Fe-excess Ions as Electronic Charge Suppliers for Zero Thermal Expansion in the Normal State of Fe1.16Te0.6Se0.4

We describe a result coming from an experiment based on an Al - Mg alloy (~5% Mg ) suspended bar hit by an electron beam and operated above and below the temperature of transition from superconducting to normal state of the material. The amplitude of the bar first longitudinal mode of oscillation, excited by the beam interacting with the bulk, and the energy deposited by the beam in the bar are the quantities measured by the experiment. These quantities, inserted in the equations describing the mechanism of the mode excitation and complemented by an independent measurement of the specific heat, allow us to determine the linear expansion coefficient α of the material. We obtain α = [(10.9±0.4)T+(1.3±0.1)T3]×10-10 K -1 for the normal state of conduction in the temperature interval 0.9 < T < 2 K and α = [(-2.45±0.60)+(-10.68±1.24)T +(0.13±0.01)T3]×10-9 K -1 for the superconducting state in the interval 0.3 < T< 0.8 K .

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ON THE THERMAL EXPANSION OF MgB2 AT NORMAL STATE

International Journal of Modern Physics B ◽

10.1142/s0217979207035947 ◽

2007 ◽

Vol 21 (01) ◽

pp. 133-143 ◽

Cited By ~ 1

Author(s):

J. MEENA DEVI ◽

K. RAMACHANDRAN

Keyword(s):

Thermal Expansion ◽

Low Temperature ◽

Specific Heat ◽

Normal State ◽

Temperature Measurements ◽

Electronic Contribution ◽

Superconducting Transition ◽

Temperature Range ◽

Lattice Specific Heat

Thermal expansion of MgB 2 at normal state is measured experimentally in the temperature range 300–400 K. Lattice and electronic contribution to the thermal expansion is determined from the Gruneisen relation using electronic and lattice specific heat. This is compared with the low temperature measurements for predicting superconducting transition.

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Microstructural and Microchemical Characterization of Nickel Sulfide Inclusions in Plate Glass

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100089123 ◽

1991 ◽

Vol 49 ◽

pp. 962-963

Author(s):

J. Cooper ◽

O. Popoola ◽

W. M. Kriven

Keyword(s):

Thermal Expansion ◽

Phase Transformation ◽

Glass Matrix ◽

Nickel Sulfide ◽

Plate Glass ◽

Thermal Expansion Mismatch ◽

Volume Increase ◽

Β Phase ◽

Microchemical Characterization

Nickel sulfide inclusions have been implicated in the spontaneous fracture of large windows of tempered plate glass. Two alternative explanations for the fracture-initiating behaviour of these inclusions have been proposed: (1) the volume increase which accompanies the α to β phase transformation in stoichiometric NiS, and (2) the thermal expansion mismatch between the nickel sulfide phases and the glass matrix. The microstructure and microchemistry of the small inclusions (80 to 250 μm spheres), needed to determine the cause of fracture, have not been well characterized hitherto. The aim of this communication is to report a detailed TEM and EDS study of the inclusions.

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