Thermodynamic study of orthorhombic Tx and tetragonal T′ lanthanum cuprate, La2CuO4

Crystal structure of Tx (orthorhombic), T′ and T (tetragonal) modifications of La2CuO4 (left to right). The space group for orthorhombic Tx is Cmce and I4/mmm for both T′ and T structures; copper cations are presented as small purple, lanthanum as large blue and oxygen as large green circles.