Pressure Dependence of the Lattice Distortion in Perovskite La0.5-xBixCa0.5MnO3 (x=0.1, 0.15, 0.2)

The in situ behavior of distorted perovskite La0.5-xBixCa0.5MnO3 (x=0.1, 0.15, 0.2) under high pressure has been studied by energy-dispersive X-ray diffraction in a diamond anvil cell. An abnormal change of the 202–040 d-spacing ascribed to the disappearance of the distortion mode Q2 in the MnO6 octahedra is observed at 1.2, 1.4, and 1.6 GPa, respectively, and it results in a reduction of the Jahn–Teller distortion commonly existing in the manganites. Effect of the unique 6s2 long-pair character of the Bi3+ ion on the pressure dependence of the lattice distortion is discussed.