Long-range Strain Fields Research Articles

Pressure-Induced Dislocations and Their Influence on Ionic Transport in Li+-Conducting Argyrodites.

The influence of the microstructure on the ionic conductivity and cell performance is a topic of broad scientific interest in solid-state batteries. The current understanding is that interfacial decomposition reactions during cycling induce local strain at the interfaces between solid electrolytes and the anode/cathode, as well as within the electrode composites. Characterizing the effects of internal strain on ion transport is particularly important, given the significant local chemomechanical effects caused by volumetric changes of the active materials during cycling. Here, we show the effects of internal strain on the bulk ionic transport of the argyrodite Li6PS5Br. Internal strain is reproducibly induced by applying pressures with values up to 10 GPa. An internal permanent strain is observed in the material, indicating long-range strain fields typical for dislocations. With increasing dislocation densities, an increase in the lithium ionic conductivity can be observed that extends into improved ionic transport in solid-state battery electrode composites. This work shows the potential of strain engineering as an additional approach for tuning ion conductors without changing the composition of the material itself.

Interfacial structure and strain accommodation in two-phase NbCo1.2Sn Heusler intermetallics

Multiphasic intermetallic materials are attractive candidates for functional applications where the constituent phases alone do not meet the property targets. The interfaces at the phase boundaries in these materials are central to their macroscopic properties, with the details of the atomic structure underpinning local thermomechanical, electrical, and magnetic behavior. Here, we characterize the interface structure in the biphasic Nb-Co-Sn system consisting of $\mathrm{Nb}{\mathrm{Co}}_{2}\mathrm{Sn}$ full Heusler (FH) precipitates embedded in a NbCoSn half Heusler (HH) matrix, which exhibits semicoherent interfaces with a 3.3% lattice parameter misfit that determines the constitution of the FH/HH interface on the nanometer scale. We use detailed transmission electron microscopy (TEM) and atomistic calculations to precisely determine the dislocation content and structure at the semicoherent interface, which modulates the strain fields in a semiregular pattern. We find that the interface forms regularly spaced paired partial dislocations with a joint Burgers vector of $a/2\ensuremath{\langle}110\ensuremath{\rangle}$, favored by misfit energy relief and chemical ordering. The interface exhibits numerous interface steps (disconnections) which in turn determine the precipitate morphology. Overall, the two phases show full coherency except in the vicinity of the misfit dislocation cores located every 11 nm, leading to a modulated strain field parallel to the interface, and no long-range strain fields as the interfacial dislocations accommodate the misfit strain.

Dislocation-mediated migration of interphase boundaries

Faceted interphase boundaries (IPBs) are commonly observed in lath-shaped precipitates in alloys consisting of simple face-centred cubic (fcc), body centred-cubic (bcc) or hexagonal closed packed (hcp) phases, which normally contain one or two sets of parallel dislocations. The influence of these dislocations on interface migration and possible accompanying long-range strain field remain unclear. To elucidate this, we carried out atomistic simulations to investigate the dislocation-mediated migration processes of IPBs in a pure-iron system. Our results show that the migration of these IPBs is accompanied with the slip of interfacial dislocations, even in high-index slip planes, with two migration modes were observed: the first mode is the uniform migration mode that occurs only when all of the dislocations slip in a common slip plane. A shear-coupled interface migration was observed for this mode. The other interfaces propagate in the stick-slip migration mode that occurs when the dislocations glide on different slip planes, involving dislocation reaction or tangling. A quantitative relationship was established to link the atomic displacements with the dislocation structure, slip plane, and interface normal. The macroscopic shear deformation due to the effect of overall atomic displacement shows a good agreement with the results obtained based on the phenomenological theory of martensite crystallography. Our findings have general implications for the understanding of phase transformations and the surface relief effect at the atomic scale.

Defect Dynamics in Self-Catalyzed III-V Semiconductor Nanowires.

