scholarly journals Studies On The Electrical Properties Of Cu Substituted Li-Ferrites

1970 ◽  
Vol 35 (2) ◽  
pp. 221-228 ◽  
Author(s):  
M Samir Ullah ◽  
S Manjura Hoque ◽  
FA Khan ◽  
Saroaut Noor ◽  
MA Hakim ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Electrical Resistivity ◽  
Diffraction Method ◽  
Lattice Parameter ◽  
Compositional Variation ◽  
X Ray Diffraction ◽  
Electron Hopping ◽  
Cu Content ◽  
In The Beginning ◽  
Increasing Temperature

Polycrystalline Li-Cu mixed ferrites were prepared by double sintering ceramic technique. Cu substituted Li ferrites having the general formula Li0.5-x/2CuxFe2.5-x/2O4 where, x = 0.0 to 1.0 and the samples were sintered at 1100°C for 3 hours in the normal atmosphere. The prepared samples were confirmed in the spinel structure by the X-ray diffraction method. The lattice parameter and porosity were calculated for different compositions. The electrical resistivity and dielectric constant have been investigated as a function of composition and temperature. It was observed that the resistivity decreased with increasing temperature and exhibited semiconducting nature of the sample. The compositional variation of resistivity and dielectric constant showed inversed trend with each other at room temperature for Cu content, x > 0.3. This was found to support the electron hopping conduction mechanism. The dielectric constant increased slowly with temperature in the beginning and after that dielectric constant increased rapidly for different samples. As the temperature increased, thermal energy provided to the sample played an important role to decrease the relaxation time and hence there was an increase in dielectric constant. Dielectric constant has been observed as a function of frequency and it decreased with increasing frequency. Key words: Electrical resistivity; Porosity; Dielectric constant; Electron hopping DOI: http://dx.doi.org/10.3329/jbas.v35i2.9428 JBAS 2011; 35(2): 221-228

scholarly journals Dielectric Properties, Resistivity and Curie temperature Of Co doped CdNi perminvar ferrite

1970 ◽  
Vol 32 (1) ◽  
pp. 23-32 ◽  
Author(s):  
DK Saha ◽  
MA Hakim
Keyword(s):  
Dielectric Constant ◽  
Curie Temperature ◽  
Single Phase ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Two Samples ◽  
Good Consistency ◽  
Increasing Temperature ◽  
Academy Of Sciences

CdNi perminvar ferrites doped with Co were prepared through the solid-state reaction using conventional ceramic technique. The compositions of the ferrite were Co0.02Cd0.20Ni0.58Fe2.2O4 and Co0.02Cd0.28Cd0.28Ni0.50Fe2.2O4. X-ray diffraction study of the samples indicates the single phase of perminvar ferrites. Lattice parameter of the samples was found to be 8.3676 and 8.4249 Å for sample no. (a) of Co0.02Cd0.20Ni0.58Fe2.2O4 and sample no. (b) of Co0.02Cd0.28Ni0.50Fe2.2O4, respectively. The porosity of the samples was found to be 10.03 and 9.53%. The values of Curie temperature for the two samples were found to be 472 ± 1 and 405 ± 1°C, respectively. Resistivity of the samples was measured from room temperature up to 600°C. At 30°C resistivity was found to be 334 and 456 ohm-cm, respectively. Frequency dependent dielectric constant for the two samples has been determined from the experimental capacitance values. The value of dielectric constant at frequency, f = 1 kHz and sintering temperature Ts = 1250°C was found to be 16.6 × 106 and 56.1 × 106, for sample no. (a) and (b), respectively. Dielectric constant was observed 3.5 times higher in the Cd rich sample of Co0.02Cd0.28Ni0.50Fe2.2O4 and Co0.02Cd0.20Ni0.58Fe2.2O4. Temperature dependent dielectric constant has been measured for the samples in the temperature range of 30 - 250°C. The value of dielectric constant initially increases slowly with increasing temperature and then rises sharply until reaching a certain temperature, then it begins to decrease with further increase of temperature. Anomalies in the resistivity curves have good consistency with the temperature dependent dielectric constant and Curie temperature values. doi: 10.3329/jbas.v32i1.2438 Journal of Bangladesh Academy of Sciences, Vol. 32, No. 1, 23-32, 2008

scholarly journals Growth of sillenite Bi12FeO20 single crystals: structural, thermal, optical, photocatalytic features and first principle calculations

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Durga Sankar Vavilapalli ◽  
Ambrose A. Melvin ◽  
F. Bellarmine ◽  
Ramanjaneyulu Mannam ◽  
Srihari Velaga ◽  
...  
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Photoelectron Spectroscopy ◽  
Diffraction Method ◽  
Lattice Parameter ◽  
First Principle ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Principle Calculations ◽  
Photodegradation Efficiency

