Transmission Electron Microscopy Study of Ruddlesden-Popper Ca n+1Mnn03n+1n = 2 and 3 Compounds

Published

September 1, 2003

Author(s)

Leonid A. Bendersky, M Greenblatt, R Chen

Abstract

Two Ruddlesden-Popper compounds Can+1MnnO3n (+ 1) with n = 2 and 3 synthesized by a citrate gel technique have been studied by TEM. The structure of Ca4Mn3O10 is consistent with the previously determined structure having the space group Pbca and a(-) a(-) c(+)/a(-) a(-) c(+) tilt system. The presence of defects suggests the possible high-temperature phase transition from untilted I4/mmm to Pbca. The structure of Ca3Mn2O7 was found to be different from the previously suggested I4/mmm symmetry. Ca3Mn2O7 forms with an orthorhombic structure with either Cmcm or Cmc2(1) space group. A structural model for Cmc2(1) based on the tilting of almost-rigid octahedra with a(+) c(-) c(-)/a(+) c(-) c(-) tilt system is proposed. The lamellar defects were shown to be twin variants of the Cmc2(1) structure with the (001)(t) interfaces, which suggests the possible tilting phase transition from the ideal I4/mmm to Cmc2(1) following the maximal group-subgroup. symmetry tree: I4/mmm-->Fmmm-->Bbmm(Cmem)-->Bb2(1)m(Cmc2(1)).

Citation

Journal of Solid State Chemistry

Volume

174

Issue

No. 2

Pub Type

Journals

Keywords

Ca(sub3)Mn(sub2)0(sub7), Ca(sub4)Mn(sub3)0(sub10), crystallography, manganates, phase transition, TEM

Citation

Bendersky, L. , Greenblatt, M. and Chen, R. (2003), Transmission Electron Microscopy Study of Ruddlesden-Popper Ca_n+1Mn_n0_3n+1n = 2 and 3 Compounds, Journal of Solid State Chemistry (Accessed October 3, 2024)