Structural Phase Diagram of PerovskiteA0.7A′0.3MnO3(A= La, Pr;A′= Ca, Sr, Ba): A NewImmaAllotype

摘要: The structural phase diagram of A{sub 1-x}A{sub x}{sup {prime}}MnO{sub 3} (A = La, Pr, Y, {hor_ellipsis}) as a function the average A-site ionic radius (r{sub A}) was determined from neutron powder diffraction data. In addition to well-known Pnma and R3c phases, new orthorhombic phase, with space group Imma, found for large at low temperatures. Refined parameters are reported La{sub 0.7}Ba{sub 0.3}MnO{sub 1.6 K (Imma) 293 (R3c). Imma {r_arrow} transition studied temperature same sample, be first order.