AbstractIdeal sillenite type Bi12FeO20 (BFO) micron sized single crystals have been successfully grown via inexpensive hydrothermal method. The refined single crystal X-ray diffraction data reveals cubic Bi12FeO20 structure with single crystal parameters. Occurrence of rare Fe4+ state is identified via X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The lattice parameter (a) and corresponding molar volume (Vm) of Bi12FeO20 have been measured in the temperature range of 30–700 °C by the X-ray diffraction method. The thermal expansion coefficient (α) 3.93 × 10–5 K−1 was calculated from the measured values of the parameters. Electronic structure and density of states are investigated by first principle calculations. Photoelectrochemical measurements on single crystals with bandgap of 2 eV reveal significant photo response. The photoactivity of as grown crystals were further investigated by degrading organic effluents such as Methylene blue (MB) and Congo red (CR) under natural sunlight. BFO showed photodegradation efficiency about 74.23% and 32.10% for degrading MB and CR respectively. Interesting morphology and microstructure of pointed spearhead like BFO crystals provide a new insight in designing and synthesizing multifunctional single crystals.

scholarly journals Dielectric and electrical properties of Cr substituted Mg ferrites

2015 ◽  
Vol 39 (1) ◽  
pp. 1-12 ◽  
Author(s):  
AKM Zakaria ◽  
Faizun Nesa ◽  
MA Saeed Khan ◽  
SM Yunus ◽  
NI Khan ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
Loss Tangent ◽  
Dielectric Loss Tangent ◽  
Lattice Parameter ◽  
Activation Energies ◽  
X Ray Diffraction ◽  
Constant E ◽  
Cr Concentration ◽  
Academy Of Sciences

The spinel ferrites MgCrxFe2-xO4 (0.0 ? × ?1.0) were prepared through the solid state reaction using conventional ceramic method at 1300°C in air. The homogeneous phase of the ferrite samples was observed from the X-ray diffraction study. Lattice parameter of the samples was found to decrease with increasing Cr concentration in the system obeying Vegard’s law. The ac electrical resistivity, measured as a function of temperature, decreases with the increase of temperature indicating the semiconducting nature of all the samples. The activation energies were calculated and found to decrease with increasing Cr content. The lower activation energies are associated with higher electrical conductivity. With the increase of temperature, dielectric constant (e`) and dielectric loss tangent are observed to be increased; while with the increase of frequency, dielectric constant (e`) and dielectric loss tangent decrease for all the samples.Journal of Bangladesh Academy of Sciences, Vol. 39, No. 1, 1-12, 2015

scholarly journals Physical properties of neodymium tin oxide pyrochlore ceramics

2017 ◽  
Vol 35 (3) ◽  
pp. 534-538 ◽  
Author(s):  
Adli A. Saleh ◽  
A. F. Qasrawi ◽  
G. Yumuşak ◽  
A. Mergen
Keyword(s):  
Electrical Resistivity ◽  
Physical Properties ◽  
Tin Oxide ◽  
Energy Band ◽  
Uv Light ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
Light Spectra ◽  
Uv Sensors

AbstractIn this work, physical properties of neodymium tin oxide pyrochlore ceramics prepared by solid state reaction technique are investigated by means of X-ray diffraction, scanning electron microscopy, ultraviolet-visible light (UV-Vis) spectrophotometry and temperature dependent electrical resistivity measurements. The pyrochlore is observed to have a cubic FCC crystal lattice with lattice parameter of 10.578 Å. The planes of the cubic cell are best oriented in the [2 2 2] direction. From the X-ray, the UV-Vis spectrophotometry and the electrical resistivity data analysis, the grain size, strain, dislocation density, optical and thermal energy band gaps, localized energy band tail states and resistivity activation energies are determined and discussed. The pyrochlore is observed to have an optical energy band gap of ~3.40 eV. This value corresponds to 365 nm UV light spectra which nominates the neodymium tin oxide pyrochlore ceramics for the use as UV sensors.

scholarly journals Investigation on microstructure and electrical properties of Bi doping Ca3Co4O9 nanoparticles synthesized by sol-gel process

2018 ◽  
Vol 7 (2.29) ◽  
pp. 31
Author(s):  
Mohammed M A ◽  
Izman Sudin ◽  
Alias Mohd Noor ◽  
Srithar Rajoo ◽  
Uday M B ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Electrical Properties ◽  
Sol Gel ◽  
Combustion Method ◽  
Variable Pressure ◽  
X Ray Diffraction ◽  
Sol Gel Process ◽  
Gel Combustion ◽  
Bi Doping ◽  
Increasing Temperature

In this study, nanoparticles of Bi doped Ca3-xCo4O9 [Ca3-xBixCo4O9 where x=0, 0.2, 0.4 and 0.6] were prepared by sol gel combustion method. The phase structures and microstructures of Bi doped Ca3-xCo4O9 powders preparation were investigated. The microstructural observations of different Bi doped Ca3-xCo4O9 powders were evaluated using X-ray diffraction analysis (XRD) and Variable Pressure Scanning Electron Microscope (VPSEM). The bulk Ca3-xBixCo4O9 samples were fabricated using uniaxial cold pressing technique. Electrical resistivity of bulk Ca3-xBixCo4O9 samples with different doping was measured using four-probe method from 300 to 700°K. The electrical resistivity was found to decrease with increasing temperature for the bulk Ca3-xBixCo4O9 samples. The electrical properties of Ca3-xBixCo4O9 are non-monotonic functions of x. 

