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Jingsheng Chen - One of the best experts on this subject based on the ideXlab platform.

  • Lattice Mismatch induced oscillatory feature size and its impact on the physical limitation of grain size
    Physical review applied, 2018
    Co-Authors: Jinyu Deng, Kaifeng Dong, Yingguo Peng, G M Chow, Jingsheng Chen
    Abstract:

    Size control of nanocrystals is becoming more crucial in growing, for example, granular ferromagnetic thin films for heat-assisted magnetic recording, or self-assembled quantum dots for quantum computing. This study identifies granular patterns with surprisingly ``quantized'' feature sizes in Fe-Pt thin film grown on Lattice-Mismatched MgO. This arises from the periodic nature of the misfit-strain energy in such a system; island lengths that are integer multiples of the misfit dislocation period are energetically favored. These results point to synthesizing nanostructured materials with well-controlled grain size by tuning the interlayer Lattice Mismatch.

  • Large Lattice Mismatch effects on the epitaxial growth and magnetic properties of FePt films
    Journal of Magnetism and Magnetic Materials, 2018
    Co-Authors: Jinyu Deng, Gan Moog Chow, Kaifeng Dong, Ping Yang, Yingguo Peng, Jingsheng Chen
    Abstract:

    Abstract Heteroepitaxial film growth is crucial for magnetic and electronic devices. In this work, we reported the effects of the large Lattice Mismatch and film thickness on the epitaxial growth and magnetic properties of FePt films on Zr x Ti 1−x N (0 0 1) intermediate layer. FePt films with different thickness were deposited on ZrTiN intermediate layers with various doping concentration of TiN in ZrN. The increase in doping concentration of TiN caused a decrease in the Lattice parameters of ZrTiN intermediate layer. It was found that (0 0 1) epitaxy of FePt 10 nm films was only achieved on ZrTiN intermediate layer when the TiN composition was ≥25 vol%, while (0 0 1) texture of 5 nm films was achieved on ZrTiN intermediate layer with a minimum of 50 vol% TiN composition. The in-plane Lattice constants of FePt and Zr 0.70 Ti 0.30 N (25 vol% TiN) were 3.870 A and 4.476 A, respectively, which resulted in a Lattice Mismatch as large as 15.7%. These large Lattice Mismatch heterostructures adopted 7/6 domain matching epitaxy. The magneto-crystalline anisotropy of FePt films was improved with the increase in Lattice Mismatch. Intrinsic magnetic properties were extrapolated for FePt (30 nm)/Zr 0.70 Ti 0.30 N (30 nm)/TaN (30 nm)/MgO, and the M s (0 K) and K 1 (0 K) were 1042 emu/cc and 5.10 × 10 7  erg/cc, respectively, which is comparable to that of bulk L1 0 FePt.

  • Lattice Mismatch-induced evolution of microstructural properties in FePt films
    Journal of Applied Physics, 2013
    Co-Authors: Kaifeng Dong, Jingsheng Chen
    Abstract:

    FePt (10, 20, 40, and 60 nm) films were fabricated on four different single crystal substrates [MgO (001), KTaO3 (001), SrTiO3 (001), and LaAlO3 (001)], and the effects of Lattice Mismatch on the microstructure and magnetic properties of FePt films were systematically investigated. The X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) results showed that the different Lattice Mismatch between the substrates and FePt films resulted in the different crystallographic texture and microstructure of the FePt films. Under the tensile strain between the FePt and substrates (MgO, KTaO3, SrTiO3), the FePt films preferred to form L10 FePt (001) texture. The perpendicular anisotropy of the FePt films grown on MgO was larger than that grown on KTaO3 and SrTiO3. For the FePt films grown on the LaAlO3 substrate, both FePt (110) and (001) orientations were found, which indicated the presence of tensile and compressive strain, respectively. With the reduction of the Lattice ...

