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Starting from the nominal compositions Tl₂Ba₂Ca_2-xY_xCu₃O_10+δ after heat treatments in Ar atmosphere in gold sealed tubes, both superconducting phases "2223" and "2212" and the paramagnetic phase BaCuO₂ were present for zero and low Y concentration (0 ≤ x ≤ 0.3). The decrease of the critical temperature from 126 to 118 K for the 2223 phase and from 114 to 100 K for the 2212 phase was considered as evidence for Y substitution on Ca sites for low x values and corresponding reduction of the hole concentration per Cu atom. Higher Y concentrations (x ≥ 0.3) destabilize the superconducting phases. Copyright 1994, 1999 Academic Press

From the temperature dependence of the specific heat of the semiconductor La2CuO4 and the high temperature superconductors La1.8Sr0.2CuO4 (Tc=37.2 K) and YBa1.9K0.1Cu3O6.9 (Tc=91.5 K) in the range 1.5–30 K, a strong similarity of the lowfrequency part of their phonon density of states with a peak around 10 meV could be inferred. In the case of La1.8Sr0.2CuO4 the thermodynamical critical field belowTc has been determined and using the Rutger's formula and the BCS model, a Sommerfeld coefficient ?=9 mJ·mol-1 K-1 was obtained, which, taking into account recent results of band structure calculations leads to an electron-phonon enhancement factor ?=1.3, value compatible withTc=36 K when using McMillan's formula forTc. A systematic study of the magnetization offered evidence for strong flux trapping effects at higher fields and for Meissner shielding by superconducting Josephson currents in fields below 6 mT at 4.2 K.

The title compound is prepared by reaction of Na2O and NaI in a closed silver crucible at 830 K. Single crystals are only obtained when a mixture with 100% excess Na2O is annealed in a corundum crucible.

Single crystals of the title compound are grown from equimolar mixtures of Na2O and NaCl at 873 K. Na3OCl crystallizes in the cubic space group Pm3m with Z=1.

RbLiO has been prepared by annealing a Li2O/Rb2O mixture (1:1, argon, 773 K, 30 d).

has been prepared by annealing a mixture of Na2S and K2S (argon, 875 K, 6 d).

Single crystals of the title compound are prepared by reaction of Li2CO3and Na2CO3with a stream of H2loaded with selenium vapor (750 °C, 10 h).

prepared as shown in the scheme (no yield given), crystallizes in the tetragonal system, space group I4/mmm, Z=2.

The very hygroscopic, colorless title compound, prepared as shown in the scheme, crystallizes in the tetragonal system, space group P4/nmm, Z=2 and is isotypic with NaLiS and KLiS (PbFCl type).

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Single crystals of the title compound are prepared by annealing an intimate mixture of Na2O and NaBr at 833 K for 4 weeks (Ag‐crucible).

Li3OBr (I) and Li7O2Br3(II) are prepared by annealing stoichiometric mixtures of Li2O and LiBr (625‐725 K, several days).

are prepared as shown in the scheme and characterized by powder XRD.

are obtained as outlined in the scheme (no yields given).