The droplet consumption step in self-catalyzed III-V semiconductor nanowires can produce material that contains a high density of line defects. Interestingly, these defects are often associated with twin boundaries and have null Burgers vector, i.e., no long-range strain field. Here, we analyze their stability by considering the forces that act on them and use in situ aberration corrected scanning transmission electron microscopy (STEM) to observe their behavior in GaAsP nanowires (NWs) using short annealing cycles. Their movement appears to be consistent with the thermally activated single- or double-kink mechanisms of dislocation glide, with velocities that do not exceed 1 nm s-1. We find that motion of individual defects depends on their size, position, and surrounding environment and set an upper limit to activation energy around 2 eV. The majority of defects (>70%) are removed by our postgrowth annealing for several seconds at temperatures in excess of 640 °C, suggesting that in situ annealing during growth at lower temperatures would significantly improve material quality. The remaining defects do not move at all and are thermodynamically stable in the nanowire.

Nondestructive Mapping of Long-Range Dislocation Strain Fields in an Epitaxial Complex Metal Oxide.

The misfit dislocations formed at heteroepitaxial interfaces create long-ranging strain fields in addition to the epitaxial strain. For systems with strong lattice coupling, such as ferroic oxides, this results in unpredictable and potentially debilitating functionality and device performance. In this work, we use dark-field X-ray microscopy to map the lattice distortions around misfit dislocations in an epitaxial film of bismuth ferrite (BiFeO3), a well-known multiferroic. We demonstrate the ability to precisely quantify weak, long-ranging strain fields and their associated symmetry lowering without modifying the mechanical state of the film. We isolate the screw and edge components of the individual dislocations and show how they result in weak charge heterogeneities via flexoelectric coupling. We show that even systems with small lattice mismatches and additional mechanisms of stress relief (such as mechanical twinning) may still give rise to measurable charge and strain heterogeneities that extend over mesoscopic length scales. This sets more stringent physical limitations on device size, dislocation density, and the achievable degree of lattice mismatch in epitaxial systems.

Stable Defects in Semiconductor Nanowires

Semiconductor nanowires are commonly described as being defect-free due to their ability to expel mobile defects with long-range strain fields. Here, we describe previously undiscovered topologically protected line defects with null Burgers vector that, unlike dislocations, are stable in nanoscale crystals. We analyze the defects present in semiconductor nanowires in regions of imperfect crystal growth, i.e., at the nanowire tip formed during consumption of the droplet in self-catalyzed vapor-liquid-solid growth and subsequent vapor-solid shell growth. We use a form of the Burgers circuit method that can be applied to multiply twinned material without difficulty. Our observations show that the nanowire microstructure is very different from bulk material, with line defects either (a) trapped by locks or other defects, (b) arranged as dipoles or groups with a zero total Burgers vector, or (c) have a zero Burgers vector. We find two new line defects with a null Burgers vector, formed from the combination of partial dislocations in twinned material. The most common defect is the three-monolayer high twin facet with a zero Burgers vector. Studies of individual nanowires using cathodoluminescence show that optical emission is quenched in defective regions, showing that they act as strong nonradiative recombination centers.

Theory of electron–phonon–dislon interacting system—toward a quantized theory of dislocations

We provide a comprehensive theoretical framework to study how crystal dislocations influence the functional properties of materials, based on the idea of a quantized dislocation, namely a ‘dislon’. In contrast to previous work on dislons which focused on exotic phenomenology, here we focus on their theoretical structure and computational power. We first provide a pedagogical introduction that explains the necessity and benefits of taking the dislon approach and why the dislon Hamiltonian takes its current form. Then, we study the electron–dislocation and phonon–dislocation scattering problems using the dislon formalism. Both the effective electron and phonon theories are derived, from which the role of dislocations on electronic and phononic transport properties is computed. Compared with traditional dislocation scattering studies, which are intrinsically single-particle, low-order perturbation and classical quenched defect in nature, the dislon theory not only allows easy incorporation of quantum many-body effects such as electron correlation, electron–phonon interaction, and higher-order scattering events, but also allows proper consideration of the dislocation’s long-range strain field and dynamic aspects on equal footing for arbitrary types of straight-line dislocations. This means that instead of developing individual models for specific dislocation scattering problems, the dislon theory allows for the calculation of electronic structure and electrical transport, thermal transport, optical and superconducting properties, etc, under one unified theory. Furthermore, the dislon theory has another advantage over empirical models in that it requires no fitting parameters. The dislon theory could serve as a major computational tool to understand the role of dislocations on multiple materials’ functional properties at an unprecedented level of clarity, and may have wide applications in dislocated energy materials.

Direct Observation of Impurity Segregation at Dislocation Cores in an Ionic Crystal.

