The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Hiroshi Funakubo - One of the best experts on this subject based on the ideXlab platform.
-
orientation control and domain structure analysis of 100 oriented epitaxial ferroelectric Orthorhombic hfo2 based thin films
Journal of Applied Physics, 2016Co-Authors: Kiliha Katayama, Takahisa Shiraishi, Takanori Kiguchi, Akihiro Akama, Shogo Nakamura, Toyohiko J Konno, Hiroshi Uchida, Osami Sakata, Takao Shimizu, Hiroshi FunakuboAbstract:Orientation control of {100}-oriented epitaxial Orthorhombic 0.07YO1.5-0.93HfO2 films grown by pulsed laser deposition was investigated. To achieve in-plane lattice matching, indium tin oxide (ITO) and yttria-stabilized zirconia (YSZ) were selected as underlying layers. We obtained (100)- and (001)/(010)-oriented films on ITO and YSZ, respectively. Ferroelastic domain formation was confirmed for both films by X-ray diffraction using the superlattice diffraction that appeared only for the Orthorhombic symmetry. The formation of ferroelastic domains is believed to be induced by the tetragonal–Orthorhombic phase transition upon cooling the films after deposition. The present results demonstrate that the orientation of HfO2-based ferroelectric films can be controlled in the same manner as that of ferroelectric films composed of conventional perovskite-type material such as Pb(Zr, Ti)O3 and BiFeO3.
-
growth of epitaxial Orthorhombic yo1 5 substituted hfo2 thin film
Applied Physics Letters, 2015Co-Authors: Takao Shimizu, Kiliha Katayama, Takanori Kiguchi, Akihiro Akama, Toyohiko J Konno, Hiroshi FunakuboAbstract:YO1.5-substituted HfO2 thin films with various substitution amounts were grown on (100) YSZ substrates by the pulsed laser deposition method directly from the vapor phase. The epitaxial growth of film with different YO1.5 amounts was confirmed by the X-ray diffraction method. Wide-area reciprocal lattice mapping measurements were performed to clarify the crystal symmetry of films. The formed phases changed from low-symmetry monoclinic baddeleyite to high-symmetry tetragonal/cubic fluorite phases through an Orthorhombic phase as the YO1.5 amount increased from 0 to 0.15. The additional annular bright-field scanning transmission electron microscopy indicates that the Orthorhombic phase has polar structure. This means that the direct growth by vapor is of polar Orthorhombic HfO2-based film. Moreover, high-temperature X-ray diffraction measurements showed that the film with a YO1.5 amount of 0.07 with Orthorhombic structure at room temperature only exhibited a structural phase transition to tetragonal phase a...
Jean-jacques Fundenberger - One of the best experts on this subject based on the ideXlab platform.
-
evolution of crystallographic texture and microstructure in the Orthorhombic phase of a two phase alloy ti 22al 25nb
Intermetallics, 2009Co-Authors: Satyam Suwas, Jean-jacques FundenbergerAbstract:Evolution of crystallographic texture in the Orthorhombic phase of a two-phase alloy Ti–22Al–25Nb (at%), consisting of Orthorhombic (O) and bcc (β/B2) phases, was studied. The material was subjected to deformation in two-phase field as well as in the single β phase field. The resulting evolution of microstructure and crystallographic texture were recorded using scanning electron microscopy and X-ray diffraction. The Orthorhombic phase underwent change in morphology (from platelets to equiaxed) on rolling in the two-phase field with the texture getting sharper with the amount of deformation. Rolling above β transus temperature led to hot deformation of single β phase microstructure and its subsequent cooling produced transformed coarse platelets of Orthorhombic phase with texture in orientation relation with the high temperature deformed β phase.
Jianwei Zhang - One of the best experts on this subject based on the ideXlab platform.
