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.

scholarly journals Lattice Dynamics and Transport Properties of Multiferroic DyMn2O5

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Javed Ahmad ◽  
Syed Hamad Bukhari ◽  
M. Tufiq Jamil ◽  
Mehr Khalid Rehmani ◽  
Hammad Ahmad ◽  
...  
Keyword(s):  
Band Gap ◽  
Energy Band ◽  
Sol Gel ◽  
Energy Band Gap ◽  
Phonon Modes ◽  
Visible Absorption ◽  
Atomic Vibrations ◽  
Uv Visible ◽  
P Type ◽  
Method Analysis

We have investigated the optical and electrical properties of polycrystalline DyMn2O5synthesized by sol-gel method. Analysis of the reflectivity spectrum has led to the observation of 18 infrared (IR) active phonon modes out of 36 predicted ones. We discuss the results in terms of different phonon bands originated as a result of atomic vibrations. Moreover, the optical energy band gap ofEg(OC)~1.78 eV has been estimated from optical conductivity(σ1(ω))spectrum. The energy band gap and optical transitions were also determined from UV-visible absorption spectrum and band gap ofEg(UV)~1.57 eV was estimated. Moreover, DC electrical resistivity shows the p-type polaronic conduction above room temperature.

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.

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.

Silver Doped Nano-Sized Bioglass Ceramics: Synthesis, Characterization and Biocompatibility Studies

2016 ◽  
Vol 860 ◽  
pp. 25-28 ◽  
Author(s):  
Chinnasamy Ramaraj Mariappan ◽  
Narender Ranga
Keyword(s):  
Sol Gel ◽  
Glass Ceramics ◽  
X Ray Diffraction ◽  
Bending Vibrations ◽  
Tem Analysis ◽  
Transmission Electron ◽  
Visible Spectra ◽  
Calcium Phosphosilicate ◽  
Uv Visible

We report on the structural and biocompatibility properties of nanosized calcium phosphosilicate bioglass ceramics doped with 0, 2, 4 and 6 mol% Ag2O. Silver doped bioceramics were synthesized by sol-gel method. The prepared samples were characterized by means of powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, UV-visible and high resolution transmission electron microscopy. The XRD reveals the glass-ceramic nature of the samples. The FT-IR spectra show the possible stretching and bending vibrations of silicate and phosphate groups. Absorptions in UV-visible spectra reveal the silver embedment as Ag+/Ago form into the glass matrix. nanosize of the glass ceramics is confirmed by HR-TEM analysis. The bioactivity of silver doped bioceramics was investigated by in-vitro method with Dulbecco’s Modified Eagel’s Medium. It confirms the formation of bone-like hydroxylapatite layer formation on the surface of bioceramics.

Experimental and Theoretical Study on Transition Metal Ion Doped TiO2

2011 ◽  
Vol 233-235 ◽  
pp. 2219-2222 ◽  
Author(s):  
Xue Chun Zhong ◽  
Zhan Chang Pan ◽  
Zhi Gang Wei ◽  
Shu Guang Xie ◽  
Zhen Jun Cheng ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Metal Ion ◽  
Anatase Phase ◽  
Sol Gel ◽  
Transition Metal Ions ◽  
Transition Metal Ion ◽  
Visible Light Range ◽  
Visible Spectra ◽  
Uv Visible

In this paper, TiO2crystallines doped with transition metal ions have been prepared by sol-gel method. The UV-visible spectra indicated that the doping with transition metal ions (especially Cu2+, Mn2+and Cr3+ions) could effectively improve the absorption of TiO2crystals in the visible-light range. The XRD results showed that the doping does not affect the anatase phase of TiO2. The band structure and the UV-vis absorption spectrum of Mn2+ions doped-TiO2were also calculated by DFT (density function theory) method, which indicated that the doping with transition metal ion could make the band gap of TiO2smaller and a red shift in optical absorption.

Phonons and Holes in Magnesium Doped GaN

1998 ◽  
Vol 512 ◽  
Author(s):  
F. Demangeot ◽  
J. Frandon ◽  
M. A. Renucci ◽  
D. Smirnov ◽  
J. Létin ◽  
...  
Keyword(s):  
Experimental Data ◽  
Raman Scattering ◽  
Present Communication ◽  
Electrical Measurements ◽  
Phonon Modes ◽  
Free Hole ◽  
Reflectivity Spectra ◽  
Dielectric Model ◽  
Raman Study ◽  
Silicon Doped

ABSTRACTP doping of gallium nitride by incorporation of magnesium in the layers was controlled recently. Only Popovici et al. [1] have published the results of a Raman study on p type GaN. In the present communication, we report on the interaction of the free hole gas with the axial A1(LO) or planar E1(LO) phonon modes, evidenced by Raman scattering: the observed coupled phononplasmon mode is found very different from the corresponding one evidenced in silicon doped (n type) GaN. We compare the experimental data with the lineshape calculated within a dielectric model, using the results of electrical measurements. These results are also compared with infrared reflectivity spectra.

