Search results for "Phase Transition"
showing 10 items of 1281 documents
Transition path to a dense efficient-packed post-delafossite phase. Crystal structure and evolution of the chemical bonding
2021
We are thankful for the financial support received from the Spanish Ministerio de Ciencia e Innovación and the Agencia Estatal de Investigación under national projects PGC2018-094417-B-I00 (co-financed by EU FEDER funds), MAT2016-75586-C4-1-P/2-P, FIS2017-83295-P, PID2019-106383GB-C41/C42 and RED2018- 102612-T (MALTA Consolider), and from Generalitat Valenciana under project PROMETEO/2018/123. D.S-P, A.O.R, and J.A.S acknowledge financial support of the Spanish MINECO for the RyC-2014-15643, RyC-2016-20301, and RyC-2015-17482 Ramón y Cajal Grants, respectively.
Co-flow microfluidic synthesis of liquid crystalline actuating Janus particles
2016
A microfluidic synthesis of stimuli-responsive actuating Janus particles composed of a liquid crystalline elastomer (LCE) and a polymeric hydrogel is reported. , In this article the microfluidic synthesis and characterization of micrometer sized actuating Janus particles containing a liquid crystalline elastomer (LCE) is presented. On one side these Janus particles consist of a hydrophobic liquid crystalline part, featuring strong shape changes during the thermotropic phase transition, whereas the other side contains a hydrophilic polyacrylamide network. The synthesis is based upon the dispersion of two immiscible monomer mixtures in a continuously flowing silicone oil, using two glass capi…
When are thin films of metals metallic? Part III
1996
Abstract A large amount of experimental information has indicated that very thin films of metallic elements can exhibit nonmetallic behavior, even on metal substrates. These films undergo a gradual nonmetal to metal transition with increasing film density or thickness. The nonmetallic behavior can be related to electron localization due to strong electron-electron correlation in low dimensional systems, as indicated by the strong enhancement of electron effective mass. The evolution in the electronic structure associated with the nonmetal to metal transition bears a striking resemblance to the behavior observed for free metal clusters. Part I [1], outlined the general concepts of a nonmetal…
Thermodynamic considerations of the grain size dependency of material properties
1994
Phase transitions which depend on grain size induce very interesting properties in materials such as zirconia or barium titanate. A new and rigorous thermodynamic treatment of this type of phase transition is proposed with consideration of the surface phenomena. An interpretation is given of the observed differences when the material—particularly BaTiO3—under consideration is a fine grain powder or is a fine grain ceramic.
Synthesis and Characterization of Lead-Free (1-x)(K0.5Na0.5)Nb1-ySbyO3-xBaTiO3
2011
In this study lead-free ceramics with a formula (1-x)(K0.5Na0.5)Nb1-ySbyO3-xBaTiO3 have been synthesized and studied. XRD studies showed that all compositions have perovskite structure with monoclinic or tetragonal cell depending on substitution level. KNN ceramics with BaTiO3 have more homogeneous structure and increased density in comparison with pure KNN or antimony substituted KNN. Dielectric measurements revealed diffuse phase transition.
Structural, magnetic, dielectric and mechanical properties of (Ba,Sr)MnO3 ceramics
2017
The authors acknowledge the CPU time allocation at Academic Computer Centre CYFRONET AGH in Cracow. This work was supported in part by PL-Grid Infrastructure and the European Regional Development Fund under the Infrastructure and Environment Programme [grant number UDA-POIS.13.01-023/09-00]. The research was partially carried out with the equipment purchased thanks to the financial support of the European Regional Development Fund in the framework of the Polish Innovation Economy Operational Program (contract no. POIG.02.01.00-12-023/08). L. Vasylechko acknowledges partial support of the Ukrainian Ministry of Education and Sciences under the Projects ?RZE?, ?KMON?, and ICDD Grant-in-Aid pro…
Control of the Magnetic Configuration of Ferromagnetic Nanostructures Across the Structural Phase Transition of Vanadium Dioxide
2016
We investigate the effect of the structural phase transition in VO 2 in magnetoelastically coupled heterostructures of VO 2 and Ni. Continuous and nano-patterned Ni layers were used, and we found reversible and reproducible magnetic domain switching induced by the VO 2 structural phase transition. The magnetic states of the nano-patterned ferromagnetic elements were dominated by topographic features which generated strong pinning but still allowed for a reversible switching between the states. Our measurements constitute a key step for the use of the VO 2 phase transition for ultrafast dynamical studies of the inverse mangetostrictive effect, and eventually employing the effect for ultrafas…
Dynamic self-assembly of non-Brownian spheres studied by molecular dynamics simulations.
2015
Granular self-assembly of confined non-Brownian spheres under gravity is studied by molecular dynamics simulations. Starting from a disordered phase, dry or cohesive spheres organize, by vibrational annealing, into body-centered-tetragonal or face-centered-cubic structures, respectively. During the self-assembling process, isothermal and isodense points are observed. The existence of such points indicates that both granular temperature and packing fraction undergo an inversion process that may be in the core of crystal nucleation. Around the isothermal point, a sudden growth of granular clusters having the maximum coordination number takes place, indicating the outcome of a first-order phas…
Depolarization Currents and Ageing in Layered Na0.5Bi8.5Ti2Nb4O27and Na0.5Bi8.5Ti2Ta4O27Ferroelectrics
2009
The present study is focused on the behaviour of polarization and depolarization currents and processes of the slow relaxation of polarization within the range of temperatures where the anomalies are displayed by the materials. Results of the study are discussed with regard to possible existence of defect complexes in disordered ferroelectrics.
Optical behavior of Eu3+-doped BaTiO3 nano-crystallites prepared by sol–gel method
2003
Abstract Eu 3+ -doped BaTiO 3 nano-crystallites with grain sizes 32–38 nm have been obtained by a sol–gel method. It has been found that the luminescence characteristics are strongly dependent on the sintering temperature. Powders sintered at temperatures below 1000 °C demonstrate a luminescence behavior at room temperature associated with a lack of the inversion symmetry of Eu 3+ sites. Above 1000 °C nano-crystallites undergo a phase transition characterized by an inversion symmetry of Eu 3+ sites. The size effect of Eu 3+ :BaTiO 3 nano-crystallites on luminescence characteristics is observed.