  • Lattice Mismatch induced evolution of microstructural properties in fept films
    Journal of Applied Physics, 2013
    Co-Authors: Kaifeng Dong, Jingsheng Chen
    Abstract:

    FePt (10, 20, 40, and 60 nm) films were fabricated on four different single crystal substrates [MgO (001), KTaO3 (001), SrTiO3 (001), and LaAlO3 (001)], and the effects of Lattice Mismatch on the microstructure and magnetic properties of FePt films were systematically investigated. The X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) results showed that the different Lattice Mismatch between the substrates and FePt films resulted in the different crystallographic texture and microstructure of the FePt films. Under the tensile strain between the FePt and substrates (MgO, KTaO3, SrTiO3), the FePt films preferred to form L10 FePt (001) texture. The perpendicular anisotropy of the FePt films grown on MgO was larger than that grown on KTaO3 and SrTiO3. For the FePt films grown on the LaAlO3 substrate, both FePt (110) and (001) orientations were found, which indicated the presence of tensile and compressive strain, respectively. With the reduction of the Lattice Mismatch between the FePt (10 nm) and substrate from 5.8% (MgO) to 2.4% (KTaO3), and 0.1% (SrTiO3), the microstructure of the FePt films changed gradually from granular to continuous films (SEM and TEM results). The microstructure of the 10 nm FePt film grown on LaAlO3 substrate showed granular structure.

  • Effect of Lattice Mismatch on chemical ordering of epitaxial L10 FePt films
    Journal of Applied Physics, 2005
    Co-Authors: Ying Ding, Jingsheng Chen, Erjia Liu, Cheng-jun Sun, Gan Moog Chow
    Abstract:

    The effect of Lattice Mismatch on the chemical ordering of epitaxial FePt films was studied. The results showed that the Lattice constant (c) of the FePt films decreased with increasing Lattice Mismatch e from about 2.23% to 6.33%. Upon further increase of e to about 8.8%, c increased. On the other hand, the variation of the Lattice constant (a) of the FePt films showed a reversal behavior to that of c with the increased Lattice Mismatch. The ratio c∕a of the FePt films held a minimum of about 0.9466, while the chemical ordering degree and magnetic anisotropy constant held maximum values for e around 6.33%. These results indicated that the strain from the Lattice Mismatch favored the ordering of the FePt films.

Kaifeng Dong - One of the best experts on this subject based on the ideXlab platform.

  • Lattice Mismatch induced oscillatory feature size and its impact on the physical limitation of grain size
    Physical review applied, 2018
    Co-Authors: Jinyu Deng, Kaifeng Dong, Yingguo Peng, G M Chow, Jingsheng Chen
    Abstract:

    Size control of nanocrystals is becoming more crucial in growing, for example, granular ferromagnetic thin films for heat-assisted magnetic recording, or self-assembled quantum dots for quantum computing. This study identifies granular patterns with surprisingly ``quantized'' feature sizes in Fe-Pt thin film grown on Lattice-Mismatched MgO. This arises from the periodic nature of the misfit-strain energy in such a system; island lengths that are integer multiples of the misfit dislocation period are energetically favored. These results point to synthesizing nanostructured materials with well-controlled grain size by tuning the interlayer Lattice Mismatch.

  • Large Lattice Mismatch effects on the epitaxial growth and magnetic properties of FePt films
    Journal of Magnetism and Magnetic Materials, 2018
    Co-Authors: Jinyu Deng, Gan Moog Chow, Kaifeng Dong, Ping Yang, Yingguo Peng, Jingsheng Chen
    Abstract:

