Effect of La³⁺ substitution on the structure and superconductivity in TlBa<inf>2-x</inf>La<inf>x</inf>CaCu<inf>2</inf>O<inf>7</inf> (x=0.0 - 1.0)

Substitution of La3+ in the BaO plane in TlBa2CaCu2O7 system reduces the hole carrier concentration in the CuO2 plane. The system TlBa2-xLaxCaCu2O7 has been synthesised and found to exhibit superconductivity with transition temperature Tc increasing from 80K for x=0.0 and passes through a maximum of 110K for x=0.3. Superconductivity is maintained even at higher substitutional levels (upto x=0.8) in contrast to RE3+ substitution at the Ca2+ site. © 1995.