp. 117-121
Author(s):  
Mochammad Alfin Naufal Nur ◽  
Budhy Kurniawan
Keyword(s):  
Sol Gel ◽  
Average Crystallite Size ◽  
Morphological Properties ◽  
X Ray Diffraction ◽  
Gel Method ◽  
Sol Gel Method ◽  
Electrical And Magnetic Properties ◽  
Ni Content ◽  
Average Grain Size ◽  
Ni Substitution

The polycrystalline Ca0.9La0.05Bi0.05Mn1-xNixO3 (x = 0.025, 0.05, 0.075) samples were synthesized by sol-gel method. All samples were calcined at 650°C for 8 hours and sintered at 900°C for 8 hours. The structural and morphological properties of the samples were measured by X-ray diffraction (XRD) and Scanning electron microscope (SEM). The rietveld refinement shows that all samples were having an orthorhombic structure with pnma space group despite having different Ni content. Furthermore, the average crystallite size decreases with Ni substituion. SEM result shows the average grain size decreases with increasing Ni substitution regardless of the same heat treatment. This result will affect other properties like electrical and magnetic properties.

The Structure-Property-Processing Relationship for Sintered Yttria-Stabilized Zirconia (YSZ)/Alumina Bioceramics

2013 ◽  
Vol 25 (04) ◽  
pp. 1350005 ◽  
Author(s):  
Sea-Fue Wang ◽  
Thomas Chung-Kuang Yang ◽  
Ya-Ting Hsu ◽  
Sheng-Yang Lee ◽  
Jen-Chang Yang
Keyword(s):  
Fracture Toughness ◽  
Relative Density ◽  
Sintering Temperature ◽  
High Hardness ◽  
Solid State Reaction Method ◽  
Sintering Behavior ◽  
Structure Property ◽  
Stabilized Zirconia ◽  
Average Grain Size ◽  
Alumina Addition

The objective of this research is to study the effects of alumina addition on the microstructure-mechanical property relationship and sintering behavior of yttria (3 mol%)-stabilized zirconia (YSZ) ceramics. Well-dispersed YSZ / Al 2 O 3 ceramics containing 10–40 wt.% Al 2 O 3 were prepared by solid state reaction method. The relative density, average grain size, lattice parameters, microhardness, and fracture toughness of YSZ / Al 2 O 3 ceramics system sintered in the temperature range of 1250~1500°C as a function of Al 2 O 3 content were investigated. Experimental results showed that the ceramics with high Al 2 O 3 content and low sintering temperature tended to reveal low bulk densities. But the Al 2 O 3 content dependence on relative density for YSZ / Al 2 O 3 ceramics becomed deminishing when increasing the sintering temperature. Dense ceramics with composition of (80/20) ( YSZ / Al 2 O 3) and sintered at temperature of 1400°C and 1450°C revealed the optimal Vickers hardness and fracture toughness properties. These ceramics with high Al 2 O 3 content tended to reveal small grain sizes. The high sintering temperature governs the slow grain growth and high hardness in materials indicating the good correlation between microstructure of fabricated dense and mechanical properties.

Effects of La Doping on the Structural and Dielectric Properties of Barium Titanate Ceramics

2014 ◽  
Vol 975 ◽  
pp. 36-41
Author(s):  
Marcelo S. Silva ◽  
Nilson S. Ferreira
Keyword(s):  
Grain Boundary ◽  
Solid State Reaction Method ◽  
Boundary Region ◽  
Homogeneous Distribution ◽  
Sem Images ◽  
Tetragonal Crystal ◽  
Brick Layer Model ◽  
Lower Temperature ◽  
Clear Shift ◽  
Titanate Ceramics

Polycrystalline samples of Ba1-xLaxTiO3 (x = 0.0, 0.002, 0.004) were prepared by a standard high-temperature solid-state reaction method. XRD studies confirmed the formation of a polycrystalline compound with a tetragonal crystal structure. SEM images suggested the presence of a polycrystalline microstructure with certain degree of porosity, and the grains appeared to be distributed inhomogeneously throughout the pallet samples. Dielectric studies indicated a ferroelectric–paraelectric phase transition with a clear shift in the Curie temperature (Tc) of BaTiO3 towards a lower temperature upon doping. The brick-layer model was used to study the potential barrier and the structure of the grain-boundary region of the Ba9.998La0.002TiO3 and Ba9.996La0.004TiO3 ceramics. These ceramics exhibited good density and a homogeneous distribution of the grains. The thickness of the grain-boundary region was calculated to be approximately 200 nm.

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