EFFECT OF Ni ON THE ELECTRICAL AND MICROSTRUCTURAL PROPERTIES OF NANOCRYSTALLITES Fe2O3/TiO2 SYSTEM

2006 ◽  
Vol 13 (04) ◽  
pp. 479-484 ◽  
Author(s):  
MAGED S. SOBHY
Keyword(s):  
Electrical Resistivity ◽  
Spinel Ferrite ◽  
Average Crystalline Size ◽  
X Ray Diffraction ◽  
X Ray ◽  
Average Value ◽  
Semiconductor Behavior ◽  
Ion Substitution ◽  
Diffraction Patterns ◽  
Increasing Temperature

Nominal compositions of Ni x Ti 1-x Fe 2 O 5-δ (x = 0, 0.2, 0.4, 0.6, 0.8 and 1) were prepared by a solid state reaction using stoichiometric amounts of Fe 2 O 3/ TiO 2 system and NiO as a dopant. The effects of small substitution of Ni ions on the electrical and structural properties were studied for the above system. The X-ray diffraction patterns revealed that the ferroelectric phase of iron titanate and the spinel ferrite phase of Ni -ferrite having a single phase at x = 0 and 1, respectively. The substitution of Ni ions increases the average value of lattice constant aav. Solid–solid interaction took place between the ternary oxides at 1200°C for 4 h yielding a new phase of NiTiO 3. The presence of the three phases was confirmed by X-ray diffraction technique. The resultant compositions have nanocrystallites with average crystalline size "D av " in the range 100–300 nm. The DC electrical resistivity ρ, Curie temperature TC and activation energies for electric conduction around TC region increase as Ni ion substitution increases. The ferrite samples have a semiconductor behavior where electrical resistivity ρ decreases on increasing temperature. The activation energy for electrical conduction was affected by both the ratio "ferroelectric/ferrite" and the position of the Curie temperatures in the compositions depending on the ( Ni , Ti ) to Fe ratio.

ELECTRIC, MAGNETIC AND STRUCTURAL PROPERTIES OF HIGH-Tc OXYDIC SUPERCONDUCTORS Y2Ba4CanCun+6O2n+14

1996 ◽  
Vol 10 (25) ◽  
pp. 1261-1266
Author(s):  
L. HOMORODEAN ◽  
I. POP ◽  
I. BURDA ◽  
M. ANDRECUT ◽  
G. BORODI
Keyword(s):  
Electrical Resistivity ◽  
Magnetic Susceptibility ◽  
Diffraction Method ◽  
Linear Increase ◽  
Thermal Variation ◽  
X Ray Diffraction ◽  
High Tc ◽  
X Ray ◽  
Diamagnetic Transition ◽  
Zero Baseline

A new series of oxydic superconductors, Y 2 Ba 4 Ca n Cu n+6 O 2n+14, was synthesized. By X-ray diffraction method was pointed out that the samples are 123 phase superconductors. The temperature dependence of the electrical resistivity pointed out the zero-baseline, a linear increase and a jump. The thermal variation of the magnetic susceptibility exhibits the diamagnetic transition i.e. Tc(χ=0).

Study of microstructure and augmentation of DC electrical resistivity due to Al3+ substitution in Ni–Zn nano ferrite system synthesized via auto combustion

2015 ◽  
Vol 29 (26) ◽  
pp. 1550151 ◽  
Author(s):  
B. Rajesh Babu ◽  
K. V. Ramesh ◽  
M. Sivaram Prasad ◽  
Y. Purushotham
Keyword(s):  
Electrical Resistivity ◽  
Spinel Phase ◽  
Spinel Ferrite ◽  
Combustion Method ◽  
Lattice Parameter ◽  
Dc Electrical Resistivity ◽  
High Electrical Resistivity ◽  
Air Atmosphere ◽  
Auto Combustion ◽  
Increasing Temperature

