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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

Quantification of the structure in Fig. 1. a Out-of-plane and b in-plane lattice parameters as a function of distance along the pink line shown in Fig. 1. c Out-of-plane and d in-plane lattice parameters as a function of distance along the green line shown in Fig. 1. In all cases, the position values <0 are in the SrTiO3 substrate, and position values >0 are in the BFMO film
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Fig2: Quantification of the structure in Fig. 1. a Out-of-plane and b in-plane lattice parameters as a function of distance along the pink line shown in Fig. 1. c Out-of-plane and d in-plane lattice parameters as a function of distance along the green line shown in Fig. 1. In all cases, the position values <0 are in the SrTiO3 substrate, and position values >0 are in the BFMO film

Mentions: Figure 2a shows a plot of the out-of-plane lattice parameter along the pink line shown in Fig. 1, which passes through the location where the APB is flat and about 1 unit cell above the STO-BFMO interface. This shows a jump to about 4.15 Å at the film-substrate interface, followed by larger jumps to either side of the APB just above the interface, with a short spacing of about 3.1 Å in between. This is entirely in accord with the previously published structure of flat terraces on such APBs [16], where the first cell on either side of the APBs has a huge c parameter of about 4.3–4.4 Å due to the stabilisation of a super-tetragonal, highly polar phase in response to the high charge density at the boundary [16]. Above the boundary, the out-of-plane parameter decays gradually over 5 or 6 unit cells back to an equilibrium level, which is slightly higher than that in the SrTiO3. Using the average spacing in the SrTiO3 as an internal calibration of 3.905 Å, this new level is a little higher at ~3.93 Å. For comparison, the in-plane lattice parameter is plotted in Fig. 2b along the same line. In this case, this is almost the same in the BFMO as in the STO, with just a slight disturbance by the internal structure of the APB.Fig. 2


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)

Quantification of the structure in Fig. 1. a Out-of-plane and b in-plane lattice parameters as a function of distance along the pink line shown in Fig. 1. c Out-of-plane and d in-plane lattice parameters as a function of distance along the green line shown in Fig. 1. In all cases, the position values <0 are in the SrTiO3 substrate, and position values >0 are in the BFMO film
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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Fig2: Quantification of the structure in Fig. 1. a Out-of-plane and b in-plane lattice parameters as a function of distance along the pink line shown in Fig. 1. c Out-of-plane and d in-plane lattice parameters as a function of distance along the green line shown in Fig. 1. In all cases, the position values <0 are in the SrTiO3 substrate, and position values >0 are in the BFMO film
Mentions: Figure 2a shows a plot of the out-of-plane lattice parameter along the pink line shown in Fig. 1, which passes through the location where the APB is flat and about 1 unit cell above the STO-BFMO interface. This shows a jump to about 4.15 Å at the film-substrate interface, followed by larger jumps to either side of the APB just above the interface, with a short spacing of about 3.1 Å in between. This is entirely in accord with the previously published structure of flat terraces on such APBs [16], where the first cell on either side of the APBs has a huge c parameter of about 4.3–4.4 Å due to the stabilisation of a super-tetragonal, highly polar phase in response to the high charge density at the boundary [16]. Above the boundary, the out-of-plane parameter decays gradually over 5 or 6 unit cells back to an equilibrium level, which is slightly higher than that in the SrTiO3. Using the average spacing in the SrTiO3 as an internal calibration of 3.905 Å, this new level is a little higher at ~3.93 Å. For comparison, the in-plane lattice parameter is plotted in Fig. 2b along the same line. In this case, this is almost the same in the BFMO as in the STO, with just a slight disturbance by the internal structure of the APB.Fig. 2

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