scholarly journals The Effect of Alkaline Earth (Ba, Sr and Ca) Doped Iron Bismuth Glasses on The Structural, Thermoelectric and Electrical Properties

2021 ◽  
Author(s):  
Ahmed Hannora ◽  
A. M. Ali ◽  
E. El-Falaky ◽  
M. M. El-Desoky
Keyword(s):  
Electrical Properties ◽  
Alkaline Earth ◽  
Small Polaron ◽  
Nominal Composition ◽  
Coupling Constant ◽  
X Ray Diffraction ◽  
Polaron Hopping ◽  
Alkaline Earth Elements ◽  
Amorphous Nature ◽  
Hopping Model

Abstract Glasses with nominal composition 70Bi2O3-30Fe2O3 and 10A-60Bi2O3-30Fe2O3 (mol%); (A = Ba, Sr and Ca) were prepared by the conventional melt quenching technique. X-ray diffraction (XRD) and Differential scanning calorimeter (DSC) confirm the amorphous nature of the glass samples. The iron-bismuth glasses show good solubility of alkaline earth elements ions. In temperatures range of 310–450 K, the dc conductivity of the glass samples containing alkaline earth elements enhanced. Glass sample containing Sr shows interesting electrical properties. All glass samples showed a transition from negative to positive Seebeck coefficient, this means that the conduction is mixed of electrons and holes charge carriers. The conduction mechanism of all samples obeys non-adiabatic small polaron hopping model of electron between iron ions. The calculated small polaron coupling constant, (γp) was found to be in the range of 10.25–17.28. Also, the calculated hopping mobility (µ) and carrier density (Nc) of glasses were in the range of 4.65\(\times {10}^{- 7}\)- 4.11\(\times {10}^{-3}\left({\text{c}\text{m}}^{2}{\text{V}}^{-1}{\text{s}}^{-1}\right)\) and 0.029-10 \(\left({\times {10}^{1 7}\text{c}\text{m}}^{-3}\right)\) at 333 K, respectively.

Enhanced Magnetic and DC Electrical Properties of Sm-Doped Bi2Fe4O9 Nanoplates Synthesized by Sol–Gel Method

NANO ◽  
2020 ◽  
Vol 15 (02) ◽  
pp. 2050020 ◽  
Author(s):  
E. M. M. Ibrahim ◽  
G. Farghal ◽  
Mai M. Khalaf ◽  
Hany M. Abd El-Lateef
Keyword(s):  
Magnetic Measurements ◽  
Small Polaron ◽  
Sol Gel ◽  
Electric Transport ◽  
X Ray Diffraction ◽  
Polaron Hopping ◽  
Gel Method ◽  
Sol Gel Method ◽  
High Temperature Measurement ◽  
Ferromagnetic Ordering

In this work, Bi[Formula: see text]SmxFe4O9 ([Formula: see text], 0.02, 0.06, 0.08, 0.1) nanoplates with an average thickness of 62–125[Formula: see text]nm were synthesized using a sol–gel method. The samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. The magnetic measurements show that the nanoplates have weak ferromagnetic ordering. The saturation magnetization of the nanoplates increases as the Sm content increases. The DC electric transport properties were studied by measuring the temperature dependence of the resistivity in the temperature range 300–680[Formula: see text]K. The materials show typical semiconductor features, and the conduction mechanisms are governed by electron and small polaron hopping in the low and high temperature measurement ranges, respectively. The Sm doping results in a significant enhancement in the electrical conductivity of the Bi2Fe4O9 nanoplates.

STRUCTURE AND ELECTRICAL PROPERTIES OF SrO-BOROVANADATE (V2O5)z(SrO)0.2(B2O3)0.8-z GLASSES

2010 ◽  
Vol 24 (11) ◽  
pp. 1471-1488
Author(s):  
A. MEKKI ◽  
G. D. KHATTAK ◽  
M. N. SIDDIQUI
Keyword(s):  
Electrical Conductivity ◽  
Temperature Dependence ◽  
Inductively Coupled Plasma ◽  
Glass Structure ◽  
Model Parameters ◽  
Nominal Composition ◽  
Polaron Hopping ◽  
X Ray ◽  
Dc Electrical Conductivity ◽  
Hopping Model

