The thermal and electrical conductivity of chromium at low temperatures

The temperature dependences of the Hall-Lorenz numbers ͑L xy ͒ in a EuBa 2 Cu 3 O y ͑Eu-123͒ single crystal before and after oxygen reduction are reported. The study is based on data on the normal state longitudinal and transversal transport coefficients. Namely, the temperature dependences of the electrical resistivity, Hall coefficient, longitudinal thermal conductivity, and transverse thermal conductivity are presented. The set of measurements was performed for an optimally doped sample ͑y Ϸ 7͒, then the oxygen content in the the same crystal was reduced to y Ϸ 6.65, and the measurements were repeated. For both cases L xy 's are about two times larger than the Sommerfeld value of the Lorenz number and depend weakly on temperature in a range 300-160 K. Below T Ϸ 160 K the Hall-Lorenz number for the optimally doped sample slowly drops, while the value of L xy for the oxygen reduced sample begins to rise. Such results suggest that the electronic system in the investigated compound may be considered as a metallic one with pseudogaps that open at the Fermi level.

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“…A very similar consideration was carried out by J.F. Goff 20,21 as an explanation of the anomaly in the Lorenz number 22,23,24 of Chromium. J.F.…”

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confidence: 75%

Lorenz number in the optimally doped and underdoped superconductorEuBa2Cu3Oy

Matusiak

Wolf

2005

Phys. Rev. B

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“…Nevertheless, rapid solidification processing leads to significant grain refinement, i.e., nanocrystalline structures. This vari- a Resistivity of bulk chromium is 12 ~ft-cm (30,31). Resistivity of nanocrystalline chromium is 94-115 ~i2-cm (7).…”

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confidence: 99%

Production and Characterization of Extremely Corrosion Resistant Chromium‐Metalloid Alloys

Moffat

Latanision

Ruf

1991

J. Electrochem. Soc.

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A series of extremely corrosion resistant chromium-metalloid alloys have been investigated. Glassy Cr72P28, Cr87P13, CrToB30, and mixed-phase glassy-nanocrystalline Cr93P7 were fabricated by thin-film processing. These binary alloys exhibit extraordinary corrosion resistance when compared with pure crystalline chromium. In 12M HC1 chromium dissolves rapidly, ca. 1 g/cm~/day, while negligible corrosion of the chromium-metalloid alloys occurred, ca. <10 7 g/cm2/day. X-ray photoelectron spectroscopic analysis of the exposed specimens revealed a strong enrichment of phosphate in the passive film and phosphorus at the metal-film interface. The interaction of the redox chemistry of chromium and the metalloids is responsible for the superior corrosion resistance.In 1974 Naka et al.(1) first reported the remarkable corrosion behavior of Fer metallic glasses. Only 8% chromium was necessary to cause spontaneous passivation and these materials showed significantly greater pitting resistance than comparable stainless steel alloys. Since that time the corrosion resistance of a series ofalloys have been assessed (2). These metastable materials are typically single phase without any long-range order and contain 20 atomic percent (a/o) of the glass forming metalloids: boron, carbon, silicon, and/or phosphorus. As in the case of corrosion resistant crystalline alloys, these materials derive their environmental stability from the presence of a protective passive film. For chromium containing glasses, metalloid composition greatly influences corrosion behavior. Phosphorus is the most beneficial metalloid while boron is the least helpful.In the case of simple binary transition metal-metalloid materials positive effects of metalloids on corrosion resistance have not been universally demonstrated. For FesoB20 and FesoP20 (3, 4) the metalloid additions were found to degrade the passive properties of these alloys relative to crystalline iron. In contrast to this, a series of sputter-deposited binary Cr-metalloid alloys (5-8) exhibit superior corrosion resistance compared to chromium.The objective of this investigation was to understand the relationship between chromium and the metalloids in promoting the passivity of these alloys. Consequently, the corrosion behavior of a series of binary chromium-metalloid alloys was examined relative to chromium and other materials of practical interest.Role of alloy structure vs. composition.--In many studies of metallic glass corrosion a great deal of consideration has been given to assessing the role of structure vs. composition in the dissolution of these m~terials (2-5, 7, 9-11). However the influence of solid-state atomic structure on dissolution behavior is difficult to resolve even for simple systems. For example, the dissolution mechanism of crystalline iron is dependent on solid-state defect density (12), while on the other hand studies of glassy and devitrified FesoB20 (3,4,9), Co80B20 (10), and Cu-Zr (11) show that electrochemical behavior is little, if at all, affected by crystal structur...

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“…The results shown below are compared with measurements of heat capacity Op (Beaumont, Ohihara, and Morrison 1960), magnetic susceptibility (Oollings, Hedgcock, and Siddiqi 1961), electrical resistivity p (Harper et al 1957), all made on A.R.L. chromium samples: the heat capacity sample showed 0 ·001 % N 2 and 0·04 % O2 ; one magnetic susceptibility sample showed 0·0004 wt.-% N 2 and probable O 2 content of 0 ·01-0 ·04%, and is identical with sample Or 5 used by Harper et aZ.…”

Section: Experim:ental Detailsmentioning

confidence: 99%

“…-Some experimental data for high-purity chromium. Liala: linear expansivity from X-rays (Straumanis and Weng 1955), Lilll: linear expansivity of Cr 1 and Cr 3, p: electrical resistivity (Harper et al 1957), X: magnetic susceptibility (Collings, Hedgcock, and Siddiqi 1961), Op: heat capacity (Beaumont, Chihara, and Morrison 1960). in some rare earth elements (e.g. Hall, Legvold, and Spedding 1960) and in ex-manganese (White and Woods 1957).…”

Section: O~~~~----------------------------~~--------~mentioning

confidence: 99%

“…This ductile chromium produced by electrodeposition from suitable solutions has a nitrogen content generally below 0 ·001 wt.-% (0 ·003 at.-%) and an oxygen content of 0 ·04 wt.-% or less. However, the observations on high-purity material have still revealed anomalies in reSistivity (for example, Harper et al 1957;de Vries and Rathenau 1957) and elastic moduli (de Vries and Rathenau 1957;Pursey 1958). In addition, Lingelbach (1958) observed a small knee-shaped anomaly in the magnetic susceptibility of a ductile chromium sample (from A.R.L.)…”

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The Anomalous Thermal Expansion of Chromium

White¹

1961

Aust. J. Phys.

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SummaryExperimental data on the linear thermal expansion between 20 and 50°C of specimens of high-purity chromium confirm the existence of an anomaly centred at 38 °C. The exact shape of this expansion anomaly between about 37 and 39°C varies markedly from sample to sample, but outside this narrow temperature interval the behaviour is more regular and seemingly related to antiferromagnetic ordering. Data on expansion are compared with other recent observations on heat capacity, magnetic susceptibility, and electrical resistivity of high-purity chromium. It is suggested that an electronic term in the expansion coefficient, observed below 20 oK to be negative, is sensitive to band structure and may be partly responsible for the change in expansion coefficient.

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The thermal and electrical conductivity of chromium at low temperatures

Cited by 30 publications

References 9 publications

Lorenz number in the optimally doped and underdoped superconductorEuBa2Cu3Oy

Lorenz number in the optimally doped and underdoped superconductorEuBa2Cu3Oy

Production and Characterization of Extremely Corrosion Resistant Chromium‐Metalloid Alloys

The Anomalous Thermal Expansion of Chromium

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