Dislocations, one-dimensional lattice defects, are known to strongly interact with impurity atoms in a crystal. This interaction is generally explained on the basis of the long-range strain field of the dislocation. In ionic crystals, the impurity-dislocation interactions must be influenced by the electrostatic effect in addition to the strain effect. However, such interactions have not been verified yet. Here, we show a direct evidence of the electrostatic impurity-dislocation interaction in α-Al2O3 by visualizing the dopant atom distributions at dislocation cores using atomic-resolution scanning transmission electron microscopy (STEM). It was found that the dopant segregation behaviors strongly depend on the kind of elements, and their valence states are considered to be a critical factor. The observed segregation behaviors cannot be explained by the elastic interactions only, but can be successfully understood if the electrostatic interactions are taken into account. The present findings will lead to the precise and quantitative understanding of impurity induced dislocation properties in many materials and devices.

Nonradiative Step Facets in Semiconductor Nanowires.

One of the main advantages of nanowires for functional applications is their high perfection, which results from surface image forces that act on line defects such as dislocations, rendering them unstable and driving them out of the crystal. Here we show that there is a class of step facets that are stable in nanowires, with no long-range strain field or dislocation character. In zinc-blende semiconductors, they take the form of Σ3 (112) facets with heights constrained to be a multiple of three {111} monolayers. Density functional theory calculations show that they act as nonradiative recombination centers and have deleterious effects on nanowire properties. We present experimental observations of these defects on twin boundaries and twins that terminate inside GaAsP nanowires and find that they are indeed always multiples of three monolayers in height. Strategies to use the three-monolayer rule during growth to prevent their formation are discussed.

Dislocation core properties of β-tin: a first-principles study

Dislocation core properties of tin (β-Sn) were investigated using the semi-discrete variational Peierls–Nabarro (SVPN) model. The SVPN model, which connects the continuum elasticity treatment of the long-range strain field around a dislocation with an approximate treatment of the dislocation core, was employed to calculate various core properties, including the core energetics, widths, and Peierls stresses for different dislocation structures. The role of core energetics and properties on dislocation character and subsequent slip behavior in β-Sn was investigated. For instance, this work shows that a widely spread dislocation core on the {110} plane as compared to dislocations on the {100} and {101} planes. Physically, the narrowing or widening of the core will significantly affect the mobility of dislocations as the Peierls stress is exponentially related to the dislocation core width in β-Sn. In general, the Peierls stress for the screw dislocation was found to be orders of magnitude higher than the edge dislocation, i.e., the more the edge component of a mixed dislocation, the greater the dislocation mobility (lower the Peierls stress). The largest Peierls stress observed was 365 MPa for the dislocation on the {101} plane. Furthermore, from the density plot, we see a double peak for the 0° (screw) and 30° dislocations which suggests the dissociation of dislocations along these planes. Thus, for the {101} slip system, we observed dislocation dissociation into three partials with metastable states. Overall, this work provides qualitative insights that aid in understanding the plastic deformation in β-Sn.

Computation of the lattice Green function for a dislocation.

Modeling isolated dislocations is challenging due to their long-ranged strain fields. Flexible boundary condition methods capture the correct long-range strain field of a defect by coupling the defect core to an infinite harmonic bulk through the lattice Green function (LGF). To improve the accuracy and efficiency of flexible boundary condition methods, we develop a numerical method to compute the LGF specifically for a dislocation geometry; in contrast to previous methods, where the LGF was computed for the perfect bulk as an approximation for the dislocation. Our approach directly accounts for the topology of a dislocation, and the errors in the LGF computation converge rapidly for edge dislocations in a simple cubic model system as well as in BCC Fe with an empirical potential. When used within the flexible boundary condition approach, the dislocation LGF relaxes dislocation core geometries in fewer iterations than when the perfect bulk LGF is used as an approximation for the dislocation, making a flexible boundary condition approach more efficient.

