scholarly journals Study of complex impedance spectroscopic properties of La 0.7− x Dy x Sr 0.3 MnO 3 perovskite oxides

2018 ◽  
Vol 5 (11) ◽  
pp. 172201 ◽  
Author(s):  
I. Sfifir Debbebi ◽  
S. Megdiche-Borchani ◽  
W. Cheikhrouhou-Koubaa ◽  
A. Cheikhrouhou
Keyword(s):  
Activation Energy ◽  
Sol Gel ◽  
Complex Impedance ◽  
Spectroscopic Properties ◽  
Perovskite Oxides ◽  
Perovskite Oxide ◽  
Frequency Range ◽  
X Ray Diffraction ◽  
Dc Conductivities ◽  
X Ray

The dysprosium perovskite La 0.7− x Dy x Sr 0.3 MnO 3 ( x = 0.00 [LSMO] and 0.03 [LDSMO]) compounds were prepared by the sol–gel reaction and characterized by the X-ray diffraction technique. The electrical conductivity and modulus characteristics of the system have been investigated in the temperature and the frequency range 311–356 K and 209–5 × 10 7 Hz, respectively, by means of impedance spectroscopy. The ac and dc conductivities were studied to explore the mechanisms of conduction of LSMO and LDSMO. The insertion of a small amount of Dy 3+ in the La-site of LSMO perovskite oxide increases the value of the activation energy from 0.2106 to 0.5357 eV and enhances electrical resistivity values for almost two orders of magnitude.

scholarly journals Sol-Gel Synthesis, X-Ray Diffraction Studies, and Electric Conductivity of Sodium Europium Silicate

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Ekaterina V. Borisova ◽  
Alexey V. Ignatov ◽  
Eugeni I. Get'man ◽  
Stanislav N. Loboda ◽  
Lyudmyla I. Ardanova ◽  
...  
Keyword(s):  
Activation Energy ◽  
Electric Conductivity ◽  
Rietveld Refinement ◽  
Sol Gel ◽  
Apatite Structure ◽  
X Ray Diffraction ◽  
Gel Method ◽  
X Ray ◽  
Sol Gel Method ◽  
Sol Gel Synthesis

Sodium europium silicate, NaEu9(SiO4)6O2, with apatite structure has been obtained and studied using X-ray diffraction and SEM. It has been shown that sodium sublimation does not take place upon synthesis by the sol-gel method. Rietveld refinement has revealed that sodium atoms are ordered and occupy the 4f position. O(4) atoms not related to silicate ions are placed at the centers of Eu(2) triangles. DC and AC electric conductivity and activation energy have been determined for the compound studied.

Structural, Magnetic and Microwave Absorbing Properties of Nanosized NiXZn1-xFe2O4 Powders Synthesized by Sol-Gel Technique

2010 ◽  
Vol 148-149 ◽  
pp. 1144-1147
Author(s):  
Xiang Rong Zhu ◽  
Lin Feng Lu ◽  
Hong Lie Shen
Keyword(s):  
Room Temperature ◽  
Structural Characteristics ◽  
Sol Gel ◽  
Frequency Range ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Gel Technique ◽  
Soft Magnetism

NixZn1-xFe2O4 (x=0.4, 0.6) powders are synthesized by sol-gel technique. The X-ray diffraction (XRD) measurements show their polycrystalline spinel structural characteristics. Both XRD and Atomic Force Microscopy demonstrate the samples are nanosized. At room temperature typical soft magnetism is exhibited by the samples. The reflection attenuation resulting from microwave absorption would reach to 1.9 dBm over the frequency range 6 GHz - 10 GHz when the samples are paved on a 10 cm  10 cm square aluminum plate with a thickness of about 0.35 mm.