    Abstract Heteroepitaxial film growth is crucial for magnetic and electronic devices. In this work, we reported the effects of the large Lattice Mismatch and film thickness on the epitaxial growth and magnetic properties of FePt films on Zr x Ti 1−x N (0 0 1) intermediate layer. FePt films with different thickness were deposited on ZrTiN intermediate layers with various doping concentration of TiN in ZrN. The increase in doping concentration of TiN caused a decrease in the Lattice parameters of ZrTiN intermediate layer. It was found that (0 0 1) epitaxy of FePt 10 nm films was only achieved on ZrTiN intermediate layer when the TiN composition was ≥25 vol%, while (0 0 1) texture of 5 nm films was achieved on ZrTiN intermediate layer with a minimum of 50 vol% TiN composition. The in-plane Lattice constants of FePt and Zr 0.70 Ti 0.30 N (25 vol% TiN) were 3.870 A and 4.476 A, respectively, which resulted in a Lattice Mismatch as large as 15.7%. These large Lattice Mismatch heterostructures adopted 7/6 domain matching epitaxy. The magneto-crystalline anisotropy of FePt films was improved with the increase in Lattice Mismatch. Intrinsic magnetic properties were extrapolated for FePt (30 nm)/Zr 0.70 Ti 0.30 N (30 nm)/TaN (30 nm)/MgO, and the M s (0 K) and K 1 (0 K) were 1042 emu/cc and 5.10 × 10 7  erg/cc, respectively, which is comparable to that of bulk L1 0 FePt.

  • Lattice Mismatch-induced evolution of microstructural properties in FePt films
    Journal of Applied Physics, 2013
    Co-Authors: Kaifeng Dong, Jingsheng Chen
    Abstract:

    FePt (10, 20, 40, and 60 nm) films were fabricated on four different single crystal substrates [MgO (001), KTaO3 (001), SrTiO3 (001), and LaAlO3 (001)], and the effects of Lattice Mismatch on the microstructure and magnetic properties of FePt films were systematically investigated. The X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) results showed that the different Lattice Mismatch between the substrates and FePt films resulted in the different crystallographic texture and microstructure of the FePt films. Under the tensile strain between the FePt and substrates (MgO, KTaO3, SrTiO3), the FePt films preferred to form L10 FePt (001) texture. The perpendicular anisotropy of the FePt films grown on MgO was larger than that grown on KTaO3 and SrTiO3. For the FePt films grown on the LaAlO3 substrate, both FePt (110) and (001) orientations were found, which indicated the presence of tensile and compressive strain, respectively. With the reduction of the Lattice ...

  • Lattice Mismatch induced evolution of microstructural properties in fept films
    Journal of Applied Physics, 2013
    Co-Authors: Kaifeng Dong, Jingsheng Chen
    Abstract:

    FePt (10, 20, 40, and 60 nm) films were fabricated on four different single crystal substrates [MgO (001), KTaO3 (001), SrTiO3 (001), and LaAlO3 (001)], and the effects of Lattice Mismatch on the microstructure and magnetic properties of FePt films were systematically investigated. The X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) results showed that the different Lattice Mismatch between the substrates and FePt films resulted in the different crystallographic texture and microstructure of the FePt films. Under the tensile strain between the FePt and substrates (MgO, KTaO3, SrTiO3), the FePt films preferred to form L10 FePt (001) texture. The perpendicular anisotropy of the FePt films grown on MgO was larger than that grown on KTaO3 and SrTiO3. For the FePt films grown on the LaAlO3 substrate, both FePt (110) and (001) orientations were found, which indicated the presence of tensile and compressive strain, respectively. With the reduction of the Lattice Mismatch between the FePt (10 nm) and substrate from 5.8% (MgO) to 2.4% (KTaO3), and 0.1% (SrTiO3), the microstructure of the FePt films changed gradually from granular to continuous films (SEM and TEM results). The microstructure of the 10 nm FePt film grown on LaAlO3 substrate showed granular structure.

Alain Jacques - One of the best experts on this subject based on the ideXlab platform.