SrO -borovanadate glasses with the nominal composition (V 2 O 5 ) z( SrO )0.2 ( B2 O 3 ) 0.8-z, 0.4≤z ≤0.8 were studied by direct current (DC) electrical conductivity, inductively coupled plasma (ICP) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and X-ray-powder-diffraction (XRD). These glasses were prepared by a normal quench technique and the actual compositions of the glasses were determined by ICP spectroscopy. XRD patterns confirm the amorphous nature of the present glasses. The temperature dependence of DC electrical conductivity of these glasses has been studied in terms of different hopping models. The IR results agree with previous investigations on similar glasses and it has been concluded that similar to SrO -vanadate glasses, metavandate chainlike structures of SrV 2 O 6 and individual VO 4 units also occur in these SrO -borovanadate glasses. The SrV 2 O 6 and VO n polyhedra predominate in the low B 2 O 3 containing SrO -borovanadate glasses as the B substitutes into the V sites of the various VO n polyhedra and only when the B 2 O 3 concentration exceeds the SrO content do BO n structures appear. This qualitative picture of three distinct structural groupings for the Sr -vanadate and Sr -borovanadate glasses is consistent with the proposed glass structure on previous IR and extended X-ray absorption fine structure (EXAFS) studies on these types of glasses. The conductivity results were analyzed with reference to theoretical models existing in the literature and the analysis shows that the conductivity data are consistent with Mott's nearest neighbor hopping model. However, both Mott VRH and Greaves models are suitable to explain the data. Schnakenberg's generalized polaron hopping model is also consistent with the temperature dependence of the activation energy, but the various model parameters such as density of states, hopping energy obtained from the best fits were found to be not in accordance with the prediction of the Mott model.

Structure and Transport Properties of Sr0.75-xCaxY0.25Co0.25Mn0.75O3-δ (0 ≤ x ≤ 0.6)

2010 ◽  
Vol 1256 ◽  
Author(s):  
Alexandra Galeeva ◽  
Philipp Napolsky ◽  
Sergey Istomin ◽  
Andrey Gippius ◽  
Dmitry Khokhlov
Keyword(s):  
Transport Properties ◽  
Low Temperatures ◽  
Small Polaron ◽  
Calcium Content ◽  
Complex Oxide ◽  
Dc Conductivity ◽  
Polaron Hopping ◽  
Ceramic Samples ◽  
Distortion Parameters ◽  
Hopping Model

AbstractNew complex oxide Sr0.75-xCaxY0.25Co0.25Mn0.75O3-δ with a perovskite-like structure has been synthesized and characterized. DC and AC transport properties of ceramic samples have been studied in the temperature range 4.2K – 1173K. DC conductivity data at T > 300K are discussed in terms of the small polaron hopping model. Dependence of the polaron activation energy on the calcium content is found to correlate with the change of structural distortion parameters. Both the temperature dependence of DC conductivity and the frequency dependence of the real part of the admittance reveal hopping transport at low temperatures.

Characterization of Cathode Materials Ln0.7Sr0.2Ca0.1Co0.7Fe0.3O2.85 (Ln=La, Pr and Nd) Synthesized by Microwave Sintering Techniques

2013 ◽  
Vol 771 ◽  
pp. 59-62
Author(s):  
Jie Zhao ◽  
Jiang Fu ◽  
Yong Fu ◽  
Yu Na Zhao ◽  
Yong Chang Ma
Keyword(s):  
Electrical Conductivity ◽  
Cathode Materials ◽  
Small Polaron ◽  
Microwave Sintering ◽  
X Ray Diffraction ◽  
Mixed Conductivity ◽  
Polaron Hopping ◽  
Expansion Behavior ◽  
Higher Temperature

Sr, Ca and Fe doped cathode materials Ln0.7Sr0.2Ca0.1Co0.7Fe0.3O2.85 (LnSCCF, Ln=La, Pr and Nd; abbreviated as L-72173, P-72173 and N-72173) were synthesized by microwave sintering (MWS) techniques. The formation process, phase structure and composition were characterized using TG/DTA, XRD and EDS. The thermal expansion behavior of the samples was analyzed in the range of 20-950 °C by thermal dilatometer. The electrical conductivity of the samples was measured with DC four-terminal method from 25 to 900 °C. The X-ray diffraction shows that the samples exhibit a single phase with rhombohedral or cubic perovskite structure after sintered at 1200 °C for 20 min. The electrical conductivity of the samples increases with temperature up to a maximum, and then decreases gradually at higher temperature owing to the creation of oxygen vacancies. The small polaron hopping is regarded as the conducting mechanism (T 550 °C). L-72173 has higher mixed conductivity ( >300 S·cm-1) in 550-800 °C. The average TECs of L-72173, P-72173 and N-72173 are 1.389× 10-5 K-1, 1.417 × 10-5 K-1 and 1.416 × 10-5 K-1 in the range of 25-800 °C, respectively. They are thermally matched to the GDC better than the YSZ and SDC.

scholarly journals Element Segregation and Electrical Properties of PMN-32PT Grown Using the Bridgman Method

