scholarly journals Detail investigation of thermoelectric performance and magnetic properties of Cs-doped Bi2Sr2Co2Oy ceramic materials

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
B. Özçelik ◽  
M. Gürsul ◽  
G. Çetin ◽  
C. Özçelik ◽  
M. A. Torres ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Electrical Resistivity ◽  
Liquid Phase ◽  
Charge Carrier ◽  
Magnetic Hysteresis ◽  
Ceramic Materials ◽  
Charge Carrier Concentration ◽  
The Other ◽  
Paramagnetic Property ◽  
Microstructural Studies

AbstractBi2Sr2−xCsxCo2Oy materials with 0 ≤ x ≤ 0.15, have been fabricated via the classical ceramic technique. XRD results have indicated that undoped and Cs-substituted samples are composed of Bi2Sr2Co2Oy phase as the major one. Microstructural studies have demonstrated the formation of a liquid phase, which allows a drastic grain growth. This factor is responsible for a drastic improvement of relative density, reaching about 95% of the theoretical one for 0.125 Cs content. On the other hand, electrical resistivity has been reduced up to 14 mΩ cm at 650 °C for 0.125 Cs content, around 40% lower than the obtained in undoped samples. As a consequence, Seebeck coefficient has been decreased due to the raise in charge carrier concentration. The highest power factor at 650 °C (0.21 mW/K2 m) has been found for 0.125 Cs substituted sample, about 40% larger than the obtained in undoped samples, and very similar to the notified in single crystals (0.26 mW/K2 m). Magnetisation with respect to temperature results have demonstrated that measured samples have a paramagnetic property above 50 K, except 0.10 Cs. Magnetic hysteresis curves have shown that the slopes and the magnitudes have increased with decreasing temperature.

Magnetoresistance, temporal evolution, and relaxation of the electrical resistivity in the re-entrant semiconducting La0.80Ba0.20CoO3 perovskite

1999 ◽  
Vol 14 (6) ◽  
pp. 2533-2539 ◽  
Author(s):  
R. D. Sánchez ◽  
J. Mira ◽  
J. Rivas ◽  
M. P. Breijo ◽  
M. A. Señarís-Rodríguez
Keyword(s):  
Magnetic Properties ◽  
Electrical Resistivity ◽  
Temporal Evolution ◽  
The Other ◽  
Inhomogeneous System ◽  
Metal Insulator ◽  
Relaxation Effects ◽  
Electrical And Magnetic Properties ◽  
Semiconducting Behavior ◽  
Insulator Sequence

We report here a study on the electrical and magnetic properties of La1−xBaxCoO3 in the re-entrant semiconducting region (x = 0.20). We find that in this material: (i) the insulator-metal-insulator sequence is unstable and evolves toward a purely semiconducting behavior; the initial r versus T curve can be reinstated upon appropriate annealing treatments; (ii) there are relaxation effects that can be seen by changing the polarity of the electrodes; (iii) there is a negative magnetoresistance Δρ/ρ ∼ 2–3%, for a field as low as 9 kOe, especially at the metal-insulating transition temperatures; and (iv) there are important fluctuations in the electrical resistivity. Taking into account these experimental observations, we can interpret this material as an inhomogeneous system where two thermodynamic phases, one semiconducting and the other metallic and ferromagnetic, coexist, although they are crystallographically indistinguishable.

TRANSPORT AND MAGNETIC PROPERTIES OF Bi BASED MULTIPHASE SUPERCONDUCTORS

1999 ◽  
Vol 13 (29n31) ◽  
pp. 3741-3743 ◽  
Author(s):  
P. Vašek ◽  
I. Janeček
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Electrical Resistivity ◽  
Magnetic Susceptibility ◽  
Volume Fraction ◽  
The Other ◽  
Hall Voltage ◽  
X Ray Diffraction ◽  
X Ray ◽  
Effective Medium Approach

A series of (Bi,Pb)SrCuCaO samples with varying volume fraction of the 2223 phase (determined by X-ray diffraction) has been prepared. Temperature dependence of the resistance, Hall effect and magnetic susceptibility has been measured. Neither susceptibility (both dc and ac) nor electrical resistivity in magnetic field reveal the presence of the low temperature (2212) phase. On the other hand the Hall voltage in the mixed state is very sensitive to the presence of different phases. Obtained results have been discussed within the frame of the effective medium approach and related to the growth mechanism of the 2223 phase.

