Abstracts Book - IMRC 2018

• SD1-O041
FIRST-PRINCIPLES INVESTIGATION OF METALLIC
FERROELECTRICS IN LAYERED PEROVSKITES HETEROSTRUCTURE
OF Ca2Nb2O7-RELATED PHASES
Javier Alanis 1 , Jorge Íñiguez 2 , Hong-Jian Zhao 2 , María Eugenia Mendoza 1
1 Benemerita Universidad Autonoma de Puebla, Instituto de Física, LRT, Mexico. 2 Luxembourg
Institute of Science and Technology, Materials Research and Technology, Luxembourg.
Ca 2 Nb 2 O 7 -related materials of general formulae A n B n X 3n+2 present a modular
structure of perovskite-like layers. Frequently, octahedral distortion and tilting
lower the symmetry of these phases, resulting often in ferroelectricity with a
spontaneous polarization along the [001] direction for compounds with n=2&4,
4, and 6 (Refs. 1, 2, 3, 4), as well as quasi-1D metallic behavior along the [100] p
direction for compound with n=5 (Ref. 2). Note that these layered perovskites
can form alternated ordered heterostructures alternating n 1 and n 2 layers.
Example of this ordering are the n=4.5 compounds, containing n 1 =4 and n 2 =5
alternated layers (Ref. 5); and the n=4.33, contains intercalated stacking of
double n 1 =4 and single n 2 =5 perovskite layers. In this work, we present a firstprinciples
investigation of metallic ferroelectrics in heterostructures of layered
perovskites with A=La or Sr and B=Ti and Nb. This structures were constructed
combining layers of the orthorhombic phases of the compounds La 4 Ti 4 O 14 (n=4),
Sr 4 Nb 4 O 14 (n=4), La 5 Ti 5 O 17 (n=5) and Sr 5 Nb 5 O 17 (n=5). Our calculations indicate a
general behavior of charge transfer occurring layers of n=5 to layers of n=4,
maintaining the structural distortions of each layer. In exception, there is no
charge transfer between layers when the n=5 layers are Sr5Nb5O17 and the n=4
layers are La4Ti4O14. The effects discussed thus establish an example of how
layered heterostructures permit the existence of native metallicity and
ferroelectricity in this family of layered perovskites materials. We discuss the
implications of our findings in the design of new multifunctional materials,
noting the possibility of having nanostructured materials with 1D photonic
crystal behavior.
Bibliography
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177, 2039-2043.
• [2] F. Lichtenberg, A. Herrnberger, K. Wiedenmann (2001). Prog. Solid
State Chem. 29, 1-70.