Crystals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 98 ◽  
Author(s):  
Sijia Wang ◽  
Zengzhe Xi ◽  
Pinyang Fang ◽  
Xiaojuan Li ◽  
Wei Long ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Inductively Coupled Plasma ◽  
Axial Direction ◽  
Element Distribution ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Inductively Coupled ◽  
Icp Ms ◽  
Plasma Mass Spectrometry ◽  
Element Segregation

A single crystal with nominal composition Pb(Mg1/3Nb2/3)O3-32PbTiO3 (PMN-32PT) was grown by the Bridgman technique. Crystal orientation was determined using the rotating orientation X-ray diffraction (RO-XRD). Element distribution was measured along different directions using inductively coupled plasma-mass spectrometry (ICP-MS). The effect of the element segregation along axial and radial directions on the electrical properties of the PMN-32PT crystal was investigated. It is indicated that the electrical properties of the samples along the axial direction were strongly dependent on the PT (PbTiO3) content. With the increase of the PT content, the piezoelectric coefficient and remnant polarization were improved. Differently, the electrical properties of the samples along the radial direction were mainly determined by the ratio of the Nb and Mg. The reasons for the element segregation and electrical properties varied with the composition were discussed.

scholarly journals Conducting Anilate-Based Mixed-Valence Fe(II)Fe(III) Coordination Polymer: Small-Polaron Hopping Model for Oxalate-Type Fe(II)Fe(III) 2D Networks

2018 ◽  
Vol 140 (39) ◽  
pp. 12611-12621 ◽  
Author(s):  
Suchithra Ashoka Sahadevan ◽  
Alexandre Abhervé ◽  
Noemi Monni ◽  
Cristina Sáenz de Pipaón ◽  
José Ramón Galán-Mascarós ◽  
...  
Keyword(s):  
Coordination Polymer ◽  
Small Polaron ◽  
Mixed Valence ◽  
Polaron Hopping ◽  
Small Polaron Hopping ◽  
Hopping Model

STRUCTURAL CHARACTERIZATION OF SULFOBORATE GLASSES CONTAINING MAGNESIUM OXIDE

2016 ◽  
Vol 78 (6-11) ◽  
Author(s):  
S. A. Dalhatu ◽  
R. Hussin ◽  
Karim Deraman
Keyword(s):  
Molar Volume ◽  
Alkaline Earth ◽  
X Ray Diffraction ◽  
X Ray ◽  
Infra Red ◽  
Amorphous Nature ◽  
Quenching Method ◽  
The Fourier Transform ◽  
Glass Compositions

Magnesium sulfoborate glasses of different compositions were prepared using melt quenching method with the purpose of using it for optical properties. The Fourier Transform Infra-red (FTIR) Spectroscopy, Nuclear Magnetic Resonance (NMR) and X-Ray Diffraction (XRD) have been carried out. Density and molar volume have been evaluated and analysed. From the results of XRD, the absent of discrete and continuous sharp peaks confirmed the amorphous nature of the glass compositions while the results from both FTIR and NMR revealed the existence of BO3, BO4 units. Addition of MgO to sulfoborate influenced the conversion of the dominant BO3 groups to BO4 groups. The BO4 groups are known for creating complex defects that transform into that stable trap good for optical phenomena. It was observed that the density of glass increases while the molar volume is decreases with respect to increase in concentration of alkaline earth oxide in the glass compositions.

Electrical Properties of Ag–La0.67Sr0.33MnO3

2011 ◽  
Vol 675-677 ◽  
pp. 1101-1104 ◽  
Author(s):  
Bao Xin Huang
Keyword(s):  
Small Polaron ◽  
Sol Gel ◽  
Metal Insulator Transition ◽  
Reaction Route ◽  
Conventional Solid State Reaction ◽  
Metal Insulator ◽  
Polaron Hopping ◽  
Ag Addition ◽  
Hopping Model ◽  
Curie Temperature Tc

A series of La0.67Sr0.33MnO3/Ag composites were synthesized using a sol-gel method followed by a conventional solid-state reaction route. The temperature dependence of the magnetic properties and electrical resistivity has been investigated between 80 and 450 K. Except for the sample with x = 0.01, Ag addition has increased the conductivity of this system dramatically. Curie temperature (TC) is almost independent of Ag content and is 352 K for Ag-dopant samples, while the metal–insulator transition temperature TP increases with Ag addition, which is mainly due to the improvement of grain boundaries and opening a new metal conductivity channel caused by the segregation of Ag on the grain surfaces. At low temperature, the ρ - T curves are fitted well by the expression of ρ= ρ0 + ρ2T2 + ρ4.5T4.5 while all data for the above TC can be fitted by using the adiabatic small-polaron-hopping model ρ = ρ0T exp(E/kBT ).

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