Search results

1

Phase transition in Bi8Fe6Ti3O27 multiferroic ceramics

100%

Patri S., Choudhary R.

Open Physics

|

2008

|

vol. 6

|

issue 3

450-453

EN

The polycrystalline Bi8Fe6Ti3O27 compound was prepared by a high-temperature solid-state reaction technique. Preliminary structural analysis by X-ray diffraction (XRD) confirms the formation of a single-phase compound in an orthorhombic crystal system at room temperature. The elemental content of the compound was analyzed by EDAX microanalysis. Microstructural analysis by scanning electron microscopy (SEM) shows that the compound has well defined grains, which are distributed uniformly throughout the surface of the pellet sample. Detailed studies of temperature-dependent dielectric response at various frequencies show dielectric anomalies at 380, 389 and 403°C for 10 kHz, 100 kHz, and 1 MHz respectively. The hysteresis loop observed by applying an electric field of 12 kV/cm on the poled sample with smaller remanent polarization supports the existence of ferroelectricity in this material. The value of d33 of the compound was found to be 19 pC/N.

2

On the thermodynamics of phase transitions in metal hydrides

100%

Vita A.

Open Physics

|

2012

|

vol. 10

|

issue 1

86-95

EN

Metal hydrides are solutions of hydrogen in a metal, where phase transitions may occur depending on temperature, pressure etc. We apply Le Chatelier’s principle of thermodynamics to a particular phase transition in TiHx, which can approximately be described as a second-order phase transition. We show that the fluctuations of the order parameter correspond to fluctuations both of the density of H+ ions and of the distance between adjacent H+ ions. Moreover, as the system approaches the transition and the correlation radius increases, we show -with the help of statistical mechanics-that the statistical weight of modes involving a large number of H+ ions (‘collective modes’) increases sharply, in spite of the fact that the Boltzmann factor of each collective mode is exponentially small. As a result, the interaction of the H+ ions with collective modes makes a tiny suprathermal fraction of the H+ population appear. Our results hold for similar transitions in metal deuterides, too. A violation of an -insofar undisputed-upper bound on hydrogen loading follows.

3

The horn, kink and step, dale: from few GeV to few TeV

100%

Rustamov A.

Open Physics

|

2012

|

vol. 10

|

issue 6

1267-1270

EN

Rich experimental data have been collected in heavy-ion collisions at high energies to study the properties of strongly interacting matter. As the theory of strong interactions, QCD, predicts asymptotic freedom, the created matter at sufficiently high temperature and density will be dominated by a state of quasi-free quarks and gluons referred to as the Quark-Qluon Plasma (QGP). Experimental signals for the onset of the QGP creation (the onset of the deconfinement) have been predicted within the statistical model for the early stage of nucleus-nucleus collisions. In this model the existence of two different phases is assumed: confined mater and the QGP, as well as a first order phase transition between them. Until recently, these predictions were confirmed only by the NA49 experiment at the CERN SPS. In this report recent results from STAR at RHIC/BNL and from ALICE at LHC/CERN, related to the onset of deconfinement, will be compared to published results from NA49.

4

Phase transitions in confined lamellar phases

100%

Ciach A.

|

2007

|

vol. 55

|

issue 2

5

Understanding of radial and elliptic expansion with quark number scaling and blast wave model in 200 GeV Au+Au at RHIC-PHENIX

100%

Ikeda Y.

Open Physics

|

2012

|

vol. 10

|

issue 6

1311-1313

EN

Measurement of azimuthal anisotropy is one of the most important study because of its relation to the initial stage. Especially, the elliptical anisotropy which is measured as the second coefficient of Fourier expansion of particle azimuthal distribution is believed to carry the information about the initial geometrical anisotropy. It seems the identified hadron v 2 depends on the number of quark contents of the hadron. The experimental result of quark number scaling of v 2 suggests quark level collectivity in the hot dense matter and quark coalescence mechanism to form hadron from quark matter via quark-gluon phase transition. The measured v 2 and p T spectra are analyzed with various assumptions based on the blast wave model in order to understand the freeze-out temperature and collective flow after the system expansion.

6

Comparative study of structural stability in [NH4−n (CH3)n]2HgCl4 and in related compounds

100%

Amami M., Salah A.

Open Chemistry

|

2004

|

vol. 2

|

issue 2

388-401

EN

The structural instability of the [NH4−n (CH3)n]2HgCl4 group has been investigated. Consideration of different crystals of this family shows that the H-bonds, obviously, hinder the appearance of incommensurate modulation. The dependence of phase transition sequence on the sizes of cation and anion may be obtained only for crystals with simple cation. The appearance of H-bonds complicates the situation and, leads to gradual disappearance of IC phase in the A2BX4 family.