-
microstructure control and mechanical properties from isothermal forging and heat treatment of ti 22al 25nb at Orthorhombic alloy
Intermetallics, 2015Co-Authors: W L Wang, Weidong Zeng, Chen Xue, Xiaobo Liang, Jianwei ZhangAbstract:Abstract The microstructural evolution, creep, and tensile deformation behavior of an Orthorhombic Ti–22Al–25Nb (at.%) alloy was investigated by thermo-mechanical processing, including common forging, isothermal forging, and heat treatment. Three different microstructures were obtained by varying the isothermal forging temperatures and heat-treatment schedule. Tensile-creep experiments were conducted from 650 to 700 °C and over a stress range of 100–200 MPa. The alloy tensile strengths at room temperature and 650 °C were also determined. As the isothermal forging temperature increases from 1040 °C to 1080 °C, three alloy microstructures result, including equiaxial, duplex, and bimodal-size lamellar Orthorhombic microstructures. Of the three, the bimodal-size lamellar Orthorhombic microstructures have the highest strength but worst ductility, whereas the equiaxial microstructures have the highest ductility but worst strength. The equiaxial microstructures have the worst creep resistance, whereas the duplex microstructures and bimodal-size lamellar Orthorhombic microstructures have a similar creep resistance.
S S A Seo - One of the best experts on this subject based on the ideXlab platform.
-
compressive strain induced metal insulator transition in Orthorhombic sriro 3 thin films
Journal of Materials Research, 2014Co-Authors: J H Gruenewald, J Nichols, J Terzic, G Cao, J W Brill, S S A SeoAbstract:Orthorhombic SrIrO 3 is a correlated metal whose electronic properties are highly susceptible to external perturbations due to the comparable interactions of spin–orbit interaction and electronic correlation. We have investigated the electronic properties of epitaxial Orthorhombic SrIrO 3 thin-films under compressive strain using transport measurements, optical absorption spectra, and magnetoresistance. The metastable, Orthorhombic SrIrO 3 thin-films are synthesized on various substrates using an epi-stabilization technique. We have observed that as in-plane lattice compression is increased, the dc-resistivity (ρ) of the thin films increases by a few orders of magnitude, and the dρ/d T changes from positive to negative values. However, optical absorption spectra show Drude-like, metallic responses without an optical gap opening for all compressively strained thin films. Transport measurements under magnetic fields show negative magnetoresistance at low temperature for compressively strained thin-films. Our results suggest that weak localization is responsible for the strain-induced metal–insulator transition for the Orthorhombic SrIrO 3 thin-films.
-
compressive strain induced metal insulator transition in Orthorhombic sriro3 thin films
arXiv: Strongly Correlated Electrons, 2014Co-Authors: J H Gruenewald, J Nichols, J Terzic, G Cao, J W Brill, S S A SeoAbstract:We have investigated the electronic properties of epitaxial Orthorhombic SrIrO3 thin-films under compressive strain. The metastable, Orthorhombic SrIrO3 thin-films are synthesized on various substrates using an epi-stabilization technique. We have observed that as in-plane lattice compression is increased, the dc-resistivity (\r{ho}) of the thin films increases by a few orders of magnitude, and the d\r{ho}/dT changes from positive to negative values. However, optical absorption spectra show Drude-like, metallic responses without an optical gap opening for all compressively-strained thin films. Transport measurements under magnetic fields show negative magneto-resistance at low temperature for compressively-strained thin-films. Our results suggest that weak localization is responsible for the strain-induced metal-insulator transition for the Orthorhombic SrIrO3 thin-films.
Xiaohui Wang - One of the best experts on this subject based on the ideXlab platform.
-
size effect on the dielectric properties of batio3 nanoceramics in a modified ginsburg landau devonshire thermodynamic theory
Physical Review B, 2006Co-Authors: Tianquan Lu, Xiaohui WangAbstract:Grain size effects on the dielectric properties of BaTiO3 nanoceramics have been studied by using the modified Ginsburg-Landau-Devonshire (GLD) thermodynamic theory. Considering the existence of internal stresses, it is found that with decreasing grain size the transition temperature of cubic-tetragonal phase decreases, while those of tetragonal-Orthorhombic and Orthorhombic-rhombohedral phases increase. With further reducing grain size, our model predicts that the two ferroelectric structures of Orthorhombic and tetragonal phases will become unstable and disappear at a critical size, leaving only one stable ferroelectric phase of rhombohedral structure. Consequently, a theoretical phase diagram of the transition temperature versus grain size is established wherein two triple points and a reentrance behavior are indicated. The results are compared with experimental data.
