Structural and magnetic chemistry of La2Sr2BMnO8 (B=Mg, Zn)

Polycrystalline samples of the layered perovskites La2Sr2MgMnO8 and La2Sr2ZnMnO8 have been studied by X-ray and neutron powder diffraction, electron diffraction and magnetometry. X-ray and neutron powder diffraction indicate that the average structure is that of K2NiF4, with disordering of Mn and (Zn, Mg) cations over the octahedral sites. Electron diffraction data indicate that cation ordering is present over these sites in the xy planes, with the xy ordered planes being stacked in a disordered manner along z. No long-range magnetic ordering is observed in the temperature range 5≤T (K)≤300. © 2002 Elsevier Science (USA)