Kinetic mechanisms for mullite formation from sol-gel precursors

1990 ◽  
Vol 5 (9) ◽  
pp. 1963-1969 ◽  
Author(s):  
Dong X. Li ◽  
William J. Thomson
Keyword(s):  
Activation Energy ◽  
Reaction Kinetics ◽  
Single Phase ◽  
Sol Gel ◽  
Mullite Formation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffusion Controlled ◽  
Kinetic Mechanisms ◽  
Kinetics Of

The reaction kinetics for the formation of mullite (3Al2O3 · 2SiO2) from sol-gel derived precursors were studied using dynamic x-ray diffraction (DXRD) and differential thermal analysis (DTA). The reaction kinetics of diphasic and single phase gels are compared and different reaction mechanisms are found for each gel. Mullite formation in the diphasic gel exhibits an Avrami type, diffusion-controlled growth mechanism with initial mullite formation temperatures of about 1250 °C and an activation energy on the order 103 kJ/mole. On the other hand, mullite formation from the single phase gel is a nucleation-controlled process with an initial formation temperature of 940 °C and a much lower activation energy of about 300 kJ/mole.

scholarly journals Investigations of microstructural and impedance spectroscopic properties of Mg0.5Co0.5Fe1.6Al0.4O4 ferrite prepared using sol-gel method

2021 ◽  
Author(s):  
Touka Dabbebi ◽  
S. Hcini ◽  
B. Alzahrani ◽  
H. Rahmouni ◽  
A. Mallah ◽  
...  
Keyword(s):  
Small Polaron ◽  
Sol Gel ◽  
Interfacial Polarization ◽  
Spectroscopic Properties ◽  
Dielectric Constants ◽  
X Ray Diffraction ◽  
Gel Method ◽  
X Ray ◽  
Sol Gel Method ◽  
Increasing Temperature

Abstract Polycrystalline Mg0.5Co0.5Fe1.6Al0.4O4 ferrite was prepared with sol-gel method. This sample was characterized by powder X-ray diffraction (XRD), Scanning electron microscopy, and impedance spectroscopy. X-ray diffraction analysis combined with the Rietveld refinement confirmed that the sample crystallizes in a single-phase cubic spinel structure with (SG: \(Fd\stackrel{-}{3}m\)). Electrical conductivity obeying the Jonscher power law indicates that the prepared material exhibits semiconductor behavior, and the conduction process follows the “non-overlapping small polaron tunnelling” model between neighbors’ sites. The behavior of dielectric constants such as permittivity and loss coefficient has been interpreted based on the Maxwell-Wagner's theory of interfacial polarization. The curves of imaginary parts of impedance (Z'') and modulus (M'') show a dielectric-relaxation phenomenon in the sample with activation energy near to that determined from the dc conductivity study. Nyquist plots (Z″ vs. Z') show a monotonic decrease in both grain resistance (Rg) and grain boundary resistance (Rgb) with increasing temperature such as Rgb > > Rg. This result confirms that the transport mechanism for Mg0.5Co0.5Fe1.6Al0.4O4 compound is governed by the grain boundaries effect.

Crystallization Kinetics of Sol-gel-derived (1x)SrBi2Ta2O9–xBi3TiTaO9 Ferroelectric Thin Films

2002 ◽  
Vol 17 (6) ◽  
pp. 1463-1468 ◽  
Author(s):  
Woo-Chul Kwak ◽  
Yun-Mo Sung
Keyword(s):  
Thin Films ◽  
Activation Energy ◽  
Crystallization Kinetics ◽  
Sol Gel ◽  
Avrami Exponent ◽  
X Ray Diffraction ◽  
X Ray ◽  
Isothermal Kinetic Analysis ◽  
Isothermal Kinetic ◽  
Kinetics Of

The crystallization kinetics of Sr0.7Bi2.3Ta2O9 (SBT) and 0.7SrBi2Ta2O9–0.3Bi3TiTaO9 (SBT-BTT) thin films formed by the sol-gel and spin coating techniques were studied. Phase formation and crystal growth are greatly affected by the film composition and crystallization temperature. Isothermal kinetic analysis was performed on the x-ray diffraction results of the thin films heated in the range of 730 to 760 °C at 10 °C intervals. Activation energy and Avrami exponent values were determined for the fluorite-to-Aurivillus phase transformation. A reduction of approximately 51 kJ/mol in activation energy was observed for the SBT-BTT thin films, and an Avrami exponent value of approximately 1.0 was obtained for both the SBT and SBT-BTT. A comparison is made, and the possible crystallization mechanism is discussed.

