Absolute linear thermal-expansion measurements on copper and aluminum from 5 to 320 K

Kroeger, F.R. Jr.; Swenson, C. A.

doi:10.1063/1.323746

Cited by 252 publications

(134 citation statements)

References 24 publications

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“…Consider copper which exhibits an expansion of ~V T between 4 K and 300 K of about 9.6 x low3, nearly a factor of two larger than what we observe for Lao.79Cao.21Mn03.y [30]. Furthermore, the bulk modulus of copper is 137 GPa [3 11 compared to our estimate of 182 GPa for the manganite.…”

Section: Volume and Its Role In The Metal-insulator Transitioncontrasting

confidence: 51%

Volume-based considerations for the metal-insulator transition of CMR oxides

Neumeier

Hundley²,

Cornelius

et al. 1998

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Section: Volume and Its Role In The Metal-insulator Transitioncontrasting

confidence: 51%

Volume-based considerations for the metal-insulator transition of CMR oxides

Neumeier

Hundley²,

Cornelius

et al. 1998

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“…the IPTS-68 was used, as mentioned by Kroeger and Swenson 15 . Taking this into account reduces the mismatch of both measurements slightly, but not significantly.…”

Section: Resultsmentioning

confidence: 99%

“…14 ) requiring additional corrections to account for the finite non-zero interval size 15 . Instead of measuring length changes, we measure the absolute length as a function of temperature.…”

Section: Introductionmentioning

confidence: 99%

Thermal expansion coefficient of single-crystal silicon from 7 K to 293 K

et al. 2015

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We measured the absolute lengths of three single crystal silicon samples by means of an imaging Twyman-Green interferometer in the temperature range from 7 K to 293 K with uncertainties of about 1 nm. From these measurements we extract the coefficient of thermal expansion with uncertainties in the order of 1 × 10 −9 /K. To access the functional dependence of the length on the temperature usually polynomials are fitted to the data. Instead we use a physically motivated model equation with 7 fit parameters for the whole temperature range. The coefficient of thermal expansion is obtained from the derivative of the best fit. The measurements conducted in 2012 and 2014 demonstrate a high reproducibility and the agreement of two independently produced samples supports single crystal silicon as reference material for thermal expansion. Although the results for all three samples agree with each other and with measurements performed at other institutes, they significantly differ from the recommended values for thermal expansion of crystalline silicon.

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“…During measurements, the sample and cell (in thermal equilibrium) are warmed at 0.2 K/min as capacitance and temperature are recorded at intervals ranging from 0.1 to 0.2 K. The data are corrected for temperature-dependent changes in capacitance of the empty cell, measured in a separate experiment, and the differential expansion of the cell/sample using data for quartz [15]. These contributions amount to 2.7 % and 4.1%, respectively, of the capacitance change due to the thermal expansion of MgB 2 over the temperature range 6 K < T < 300 K; the latter correction would be 63 times larger if a conventional copper dilatometer cell were used to measure MgB 2 , because of copper's large thermal expansion [16]. The specimen was measured along two perpendicular axes (4238 µm and 3665 µm long) to search for preferred crystallographic orientation effects (none were detected).…”

mentioning

confidence: 99%

Negative thermal expansion ofMgB2in the superconducting state and anomalous behavior of the bulk Grüneisen function

et al. 2005

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The thermal expansion coefficient α of MgB2 is revealed to change from positive to negative on cooling through the superconducting transition temperature Tc. The Grüneisen function also becomes negative at Tc followed by a dramatic increase to large positive values at low temperature. The results suggest anomalous coupling between superconducting electrons and low-energy phonons.PACS numbers: 74.70.Ad, 74.62.Fj Superconductivity in the binary compound MgB 2 near 39 K is a fascinating development. Over the last few years, scientists have argued that a lattice instability [1] and/or anomalous phonon behavior [2] might be responsible for the high transition temperature. Specific attention has focused on the E 2g phonon, a bond-stretching phonon within the plane of the hexagonal crystal structure [2,3,4]. In-plane tensile strain, induced by lattice mismatch through thin-film growth, increases the superconducting transition temperature T c to 41.8 K; this enhancement was attributed to a decrease in the E 2g phonon frequency [5]. Phonons can be studied with techniques such as Raman spectroscopy [3,4] and heat capacity [6,7,8]. Often neglected in the study of phonons is thermal expansion, partly because of the exceptional resolution needed to resolve the transition at T c .Thermal expansion from powder diffraction measurements [9, 10] of MgB 2 have revealed an anomalous volume expansion on cooling below T c . However, highresolution thermal expansion measurements (dilatometry) with a relative sensitivity approximately four orders of magnitude better than powder diffraction are required for meaningful thermodynamic analysis. Such measurements of polycrystalline MgB 2 were reported [11], but discrepancies with the diffraction data, such as the temperature at which the thermal expansion coefficient α changes from positive to negative, are apparent.In this Letter, high-resolution thermal expansion measurements of polycrystalline MgB 2 are presented. The results reveal a change in sign of α at T c , with negative thermal expansion below T c ; these data agree with diffraction investigations [9,10], but offer exceedingly greater detail. Analysis of the bulk Grüneisen function reveals anomalous behavior due to dominant low-energy phonon modes. The change in sign of α at precisely T c suggests a connection between these phonon modes and superconductivity.MgB 2 , synthesized with 11 B as described previously [12], was pelletized (diameter = 4.6 mm), placed in a boron nitride crucible and heated to 800• C for 30 min at 3 GPa using a cubic multi-anvil press. A very thin black layer, impurities from surface reaction with boron nitride, was removed, leaving behind a brilliant goldcolored MgB 2 sample with density 2.56 g/cm 3 (100% of theoretical density). Heat capacity was measured with a thermal-relaxation technique. T c versus pressure was determined inductively (0.12 Oe rms field at 1023 Hz) to 0.63 GPa using a helium pressure medium; a manganin sensor at room temperature served as a manometer [13].Thermal expansion was meas...

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Absolute linear thermal-expansion measurements on copper and aluminum from 5 to 320 K

Cited by 252 publications

References 24 publications

Volume-based considerations for the metal-insulator transition of CMR oxides

Volume-based considerations for the metal-insulator transition of CMR oxides

Thermal expansion coefficient of single-crystal silicon from 7 K to 293 K

Negative thermal expansion ofMgB2in the superconducting state and anomalous behavior of the bulk Grüneisen function

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