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Phase Transition (phase + transition)
Kinds of Phase Transition Terms modified by Phase Transition Selected AbstractsThermodynamic Properties and Plasma Phase Transition in dense HydrogenCONTRIBUTIONS TO PLASMA PHYSICS, Issue 5-6 2004V. S. Filinov Abstract The internal energy and equation of state of dense hydrogen are investigated by direct path integral Monte Carlo method simulations which are further improved in comparison to our previous results. Data for four isotherms , T = 10, 000K, 30, 000K, 50, 000K, and 100, 000K , are presented. For T = 10, 000K it is shown that the internal energy is lowered due to droplet formation for densities of the order 1023cm,3 giving direct support for the existence of a plasma phase transition in megabar hydrogen. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Order-Disorder Phase Transition in Type-I Clathrate Cs8Sn44,2,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 26 2007Andreas Kaltzoglou Abstract The clathrate compound ,-Cs8Sn44,2 has been synthesized from its elements under inert gas conditions and has been characterized by single-crystal and powder X-ray diffraction. At room temperature, it crystallizes with cubic symmetry [a = 24.256(3) Å, space group Iad, Z = 8] and adopts a 2,×,2,×,2 superstructure of the type-I clathrate and a high ordering of the vacancies (,) in the Sn framework. Single crystals of ,-Cs8Sn44,2 reversibly transform at 90 °C to the high-temperature , form with primitive symmetry [a = 12.135(1) Å, space group Pmn, Z = 1] and a lower ordering of the defects. Differential thermal analysis corroborates the reversible character of the phase transition, which occurs with an enthalpy change of approximately 0.38 J,g,1. An atom-migration mechanism describing the order-disorder transition involving spiro-connected six-membered rings only (scsr mechanism) is proposed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] A Crystalline Phase Transition and Optical Properties in a CoIICuII Oxamato-Bridged Ferrimagnetic ChainEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 24 2005Cynthia L. M. Pereira Abstract The compound [CoCu(opba)(DMSO)3] (1) [opba = ortho -phenylenebis(oxamato)] has been synthesized and characterized. Its crystal structure has been analyzed by X-ray diffraction techniques at 100 and 298 K. A structural phase-transition has been detected at around 150 K. An orthorhombic crystalline system is found at both temperatures, with very similar unit-cell dimensions. At room temperature 1 crystallizes in the Pnam space group (, -1 phase), with a = 7.6712(2), b = 14.8003(3), c = 21.0028(5) Å, and Z = 4, whereas at low temperature it crystallizes in the Pna21 space group (, -1 phase), with a = 7.3530(2), b = 14.5928(4), c = 21.0510(7) Å, and Z = 4. Both crystalline phases consist of linearly ordered bimetallic chains with the [Cu(opba)]2, units tied by CoII ions to form a one-dimensional system. The DMSO molecules in , -1, which are coordinated to either CuII or CoII, are disordered. At low temperature, a small reorganization of the CuII and CoII environments is observed. The origin of this phase transition, which is completely reversible, is the modification of the crystalline packing with the temperature. Linear birefringence measurements were done on single crystals in the 100,300 K temperature range. Around 150 K, the linear birefringence curve shows an inflexion that is interpreted as being related to the conversion of ,-1 into , -1. Both dc and ac magnetic measurements were performed on the polycrystalline sample. The results reveal a one-dimensional ferrimagnetic behavior. Single crystal optical characterization at room temperature shows that 1 presents a very strong dichroism superposed on the linear birefringence. