Effect of Zn2+doping on the structure and metal - insulator transition of La2Cuo4 ceramics

The structure and electrical properties of layered perovskites La 2 Cu 1- x Zn x O 4 have been investigated. The resistivity of these samples has been measured in the temperature range of 90-300 K. The Zn 2+ doping induces a shift of the metal-insulator transition temperature towards the high-temperature region. The d 9 electronic configuration of Cu 2+ in La 2 CuO 4 leads to an uneven distribution of electron clouds, inducing axial stretching of the surrounding oxygen octahedra and resulting in Jahn-Teller distortion. After Zn 2+ doping, the charge compensation induces a partial transformation of Cu 2+ to Cu + . As a result, the positions occupied by Cu 2+ are replaced by Zn 2+ and Cu + with perfectly symmetric electron clouds in the 3d 10 outer electronic configuration, thus suppressing the Jahn-Teller effect. This shifts the phonon scattering, which is responsible for the emergence of the metal's conductive properties, to higher temperatures.