scholarly journals Influence of A-site Cation on Structure and Dielectric Properties in A2DyBiO6 (A=Mg, Ca, Sr, Ba) Double Perovskites

2014 ◽  
Vol 67 (2) ◽  
pp. 250 ◽  
Author(s):  
Simona Feraru ◽  
Adrian I. Borhan ◽  
Petrisor Samoila ◽  
Gigel G. Nedelcu ◽  
Alexandra R. Iordan ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Sol Gel ◽  
Double Perovskite ◽  
Combustion Method ◽  
Xrd Analysis ◽  
Double Perovskites ◽  
Structural Characterisation ◽  
Auto Combustion ◽  
Xrd Patterns ◽  
A Site

Double perovskite metal oxides with formula A2DyBiO6 (A = Mg, Ca, Sr, Ba) were synthesised by a sol–gel auto-combustion method, using citric acid as the combustion agent. The effects of A-site cation on the structure, morphology, and dielectric properties were examined. The synthesis was monitored using Fourier transform infrared spectroscopy (FTIR) to indicate the absence of organic phase. X-ray diffraction (XRD) analysis showed that the compounds have three different perovskite structures. Structural characterisation of the samples was evaluated using XRD patterns. Scanning electron microscopy showed that all samples are formed by agglomerated particles. Dielectric properties were evaluated using dielectric permittivity and dielectric losses. Cole–Cole plots show a single semicircle for all materials, indicating that the double perovskites obtained are composed of well conducting grain boundaries and poorly conducting grains.

scholarly journals Nickel substituted effect of on structural, Mössbauer and dielectric properties of spinel-type lithium ferrites

2020 ◽  
Vol 21 (3) ◽  
pp. 453-461
Author(s):  
Ju. Mazurenko
Keyword(s):  
Dielectric Properties ◽  
Sol Gel ◽  
Combustion Method ◽  
Lithium Ferrite ◽  
Random Component ◽  
Lithium Ions ◽  
Spinel Type ◽  
Nickel Ions ◽  
Auto Combustion ◽  
A Site

Ni-substituted lithium ferrite Li0.5-x/2NixFe2.5-x/2O4, where (х=0.0, 0.2, 0.4, 0.6, 0.8, 1.0) synthesized through sol-gel auto-combustion method was investigated for its structural, Mossbauer, and dielectric properties. At low doses of substitution, two spinels of the same composition coexist in the structure, one of spatial group P4332, so-called spinel with superstructure, in which the iron and lithium ions are arranged along the crystallographic direction <110> and the other is a spatial group Fd3m, random spinel. The presence of both spinels is observed at low content of the doped element (x = 0.2 and 0.4). In case of increase Ni2+ ions, random component disappears and only the ordered phase remains. The particle sizes of the synthesized product are around 22-45 nm. According to the proposed cationic distribution of Nickel ions are localized in the A-site and lithium ions in the B-site. Iron ions are redistributed over both sites at a ratio of about 1:2. It is shown, that the conductive and dielectric properties of the synthesized powders have a frequency dependence characteristic of ferrite materials, the behavior of which is explained based on the hopping mechanism of conductivity and inter-grain polarization. 

Influence of the B-site cation nature on dielectric properties of Ca2XBiO6 (X = Dy, Fe, Al) double perovskite

2013 ◽  
Vol 67 (10) ◽  
Author(s):  
Simona Feraru ◽  
Petrisor Samoila ◽  
Valentin Nica ◽  
Alexandra Iordan ◽  
Mircea Palamaru
Keyword(s):  
Dielectric Properties ◽  
Sol Gel ◽  
Double Perovskite ◽  
Combustion Method ◽  
Dielectric Behavior ◽  
X Ray Diffraction ◽  
Auto Combustion ◽  
Semiconductor Behavior ◽  
The Fourier Transform ◽  
First Time

AbstractFor the synthesis of Ca2XBiO6 (X = Dy, Fe, Al) metal oxides with ordered double-perovskite structure, the sol-gel auto-combustion method has been used for the first time. The synthesis progress was followed by the Fourier transform infrared spectroscopy and the samples structure was investigated by X-ray diffraction. The samples morphology was studied by means of scanning electron microscopy. The influence of the nature of the trivalent B-site cation on the dielectric properties was evaluated by resistivity measurements in vacuum at frequencies between 102–105 Hz. The best dielectric behavior was obtained for Ca2AlBiO6 and Ca2DyBiO6, while the best semiconductor behavior was found for Ca2FeBiO6.

