TY  - JOUR
AU  - Sazonov, Andrew
AU  - Hutanu, Vladimir
AU  - Meven, Martin
AU  - Roth, Georg
AU  - Georgii, Robert
AU  - Masuda, Takatsugu
AU  - Náfrádi, Bálint
TI  - Crystal Structure of Magnetoelectric Ba$_2$MnGe$_2$O$_7$ at Room and Low Temperatures by Neutron Diffraction
JO  - Inorganic chemistry
VL  - 57
IS  - 9
SN  - 1520-510X
CY  - Washington, DC
PB  - American Chemical Society
M1  - FZJ-2019-00340
SP  - 5089 - 5095
PY  - 2018
AB  - For a symmetry-consistent theoretical description of the ferroelectric phase of Ba2MnGe2O7 melilite compound, a precise knowledge of its crystal structure is a prerequisite. Here we report results of single-crystal neutron diffraction experiments on Ba2MnGe2O7 at room (300 K) and low (10 K) temperatures. The structural model based on the tetragonal space group P4̅21m describes the Ba2MnGe2O7 symmetry both at room and low temperatures. We found reflections forbidden in the typical P4̅21m melilite-type structure. A comparison of the experimental data collected by means of both thermal and cold neutrons with simulated multiple diffraction patterns allows us to unambiguously demonstrate that forbidden peaks originate from multiple diffraction (Renninger effect) rather than from real symmetry lowering. The precise structural parameters at 300 and 10 K are presented for the first time and compared with those of other magnetoelectric melilite-type germanates.
LB  - PUB:(DE-HGF)16
C6  - pmid:29630373
UR  - <Go to ISI:>//WOS:000431833500039
DO  - DOI:10.1021/acs.inorgchem.8b00058
UR  - https://juser.fz-juelich.de/record/859487
ER  -