New quadruple perovskite Gd2Ba2Ti2Cu2O11: a potential superconducting parent phase
Abstract
The compound Gd2Ba2Cu2Ti2O11 has been synthesized by reaction of the component oxides at 1025 °C and its structure refined from powder X-ray diffraction data. The material crystallises with a quadrupled perovskite unit cell, similar to that of La2Ba2Cu2Sn2O11 containing alternating double layers of copper and titanium. A reduction in the copper–oxygen distance in the CuO2 planes from 2.007 Å in La2Ba2Cu2Sn2O11 to 1.951 Å in Gd2Ba2Cu2Ti2O11 produces a copper–oxygen interaction similar to that found in high-temperature superconductors.