11. |
|
|
12. |
- Sundqvist, Bertil, et al.
(författare)
-
Resistivity of high-Tc superconductors: Linear in T at constant p, non-linear at constant V
- 1990
-
Ingår i: Solid State Communications. - : Elsevier Science Ltd. - 0038-1098 .- 1879-2766. ; 76:8, s. 1019-1022
-
Tidskriftsartikel (refereegranskat)abstract
- The observed constant-pressure resistivity varrhop of most high-Tc superconductors is linear in temperature T over large ranges. We show that this is not true for the constant-volume resistivity varrhov; for 1–2–3 YBCO the correction from varrhop to varrhov is -32% at 500 K relative to the low-T value. Since theory predicts varrhov rather than varrhop, the observed linearity of varrho probably cannot be used as a tool to choose between theories for high-Tc superconductivity.
|
|
13. |
- Sundqvist, Bertil, et al.
(författare)
-
Thermal conductivity of bulk YBa2Cu4O8 and the phonon transport model
- 1994
-
Ingår i: Physica C, volume 235-240. - : Elsevier Science B.V.. ; , s. 1377-1378
-
Konferensbidrag (refereegranskat)abstract
- We have measured the thermal conductivity varkappa of bulk YBa2Cu4O8 (1-2-4) between 30 and 310 K and at pressures p up to 1 GPa. At p = 0, varkappa = 10 Wm−1K−1 near 100 K, twice that of sintered YBa2Cu3O−δ (1-2-3). varkappa also decreases with increasing T more rapidly than in 1-2-3, to 7.4 Wm−1K−1 at 300 K. Under pressure, varkappa increases slowly with p above 150 K, but dvarkappa/dp decreases at lower T. Our results are in excellent agreement with a semi-classical model for phonon thermal conductivity, provided we assume significant charge transfer with pressure. The calculated phonon mean free path is much larger than the lattice spacing at all T.
|
|