scholarly journals Electrical Properties of Double Perovskite LaPbFeTiO6 Synthesized by Sol-Gel Method

2021 ◽  
Author(s):  
K. Iben Nassar ◽  
M. Slimi ◽  
N. Rammeh ◽  
Manuel. P. F. Graça
Keyword(s):  
Electrical Properties ◽  
Electrical Impedance ◽  
Sol Gel ◽  
Complex Impedance ◽  
Double Perovskite ◽  
X Ray Diffraction ◽  
X Ray ◽  
Average Grain Size ◽  
Increasing Temperature ◽  
Electronic Field

Abstract The double perovskite structure is interesting for many researches in various fields of physics and their technological applications. The LaPbFeTiO6 (LPFTO) compound is a very important for many technologies because it has dielectric and electrical properties. It has made an attractive semiconductor material for the electronic field, such as the realization of filters or capacitors. In this work, LaPbFeTiO6 was prepared by the sol-gel method.The structural, morphological and electrical properties of this sample were studied using different techniques. X-ray diffraction analysis, the sample crystallized in the rhombohedral system with space group R C. The surface of the sample and the average grain size were examined by scanning electron microscope (SEM). The electrical conductivity and dielectric characterizations were studied as a function of frequency and temperature (200-380K) by impedance spectroscopy. Indeed, the dielectric constant increases with increasing temperature. The AC conductivity obeys the Jonscher power law. The activation energy obtained from the complex impedance and the conductivity are close. The frequency dependence of the electrical impedance shows the existence of a relaxation phenomenon.

Kinetics Transformation of Anatase to Rutile Phase for Titanium Dioxide Nanoparticles Prepared by Sol-Gel Method

2013 ◽  
Vol 756 ◽  
pp. 11-15
Author(s):  
Muneer M. Ba-Abbad ◽  
Abdul Amir Hassan Kadhum ◽  
Abu Bakar Mohamad ◽  
Mohd Sobri Takriff ◽  
Kamaruzzaman Sopian ◽  
...  
Keyword(s):  
Activation Energy ◽  
Titanium Dioxide Nanoparticles ◽  
Sol Gel ◽  
Rutile Phase ◽  
Phase Changes ◽  
Avrami Equation ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
X Ray ◽  
Calcination Temperatures

Simple sol-gel route was used to synthesis the TiO2 nanoparticles and examined by X-ray diffraction (XRD). The small particle size and uniform morphology of the TiO2 were found at different calcination temperatures. The kinetic study of phase changes from the anatase to rutile using the X-ray diffraction data with Avrami equation was investigated. The transformation of anatase to rutile was started after 500 °C and above by decreasing of XRD peaks intensity of anatase with rutile increased. The activation energy of the rutile phase was found lower which indicated that uniform shape and morphology of TiO2 nanoparticles. At same time, changes of activation energy value depended on the experimental conditions was observed.

Magnetoelectric properties of Co-doped BiFeO3 nanoparticles

2018 ◽  
Vol 32 (12) ◽  
pp. 1850143 ◽  
Author(s):  
V. G. Shrimali ◽  
K. N. Rathod ◽  
Davit Dhruv ◽  
Alpa Zankat ◽  
Khushal Sagapariya ◽  
...  
Keyword(s):  
Spin Structure ◽  
Room Temperature ◽  
Sol Gel ◽  
Equivalent Circuit Model ◽  
Frequency Range ◽  
X Ray Diffraction ◽  
X Ray ◽  
Universal Power Law ◽  
Coupling Parameters ◽  
Spiral Spin

The magnetoelectric (ME) properties of sol–gel grown BiFe[Formula: see text]Co[Formula: see text]O3 (BFCO) nanoceramics, with different sizes, were investigated at room-temperature. X-ray diffraction (XRD) measurement was performed to investigate structural properties of the samples understudy. Magnetic field-dependent dielectric permittivity has been systematically investigated in the frequency range of 20 Hz to 1 MHz. To ensure the origin of magnetodielectric response, the magnetoimpedance (MI) spectroscopy was adopted using equivalent circuit model. The a.c. conductivity was found to obey the Jonscher’s universal power law. The modifications in spiral spin structure in the BFCO nanoparticles with size less than [Formula: see text]62 nm significantly affect the ME coupling parameters.

