Pm. Keane et al., SYNTHESIS, SINGLE-CRYSTAL STRUCTURE, AND SUPERCONDUCTIVITY OF THE RUBIDIUM-SUBSTITUTED LA2CUO4, Physica. C, Superconductivity, 226(3-4), 1994, pp. 353-359
The new compound La2-xRbxCuO4 (x = 0.055(3)) has been synthesized thro
ugh a low-temperature (<450-degrees-C) technique employing molten hydr
oxide salts. For rubidium-doped La2CuO4, RbOH acts not only as a low-t
emperature flux but also as a reactant that contributes the alkali met
al to the final product. La1.945Rb0.055CuO4 crystallizes in the tetrag
onal space group D4h17-I4/mmm with two formula units in a cell of dime
nsions a = 3.7858(6) and c = 13.276(3) angstrom (T = 298 K). The struc
ture has been determined by single-crystal X-ray diffraction methods.
Superconductivity is observed for the first time in the La2-xRbxCuO4 s
ystem with a T(c onset) almost-equal-to 22 K for x = 0.055. This molte
n-salts method was also employed to synthesize single crystals of sodi
um- and potassium-substituted La2CuO4. These compounds exhibit superco
nductivity with a T(c onset) of approximately 28 and 20 K, respectivel
y.