Lone pair cations like Bi3+ and Pb2+ allow for asymmetric coordination environments which can be used to create crystallographic shear planes in perovskite structures. Shear planes involve shifting one part of the structure relative to the other. This results in a new class of anion-deficient perovskite structures called the AnBnO3n-2 homologous series. Unlike other homologous series, these structures have electrically and magnetically active interfaces between perovskite blocks, resulting in frustrated magnetic structures. The orientation and spacing of shear planes can be controlled through composition.

2. A
Lone pair cations like Bi3+ or Pb2+ are comfortable
in an asymmetric coordination environment...

3. ...and we use this to create interfaces to get
new types of structures.

4. One type is the focus of this presentation:

5. Shift one part
of the structure
relative to the
other.

6. This is called a
shear plane.

7. This gives us perovskite based crystallographic
shear plane structures.

8. Shear plane structures were known in
other compounds ,but were believed
to be impossible in perovskites.

9. (101) CS planes
(h0l) CS planes
We can vary orientation...
Pb1-xSrxFeO2.5+δ
...by playing with the ratio lone pair
to non lone pair cations
higher Pb:Sr
lower Pb:Sr

10. Pb2+:Bi3+=7:0.5
We can vary the distance between the interfaces...
Pb2+:Bi3+=7:3
Pb2+:Bi3+= 7:5 Pb2+:Bi3+= 7:8
HAADF-
STEM
images
Pb1-xBixFeO2.5+x/2
...by playing with the oxygen content.

11. n=4
n=6
n=5
This also gives a new homologous series.
AnBnO3n-2

12. 27
Ruddlesden-Popper
An+1BnO3n+1
Dion-Jacobson
AnBnO3n+1
Aurivillius
Bi2An-1BnO3n+3
AnBnO3n-2
AO―
AO―
A―
A―
A―
O2―
ABO―
ABO―
If you compare to other homologous series...

13. 27
Ruddlesden-Popper
An+1BnO3n+1
Dion-Jacobson
AnBnO3n+1
Aurivillius
Bi2An-1BnO3n+3
AnBnO3n-2
AO―
AO―
A―
A―
A―
O2―
ABO―
ABO―
...the others have electrically and magnetically inactive
interfaces between the perovskite blocks...

14. 27
Ruddlesden-Popper
An+1BnO3n+1
Dion-Jacobson
AnBnO3n+1
Aurivillius
Bi2An-1BnO3n+3
AnBnO3n-2
AO―
AO―
A―
A―
A―
O2―
ABO―
ABO―
...in the new series the perovskite blocks still interact...

15. ...this leads to a magnetically frustrated structure!

16. G-type
The perovskite block are antiferromagnetically
ordered within...

17. J2
J1
Fe
O
Fe
Fe
O
J1
...but when you stack two blocks,some spins at
the interface cannot satisfy all exchange
interactions.
G-type

18. J2
J1
Fe
O
Fe
Fe
O
J1
Goodenough-Kanamoori rules say...

19. J2
J1
Fe
O
Fe
Fe
O
J1
Goodenough-Kanamoori rules say...
AFM

20. J2
J1
Fe
O
Fe
Fe
O
J1
Goodenough-Kanamoori rules say...
FM FM
AFM

21. J2
J1
Fe
O
Fe
Fe
O
J1
Goodenough-Kanamoori rules say...
FM FM
AFM
...but that is impossible.

22. Just to close off,we can get some funny interfaces too:
HAADF-
STEM
image

23. For all details,on which compounds,how and why,
you'll have to look up the papers:
Dmitry Batuk, Maria Batuk, Artem M. Abakumov, Alexander A. Tsirlin, Catherine McCammon, Leonid Dubrovinsky, Joke Hadermann
"Effect of lone electron pair cations on the orientation of crystallographic shear planes in anion-deficient perovskites"
Submitted to Inorganic Chemistry (2013)
M. Batuk, O. A. Tyablikov, A. A. Tsirlin, S. M. Kazakov, M. G. Rozova, K. V. Pokholok, D. S. Filimonov, E. V. Antipov, A. M. Abakumov, J.
Hadermann.
“Structure and magnetic properties of a new anion-deficient perovskite Pb2Ba2BiFe4ScO13 with crystallographic shear structure”
Materials Research Bulletin 48 (2013) 3459-3465
A. M. Abakumov, M. Batuk, A. A. Tsirlin, O. A. Tyablikov, D. V. Sheptyakov, D. S. Filimonov, K. V. Pokholok, V. S. Zhidal, M. G. Rozova, E. V.
Antipov, J. Hadermann, G. Van Tendeloo.
“Structural and magnetic phase transitions in Pb2Ba2BiFe5O13 and Pb1.5Ba2.5Bi2Fe6O16: 5th and 6th members of the AnBnO3n-2
perovskite-based homologous series”
Inorganic Chemistry 52 (2013) 7834-7843
Turner, S.; Egoavil, R.; Batuk, M.; Abakumov, A. A.; Hadermann, J.; Verbeeck, J.; Van Tendeloo, G.
"Site-specific mapping of transition metal oxygen coordination in complex oxides. "
Applied Physics Letters 101, 241910 (2012).
continued on next slide

