Structural phase transitions in La2−x−yREySrxCuO4

Abstract We present a powder neutron diffraction study of the structural phase transitions in La 1.7−x Sr x Nd 0.3 CuO 4 for x = 0.0 – 0.20 The tilting angle of the CuO 6 octahedra increases from T HT with decreasing temperature. Below 100 K it is nearly temperature independent without any significant change even at T LT . Due to the decrease of T HT the tilting angle decreases with the Sr content. The tilting axis changes from 〈 0,1,0 〉 towards 〈 1,1,0 〉 at the LT-transition. For the LTO phase a linear relationship is found between the orthorhombic splitting and the square of the tilting angle.