Influence of Ca-Doping on Structural, Magnetic and Dielectric Properties of Ba3Co2-xCaxFe24O41 Hexaferrite Powders

2015 ◽  
Vol 241 ◽  
pp. 226-236 ◽  
Author(s):  
Neha Solanki ◽  
Rajshree B. Jotania
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Sol Gel ◽  
Calcium Content ◽  
Combustion Method ◽  
Dielectric Behavior ◽  
Dielectric Parameters ◽  
Ca Doping ◽  
Auto Combustion ◽  
Magnetic And Dielectric Properties

Influence of Ca substitution on structural, magnetic and dielectric properties of Ba3Co2-xCaxFe24O41(where x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0), prepared by Sol-Gel auto-combustion method, has been investigated in present studies. The obtained powder was sintered at 950 oC for 4 hrs. in the static air atmosphere. Structural analysis of Ca-doped Ba3Co2-xCaxFe24O41powders revealed pure Z-type hexaferrite phase at low temperature. The frequency dependent dielectric constant (Єʹ) and magnetic properties such as remanent magnetization (Mr), saturation magnetization (Ms) and coercivity (Hc) were studied. It is observed that coercivity increased gradually with increase in calcium content. The real dielectric constant (Єʹ) and dielectric loss tangent (tan δ) were studied in the frequency range of 20Hz to 2MHz. The dielectric parameters for all samples show normal dielectric behavior as observed in hexaferrites. Contents of Paper

LiMn1.5Ni0.25Fe0.2M0.05O4 Nanoparticles as a Cathode Material for Rechargeable Li-Ion Batteries

2020 ◽  
Vol 835 ◽  
pp. 149-154
Author(s):  
Haitham A. Abdellatif ◽  
Mostafa M.M. Sanad ◽  
Elsayed M. Elnaggar ◽  
Mohamed M. Rashad ◽  
Gamal M. El-Kady
Keyword(s):  
Annealing Temperature ◽  
Sol Gel ◽  
Combustion Method ◽  
Xrd Analysis ◽  
Charge Transfer Resistance ◽  
Li Ion Batteries ◽  
Transfer Resistance ◽  
Auto Combustion ◽  
Li Ion ◽  
Kinetic Diffusion

New series of spinel LiNi0.25Fe0.2Mˊ0.05Mn1.5O4 (Mˊ = Cu, Mg or Zn) cathode materials have been purposefully tailored using sol-gel auto-combustion method at low annealing temperature ~ 700°C for 3 h. The XRD analysis showed that all substituted (LNFMO-Mˊ) samples are comported with the main structure of undoped (LNFMO) with crystalline disordered spinel Fd-3m structure. TEM images revealed the octahedron-shape like morphology for the particles and the LNFMO-Zn sample has the widest particle size distribution. EIS spectra evidenced that a typical one semicircle (LNFMO-Mg) was revealed for each cell, suggesting the absence of ionic conductivity contribution. The values of charge transfer resistance (Rct) were equal to 9.3, 6.7, 6.0 and 4.4 kΩ for LNFMO, LNFMO-Cu, LNFMO-Mg indicating that the Zn-doped sample has the fastest kinetic diffusion rate and lowest activation energy of conduction.

Structural, magnetic and high frequency (1–6 GHz) parameters of Sr-substituted BaFe2O4 monoferrites synthesized by sol–gel method

2019 ◽  
Vol 33 (19) ◽  
pp. 1950219 ◽  
Author(s):  
Mukhtar Ahmad ◽  
Jawaria Shaheen ◽  
Waseem Abbas Hashmi ◽  
Majid Niaz Akhtar ◽  
Muhammad Asif
Keyword(s):  
Single Phase ◽  
Sol Gel ◽  
Combustion Method ◽  
Xrd Analysis ◽  
Anisotropy Constant ◽  
Dielectric Parameters ◽  
Single Phase Sample ◽  
Heat Treated Sample ◽  
Auto Combustion ◽  
Phase Spinel

In this work, Sr-substituted samples of single-phase spinel monoferrites with chemical formula [Formula: see text] (x = 0.00, 0.33, 0.67, 1.00) were synthesized using sol–gel auto-combustion method. In order to confirm the single-phase formation of these samples, a sample (x = 0.00) was chosen for heat treatment at different temperatures (100, 300, 400, 600 and [Formula: see text]) for 4 h. The heat treated sample was then investigated by X-ray diffraction (XRD) analysis and results showed that a single-phase sample can be successfully synthesized at a temperature of [Formula: see text], which is much lower than that reported in earlier literature for synthesis of same structured samples. All the synthesized samples were then sintered at [Formula: see text] for 4 h to achieve better crystallinity. From XRD patterns, lattice parameters, cell volume and XRD density as a function of Sr-substitution were calculated. Scanning electron microscopy (SEM) results showed that the grain size increased as the temperature was increased. Fourier transform infrared spectroscopy (FTIR) results confirmed the single-phase spinel monoferrites at [Formula: see text]. From M–H loops (x = 0.0, 0.33, 0.67 and 1.00), different magnetic parameters such as saturation magnetization [Formula: see text], remanance [Formula: see text], coercivity [Formula: see text] and magnetic moment [Formula: see text] were calculated. Magnetocrystalline anisotropy constant and Y–K angles of Sr-doped Ba monoferrites were also calculated. In addition, the variation of different dielectric parameters (real permittivity, imaginary permittivity, real permeability, imaginary permeability, ac conductivity and loss tangent) as a function of frequency (1–6 GHz) has been discussed in this work. The results suggest that the synthesized materials have many advantages over previously reported single-phase spinel monoferrites.

