scholarly journals Insight into Structural and Optical Properties of Pristine and Sr2+ Doped La2NiMnO6

2021 ◽  
Vol 58 (2) ◽  
pp. 59-71
Author(s):  
Javed Ahmad ◽  
Shoaib Hassan ◽  
Jamshaid Alam Khan ◽  
Umair Nissar ◽  
Hammad Abbas
Keyword(s):  
Sol Gel ◽  
Average Crystallite Size ◽  
Tangent Loss ◽  
Double Perovskites ◽  
Phonon Modes ◽  
Lorentz Oscillator ◽  
Reflectivity Spectra ◽  
Gel Technique ◽  
A Site ◽  
Insight Into

Double perovskites oxide (DPO) multiferroics La2-xSrxNiMnO6(x=0.0, 0.1, 0.2, 0.4, 0.6) are synthesized by sol-gel technique. The structural, optical and electrical (both DC and AC) properties of La2-xSrxNiMnO6 have been investigated by XRD and FTIR spectroscopy and two-probe resistivity and dielectric measurements as a function of temperature, respectively. The effect of doping of Strontium at A-site in double perovskites is discussed. XRD has revealed the formation of monoclinic structure of La2-xSrxNiMnO6 with space group P21 / n for x=0.0 and P21 for x=0.1, 0.2, 0.4, 0.6. The average crystallite size has been calculated to be in the range 31 to 46 nm as determined by Debye Scherrer equation. Infrared active optical phonons observed from reflectivity spectra have been analysed fitting the theoretical oscillators using Lorentz oscillator model. We have observed several well-resolved phonon modes in La2-xSrxNiMnO6 with increasing dopant concentration. Activation energy calculated using Arrhenius Plot is in the range of 0.31 to 0.18 eV, confirming the semiconducting nature of all samples. The dielectric constant and tangent loss as a function of temperature and frequency are also discussed for these multiferroics.

Optical phonons and its effect on physical properties of rare-earth orthoferrites RFeO3 (R = La, Nd, Gd, Dy, Er): IR reflectivity measurements

2018 ◽  
Vol 32 (21) ◽  
pp. 1850229
Author(s):  
Muhammad Tufiq Jamil ◽  
Javed Ahmad ◽  
Syed Hamad Bukhari ◽  
Hammad Ahmad
Keyword(s):  
Sol Gel ◽  
Structural Evolution ◽  
Electrical Measurements ◽  
Phonon Modes ◽  
Lorentz Oscillator ◽  
Reflectivity Spectra ◽  
Visible Spectra ◽  
Atomic Vibrations ◽  
Uv Visible ◽  
Method Analysis

We have investigated the infrared reflectivity, UV-visible spectra and electrical property of polycrystalline RFeO3 (R = La, Nd, Gd, Dy, Er) synthesized by sol–gel method. Analysis of IR reflectivity spectra through Lorentz oscillator model has led to the observation of 14 IR active phonon modes out of 25 predicted modes. The results have been discussed in terms of different phonon bands related to the origin of atomic vibrations, which provides information about the structural evolution. The energy bandgap [Formula: see text]1.67–1.90 eV estimated from optical conductivity ([Formula: see text]([Formula: see text])) spectrum is found consistent both with that calculated from UV-visible spectra and estimated from electrical measurements.

Structural and Optical Characterization of Synthesized TiO2 Nanopowder Using Sol–Gel Technique

2016 ◽  
Vol 15 (01n02) ◽  
pp. 1650002 ◽  
Author(s):  
S. Lourduraj ◽  
R. Victor Williams
Keyword(s):  
Anatase Phase ◽  
Sol Gel ◽  
Visible Spectrum ◽  
Average Crystallite Size ◽  
Xrd Analysis ◽  
Force Microscopy ◽  
Morphological Studies ◽  
Atomic Force ◽  
Gel Technique

The nanocrystalline TiO2 powder was synthesized by sol–gel method. The XRD analysis reveals that TiO2 powder was highly crystalline (anatase phase) and nanostructured with tetragonal system. The average crystallite size after calcined at 673[Formula: see text]K is found to be 7.7[Formula: see text]nm. The surface morphological studies using scanning electron microscopy (SEM) exhibit that the formation of nanosized TiO2 particles with less densification nature. Atomic force microscopy (AFM) topography exhibits the uniform distribution of spherical-shaped particles. The energy dispersive X-ray spectroscopy (EDX) confirms the presence of Titanium and Oxygen in synthesized TiO2 nanopowder. The value of optical bandgap of TiO2 nanopowder calculated from UV-Visible spectrum is 3.45[Formula: see text]eV. The presence of TiO2 particles is confirmed from the dominant fourier transform infrared (FTIR) peaks at 621[Formula: see text]cm[Formula: see text] and 412[Formula: see text]cm[Formula: see text].

