TITLE

High pressure studies of T[sub c] and lattice parameters of MgB[sub 2]

AUTHOR(S)
Schlachter, Sonja I.; Fietz, Walter H.; Grube, Kai; Goldacker, Wilfried
PUB. DATE
May 2002
SOURCE
AIP Conference Proceedings;2002, Vol. 614 Issue 1, p809
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
We performed ac-susceptibility measurements of magnesium diboride powder samples under pure hydrostatic pressures up to 0.4 GPa and under quasi-hydrostatic pressure conditions up to 8 GPa in a helium gas pressure cell and a diamond-anvil cell (DAC), respectively. Furthermore, the DAC has been used to investigate the lattice compression by X-ray diffraction. Under helium gas pressure the superconducting transition temperature shows a linear decrease dT[sub c]/dp = -1.13 K/GPa. The pressure effect is fully reversible with a return to the initial T[sub c] of 37.5 K after pressure release. In the diamond-anvil cell the application of pressure leads to a stronger T[sub c]-decrease than in the helium gas pressure cell, and after the release of pressure a degradation effect with lower T[sub c] and a broader transition compared to the first measurement at ambient pressure occurs. Such degradation may be explained by shear stresses and uniaxial pressure components, which cannot be avoided in a DAC at low temperatures. Considering the anisotropic AlB[sub 2]-type structure with alternating honeycomb boron and magnesium layers, MgB[sub 2] seems to be very sensitive to such non-hydrostatic pressure components, which would explain the spread of dT[sub c]/dp values reported in the literature.
ACCESSION #
6666086

 

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