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Strain Localization in Thin Films of Bi(Fe,Mn)O3 Due to the Formation of Stepped Mn(4+)-Rich Antiphase Boundaries.

MacLaren I, Sala B, Andersson SM, Pennycook TJ, Xiong J, Jia QX, Choi EM, MacManus-Driscoll JL - Nanoscale Res Lett (2015)

Bottom Line: These have the effect of confining the material below the pyramids in a highly strained state with an out-of-plane lattice parameter close to 4.1 Å.Outside the area enclosed by the antiphase boundaries, the out-of-plane lattice parameter is much closer to bulk values for BFMO.Since the antiphase boundaries seem to form from the interaction of Mn with the Ti in the substrate, one route to perform this would be to grow a thin buffer layer of pure BiFeO3 on the SrTiO3 substrate to minimise any Mn-Ti interactions.

View Article: PubMed Central - PubMed

Affiliation: SUPA School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK. ian.maclaren@glasgow.ac.uk.

ABSTRACT
The atomic structure and chemistry of thin films of Bi(Fe,Mn)O3 (BFMO) films with a target composition of Bi2FeMnO6 on SrTiO3 are studied using scanning transmission electron microscopy imaging and electron energy loss spectroscopy. It is shown that Mn(4+)-rich antiphase boundaries are locally nucleated right at the film substrate and then form stepped structures that are approximately pyramidal in three dimensions. These have the effect of confining the material below the pyramids in a highly strained state with an out-of-plane lattice parameter close to 4.1 Å. Outside the area enclosed by the antiphase boundaries, the out-of-plane lattice parameter is much closer to bulk values for BFMO. This suggests that to improve the crystallographic perfection of the films whilst retaining the strain state through as much of the film as possible, ways need to be found to prevent nucleation of the antiphase boundaries. Since the antiphase boundaries seem to form from the interaction of Mn with the Ti in the substrate, one route to perform this would be to grow a thin buffer layer of pure BiFeO3 on the SrTiO3 substrate to minimise any Mn-Ti interactions.

No MeSH data available.


Related in: MedlinePlus

Nucleation of an antiphase boundary at the SrTiO3:BFMO interface. (left) HAADF image showing antiphase boundary features either at (left) or above (right) the film-substrate interface, as well as showing the area used for EELS-SI. (right) Elemental map from processing of the EELS-SI data where Fe is red, Mn is green, Ti is blue and the simultaneously acquired HAADF signal is purple
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Fig3: Nucleation of an antiphase boundary at the SrTiO3:BFMO interface. (left) HAADF image showing antiphase boundary features either at (left) or above (right) the film-substrate interface, as well as showing the area used for EELS-SI. (right) Elemental map from processing of the EELS-SI data where Fe is red, Mn is green, Ti is blue and the simultaneously acquired HAADF signal is purple

Mentions: Figure 3 shows an atomic resolution chemical map of the area where an APB is in direct contact with the underlying SrTiO3. It should be noted that the APB does not lie right on the interface, even on the left-hand side, but one cell inside the BFMO. Chemical maps show that there is an enrichment of Mn on the B-sites at the interface on the left-hand side. This corresponds to where the APB runs right along the film-substrate interface, and there is also a small but significant concentration of Ti along with the Mn on the B-sites at the interface, as reported previously by Choi et al. [13]. On the right-hand side, where the APB steps up and away from the film-substrate interface, there is also a strong enrichment of Mn to the boundaries. The fact that Mn is already segregating to the film-substrate interface and that a flat APB forms here clearly shows that Mn is associated with the nucleation of the APBs in the first unit cell above the film-substrate interface, possibly in association with a little Ti from the substrate. In our previous studies [16], it was found that these boundaries were formed in BiFeO3 in the presence of excess Ti4+, and it seems that Mn can play a similar role. It is then seen that the Mn segregation is key to how these boundaries then step away from the film-substrate interface into the pyramid structures shown in Fig. 1.Fig. 3


Strain Localization in Thin Films of Bi(Fe,Mn)O3 Due to the Formation of Stepped Mn(4+)-Rich Antiphase Boundaries.