Infrared reflectance spectroscopy of MgAl2O4 nanoparticles substituted by K+ ions

2018 ◽  
Vol 32 (06) ◽  
pp. 1850067 ◽  
Author(s):  
Javed Ahmad ◽  
M. Qadeer Awan ◽  
Roomana Yasmin ◽  
Maria Sabir ◽  
Shafiq Anwar ◽  
...  
Keyword(s):  
Room Temperature ◽  
Longitudinal Optical ◽  
Reflectance Spectroscopy ◽  
Optical Parameters ◽  
Frequency Range ◽  
Phonon Modes ◽  
Metallic Behavior ◽  
Lorentz Oscillator ◽  
Reflectivity Spectra ◽  
Ftir Spectrometer

The infrared reflectivity spectra for potassium-doped polycrystalline magnesium aluminates Mg[Formula: see text]K[Formula: see text]Al2O4 (x=0, 0.25, 0.50, 0.75, 1) are measured in the frequency range between 10–15, 500 cm[Formula: see text] using FTIR spectrometer at room-temperature. Four optical phonon modes are observed in measured spectra, which are fitted by Lorentz oscillator model for semiconducting behavior and Lorentz–Drude model for metallic behavior. Moreover, optical parameters are also determined for these modes which may attribute to spinel structure for samples Mg[Formula: see text]K[Formula: see text]Al2O4, their reflectivity spectra shows a typical semiconducting nature. To study ionicity and effect of polarization, Born and Szigeti effective charges are calculated from longitudinal optical and transverse optical (LO–TO) splitting of modes for all samples. Optical bandgap has been estimated through optical conductivity ([Formula: see text]([Formula: see text])) and found to be x dependent.

Effect of A-site cationic radius on ceramic La0.67−xDyxSr0.33MnO3 prepared by sol–gel technique

2020 ◽  
Vol 31 (10) ◽  
pp. 7623-7629
Author(s):  
Fuxin Ling ◽  
Di Li ◽  
Ling Li ◽  
Hui Zhang ◽  
Ping Yu ◽  
...  
Keyword(s):  
Sol Gel ◽  
Gel Technique ◽  
Cationic Radius ◽  
A Site

scholarly journals Influence of Ni substitution on structural, morphological, dielectric, magnetic and optical properties of Cu–Zn ferrite by double sintering sol–gel technique

2019 ◽  
Vol 09 (02) ◽  
pp. 1950020 ◽  
Author(s):  
Mohammad Sajjad Hossain ◽  
Yeasmin Akter ◽  
Mohammad Shahjahan ◽  
Muhammad Shahriar Bashar ◽  
Most. Hosney Ara Begum ◽  
...  
Keyword(s):  
Optical Properties ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
Combustion Method ◽  
Lattice Parameter ◽  
Munk Function ◽  
Zn Ferrite ◽  
Auto Combustion ◽  
Elemental Analyses ◽  
Gel Technique

Polycrystalline NiCuZn ferrite (NixCu[Formula: see text]Zn[Formula: see text]Fe2O4; [Formula: see text], 0.3, 0.4 and 0.5) were prepared through sol–gel auto combustion method applying double sintering technique. Structural, morphological, elemental analyses (EDS), Fourier-transform infrared spectroscopy (FTIR), Direct Current (DC) electrical resistivity, dielectric, magnetic and optical properties of prepared samples were analyzed. XRD profiles reveal the formation of simple cubic spinel structure without any traceable impurity. The average crystallite size lies within the range of 22–29[Formula: see text]nm. Lattice parameter decreases with increasing Ni concentration. Room temperature DC resistivity was recorded from [Formula: see text] to [Formula: see text][Formula: see text][Formula: see text][Formula: see text]cm. Both dielectric constant ([Formula: see text]) and loss factor (tan[Formula: see text]) were decreased with increase of frequency while AC conductivity increases. FTIR absorption peak occurred at three different frequency ranges at 570–577[Formula: see text]cm[Formula: see text], 1635–1662[Formula: see text]cm[Formula: see text] and 3439–3448[Formula: see text]cm[Formula: see text]. Magnetic properties were investigated by using vibrating sample magnetometer (VSM). Decreasing trends were observed for saturation magnetization ([Formula: see text]), magnetic coercivity ([Formula: see text]) and remanant magnetization ([Formula: see text]) with the increase of Ni content. Optical band gap ([Formula: see text]2.70–2.79[Formula: see text]eV) were calculated from diffuse reflectance data by using Kubelka–Munk function.

