ausblenden:
Schlagwörter:
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Zusammenfassung:
High-resolution thermal-expansion experiments on (i) insulating
La2CuO4+delta, (ii) its Sr- and Ba-doped metallic counterparts with
reduced T(c) values, and (iii) Nd(1.85)Ce0.15CuO4-delta (T(c)
congruent-to 24 K) reveal distinct lattice instabilities at T1 = 32 +/-
1 K and T2 = 36 +/- 1 K. T2 coincides with T(c)max found upon 15 at.% Sr
doping. For YBa2Cu3O6.5 (T(c) = 49 K), a lattice instability occurs at T
= 90 +/- 1 K, i.e., again close to T(c)max = 92 K.