A Nanocomposite Gel Electrolyte Made by the Sol-Gel Route for a Solid-State Dye-Sensitized Photoelectrochemical and Electrochromic Cells

2002 ◽  
Vol 725 ◽  
Author(s):  
Boris Orel ◽  
Urska Lavreněiě Štangar ◽  
Angela Šurca Vuk ◽  
Panagiotis Lianos ◽  
Philippe Colomban
Keyword(s):  
Counter Electrode ◽  
Short Circuit ◽  
Sol Gel ◽  
Gel Electrolyte ◽  
Inorganic Hybrid ◽  
Dye Sensitized ◽  
Visible Spectra ◽  
Hydrolysis And Condensation ◽  
Uv Visible ◽  
Resonance Raman Spectra

AbstractThis work describes the properties of an organic-inorganic hybrid gel with an incorporated I-/I3-redox couple that serves as a solid electrolyte for a dye-sensitized TiO2 photoelectrochemical (DSPEC) cell with an efficiency of 4% [1]. The influence of the AcOH on the hydrolysis and condensation reactions of the gels was studied with the help of infrared spectroscopy, while the presence and the formation of the I3 - species were established from the UV-visible spectra of the gels and independently evaluated from the confocal micro-resonance Raman spectra of the electrolyte encapsulated in the DSPEC during open- and short-circuit conditions. Finally, the same gel electrolyte was used for the construction of an electrochromic (EC) window without a counter electrode with intercalation properties (transmission and reflective configuration).

Effect of MCl (M = Na, K) addition on microstructure and electrical conductivity of forsterite

2020 ◽  
Vol 92 (1) ◽  
pp. 10901
Author(s):  
Saloua El Asri ◽  
Hamid Ahamdane ◽  
Lahoucine Hajji ◽  
Mohamed El Hadri ◽  
Moulay Ahmed El Idrissi Raghni ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Electrical Conductivity ◽  
Single Phase ◽  
Sol Gel ◽  
Complex Impedance ◽  
Transmission Spectra ◽  
Electrical Measurements ◽  
Cation Type ◽  
Edx Analyses ◽  
The Fourier Transform

Forsterite single phase powder Mg2SiO4 was synthesized by sol–gel method alongside with heat treatment, using two different cation alkaline salts MCl as mineralizers (M = Na, K) with various mass percentages (2.5, 5, 7.5, and 10 wt.%). In this work, we report on the effect of the cation type and the added amount of used mineralizer on microstructure and electrical conductivity of Mg2SiO4. The formation of forsterite started at 680–740  °C and at 630–700  °C with KCl and NaCl respectively, as shown by TG-DTA and confirmed by XRD. Furthermore, the Fourier transform infrared (FTIR) transmission spectra indicated bands corresponding to vibrations of forsterite structure. The morphology and elemental composition of sintered ceramics were examined by SEM-EDX analyses, while their densities, which were measured by Archimedes method, increased with addition of both alkaline salts. The electrical measurements were performed by Complex Impedance Spectroscopy. The results showed that electrical conductivity increased with the addition of both mineralizers, which was higher for samples prepared with NaCl than those prepared with KCl.

Infrared and UV-visible spectra of layer semiconductors Gas, GaSe and GaTe

1977 ◽  
Vol 38 (10) ◽  
pp. 1293-1299 ◽  
Author(s):  
U. Giorgianni ◽  
G. Mondio ◽  
P. Perillo ◽  
G. Saitta ◽  
G. Vermiglio
Keyword(s):  
Visible Spectra ◽  
Uv Visible

Development of High Permeability Core Materials for Embeddable Inductors in Flexible Organic Substrates

2003 ◽  
Vol 769 ◽  
Author(s):  
C. K. Liu ◽  
P. L. Cheng ◽  
S. Y. Y. Leung ◽  
T. W. Law ◽  
D. C. C. Lam
Keyword(s):  
Low Temperature ◽  
Sol Gel ◽  
Circuit Board ◽  
Organic Substrates ◽  
Circuit Boards ◽  
High Permeability ◽  
Electrical Measurements ◽  
Different Temperatures ◽  
Spiral Inductors ◽  
Ceramic Tape

AbstractCapacitors, resistors and inductors are surface mounted components on circuit boards, which occupy up to 70% of the circuit board area. For selected applications, these passives are packaged inside green ceramic tape substrates and sintered at temperatures over 700°C in a co-fired process. These high temperature processes are incompatible with organic substrates, and low temperature processes are needed if passives are to be embedded into organic substrates. A new high permeability dual-phase Nickel Zinc Ferrite (DP NZF) core fabricated using a low temperature sol-gel route was developed for use in embedded inductors in organic substrates. Crystalline NZF powder was added to the sol-gel precursor of NZF. The solution was deposited onto the substrates as thin films and heat-treated at different temperatures. The changes in the microstructures were characterized using XRD and SEM. Results showed that addition of NZF powder induced low temperature transformation of the sol-gel NZF phase to high permeability phase at 250°C, which is approximately 350°C lower than transformation temperature for pure NZF sol gel films. Electrical measurements of DP NZF cored two-layered spiral inductors indicated that the inductance increased by three times compared to inductors without the DP NZF cores. From microstructural observations, the increase is correlated with the changes in microstructural connectivity of the powder phase.

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