X-ray structure determination of the rare earth oxides (Er1−uGdu)2O3applying the Rietveld method

2002 ◽  
Vol 35 (5) ◽  
pp. 577-580 ◽  
Author(s):  
Zein Heiba ◽  
Hasan Okuyucu ◽  
Y. S. Hascicek
Keyword(s):  
Rare Earth ◽  
Rietveld Method ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gel Technique ◽  
Average Size

Nanosized polycrystalline samples of (Er1−uGdu)2O3(0 ≤u≤ 1.0) were synthesized by a sol–gel technique. X-ray diffraction data were collected and the crystal structures were refined by the Rietveld method. All samples are found to have the same crystal system and formed solid solutions over the whole range ofu. The Er3+and Gd3+ions were randomly distributed over two cationic sites, 8band 24d, in the space groupIa\bar{3} (206) in all refined structures. The lattice parameter was found to vary non-linearly with the composition (u). The average microstrain and average crystallite size have been calculated from the Williamson–Hall plots for each sample. The average size ranges from 50 to 70 nm, and the microstrain from 0.4 to 1.7%.

scholarly journals Synthesis and comparative study on the structural and optical properties of ZnO doped with Ni and Ag nanopowders fabricated by sol gel technique

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
S. Al-Ariki ◽  
Nabil A. A. Yahya ◽  
Sua’ad A. Al-A’nsi ◽  
M. H. Hj Jumali ◽  
A. N. Jannah ◽  
...  
Keyword(s):  
Optical Properties ◽  
Sol Gel ◽  
Visible Region ◽  
Average Crystallite Size ◽  
Band Gaps ◽  
Structural And Optical Properties ◽  
Crystallite Sizes ◽  
Gel Technique ◽  
Uv Visible ◽  
Xrd Patterns

AbstractIn this work we have tried to prepare Ni and Ag doped ZnO nanopowders using the sol gel technique. The influence of Ni and Ag (1, 3 and 5 mol.%) on the crystalline structure and optical properties of ZnO was investigated. The samples were characterized by XRD, FTIR and UV–visible spectrophotometer. XRD patterns confirmed the wurtzite formation of doped and undoped ZnO nanopowders. The average crystallite sizes of the prepared samples found from XRD were 19 nm for undoped ZnO, from 17 to 22 nm for Ni-ZnO and from 19 to 26 nm for Ag-ZnO. The average crystallite size of Ag-ZnO increased with increasing Ag contents. Different optical properties of Ni-ZnO and Ag-ZnO nanopowders were observed for different Ni and Ag content. The band gaps of Ni-ZnO and Ag-ZnO nanopowders were lower than that of the undoped ZnO (3.1 eV). The band gaps of Ag-ZnO were lower than that of Ni-ZnO. The optical properties of ZnO were enhanced by Ni (mol.%) in the UV region and by Ag (3 and 5 mol.%) in the visible region.