X-ray asterism and the structure of cracks from indentations in silicon

The asterism observed in white radiation X-ray diffraction images (topographs) of extended cracks in silicon is investigated and found to be associated with material that is close to breakout and surrounded by extensive cracking. It is a measure of the mechanical damage occurring when the fracture planes do not follow the low-index cleavage planes associated with the crystal structure. It is not related to a propensity for some cracked wafers to shatter during subsequent high-temperature processing. There is no correlation between crack morphology and alignment of an indenter with respect to the orientation of a silicon wafer, the cracks being generated from the apices of the indenter and having threefold symmetry for Berkovich indents and fourfold symmetry for Vickers indents. X-ray diffraction imaging (XRDI) of indents does not reveal this underlying symmetry and the images exhibit a very substantial degree of variation in their extent. This arises because the XRDI contrast is sensitive to the long-range strain field around the indent and breakout reduces the extent of this long-range strain field. Breakout is also detected in the loss of symmetry in the short-range strain field imaged by scanning micro-Raman spectroscopy. Weak fourfold symmetric features at the extremes of the images, and lying along 〈110〉 directions, are discussed in the context of slip generated below the room-temperature indents. Scanning electron microscopy imaging of the region around an indent during focused ion beam milling has permitted the three-dimensional reconstruction of the crack morphology. The surface-breaking Palmqvist cracks are found to be directly connected to the median subsurface cracks, and the presence of extensive lateral cracks is a prerequisite for material breakout at indenter loads above 200 mN. The overall crack shape agrees with that predicted from simulation.

Topology and temperature dependence of the diffuse X-ray scattering in Na0.5Bi0.5TiO3 ferroelectric single crystals.

The results of high-resolution measurements of the diffuse X-ray scattering produced by a perovskite-based Na0.5Bi0.5TiO3 ferroelectric single crystal between 40 and 620 K are reported. The study was designed as an attempt to resolve numerous controversies regarding the average structure of Na0.5Bi0.5TiO3, such as the mechanism of the phase transitions between the tetragonal, P4bm, and rhombohedral | monoclinic, R3c | Cc, space groups and the correlation between structural changes and macroscopic physical properties. The starting point was to search for any transformations of structural disorder in the temperature range of thermal depoling (420-480 K), where the average structure is known to remain unchanged. The intensity distribution around the {032} pseudocubic reflection was collected using a PILATUS 100K detector at the I16 beamline of the Diamond Light Source (UK). The data revealed previously unknown features of the diffuse scattering, including a system of dual asymmetric L-shaped diffuse scattering streaks. The topology, temperature dependence, and relationship between Bragg and diffuse intensities suggest the presence of complex microstructure in the low-temperature R3c | Cc phase. This microstructure may be formed by the persistence of the higher-temperature P4bm phase, built into a lower-temperature R3c | Cc matrix, accompanied by the related long-range strain fields. Finally, it is shown that a correlation between the temperature dependence of the X-ray scattering features and the temperature regime of thermal depoling is present.

IntrinsicLiNbO3point defects from hybrid density functional calculations

The formation energies and charge transition levels of the most relevant LiNbO3 intrinsic point defects, i.e., Nb antisites and Li as well Nb vacancies, are studied from first principles. Thereby isolated defects are modeled in the framework of the density functional theory with local and hybrid exchange-correlation functionals. The inclusion of nonlocal exchange opens the LiNbO3 fundamental band gap by nearly 2 eV and modifies considerably the relative stability of the investigated defects with respect to values calculated with local functionals. On the other hand, supercell symmetry and finite-size errors in calculations using periodic boundary conditions are found to have a major influence on the outcome of the simulations. It is found that, in particular, the Nb vacancy causes a long-range strain field and requires very large supercells for its adequate modeling. Compared to previous theoretical results we find an enhanced stability of the Nb vacancy with respect to the other defects. The V−5 Nb is predicted to be stable for Fermi level positions in the upper part of the band gap.

Atomistic study of stress-induced switching of 90° ferroelectric domain walls in PbTiO3: size, temperature and structural effect

Molecular dynamics simulations based on the shell model potential for PbTiO3 were carried out to investigate the effect of the cell dimension, temperature and kink structure on the domain switching of 90° ferroelectric domain walls. It was found that the critical shear stress is linearly dependent on the inverse of the cell dimension, which is identified as a manifestation of the artificial electric field caused by the periodic boundary conditions. Ab initio density functional theory calculations were carried out to confirm this effect and a similar result was observed. Finite temperature simulations based on a molecular dynamics approach have shown a reduction in the critical shear stress and maximum shear strain due to the increase in thermal agitation. At a finite temperature, the domain wall structure is characterized by perovskite units cells with a preferential polarization along the 〈0 1 1〉-direction. Simulations of kink structures revealed a long-range strain field caused by local disorder of the crystal lattice in the area surrounding the kink. As a direct consequence, careful size considerations on the separation distances between kinks have to be made prior to performing shear strain simulations. It was found that kink structures significantly facilitate the motion of 90° domain walls in PbTiO3.