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Nonquenchable Chemical Order,Disorder Phase Transition in Yttrium OxyfluorideEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2005Igor Levin Abstract A chemical order,disorder polymorphic phase transition in yttrium oxyfluoride (YOF) was studied in situ by X-ray and neutron powder diffraction. The high-temperature form of YOF crystallizes with a cubic Fmm fluorite structure in which the O and F atoms are disordered among the tetrahedrally coordinated sites. The low-temperature form of YOF exhibits rhombohedral Rm symmetry and evolves from the high-temperature form by the phase transition associated with the ordering of the O and F atoms. The transition occurs around 560 °C. The superstructure contains layers of [OY4] and [FY4] tetrahedra alternating along the c -axis of the trigonal cell (parallel to the <111> direction of the parent cubic structure). The ordering of the O and F atoms is accompanied by the significant displacements of the Y, O, and F atoms from their ideal positions in the cubic phase. Bond valence sum calculations indicate considerable bond strain for both O and F in the cubic structure; the strain is relieved in the ordered low-temperature phase. The order,disorder transition in YOF is completely reversible and exhibits fast nonquenchable kinetics. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Chemical-to-Electrical-Signal Transduction Synchronized with Smart Gel Volume Phase TransitionADVANCED MATERIALS, Issue 43 2009Akira Matsumoto A stimulus-responsive polymer gel designed on a field-effect transistor gate undergoes a reversible volume phase transition in response to a specific biomolecule. An abrupt permittivity change at the gel/gate interface during the transition gives rise to a chemical to electrical signal conversion; the signal is thus detectable via a transistor without the limit of the Debye length. [source] Reversible Switching of Water-Droplet Mobility on a Superhydrophobic Surface Based on a Phase Transition of a Side-Chain Liquid-Crystal PolymerADVANCED MATERIALS, Issue 42 2009Chao Li Reversible switching of the mobility of a water microdroplet between rollable and pinned simply by changing the temperature is realized by coordination of the phase transition of a side-chain liquid-crystal polymer (SCLCP) with optimized surface roughness of a superhydrophobic surface. The responsive surface has potential applications in microreactor design and microfluidic control systems. [source] Comment on "The Magnetocaloric Effect of LaFe11.6Si1.4, La0.8Nd0.2Fe11.5Si1.5, and Ni43Mn46Sn11 Compounds in the Vicinity of the First-Order Phase Transition"ADVANCED MATERIALS, Issue 37 2009Lluís Mañosa The aim of the present comment is to show that when both calorimetric and magnetization measurements are properly executed, there is no significant discrepancy in the entropy values obtained from the two methods, thus validating the use of the Maxwell relations, which is the most commonly used technique in the study of the magnetocaloric effect. [source] Reply to "Comment on the Magnetocaloric Effect of LaFe11.6Si1.4, La0.8Nd0.2Fe11.5Si1.5, and Ni43Mn46Sn11 Compounds in the Vicinity of the First-Order Phase Transition"ADVANCED MATERIALS, Issue 37 2009Jun-Ding Zou The magnetocaloric effect (MCE) of Ni43Mn46Sn11 in the vicinity of a first-order martensitic phase transition is discussed by using magnetic measurements, heat capacity measurements and differential scanning calorimetry (DSC) measurements. The results confirm that the MCE of Ni43Mn46Sn11 obtained by magnetic measurements (via the Maxwell relation) may be seriously overestimated and Ni-Mn-Sn alloys should be treated carefully. [source] Erratum: The Magnetocaloric Effect of LaFe11.6Si1.4, La0.8Nd0.2Fe11.5Si1.5, and Ni43Mn46Sn11 Compounds in the Vicinity of the First-Order Phase TransitionADVANCED MATERIALS, Issue 37 2009Jun-Ding Zou No abstract is available for this article. [source] The Magnetocaloric Effect of LaFe11.6Si1.4, La0.8Nd0.2Fe11.5Si1.5, and Ni43Mn46Sn11 Compounds in the Vicinity of the First-Order Phase TransitionADVANCED MATERIALS, Issue 6 2009Jun-Ding Zou The magnetocaloric effect is discussed in terms of the thermodyna mic Maxwell relation and its necessary conditions. The origin of the sharp "spikes" that appear in entropy-change curves is discussed. The Maxwell relation and heat-capacity measurements are then used to determine the entropy change and are applied to the discussion of LaFe11.6Si1.4, La0.8Nd0.2Fe11.5Si1.5, and Ni43Mn46Sn11 compounds. [source] Unprecedented "One-Finger-Push"-Induced Phase Transition With a Drastic Color Change in an Inorganic Material,ADVANCED MATERIALS, Issue 21 2007M. Gaudon A drastic color transition from green to brownish-red in the CuMo1,xWxO4 system occurs during a first-order phase transition. This study shows that it is possible to control this transition in terms of temperature or pressure with respect to the tungsten content (see figure). Hence, the