24. Korneychik, O. E.; Batuk, M.; Abakumov, A. M.; Hadermann, J.; Rozova, M. G.; Sheptyakov, D. V.; Pokholok, K. V.; Filimonov, D. S.; Antipov, E. V.
"Pb2.85Ba2.15Fe4SnO13: A new member of the AnBnO3n−2 anion-deficient perovskite-based homologous series. " Journal of Solid State Chemistry
184, 3150–3157 (2011).
Batuk, D.; Hadermann, J.; Abakumov, A.; Vranken, T.; Hardy, A.; Van Bael, M.; Van Tendeloo, G. "Layered perovskite-like Pb2Fe2O5 structure as a
parent matrix for the nucleation and growth of crystallographic shear planes." Inorganic chemistry 50, 4978–86 (2011).
Abakumov, A. M.; Batuk, D.; Hadermann, J.; Rozova, M. G.; Sheptyakov, D. V.; Tsirlin, A. A.; Niermann, D.; Waschkowski, F.; Hemberger, J.; Van
Tendeloo, G.; Antipov, E. V. "Antiferroelectric (Pb,Bi)1− xFe1+ xO3− y Perovskites Modulated by Crystallographic Shear Planes." Chemistry of
Materials 23, 255–265 (2011).
Hadermann, J.; Abakumov, A. M.; Perkisas, T.; D’Hondt, H.; Tan, H.; Verbeeck, J.; Filonenko, V. P.; Antipov, E. V.; Van Tendeloo, G. "New perovskite
based manganite Pb2Mn2O5", Journal of Solid State Chemistry 183, 2190–2195 (2010).
Abakumov, A. M.; Hadermann, J.; Batuk, M.; D’Hondt, H.; Tyablikov, O. A.; Rozova, M. G.; Pokholok, K. V; Filimonov, D. S.; Sheptyakov, D. V; Tsirlin,
A. A.; Niermann, D.; Hemberger, J.; Van Tendeloo, G.; Antipov, E. V "Slicing the perovskite structure with crystallographic shear planes: the
AnBnO3n-2 homologous series." Inorganic chemistry 49, 9508–16 (2010).
Van Tendeloo, G.; Hadermann, J.; Abakumov, A. M.; Antipov, E. V. "Advanced electron microscopy and its possibilities to solve complex
structures: application to transition metal oxides. " Journal of Materials Chemistry 19, 2660 (2009).
I.V. Nikolaev, H. D'Hondt, A.M. Abakumov, J. Hadermann, A.M. Balagurov, I.A. Bobrikov, D.V. Sheptyakov, V.Yu. Pomjakushin, K.V. Pokholok, D.S.
Filimonov, G. Van Tendeloo, E.V. Antipov, "Crystal structure, phase transition, and magnetic ordering in perovskitelike Pb2-xBaxFe2O5 solid
solutions", Phys. Rev. B, 78:2 (2008) p. 024426, 1-12
Abakumov, A.M., Hadermann, J., Van Tendeloo, G., Antipov, E.V., "Chemistry and structure of anion deficient perovskites with translational
interfaces", Journal of the American Ceramic Society 91,6 (2008) 1807-1813
Hadermann, J., Abakumov, A.M., Nikolaev, I.V., Antipov, E.V., Van Tendeloo, G., "Local structure of perovskite-based "Pb2Fe2O5" ", Solid State
Sciences 10, 4 (2008) 382-389
Abakumov, A.M., Hadermann, J., Bals, S., Nikolaev, I.V., Antipov, E.V., Van Tendeloo, G. "Crystallographic Shear Structures as a Route to Anion-
Deficient Perovskites", Angewandte Chemie International Edition,Volume 45, Issue 40 (2006) 6697-6700