Hydrogen trapping at dislocation cores at room temperature in deformed Pd

Abstract Small-angle neutron scattering (SANS) measurements of hydrogen segregation at dislocations in heavily deformed single crystal Pd have been performed at very low solute concentration (PdH0.0016) at equilibrium with respect to hydrogen gas at 295 K. The net (the without-hydrogen measurement subtracted from with-hydrogen measurement) absolute differential macroscopic scattering cross section has been fit with a cylindrical form factor to represent the Cottrell atmosphere, yielding local trapped concentration δ ∼ 0.06 [H]/[Pd], local volumetric dilatation f ∼ 1.01, and trapping radius R ∼ 4 A of the segregated hydrogen. This measurement augments SANS results below ambient temperature [B.J. Heuser, H. Ju, Phys. Rev. B 83 (2011) 094103]. The temperature dependence of the measured radius is confirmed by a Fourier transform of hydrogen occupation at dislocations based on an elastic continuum treatment [Trinkle et al., Phys. Rev. B 83 (2011) 174116]. The measured trapping parameters are consistent with a depopulation of weak long-range dislocation strain fields at ambient temperature; hydrogen binding to stronger core dislocation sites persists at 295 K and results in the measured net scattering. The local solute concentration and trapping radius (less than two Burgers vectors in Pd), are both too small to support optic mode dispersion due to inter-hydrogen interactions. This result supports the conclusion that trapped hydrogen undergoes a hydride to solid solution phase transformation between 200 and 300 K based on hydrogen vibration density of states measurements using incoherent inelastic neutron scattering [Trinkle et al., Phys. Rev. B 83 (2011) 174116, Ju et al., Nucl. Instr. Meth. Phys. Res. A 654, (2011) 522, and Heuser et al., Phys. Rev. B 78 (2008) 214101].

Minimization of thermodynamic costs in cancer cell invasion

Metastasis, the truly lethal aspect of cancer, occurs when metastatic cancer cells in a tumor break through the basement membrane and penetrate the extracellular matrix. We show that MDA-MB-231 metastatic breast cancer cells cooperatively invade a 3D collagen matrix while following a glucose gradient. The invasion front of the cells is a dynamic one, with different cells assuming the lead on a time scale of 70 h. The front cell leadership is dynamic presumably because of metabolic costs associated with a long-range strain field that precedes the invading cell front, which we have imaged using confocal imaging and marker beads imbedded in the collagen matrix. We suggest this could be a quantitative assay for an invasive phenotype tracking a glucose gradient and show that the invading cells act in a cooperative manner by exchanging leaders in the invading front.

Atomistic modeling of long-term evolution of twist boundaries under vacancy supersaturation

Vacancy accumulation in 4${}^{\ensuremath{\circ}}$ ${110}$ bcc Fe and 2${}^{\ensuremath{\circ}}$ ${111}$ fcc Cu twist boundaries (TBs) has been studied. These interfaces are characterized by different sets of screw dislocations: two sets of $\frac{{a}_{0}}{2}$$\ensuremath{\langle}$111$\ensuremath{\rangle}$ and one set of $\frac{{a}_{0}}{2}$$\ensuremath{\langle}$100$\ensuremath{\rangle}$ in Fe and three sets of $\frac{{a}_{0}}{6}$$\ensuremath{\langle}$112$\ensuremath{\rangle}$ in Cu. We observe that vacancies agglomerate preferentially at the misfit dislocation intersections (MDIs), where their formation energy is lower. In bcc the dislocation structure remains stable, but in fcc the interface rearranges itself increasing the stacking fault area. To perform this study a kinetic Monte Carlo algorithm coupled with the molecular dynamics code LAMMPS has been developed. Atomic positions are relaxed at every step after an event takes place to account for long-range strain fields. The events considered in this work are vacancy migration hops. The rates are calculated via harmonic transition state theory with the energy at the saddle point obtained either by a linear approximation considering the relaxed energy of the initial and final configurations or the nudged-elastic band method depending on the vacancy position in the sample. Vacancy diffusivities at both interfaces have also been calculated. For the ${110}$ TB in Fe the diffusivity is of the same order of magnitude as in bulk (${D}_{\mathrm{TB}}^{\text{Fe}}=2.60\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}13}\phantom{\rule{4.pt}{0ex}}{\text{m}}^{2}/\text{s}$) while at the ${111}$ TB in Cu, diffusivities are two orders of magnitude larger than in bulk (${D}_{\mathrm{TB}}^{\text{Cu}}=2.06\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}12}\phantom{\rule{4.pt}{0ex}}{\text{m}}^{2}/\text{s}$). The correlation factors at both interfaces are extremely low (${f}_{\mathrm{TB}}^{\text{Fe}}=1.61\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ and ${f}_{\mathrm{TB}}^{\text{Cu}}=3.34\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$), highlighting the importance of trapping sites at these interfaces.