use of these compounds for new applications as temperature indicators or shock detectors is feasible. [source] Neutron Powder Diffraction Study of a Phase Transition in La0.68(Ti0.95Al0.05)O3JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2006Roushown Ali Crystal structures and structural changes of the compound La0.68(Ti0.95Al0.05)O3 have been studied using neutron powder diffraction data and the Rietveld method in the temperature range from 25° to 592°C. The Rietveld profile-fitting analyses of the neutron data and the synchrotron diffraction profile revealed that the crystal symmetry of the low-temperature phase of La0.68(Ti0.95Al0.05)O3 is orthorhombic Cmmm (2ap× 2ap× 2ap; p: pseudo-cubic perovskite). The unit-cell and structural parameters were successfully refined with the orthorhombic Cmmm for the intensity data measured at 25°, 182°, and 286°C, and with the tetragonal P4/mmm (ap×ap× 2ap) for intensity data obtained at 388° and 592°C. The P4/mmm -to- Cmmm phase transition was found to be induced by tilting of the (TiAl)O6 octahedron. The tilt angle decreased with increasing temperature, reaching 0° at the Cmmm,P4/mmm transition temperature. [source] Phase Transition and Failure at High Temperature of Bismuth-Layered Piezoelectric CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2006Liaoying Zheng High-temperature bismuth-layered piezoelectric ceramics (CaxSr1,x)Bi4Ti4O15 have been prepared by the conventional solid reaction method. Our results reveal that there is a "phase transition induced by the composition" taking place in the solid solution at around x=0.4. During transition, the crystal structure changes from orthorhombic to pseudo-tetragonal and then back to orthorhombic. Although all (CaxSr1,x)Bi4Ti4O15 (with any x value) undergo a second-order ferroelectric-to-ferroelectric phase transition at about 200°C below their Curie temperature, only the ceramic with x=0.4 exhibits a failure in piezoelectric properties during the transition. It is suggested that, on the basis of the X-ray photoelectron spectroscopy results, this material failure is induced by the high concentration of oxygen vacancies in the material during the phase transition. [source] Effect of Divalent Cation Additives on the ,-Al2O3 -to-,-Al2O3 Phase TransitionJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2000Kiyoshi Okada The effect on the ,-Al2O3 -to-,-Al2O3 phase transition of adding divalent cations was investigated by differential thermal analysis, X-ray diffractometry, and surface-area measurements. The cations, Cu2+, Mn2+, Co2+, Ni2+, Mg2+, Ca2+, Sr2+, and Ba2+, were added by impregnation, using the appropriate nitrate solution. These additives were classified into three groups, according to their effect: (1) those with an accelerating effect (Cu2+ and Mn2+), (2) those with little or no effect (Co2+, Ni2+, and Mg2+), and (3) those with a retarding effect (Ca2+, Sr2+, and Ba2+). The crystalline phase formed by reaction of the additive with ,-Al2O3 at high temperature was a spinel-type structure in groups (1) and (2) and a magnetoplumbite-type structure in group (3). In groups (2) and (3), a clear relationship was found between the transition temperature and the difference in ionic radius of Al3+ and the additive (,r): The transition temperature increased as ,r increased. This result indicates that additives with larger ionic radii are more effective in suppressing the diffusion of Al3+ and O2, in ,-Al2O3, suppressing the grain growth of ,-Al2O3, and retarding the transformation into ,-Al2O3. [source] Multiphysics Modelling of Volume Phase Transition of Ionic Hydrogels Responsive to Thermal StimulusMACROMOLECULAR BIOSCIENCE, Issue 9 2005Hua Li Abstract Summary: This paper presents the analysis of the volume phase transition of ionic thermo-sensitive hydrogels to thermal stimulus through mathematical modelling. The model is termed the multi-effect-coupling thermal-stimulus (MECtherm) model and it considers the effects of multi-phases and multi-physics. Its application to steady-state analysis of the hydrogels in swelling equilibrium is validated against available experimental data for the relation between volume swelling ratio and temperature, in which very good agreement is achieved. The phenomenon of volume phase transition is studied for the thermal-stimulus responsive hydrogel. The numerical studies predict well the influences