scholarly journals THE EFFECT OF HIGH ENERGY MILLING ON THE SR-HEXAFERRITE NANOCRYSTALLINE POWDER SYNTHESIZED BY A SOL-GEL AUTOCOMBUSTION METHOD

2012 ◽  
Vol 05 ◽  
pp. 765-770
Author(s):  
S. SADEGHI-NIARAKI ◽  
S. A. SEYYED EBRAHIM ◽  
SH. RAYGAN
Keyword(s):  
Ball Mill ◽  
Sol Gel ◽  
Combustion Method ◽  
High Energy ◽  
Subsequent Annealing ◽  
Strontium Hexaferrite ◽  
Nanocrystalline Powder ◽  
X Ray ◽  
Auto Combustion ◽  
Xrd Patterns

In this research SrFe 12 O 19 nanocrystalline synthesized by sol-gel auto-combustion method and subsequent annealing at 1000°C for 1h subjected to mechanochemical treatment in a high-energy ball mill and then re-annealing. A planetary ball mill (Fritsch Pulveristte 6) was used to mill the strontium hexaferrite powder at 300 rpm in air for 10, 20 and 40 hours. The process was studied by X-ray diffraction technique and scanning electron microscopy. The X-ray study showed that SrFe 12 O 19 phase was decomposed by milling. Strontium hexaferrite and α- Fe 2 O 3 were obtained with 10 hours milling. There were α- Fe 2 O 3 and strontium hexaferrite in XRD patterns of 20 hours milled sample. With increasing of the milling time to 40 hours, strontium hexaferrite was decomposed completely. The annealing of the 20 and 40 h milled powders at 900°C for 1h led to the formation of single phase strontium hexaferrite with smaller crystallite size compare to that of the hexaferrite powder before milling and subsequent annealing.

Study of the magnetic and structural properties of Al–Cr codoped Y-type hexaferrite prepared via sol–gel auto-combustion method

2015 ◽  
Vol 29 (14) ◽  
pp. 1550090 ◽  
Author(s):  
O. Mirzaee ◽  
R. Mohamady ◽  
A. Ghasemi ◽  
Y. Alizad Farzin
Keyword(s):  
Magnetic Properties ◽  
Sol Gel ◽  
Combustion Method ◽  
Vibrating Sample Magnetometer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hexagonal Shape ◽  
Auto Combustion ◽  
Xrd Patterns ◽  
Cr Doping

Nanostructure of Y-type hexaferrite with composition of Sr 2 Ni 2 Al x/2 Cr x/2 Fe 12-x O 22 (where x are 0, 0.6, 1.2, 1.8, 2.4 and 3) were prepared by sol–gel auto-combustion method. The influence of Al and Cr doping on the structural and magnetic properties has been investigated. The X-ray diffraction (XRD) patterns confirm phase formation of Y-type hexaferrite. The microstructure and morphology of prepared samples were studied by high resolution field emission scanning electron microscope (FESEM) which shows the hexagonal shape for all of the samples. Magnetic properties were characterized using vibrating sample magnetometer (VSM). The magnetic results revealed that by increasing the Al and Cr to the structure, the coercivity was also increased from 840 Oe to 1160 Oe. Moreover it has been shown that with addition of dopants, saturation magnetization (Ms) and remnant magnetization (Mr) were decreased from 39.61 emu/g to 30.11 emu/g and from 17.51 emu/g to 14.62 emu/g, respectively, due to the entrance of nonmagnetic ions into Fe 3+ sites.

Effect of annealing temperature on dielectric properties of iron oxide prepared by sol–gel auto combustion method

2021 ◽  
Vol 577 (1) ◽  
pp. 38-51
Author(s):  
Sk Yasnur ◽  
Prasenjit Maji ◽  
Apurba Ray ◽  
Himadri Mullick ◽  
Sachindranath Das
Keyword(s):  
Iron Oxide ◽  
Dielectric Properties ◽  
Annealing Temperature ◽  
Sol Gel ◽  
Combustion Method ◽  
Auto Combustion
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