Microanalysis of silicate glass films grown on α-Al2O3 by pulsed-laser deposition

1993 ◽  
Vol 51 ◽  
pp. 438-439
Author(s):  
Michael P. Mallamaci ◽  
James Bentley ◽  
C. Barry Carter
Keyword(s):  
Liquid Phase ◽  
Single Crystal ◽  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
Ceramic Materials ◽  
Laser Deposition ◽  
Triple Junctions ◽  
Ion Milling ◽  
Multicomponent Oxides ◽  
Glass Films

Glass-oxide interfaces play important roles in developing the properties of liquid-phase sintered ceramics and glass-ceramic materials. Deposition of glasses in thin-film form on oxide substrates is a potential way to determine the properties of such interfaces directly. Pulsed-laser deposition (PLD) has been successful in growing stoichiometric thin films of multicomponent oxides. Since traditional glasses are multicomponent oxides, there is the potential for PLD to provide a unique method for growing amorphous coatings on ceramics with precise control of the glass composition. Deposition of an anorthite-based (CaAl2Si2O8) glass on single-crystal α-Al2O3 was chosen as a model system to explore the feasibility of PLD for growing glass layers, since anorthite-based glass films are commonly found in the grain boundaries and triple junctions of liquid-phase sintered α-Al2O3 ceramics.Single-crystal (0001) α-Al2O3 substrates in pre-thinned form were used for film depositions. Prethinned substrates were prepared by polishing the side intended for deposition, then dimpling and polishing the opposite side, and finally ion-milling to perforation.

Structural and Magnetic Hysteresis Properties of Co-Zr Substituted Hexagonal Barium Ferrites

2015 ◽  
Vol 7 (1) ◽  
pp. 1346-1351
Author(s):  
Ch.Gopal Reddy ◽  
Ch. Venkateshwarlu ◽  
P. Vijaya Bhasker Reddy
Keyword(s):  
Magnetic Properties ◽  
Single Phase ◽  
Magnetic Hysteresis ◽  
Grain Morphology ◽  
Hexagonal Structure ◽  
Ion Composition ◽  
X Ray Diffraction ◽  
Ceramic Method ◽  
Barium Ferrites ◽  
Xrd Patterns

Co-Zr substituted M-type hexagonal barium ferrites, with chemical formula BaCoxZrxFe12-2xO19 (where x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0), have been synthesized by double sintering ceramic method. The crystallographic properties, grain morphology and magnetic properties of these ferrites have been investigated by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometer (VSM). The XRD patterns confirm the single phase with hexagonal structure of prepared ferrites. The magnetic properties have been investigated as a function of Co and Zr ion composition at an applied field in the range of 20 KOe. These studies indicate that the saturation magnetization (Ms) in the samples increases initially up to the Co-Zr composition of x=0.6 and decreases thereafter. On the other hand, the coercivity (Hc) and Remanent magnetization (Mr) are found to decrease continuously with increasing Co-Zr content. This property is most useful in permanent magnetic recording. The observed results are explained on the basis of site occupation of Co and Zr ions in the samples.

Investigation of the Structure and Magnetic Properties of Bulk Amorphous FeCoYB Alloy

2017 ◽  
Vol 68 (9) ◽  
pp. 2162-2165 ◽  
Author(s):  
Katarzyna Bloch ◽  
Mihail Aurel Titu ◽  
Andrei Victor Sandu
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Hyperfine Field ◽  
Irreversible Processes ◽  
Magnetization Process ◽  
Casting Method ◽  
The Core ◽  
Injection Casting ◽  
Core Losses ◽  
Microstructural Studies

The paper presents the results of structural and microstructural studies for the bulk Fe65Co10Y5B20 and Fe63Co10Y7B20 alloys. All the rods obtained by the injection casting method were fully amorphous. It was found on the basis of analysis of distribution of hyperfine field induction that the samples of Fe65Co10Y5B20 alloy are characterised with greater atomic packing density. Addition of Y to the bulk amorphous Fe65Co10Y5B20 alloy leads to the decrease of the average induction of hyperfine field value. In a strong magnetic field (i.e. greater than 0.4HC), during the magnetization process of the alloys, where irreversible processes take place, the core losses associated with magnetization and de-magnetization were investigated.

