Space group determination and first-principles structure optimization of the A -site ordered perovskite-type manganite NdBaMn2 O6

Md Shafiqul Islam, Daisuke Morikawa, Shigeki Yamada, Bikas Aryal, Kenji Tsuda, Masami Terauchi

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Abstract

Space groups and crystal structures of A-site ordered NdBaMn2O6 perovskite have been investigated by a combination of selected-area electron diffraction (SAED), convergent-beam electron diffraction (CBED), and first-principles methods at high-temperature (HT ≈ 450 K), room-temperature (RT ≈ 293 K), and low-temperature (LT ≈ 95 K) phases. By symmetry analysis of the CBED patterns, space groups of NdBaMn2O6 at HT, RT, and LT phases have been determined to be P4/mmm (No. 123), C2mm (No. 38), and P21am (No. 26), respectively. The space groups and the optimized structures using first-principle calculations at the HT and RT phases allow a single crystallographic site for Mn atoms, indicating no charge ordering state. At the LT phase, the observed SAED and CBED patterns revealed the existence of fourfold periodicity along the c axis compared with the pseudocubic unit cell. The optimized structure of the LT phase suggested four inequivalent Mn sites classified into two crystallographically different MnO2 layers. Moreover, the structure showed that the four distinct MnO6 octahedra are similarly compressed in the apical direction.

Original languageEnglish
Article number174114
Number of pages9
JournalPhysical Review B
Volume105
Issue number17
DOIs
Publication statusPublished - 1 May 2022
Externally publishedYes

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