Structure Analysis of Nanocrystalline MgO Aerogel Prepared by Sol-Gel Method

2007 ◽  
Vol 130 ◽  
pp. 203-206 ◽  
Author(s):  
Grzegorz Dercz ◽  
Lucjan Pająk ◽  
Krystian Prusik ◽  
Roman Pielaszek ◽  
Janusz J. Malinowski ◽  
...  
Keyword(s):  
Crystallite Size ◽  
Magnesium Oxide ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Gel Technique ◽  
Microscopy Images ◽  
Nanocrystalline Mgo

Wet gel obtained by sol-gel technique was dried in supercritical CO2 to prepare hydrated form of magnesium oxide. Calcination at 723 K under vacuum yielded nanocrystalline MgO aerogel. Structure studies were performed by X-ray diffraction, scanning and transmission electron microcopies. Electron microscopy images reveal rough, unfolded and ramified structure of solid skeleton. Specific surface area SBET was equal to 238 m2/g. X-ray pattern reveals the broadened diffraction lines of periclase, the only crystalline form of magnesium oxide. The gamma crystallite size distribution was determined using FW 5 4 / 5 1 M method proposed by R. Pielaszek. The obtained values of <R> and σ (measure of polydispersity) of particle size parameters are equal to 6.5 nm and 1.8 nm, respectively, whereas the average crystallite size estimated by Williamson-Hall procedure was equal to 6.0 nm. The obtained at Rietveld refinement Rwp, and S fitting parameters equal to 6.62% and 1.77, respectively, seem to be satisfactory due to the nanosize of MgO crystallites and because of the presence of amorphous phase.

scholarly journals Synthesis and Characterization of Copper Doped Lithium Ferrite Nanocomposite

2019 ◽  
Vol 9 (2) ◽  
pp. 33-37
Keyword(s):  
Tetrahedral Site ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
Ferrite Nanoparticles ◽  
Cubic Phase ◽  
Lithium Ferrite ◽  
Sem Image ◽  
Ft Ir ◽  
Gel Technique

n this paper copper doped lithium ferrite nanoparticles effectively synthesized using sol-gel technique. The synthesized product was analyzed by using TG/DTA, XRD, FT-IR, FE-SEM, HR-TEM, VSM and CV studies. TG/DTA study indicates that the thermal stable of the prepared copper doped lithium ferrite nanoparticles. XRD result confirms that copper doped lithium ferrite nanoparticles have development of cubic phase with Fd3m group and also average crystallite size calculated for different ratios using Scherrer’s formula around 40 nm. FT-IR spectra confirm the presence of absorption band of lower frequency (ν2) at octahedral site and higher frequency (ν1) at tetrahedral site of prepared nanocomposites. The FE-SEM image of CuxLi1-xFe2O4 (x=0.2) nanocomposites clearly specifies that the spherical morphology with agglomerated particles and the same is confirmed by HR-TEM study. The EDAX analysis showed that the existence of Cu, Fe and O elements. VSM study reveals that copper doped lithium ferrite nanoparticles are paramagnetic in nature. Copper doped lithium ferrite nano composites exhibits the higher specific capacitance value at 587 Fg-1 for 10 mVs-1 studied from CV.

scholarly journals Structural and Dielectric Progression of 5 % Gd Doped BiFeO3 Nanoparticles Through Cr (2-8%) Doping

2022 ◽  
Vol 12 (3) ◽  
pp. 101-110
Author(s):  
MN Hossain ◽  
MA Matin ◽  
MM Rhaman ◽  
MA Ali ◽  
MA Hakim ◽  
...  
Keyword(s):  
Bismuth Ferrite ◽  
Sol Gel ◽  
Wide Frequency Range ◽  
Dielectric Characteristics ◽  
X Ray ◽  
Structural Modifications ◽  
Multiferroic Bifeo3 ◽  
Gel Technique ◽  
A Site ◽  
Cr Doping

This study reports the structural modifications in undoped multiferroic BiFeO3 (bismuth ferrite or BFO) nanoparticles caused by doping at both the A-site (by 5% Gd) and B-site (by 2-8% Cr) and the resulting improvements in dielectric characteristics. Both un-doped and doped BFO nanoparticles were synthesized using the sol-gel technique and annealed at 600°C for crystallization. X-ray diffractometry (XRD) reveals a phase transition from rhombic (R3c) to orthorhombic (Pn21a). Field Emission Scanning Electron Microscopy (FESEM) study shows the production of nanoparticles with sizes ranging from 80 to 130 nm. Impedance analyzer experiments (100 Hz-10 MHz) show that the dielectric characteristics of doubly doped BFO are very stable over a wide frequency range. The dielectric permittivity of co-doped BFO decreases with Cr doping concentration up to x = 0.06 before reversing. The conductivity drops dramatically as the Cr content rises. Journal of Engineering Science 12(3), 2021, 101-110

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