  • measurement of the effective γ γ Lattice Mismatch during high temperature creep of ni based single crystal superalloy
    Materials Characterization, 2013
    Co-Authors: Laura Dirand, Jonathan Cormier, Alain Jacques, Thomas Schenk, Olivier Ferry, Jeanphilippe Chateaucornu, Pierre Bastie
    Abstract:

    The high temperature effective (constrained) gamma/gamma' Lattice Mismatch of a Ni-based single crystal superalloy has been measured in a wide temperature range [930 degrees C-1125 degrees C] using three different techniques: in-situ X-ray diffraction under synchrotron radiation, and post-mortem gamma/gamma' interfacial dislocation network mesh size measurements using Transmission Electron Microscopy (TEM) or high resolution Scanning Electron Microscopy (SEM). It is shown that all three techniques are complementary considering precision and spatial distribution of Lattice Mismatches in the analyzed volume and that they provide a very similar average value of the gamma/gamma' Lattice Mismatch. Since isothermal creep experiments were performed under variable applied stress, it is deduced that the post-mortem Lattice misfit measurements using both TEM and SEM are representative of the very last loading step of the experiments, even if dislocation networks are out of an equilibrium configuration. Contrary to the unconstrained gamma/gamma' Lattice Mismatch, it is shown that the effective Lattice Mismatch is a function of the temperature, applied stress and accumulated plastic strain, i.e. of the thermomechanical histories of the samples.

  • in situ measurement of the γ γ Lattice Mismatch evolution of a nickel based single crystal superalloy during non isothermal very high temperature creep experiments
    Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2012
    Co-Authors: Laura Dirand, Jonathan Cormier, Alain Jacques, Thomas Schenk, Olivier Ferry, Jeanbriac Le Graverend, Franck Gallerneau, Serge Kruch
    Abstract:

    The evolution of the γ/γ′ Lattice Mismatch of the AM1 single-crystal superalloy was measured during in situ non-isothermal very high-temperature creep tests under X-ray synchrotron radiation. The magnitude of the effective Lattice Mismatch in the 1273 K to 1323 K (1000 °C to 1050 °C) temperature range always increased after overheatings performed at temperatures lower than 1403 K (1130 °C). In contrast, a decrease of its magnitude was observed after overheatings at temperatures greater than 1453 K (1180 °C) due to massive dislocation recovery processes occurring at very high temperature.

  • in situ measurement of the Lattice parameter Mismatch of a nickel base single crystalline superalloy under variable stress
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2004
    Co-Authors: Alain Jacques, Frederic Diologent, P Bastie
    Abstract:

    Abstract The evolution of the Lattice parameters of the γ matrix and γ′ precipitates was measured in situ during high temperature tests of specimens with a raft microstructure at 1080 °C under variable load (0–300 MPa), done at the ESRF. Under low applied tensile stresses, the behavior of the specimens is purely elastic, while under stresses higher than the pre-strain stress plastic deformation takes place and results in changes of the effective Lattice Mismatch at the γ/γ′ interfaces. Modeling suggests a linear dependence of the Lattice Mismatch versus the applied stress, which is observed during the experiment.

  • the evolution of the Lattice parameter Mismatch of a nickel based superalloy during a high temperature creep test
    Philosophical Magazine, 2003
    Co-Authors: Alain Jacques, Pierre Bastie
    Abstract:

    We report in-situ measurement of both (200) and (002) diffraction profiles (parallel and perpendicular to the tensile axis) and of the Lattice Mismatch of the AM1 superalloy during a tensile creep experiment (150 MPa; 1080°C). The measurements were made by high-resolution high-energy X-ray diffraction at the ID 15A beam line of the European Synchrotron Radiation Facility. Peak shape and Lattice Mismatch have well-defined non-monotonic behaviours clearly related to the evolution of the microstructure (rafting, ripening and encapsulation of the γ phase) and the different stages of the creep curve. Modelling of the raft microstructure as a multilayer gives a good description of the experimental parameters (peak shape and Lattice Mismatch) during stage II, and a qualitative explanation of their behaviour during stage III.

Gan Moog Chow - One of the best experts on this subject based on the ideXlab platform.