MacLaren I, Sala B, Andersson SM, Pennycook TJ, Xiong J, Jia QX, Choi EM, MacManus-Driscoll JL - Nanoscale Res Lett (2015)

Nucleation of an antiphase boundary at the SrTiO3:BFMO interface. (left) HAADF image showing antiphase boundary features either at (left) or above (right) the film-substrate interface, as well as showing the area used for EELS-SI. (right) Elemental map from processing of the EELS-SI data where Fe is red, Mn is green, Ti is blue and the simultaneously acquired HAADF signal is purple
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4608946&req=5

Fig3: Nucleation of an antiphase boundary at the SrTiO3:BFMO interface. (left) HAADF image showing antiphase boundary features either at (left) or above (right) the film-substrate interface, as well as showing the area used for EELS-SI. (right) Elemental map from processing of the EELS-SI data where Fe is red, Mn is green, Ti is blue and the simultaneously acquired HAADF signal is purple
Mentions: Figure 3 shows an atomic resolution chemical map of the area where an APB is in direct contact with the underlying SrTiO3. It should be noted that the APB does not lie right on the interface, even on the left-hand side, but one cell inside the BFMO. Chemical maps show that there is an enrichment of Mn on the B-sites at the interface on the left-hand side. This corresponds to where the APB runs right along the film-substrate interface, and there is also a small but significant concentration of Ti along with the Mn on the B-sites at the interface, as reported previously by Choi et al. [13]. On the right-hand side, where the APB steps up and away from the film-substrate interface, there is also a strong enrichment of Mn to the boundaries. The fact that Mn is already segregating to the film-substrate interface and that a flat APB forms here clearly shows that Mn is associated with the nucleation of the APBs in the first unit cell above the film-substrate interface, possibly in association with a little Ti from the substrate. In our previous studies [16], it was found that these boundaries were formed in BiFeO3 in the presence of excess Ti4+, and it seems that Mn can play a similar role. It is then seen that the Mn segregation is key to how these boundaries then step away from the film-substrate interface into the pyramid structures shown in Fig. 1.Fig. 3

Bottom Line: These have the effect of confining the material below the pyramids in a highly strained state with an out-of-plane lattice parameter close to 4.1 Å.Outside the area enclosed by the antiphase boundaries, the out-of-plane lattice parameter is much closer to bulk values for BFMO.Since the antiphase boundaries seem to form from the interaction of Mn with the Ti in the substrate, one route to perform this would be to grow a thin buffer layer of pure BiFeO3 on the SrTiO3 substrate to minimise any Mn-Ti interactions.

View Article: PubMed Central - PubMed

Affiliation: SUPA School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK. ian.maclaren@glasgow.ac.uk.

ABSTRACT
The atomic structure and chemistry of thin films of Bi(Fe,Mn)O3 (BFMO) films with a target composition of Bi2FeMnO6 on SrTiO3 are studied using scanning transmission electron microscopy imaging and electron energy loss spectroscopy. It is shown that Mn(4+)-rich antiphase boundaries are locally nucleated right at the film substrate and then form stepped structures that are approximately pyramidal in three dimensions. These have the effect of confining the material below the pyramids in a highly strained state with an out-of-plane lattice parameter close to 4.1 Å. Outside the area enclosed by the antiphase boundaries, the out-of-plane lattice parameter is much closer to bulk values for BFMO. This suggests that to improve the crystallographic perfection of the films whilst retaining the strain state through as much of the film as possible, ways need to be found to prevent nucleation of the antiphase boundaries. Since the antiphase boundaries seem to form from the interaction of Mn with the Ti in the substrate, one route to perform this would be to grow a thin buffer layer of pure BiFeO3 on the SrTiO3 substrate to minimise any Mn-Ti interactions.

No MeSH data available.


Related in: MedlinePlus