Ab initiobased empirical potential used to study the mechanical properties of molybdenum

Density-functional theory energies, forces, and elastic constants determine the parametrization of an empirical, modified embedded-atom method potential for molybdenum. The accuracy and transferability of the potential are verified by comparison to experimental and density-functional data for point defects, phonons, thermal expansion, surface and stacking fault energies, and ideal shear strength. Searching the energy landscape predicted by the potential using a genetic algorithm verifies that it reproduces not only the correct bcc ground state of molybdenum but also all low-energy metastable phases. The potential is also applicable to the study of plastic deformation and used to compute energies, core structures, and Peierls stresses of screw and edge dislocations. Molybdenum's high strength and high-temperature stability make this refractory metal very attractive for use in advanced process technologies. The motion of dislocations is generally accepted to be responsible for the complex deformation behavior of this transition metal. 1-8 In recent years progress has been made on the description of the properties of screw dislocations using density-functional theory (DFT), tight- binding calculations, and empirical potentials. 9-19 However, DFT and tight-binding techniques are limited to small system sizes, which is problematic due to the long-range strain field of dislocations, and current empirical potentials lack the required accuracy for the description of the dislocation structure. Simulations of dislocation motion and interactions require efficient interatomic potentials which accurately describe the dislocation energies, core structures, and motion. In this work we develop an empirical potential for Mo which predicts the ideal shear strength, generalized stacking fault en- ergies, energies of dislocations, and the Peierls stress and core structure of the � 111� /2 screw dislocation. The potential form is given by the modified embedded-atom method (MEAM) and the potential parameters are optimized usingabinitio energies, lattice parameters, forces, and elastic constants. Section II describes the calculations for the DFT database, the functional form of the MEAM potential, and the optimization of the potential parameters to the DFT database. The accuracy of the potential for structural, elastic, and defect properties is verified in Sec. III by comparison to DFT results and experiments. A genetic algorithm search of the energy landscape of the MEAM potential confirms that the potential reproduces the correct bcc ground state and predicts several low-energy metastable structures whose energies agree well with DFT results. Results of the MEAM potential for formation energies of point defects, phonon dispersion, thermal expansion, surface energies, ideal shear strength, and generalized stacking faults for the MEAM potential closely match DFT results and available experimental data. In Sec. IV we apply the potential to determine energies and Peierls stresses of the screw and edge dislocation in bcc Mo. The results show that the MEAM potential accurately describes the structural and mechanical properties of Mo and should be applicable to simulate the motion of dislocations and the plastic deformation of Mo.

Chemistry of Ruddlesden–Popper planar faults at a ferroelectric–ferromagnet perovskite interface

We investigate the interfacial structure of PbZr0.20Ti0.80O3 (PZT)/La0.67Sr0.33MnO3 (LSMO)/SrTiO3 heterostructures by combining low-magnification transmission electron microscopy imaging and spectroscopy techniques with high-resolution spherical-aberration corrected scanning transmission electron microscopy imaging, geometrical phase analysis, and spectroscopy results. For certain thickness regimes, the interface between PZT and LSMO is found to have a significant density of planar defects at the interface. Both A-site cation (Pb) diffusivity and highly inhomogeneous local strains are observed at the boundaries of the defect areas. It is proposed that Pb is incorporated as PbO Ruddlesden–Popper planar fault within the LSMO. These results underline the importance of chemical fluctuations caused by long-range strain fields associated with defect cores.