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Petrovic A.P.,Nanyang Technological University | Kato Y.,Los Alamos National Laboratory | Sunku S.S.,Nanyang Technological University | Ito T.,Japan National Institute of Advanced Industrial Science and Technology | And 11 more authors.
Physical Review B - Condensed Matter and Materials Physics

We present a study of the thermodynamic and magnetic properties of single-crystal EuTiO3. Signatures of metastability are visible in the heat capacity below the cubic-tetragonal phase transition at 283 K, supporting the evidence for a mismatch between long and short range structural order from previous x-ray diffraction studies. Employing the anisotropic magnetization as an indirect structural probe, we confirm the emergence of multiple orthogonal domains at low temperature. Torque magnetometry is capable of revealing the nature and temperature dependence of the magnetic anisotropy in spite of the domain misalignment; we hence deduce that tetragonal EuTiO3 enters an easy-axis antiferromagnetic phase at 5.6 K, with a first-order phase transition to an easy-plane ground state below 3 K. Our experimentally determined magnetic phase diagram is accurately reproduced by a three-dimensional (3D) anisotropic Heisenberg spin model. Furthermore, we demonstrate that electric field cooling acts to suppress this orientational disorder by realigning the domains due to the strong coupling between electric fields and lattice dipoles characteristic of paraelectric materials. © 2013 American Physical Society. Source

Liu Z.,University Street | Biswas A.,University Street
Applied Catalysis A: General

Ring-opening polymerization of epoxidized soybean oil (ESO) catalyzed by a super acid, fluoroantimonic acid hexahydrate (HSbF6·6H 2O) in ethyl acetate was conducted in an effort to develop useful biodegradable polymers. The resulting polymerized ESO (SA-RPESO) was characterized using infrared (IR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), 1H NMR, 13C NMR, solid state 13C NMR, and gel permeation chromatography (GPC). The results indicated that ESO was effectively polymerized by fluoroantimonic acid and formed polymers with relatively high crosslink density. Glass transition temperatures of these polymers ranged from -13 °C to -21 °C. TGA results showed the SA-RPESO polymers were thermally stable at temperatures up to 200 °C. Decomposition of the polymers was found to occur at temperatures greater than 350 °C. GPC results indicated the extracted soluble substances from SA-RPESO polymers were oligomers of ESO. These soybean oil-based polymers will be functionalized to hydrogels and their applications explored in the personal and health care areas. Source

Lupu C.,Polytechnic University of Bucharest | Bandici L.,University of Oradea | Bandici L.,University Street | Molnar C.,University of Oradea | And 2 more authors.
Journal of Electrical and Electronics Engineering

The main ideea of the paper is to reduce the hardware and software effort required for a simulation process using an identified model. Since the results are consistent, based on the observations of the data related relationship to the minimum necessary is proposed for a simulation that leads to a neglectable error. This relationship is used in the case study made on a multiple model control type architecture that aims to switch smooth control algorithms. The proposed system is implemented and tested in real-time software for a nonlinear plant laboratory. Source

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