The Reactivity of Different Active Forms of Sodium Carbonate with Respect to Sulfur Dioxide

1992 ◽  
Vol 57 (11) ◽  
pp. 2302-2308
Author(s):  
Karel Mocek ◽  
Erich Lippert ◽  
Emerich Erdös
Keyword(s):  
Thermal Decomposition ◽  
Liquid Phase ◽  
Sulfur Dioxide ◽  
Specific Surface ◽  
Surface Area ◽  
Sodium Carbonate ◽  
Room Temperature ◽  
Active Form ◽  
The Other ◽  
Kinetics Of

The kinetics of the reaction of solid sodium carbonate with sulfur dioxide depends on the microstructure of the solid, which in turn is affected by the way and conditions of its preparation. The active form, analogous to that obtained by thermal decomposition of NaHCO3, emerges from the dehydration of Na2CO3 . 10 H2O in a vacuum or its weathering in air at room temperature. The two active forms are porous and have approximately the same specific surface area. Partial hydration of the active Na2CO3 in air at room temperature followed by thermal dehydration does not bring about a significant decrease in reactivity. On the other hand, if the preparation of anhydrous Na2CO3 involves, partly or completely, the liquid phase, the reactivity of the product is substantially lower.

The influence of composition on polymorphism, structure and charge carrier concentration in TL-2201.

1994 ◽  
Vol 235-240 ◽  
pp. 539-540
Author(s):  
C. Ström ◽  
S.-G. Eriksson ◽  
J. Albertsson ◽  
N. Winzek
Keyword(s):  
Charge Carrier ◽  
Carrier Concentration ◽  
Charge Carrier Concentration

scholarly journals When band convergence is not beneficial for thermoelectrics

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Junsoo Park ◽  
Maxwell Dylla ◽  
Yi Xia ◽  
Max Wood ◽  
G. Jeffrey Snyder ◽  
...  
Keyword(s):  
Charge Carrier ◽  
First Principles ◽  
Design Principle ◽  
Phonon Scattering ◽  
Charge Carrier Concentration ◽  
Deformation Potential ◽  
Interband Scattering ◽  
Improved Performance ◽  
Full Heusler ◽  
Electron Phonon Scattering

AbstractBand convergence is considered a clear benefit to thermoelectric performance because it increases the charge carrier concentration for a given Fermi level, which typically enhances charge conductivity while preserving the Seebeck coefficient. However, this advantage hinges on the assumption that interband scattering of carriers is weak or insignificant. With first-principles treatment of electron-phonon scattering in the CaMg2Sb2-CaZn2Sb2 Zintl system and full Heusler Sr2SbAu, we demonstrate that the benefit of band convergence can be intrinsically negated by interband scattering depending on the manner in which bands converge. In the Zintl alloy, band convergence does not improve weighted mobility or the density-of-states effective mass. We trace the underlying reason to the fact that the bands converge at a one k-point, which induces strong interband scattering of both the deformation-potential and the polar-optical kinds. The case contrasts with band convergence at distant k-points (as in the full Heusler), which better preserves the single-band scattering behavior thereby successfully leading to improved performance. Therefore, we suggest that band convergence as thermoelectric design principle is best suited to cases in which it occurs at distant k-points.

scholarly journals Electrical resistivity of high melting metals up into the liquid phase (V, Nb, Ta, Mo, W)

2008 ◽  
Vol 98 (6) ◽  
pp. 062002 ◽  
Author(s):  
T Hüpf ◽  
C Cagran ◽  
G Lohöfer ◽  
G Pottlacher
Keyword(s):  
Electrical Resistivity ◽  
Liquid Phase ◽  
High Melting

The Archaeology of the Cave of the Owls in the Upper Montana of Peru

1963 ◽  
Vol 29 (1) ◽  
pp. 27-38 ◽  
Author(s):  
Donald W. Lathrap ◽  
Lawrence Roys
Keyword(s):  
Ceramic Materials ◽  
The Other

AbstractCollections from an unusual cave site in the Peruvian Montaña near Tingo María are placed on record along with the circumstances under which they were obtained. The ceramic materials seem to represent two components. The more common of these, designated Cave of the Owls Fine Ware, would appear to have been contemporary with Kotosh II in the Huánuco Basin and with Late Tutishcainyo of the long ceramic sequence established for Yarinacocha near Pucallpa. A date of around 200 or 300 B.C. is suggested. The other ceramics, designated Monzón Coarse Ware, show strong similarities to the later part of the Yarinacocha sequence and probably date after A.D. 1000.

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