Theoretical and experimental study of octahedral tilting of Ca1−xGdxMnO3 (x = 0.05, 0.1, 0.15, 0.2) nanometric powders

Abstract In order to estimate theoretical stability of the perovskite structure for synthesized Ca 1− x Gd x MnO 3 ( x  = 0.05, 0.1, 0.15, 0.2) nanopowders, the Goldschmidt tolerance factor G t and global instability index GII were calculated. Furthermore, we have performed structure prediction of Ca 1− x Gd x MnO 3 perovskites and found several possible perovskite-related phases. The influence of gadolinium amount on Mn─O bond angles and distances, tilting of MnO 6 octahedra around all three axes and deformation due to the presence of the Jahn–Teller distortion around Mn 3+ cation, as well as the influence of the amount of Mn 3+ cation on Ca 1− x Gd x MnO 3 compound, was examined. Ion Mn valence states were determined by bond valence calculations (BVC). Infrared active phonon modes in Ca 1− x Gd x MnO 3 were studied by infrared reflection spectroscopy and magnetic properties were studied by using EPR (electron paramagnetic resonance) measurements.