scholarly journals Structural Dependent Eu3+ Luminescence, Photoelectric and Hysteresis Effects in Porous Strontium Titanate

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5767
Author(s):  
Maryia Rudenko ◽  
Nikolai Gaponenko ◽  
Vladimir Litvinov ◽  
Alexander Ermachikhin ◽  
Eugene Chubenko ◽  
...  
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Sol Gel ◽  
Hysteresis Loops ◽  
Xrd Analysis ◽  
Frequency Range ◽  
X Ray Diffraction ◽  
X Ray ◽  
Capacitance Voltage ◽  
Voltage Hysteresis ◽  
Secondary Ion

Eu3+ doped porous nanostructured SrTiO3 films and powder fabricated by sol-gel route without using any precursor template are characterized by different morphology and phase composition. The films and the power show red and yellow luminescence with the most intensive photoluminescence (PL) bands at 612 nm and 588 nm, respectively. Raman, secondary ion mass spectrometry (SIMS), and X-ray diffraction (XRD) analysis of undoped nanostructured porous SrTiO3 films showed the presence of TiO2, SrO, and SrTiO3 phases and their components. The undoped porous SrTiO3 films are photosensitive and demonstrate resistive switching. The capacitance-voltage hysteresis loops with the width of about 6 V in the frequency range of 2 kHz—2 MHz were observed.

PENGGUNAAN TiO2 PARTIKEL NANO HASIL SINTESIS BERBASIS AIR MENGGUNAKAN METODA SOL-GEL PADA BAHAN KAPAS SEBAGAI APLIKASI UNTUK TEKSTIL ANTI UV

Arena Tekstil ◽  
2013 ◽  
Vol 28 (1) ◽  
Author(s):  
Maya Komalasari ◽  
Bambang Sunendar
Keyword(s):  
Fourier Transform ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Sol Gel ◽  
Crosslinking Agent ◽  
X Ray Diffraction ◽  
Nano Tio2 ◽  
X Ray ◽  
Infra Red ◽  
Scanning Electron

Partikel nano TiO2 berbasis air dengan pH basa telah berhasil disintesis dengan menggunakan metode sol-gel dan diimobilisasi pada kain kapas dengan menggunakan kitosan sebagai zat pengikat silang. Sintesis dilakukan  dengan prekursor TiCl4 pada konsentrasi 0,3 M, 0,5 M dan 1 M, dan menggunakan templat kanji dengan proses kalsinasi pada suhu 500˚C selama 2 jam. Partikel nano TiO2 diaplikasikan ke kain kapas dengan metoda pad-dry-cure dan menggunakan kitosan sebagai crosslinking agent. Berdasarkan hasil Scanning Electron Microscope (SEM),diketahui bahwa morfologi partikel TiO2 berbentuk spherical dengan ukuran nano (kurang dari 100 nm). Karakterisasi X-Ray Diffraction (XRD) menunjukkan adanya tiga tipe struktur kristal utama, yaitu (100), (101) dan (102) dengan fasa kristal yang terbentuk adalah anatase dan rutile. Pada karakterisasi menggunakan SEM terhadap serbuk dari TiO2 yang telah diaplikasikan ke permukaan kain kapas, terlihat adanya imobilisasi partikel nano TiO2 melalui ikatan hidrogen silang dengan kitosan pada kain kapas. Hasil analisa tersebut kemudian dikonfirmasi dengan FTIR (Fourier Transform Infra Red) yang hasilnya memperlihatkan puncak serapan pada bilangan gelombang 3495 cm-1, 2546 cm-1, dan 511 cm-1,  yang masing-masing diasumsikan sebagai adanya vibrasi gugus fungsi O-H, N-H dan Ti-O-Ti. Hasil SEM menunjukkan pula bahwa kristal nano yang terbentuk diantaranya adalah fasa rutile , yang berdasarkan literatur terbukti dapatberfungsi sebagai anti UV.

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