Influence of pressure on the crystal structure of Nd2CuO4

Abstract

The pressure evolution of the crystal structure of Nd ₂ CuO ₄ (tetragonal T′-type) was studied at room temperature up to 36 GPa using synchrotron radiation. At P _T =21.5 GPa a structural transformation into the T-structure (tetragonal K ₂ NiF ₄ -type) occurred. Upon releasing pressure a gradual distortion of the T-structure into the orthorhombic O-phase (Cmca) was found in the pressure range 10<P<18 GPa, and at lower pressure the starting T-phase was restored. The pressure evolution of the unit-cell parameters and the interatomic distances were determined by Rietveld refinement of the diffraction pattern.