of initially fixed charge density and initial volume fraction of polymeric network on the swelling equilibrium of the hydrogels. Comparison of numerical simulations with the experimental swelling data for the thermo-sensitive PNIPA hydrogels in pure water. [source] Self-Similar Wave of Swelling/Collapse Phase Transition along Polyelectrolyte GelMACROMOLECULAR THEORY AND SIMULATIONS, Issue 8 2004Andrey Yu. Abstract Summary: Theoretical analysis of the possibility of collapse/swelling phase transition propagation along a polyelectrolyte gel thread has been performed. A differential equation that determines the time dependence of the degree of swelling of polymer thread under the radial mechanical force has been obtained. It formally coincides with the equation of diffusion of an impurity in a medium with a certain source density that depends on excluded-volume and Coulomb interactions, osmotic pressure of counterions, and entropy of the subchains. Two stationary points of this equation correspond to contracted and swollen states. It has been shown that once activated, the phase transition between these stationary points could propagate along the thread in the form of a wave with positive speed if the initial state is characterized by a higher level of free energy than the final state. The results of numerical calculations illustrating the process of phase transition propagation along polyelectrolyte gel thread show that propagation of the swelling/collapse phase transition takes place in the form of the stepwise self-similar wave with steep front. The sharp boundary between swollen and collapsed zones is observed and does not tend to dissipate as propagation proceeds. [source] ChemInform Abstract: Tetragonal to Orthorhombic Phase Transition in SmFeAsO: A Synchrotron Powder Diffraction Investigation.CHEMINFORM, Issue 33 2009A. Martinelli Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: High Temperature Phase Transition in SOFC Anodes Based on Sr2MgMoO6-,.CHEMINFORM, Issue 30 2009D. Marrero-Lopez Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Low Temperature Structural Phase Transition of Ba3NaIr2O9.CHEMINFORM, Issue 23 2009Hans-Conrad zur Loye Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Ab initio Study on Structure and Phase Transition of A- and B-Type Rare-Earth Sesquioxides Ln2O3 (Ln: La,Lu, Y, and Sc) Based on Density Function Theory.CHEMINFORM, Issue 19 2008Bo Wu Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Structural Phase Transition of Gd3RuO7.CHEMINFORM, Issue 13 2008Nobuo Ishizawa Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Hg0.04Zn3.96Sb3: Synthesis, Crystal Structure, Phase Transition, and Thermoelectric Properties.CHEMINFORM, Issue 9 2008B. L. Pedersen Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Order-Disorder Phase Transition in Type-I Clathrate Cs8Sn44,2.CHEMINFORM, Issue 47 2007Andreas Kaltzoglou Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] The Network Structure [SbHg2]GaCl4: An X-Ray Study of a Temperature Driven Phase Transition.CHEMINFORM, Issue 35 2007J. Schlirf Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Atomistic Simulation Study of the Order/Disorder (Monoclinic to Hexagonal) Phase Transition of Hydroxyapatite.CHEMINFORM, Issue 25 2005Oliver Hochrein No abstract is available for this article. [source] On the Mechanism of the Pressure-Induced Wurtzite- to NaCl-Type Phase Transition in CdS: An X-Ray Diffraction Study.CHEMINFORM, Issue 14 2005Heidrun Sowa Abstract For Abstract see ChemInform Abstract in Full Text. [source] X-Ray Diffraction Studies on the Nature of the Phase Transition in the Stoichiometric LiMn2O4.CHEMINFORM, Issue 5 2005Pawel Piszora Abstract For Abstract see ChemInform Abstract in Full Text. [source] A Large Thermal Hysteresis Loop Produced by a Charge-Transfer Phase Transition in a Rubidium Manganese Hexacyanoferrate.CHEMINFORM, Issue 42 2004Hiroko Tokoro Abstract For Abstract see ChemInform Abstract in Full Text. [source] Pressure Induced Phase Transition and Amorphization of Na3ONO2.CHEMINFORM, Issue 22 2004Haozhe Liu Abstract For Abstract see ChemInform Abstract in Full Text. [source] Study of the Nature and Mechanism of the Rhombohedral-to-Cubic Phase Transition in ,-AlF3 with Molecular Dynamics Simulations.CHEMINFORM, Issue 21 2004Santanu Chaudhuri No abstract is available for this article. [source] | |||||||||||||||||||||||||||||||||||||||||||