  • Large Lattice Mismatch effects on the epitaxial growth and magnetic properties of FePt films
    Journal of Magnetism and Magnetic Materials, 2018
    Co-Authors: Jinyu Deng, Gan Moog Chow, Kaifeng Dong, Ping Yang, Yingguo Peng, Jingsheng Chen
    Abstract:

    Abstract Heteroepitaxial film growth is crucial for magnetic and electronic devices. In this work, we reported the effects of the large Lattice Mismatch and film thickness on the epitaxial growth and magnetic properties of FePt films on Zr x Ti 1−x N (0 0 1) intermediate layer. FePt films with different thickness were deposited on ZrTiN intermediate layers with various doping concentration of TiN in ZrN. The increase in doping concentration of TiN caused a decrease in the Lattice parameters of ZrTiN intermediate layer. It was found that (0 0 1) epitaxy of FePt 10 nm films was only achieved on ZrTiN intermediate layer when the TiN composition was ≥25 vol%, while (0 0 1) texture of 5 nm films was achieved on ZrTiN intermediate layer with a minimum of 50 vol% TiN composition. The in-plane Lattice constants of FePt and Zr 0.70 Ti 0.30 N (25 vol% TiN) were 3.870 A and 4.476 A, respectively, which resulted in a Lattice Mismatch as large as 15.7%. These large Lattice Mismatch heterostructures adopted 7/6 domain matching epitaxy. The magneto-crystalline anisotropy of FePt films was improved with the increase in Lattice Mismatch. Intrinsic magnetic properties were extrapolated for FePt (30 nm)/Zr 0.70 Ti 0.30 N (30 nm)/TaN (30 nm)/MgO, and the M s (0 K) and K 1 (0 K) were 1042 emu/cc and 5.10 × 10 7  erg/cc, respectively, which is comparable to that of bulk L1 0 FePt.

  • Effect of Lattice Mismatch on chemical ordering of epitaxial L10 FePt films
    Journal of Applied Physics, 2005
    Co-Authors: Ying Ding, Jingsheng Chen, Erjia Liu, Cheng-jun Sun, Gan Moog Chow
    Abstract:

    The effect of Lattice Mismatch on the chemical ordering of epitaxial FePt films was studied. The results showed that the Lattice constant (c) of the FePt films decreased with increasing Lattice Mismatch e from about 2.23% to 6.33%. Upon further increase of e to about 8.8%, c increased. On the other hand, the variation of the Lattice constant (a) of the FePt films showed a reversal behavior to that of c with the increased Lattice Mismatch. The ratio c∕a of the FePt films held a minimum of about 0.9466, while the chemical ordering degree and magnetic anisotropy constant held maximum values for e around 6.33%. These results indicated that the strain from the Lattice Mismatch favored the ordering of the FePt films.

Hans Boschker - One of the best experts on this subject based on the ideXlab platform.

  • symmetry and Lattice Mismatch induced strain accommodation near and away from correlated perovskite interfaces
    Applied Physics Letters, 2014
    Co-Authors: Arturas Vailionis, Hans Boschker, Zhaoliang Liao, J R A Smit, Guus Rijnders, Mark Huijben, Gertjan Koster
    Abstract:

    Distinct MnO6 octahedral distortions near and away from the La0.67Sr0.33MnO3/SrTiO3(001) (LSMO/STO) interface are quantified using synchrotron x-ray diffraction and dynamical x-ray diffraction simulations. Three structural regions of stress accommodation throughout the film thickness were resolved: near the LSMO/STO interface, intermediate region farther from the interface, and the main layer away from the interface. The results show that within the first two unit cells stress is accommodated by the suppression of octahedral rotations in the film, leading to the expansion of the c-axis Lattice parameter. Farther from the interface film structure acquires octahedral tilts similar to thicker perovskite films under tensile stress, leading to a reduced c-axis parameter. We demonstrate that these regions are related to two different strain coupling mechanisms: symmetry Mismatch at the interface and Lattice Mismatch in the rest of the film. The findings suggest new routes for strain engineering in correlated perovskite heterostructures.