Nanocrystalline Ni–Zn–Al spinel ferrite was synthesized via citrate-gel auto combustion method. The as-prepared powders have been separated into two batches in which one batch of powders were sintered at 1000[Formula: see text]C for 4 h and the other batch were pressed into pellets and were sintered at the same temperature. Sintering of the samples was done in air atmosphere followed by natural cooling to room temperature. The heat treated powders have then been characterized using TG–DTA, XRD, SEM and TEM for thermal, structural and microstructural aspects while the DC electrical resistivity measurements were carried out on the sintered pellets. The X-ray diffraction patterns displayed the formation of the spinel phase for all powders and the lattice parameter was obtained using Bragg’s law. The crystallite size for all compositions were found to be in nano dimensions and obtained from the Williamson–Hall method. TG–DTA analysis of the undoped [Formula: see text] indicated the formation of the spinel phase is around 400[Formula: see text]C while almost uniform microstructure with a more or less spherical grains has been noticed in the SEM micrograph. An enhancement in the DC electrical resistivity ([Formula: see text]-cm) has been observed in [Formula: see text] synthesized using this technique in comparison with that processed through conventional ceramic technique and a modification in the resistivity has been observed on substituting [Formula: see text] in place of [Formula: see text]. High electrical resistivity makes these ferrites suitable for high-frequency applications due to possible reduction of the eddy current losses. The observed variation in resistivity has been discussed on amendments in structure, microstructure and unavailability of [Formula: see text] ions with increasing [Formula: see text] ions in the light of existing understanding. The decrease in resistivity with increasing temperature confirms the semiconducting behavior of all samples. Activation energies for conduction were obtained from the slope of the log [Formula: see text] versus [Formula: see text] plots and observed to be in the range of 0.6–0.45 eV. The variation in the activation energy for conduction followed a similar trend as the DC resistivity. The drift mobility decreases with increasing [Formula: see text] ions concentration and increases with increasing temperature.

Temperature Stable Bi1.3Yb0.7O3-BaTiO3 Relaxor Ferroelectric

2011 ◽  
Vol 415-417 ◽  
pp. 1046-1050
Author(s):  
Jun Ting Qi ◽  
Jun Jie Hao ◽  
Yun Xia Zhang ◽  
Bo Liu ◽  
Xiao Jia Wang
Keyword(s):  
Dielectric Constant ◽  
Grain Size ◽  
Dielectric Loss ◽  
Diffraction Method ◽  
Relative Dielectric Constant ◽  
Relaxor Ferroelectric ◽  
X Ray Diffraction ◽  
Low Dielectric ◽  
Fracture Morphologies ◽  
Thermal Stability Of

A new system, Bi1.3Yb0.7O3-BaTiO3 was found as a perovskite dielectrics with some advantageous properties. The structure was identified by X-ray diffraction method and SEM was also employed to observe the surface and fracture morphologies. The studies indicate that the relative dielectric constant initially increases and then decreases slightly, the dielectric loss initially decreases and finally close to a stable value. The experimental results reveal that the grain size became smaller initially, then increase after the sample E and finally the sample F had the maximum grain size. Experiments show the system Bi1.3Yb0.7O3-BaTiO3 can significantly improve the thermal stability of the BaTiO3 ceramics. Electric hysteresis loop show that the system is relaxor ferroelectric. The samples doped with 20% BiYbO3 calcined at 750°C for 2h and then sintered at 1280°C for 2h exhibited attractive properties, including high relative dielectric constant (>1000), low dielectric loss (<2.5%), low temperature coefficient of capacitor (<±15%) over a wide temperature range from －55°C to +180°C, satisfying EIA X8R specifications.

scholarly journals Effect of Zinc Oxide Nano Particle Concentration in the Polyaniline-Zinc Oxide Nanocomposite on the Dielectric Property

2014 ◽  
Vol 11 (2) ◽  
pp. 146-152 ◽  
Author(s):  
N Verma
Keyword(s):  
Zinc Oxide ◽  
Zno Nanoparticles ◽  
Solid Phase ◽  
Diffraction Method ◽  
Lattice Parameter ◽  
Wave Number ◽  
Dielectric Study ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Imaging Mode

Films of polyaniline and polyaniline–ZnO composites were synthesized by spin coating. The spin coated films were deposited over glass substrate. In order to confirm the dispersion quality and the size of the dispersed ZnO, Transmission electron microscopy was done. The TEM images show that ZnO nanoparticles were spherical in shape. Dark imaging mode confirmed these particles in solid phase and revealed the uniform distribution of the particles in the PANI matrix. The absorption peaks in FTIR spectra of PANI–ZnO composite film were found to shift to higher wave number when compared with pure PANI. The observed shifts were attributed to the interaction between the ZnO particle and PANI molecular chains. A change in the value of lattice parameter of ZnO as confirmed through the X ray diffraction method in the composite indicated the presence of interaction between ZnO particles and matrix. The dielectric study of PANI and PANI–ZnO composites demonstrated a significant decrease in the value of dielectric constant after the incorporation of the ZnO nanoparticles in the polymer matrix.

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