A Guide to the Literature for Metallic Elements and Their Binary Metallic Alloys

Hurd, C. M.

doi:10.1007/978-1-4757-0465-5_8

Cited by 3 publications

(3 citation statements)

References 283 publications

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“…The relevant transport properties were determined from the calculated band structures using the standard kinetic theory as given by Ziman and others 16,17 . For the electrical conductivity, the Bloch-Boltzmann kinetic equation in lowest order along x-direction is (similarly for the other Cartesian directions)…”

Section: Figmentioning

confidence: 99%

“…Ordinarily, the first term is the most energy dependent, but there are exceptions 19 , e.g. Pd metal where E F occurs near a very sharp feature in N (ǫ) and Kondo systems where there is resonant scattering 17 . Since β-Zn 4 Sb 3 does not show any indication of such behavior, we have approximated the energy dependence of σ using only the N v 2 x term.…”

Section: Figmentioning

confidence: 99%

“…For isotropic scattering, which is often a reasonable approximation, the relaxation time does not enter the expression for the Hall concentration, yielding 18,17 :…”

Section: Figmentioning

confidence: 99%

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First-principles study of Zn-Sb thermoelectrics

1998

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We report first principles LDA calculations of the electronic structure and thermoelectric properties of β-Zn4Sb3. The material is found to be a low carrier density metal with a complex Fermi surface topology and non-trivial dependence of Hall concentration on band filling. The band structure is rather covalent, consistent with experimental observations of good carrier mobility. Calculations of the variation with band filling are used to extract the doping level (band filling) from the experimental Hall number. At this band filling, which actually corresponds to 0.1 electrons per 22 atom unit cell, the calculated thermopower and its temperature dependence are in good agreement with experiment. The high Seebeck coefficient in a metallic material is remarkable, and arises in part from the strong energy dependence of the Fermiology near the experimental band filling. Improved thermoelectric performance is predicted for lower doping levels which corresponds to higher Zn concentrations.There has been a recent revival of activity in the search for improved thermoelectric materials, with an emphasis on new materials systems 1 . The efficiency of a thermoelectric is characterized by a dimensionless figure of merit, ZT = σS 2 T /κ = S 2 /L, where T is the temperature, σ is the electrical conductivity, S is the Seebeck coefficient (thermopower) and κ is the thermal conductivity, which contains both electronic and lattice contributions, κ = κ el + κ lat . The ratio L = κ/σT , which is often called the Lorentz number, is ordinarily limited from below by its electronic value, κ el /σT , given by the Wiedemann-Franz value, L = (π 2 /3)(k B /e) 2 . Current thermoelectric materials have ZT ≈ 1. With the Wiedemann-Franz value for L, ZT > 1 requires S > 160µV/K. Since doped semiconductors naturally have large thermopower, much of the thermoelectric research over the past 40 years has focused on covalent semiconducting compounds and alloys, composed of 4th and 5th row elements, with a view to finding low thermal conductivity materials that have reasonable carrier mobilities and high band masses, e.g. Bi 2 Te 3 , Si-Ge and PbTe compounds. Despite the research efforts spanning three decades, little progress in increasing ZT has been achieved until recently, and in particular Bi 2 Te 3 /Sb 2 Te 3 has remained as the material of choice for room temperature applications.In the last two years, however, three new materials with ZT > ∼ 1 have been reported 2-4 , and these do not clearly fall into the same class as previous thermoelectric materials. One of these novel materials, β-Zn 4 Sb 3 , with reported ZT ≈ 1.3 at temperature relevant to waste heat recovery, has a large region of linear temperature dependence of the resistivity (Fig.

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Section: Figmentioning

confidence: 99%

Section: Figmentioning

confidence: 99%

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First-principles study of Zn-Sb thermoelectrics

1998

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Magnetotransport Properties of Microstructured ZnO Thin Films Grown on a‐ and r‐Plane Sapphire Substrates

Barzola‐Quiquia¹,

Zelaya

Espíndola

et al. 2023

Physica Status Solidi (b)

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The transparent semiconductor ZnO has attracted substantial interest in the research community because of its potential applications as a transparent thin film, [1][2][3] transistor, [4][5][6] optoelectronic devices, [7][8][9] light-emitting diode, [10,11] among others. Another promising, non-inherent property is its roomtemperature ferromagnetism, which was first theoretically predicted to occur through doping with transition magnetic ions such as Fe, Co, or Ni. [12] However, many experimental studies revealed that the observed magnetic order is not related to the doping but certain defects. [13][14][15][16][17] A ferromagnetic ZnO, free of d-elements, opens new opportunities for applications in spintronics. The origin of the defect-induced magnetism (DIM) in defective ZnO samples is not always simple to explain, especially in samples where defects are introduced during the preparation of the samples, like Zn-or O-vacancies [15] or grain boundaries. [18] In these cases, the reproducibility of the magnetic order is low. Also, usual experimental techniques, such as SQUID (superconducting quantum interface device) magnetometry, cannot simply distinguish between defect-induced magnetic signals and those from other sources, like magnetic impurities on the samples or substrates. [19] However, recent theoretical and experimental studies using element-specific magnetic probes like X-ray magnetic circular dichroism (XMCD) in X-ray absorption spectroscopy [20] strongly suggest that Zn vacancies are the primary origin for the observed magnetic order in this compound. Oxygen vacancies, present in a more significant concentration than Zn vacancies, do not substantially contribute to the magnetic order due to their much smaller magnetic moment.Due to the low mass of thin films and weak magnetic signals (compared to the substrate), standard SQUID magnetometers are not the best choice for the magnetic characterization of ZnO thin films. Accounting for the influence of substrates by performing electrical transport measurements with an applied magnetic field is helpful. The measurement of the magnetoresistance (MR) and Hall effect (HE) [21] are powerful tools to explore the magnetic properties of conducting materials. In the case of MR, the sign of ferromagnetism is the opening of a butterfly-like hysteresis around zero field with extremes at fields corresponding to the coercive fields (H C ). When considering the HE, the appearance of an anomalous nonlinear contribution at low fields, in addition to the opening of a hysteresis with sign changes at fields corresponding to the coercive field, would be the case. We notice, however, that the field hysteresis depends on the coercive field of the investigated sample. Because H C is relatively weak in magnetic ZnO samples, that is, μ 0 Â H C ≤ 0.1 T, [15] high resolution is necessary to measure the hysteresis around zero field in the MR or HE. In general, with the field and temperature dependence of electrical-transport properties, it is possible to

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Relation between the structure of metallic elements and their Hall coefficients

Ogorelec

1988

J Mater Sci Lett

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A Guide to the Literature for Metallic Elements and Their Binary Metallic Alloys

Cited by 3 publications

References 283 publications

First-principles study of Zn-Sb thermoelectrics

First-principles study of Zn-Sb thermoelectrics

Magnetotransport Properties of Microstructured ZnO Thin Films Grown on a‐ and r‐Plane Sapphire Substrates

Relation between the structure of metallic elements and their Hall coefficients

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