7

Diffusive and Displacive Phase Transformations in Nanocomposites under High Pressure Torsion

88%

Straumal B., Kilmametov A., Gornakova A., Mazilkin A., Baretzky B., Korneva A., Zięba P.

Archives of Metallurgy and Materials

|

2019

|

vol. 64

|

issue 2

8

Reconstruction of the finite size canonical ensemble from incomplete micro-canonical data

88%

Lundow P., Markström K.

Open Physics

|

2009

|

vol. 7

|

issue 3

490-502

EN

In this paper we discuss how partial knowledge of the density of states for a model can be used to give good approximations of the energy distributions in a given temperature range. From these distributions one can then obtain the statistical moments corresponding to e.g. the internal energy and the specific heat. These questions have gained interest apropos of several recent methods for estimating the density of states of spin models. As a worked example we finally apply these methods to the 3-state Potts model for cubic lattices of linear order up to 128. We give estimates of e.g. latent heat and critical temperature, as well as the micro-canonical properties of interest.

9

Properties of Pb1–xBax(Zr1–yTiy)1–zSnzO3 (x = 0.03, y = 0.02, z = 0÷0.08) Ceramics

88%

Brzezińska D., Brzezińska D.

|

10

Alternative, Direct Synthesis Method of the Ceramic Solid Solutions Based on BaTiO3 Through a High Energy Ball Milling

75%

Bąk W., Dulian P., Garbarz-Glos B., Czekaj D., Lisińska-Czekaj A., Bąk W., Dulian P., Garbarz-Glos B., Czekaj D., Lisińska-Czekaj A.

|

11

NMR study of heterogeneity in pyridine-N-oxide...HCl crystal

75%

Balevicius V., Gacesa A., Plavec J.

Open Physics

|

2004

|

vol. 2

|

issue 1

120-131

EN

An origin of narrow 1H NMR signals in pyridine-N-oxide (PyO)...HCl crystal has been investigated by means of MAS, SPEDAS, NOESY and COSY techniques. Spectra of crystalline samples are compared with those of solid phase obtained from liquid PyO...HCl solutions (in acetonitile/H2O) after the heterogeneous phase separation. It has been concluded that partially resolved peaks in 1H NMR spectra of solids are related with heterogeneity of spin system and presence of different H-bond clusters of water molecules. NOESY spectra show no cross-peaks even at very long mixing time (500 ms). This indicates there is no exchange process between spins causing different peaks, and thus the corresponding molecular aggregates are captured in “islands of mobility8 without any channels sufficient for exchange. Appearance of MAS side bands as “pseudo8 cross-peaks in 2D NMR spectra using MAS/COSY technique is reported. In the case of accidental coincidence of spinning frequency (ωMAS) with spectral distances between some diagonal signals, intensive non-diagonal peaks are observed at the corresponding cross-positions. A misleading conclusion concerning spin coupling is easy to avoid using various ωMAS.

12

A bicontinuous structure in some systems with cubic mesophases

63%

Yakunin A.

Open Physics

|

2004

|

vol. 2

|

issue 3

535-555

EN

A cubic structure of polymer colloid complexes is studied. The technique of the research includes i) an analysis of well-known literature SAXS data; on this basis, ii) constructing a simple model to estimate geometric structure parameters and to obtain a simulated scattering curve; and iii) comparing the model with the real structure obtained from the SAXS data, using the reconstruction of electron density distribution. A bicontinuous structure in cubic mesophases is formed.

Refine search results

Phase transition in Bi8Fe6Ti3O27 multiferroic ceramics

On the thermodynamics of phase transitions in metal hydrides

The horn, kink and step, dale: from few GeV to few TeV

Phase transitions in confined lamellar phases

Understanding of radial and elliptic expansion with quark number scaling and blast wave model in 200 GeV Au+Au at RHIC-PHENIX

Comparative study of structural stability in [NH4−n (CH3)n]2HgCl4 and in related compounds

Diffusive and Displacive Phase Transformations in Nanocomposites under High Pressure Torsion

Reconstruction of the finite size canonical ensemble from incomplete micro-canonical data

Properties of Pb1–xBax(Zr1–yTiy)1–zSnzO3 (x = 0.03, y = 0.02, z = 0÷0.08) Ceramics

Alternative, Direct Synthesis Method of the Ceramic Solid Solutions Based on BaTiO3 Through a High Energy Ball Milling

NMR study of heterogeneity in pyridine-N-oxide...HCl crystal

A bicontinuous structure in some systems with cubic mesophases