Elastic behavior, phase transition, and pressure induced structural evolution of analcime

2006 ◽  
Vol 91 (4) ◽  
pp. 568-578 ◽  
Author(s):  
G. D. Gatta ◽  
F. Nestola ◽  
T. B. Ballaran
Keyword(s):  
Phase Transition ◽  
Structural Evolution ◽  
Elastic Behavior

Static and dynamical elastic behavior of Lu5Ir4Si10 around its first-order structural phase transition

2020 ◽  
Vol 34 (12) ◽  
pp. 2050116
Author(s):  
M. Saint-Paul ◽  
C. Opagiste ◽  
C. Guttin
Keyword(s):  
Phase Transition ◽  
Theoretical Approach ◽  
Order Parameter ◽  
Landau Theory ◽  
Structural Phase ◽  
Elastic Stiffness ◽  
Elastic Behavior ◽  
Velocity Measurements ◽  
First Order ◽  
First Order Transition

Ultrasonic velocity measurements could be performed on a good quality single crystal of [Formula: see text] around its transition around 80 K. The behavior of the stiffness components demonstrates a first-order transition. The temperature dependence of the longitudinal elastic stiffness components [Formula: see text] and [Formula: see text] can be analyzed by the classical Landau theory and assuming a stricter coupling between the strain and the order parameter. A theoretical approach and experimental results are discussed.

High-temperature structural evolution of hexagonal multiferroic YMnO3and YbMnO3

2007 ◽  
Vol 40 (4) ◽  
pp. 730-734 ◽  
Author(s):  
Il-Kyoung Jeong ◽  
N. Hur ◽  
Th. Proffen
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Powder Diffraction ◽  
Structural Parameters ◽  
Structural Evolution ◽  
Neutron Powder Diffraction ◽  
Temperature Behaviour ◽  
Rietveld Refinements ◽  
Polar Structure ◽  
Diffraction Patterns

Neutron powder diffraction studies on the structural evolution of hexagonal multiferroic YMnO3and YbMnO3from 1000 K to 1400 K, and from 1000 K to 1350 K, respectively, are presented. The temperature evolution of diffraction patterns suggests that YMnO3undergoes a phase transition to a non-polar structure above 1200 K, while YbMnO3remains ferroelectric up to 1350 K. Detailed structural parameters were obtained as a function of temperature from Rietveld refinements. Based on this result, the distinct differences in temperature behaviour between YMnO3and YbMnO3, and the origin of the ferroelectricity in these hexagonal multiferroics are discussed.

scholarly journals Investigation of structural phase evolution and dielectric response of Co-doped BaTiO3

2018 ◽  
Vol 08 (04) ◽  
pp. 1850024 ◽  
Author(s):  
Amantulla Mansuri ◽  
Ilyas Noor Bhatti ◽  
Imtiaz Noor Bhatti ◽  
Ashutosh Mishra
Keyword(s):  
Phase Transition ◽  
Structural Study ◽  
Structural Phase ◽  
Structural Evolution ◽  
Phase Evolution ◽  
Dielectric Measurement ◽  
Cubic Phase ◽  
Tangent Loss ◽  
Ionic Radii ◽  
Co Doping

In the present study, we have synthesized polycrystalline samples of BaTi[Formula: see text]CoxO3 (BTCO) ([Formula: see text], 0.01, 0.03, 0.05, 0.07 and 0.10) with standard solid state reaction technique. The obtained samples are characterized by X-ray diffraction (XRD) and Raman spectroscopy for structural study. The detailed structural analysis has been performed by Rietveld refinement using Fullprof program. We observed an increase in lattice parameters, which results due to substitution of Co[Formula: see text] with large ionic radii (0.9[Formula: see text]Å) for smaller ionic radii (0.6[Formula: see text]Å) Ti[Formula: see text]. Moreover, peak at 45.5∘ shifts to 45∘ on Co doping, which is due to structure phase transition from tetragonal to cubic. Raman study infers that the intensity of characteristic peaks decreases and line width increases with Co doping. The bands linked with the tetragonal structure (305[Formula: see text]cm[Formula: see text]) decreased due to the tetragonal-to-cubic phase transition with Co doping. Our structural study reveals the expansion of BTCO unit cell and tetragonal-to-cubic phase transformation takes place. The results from different characterization techniques are conclusive and show structural evolution with Co doping. The samples are further characterized by dielectric spectroscopy, dielectric measurement reveals the increase of dielectric constant and transition [Formula: see text]C is observed for Barium titanate (BaTiO3), whereas transition disappears with Co doping. Both temperature and frequency-dependent tangent loss is also studied.

Ultrasonic Investigation of the Ni40Ti50Cu10 Alloy

2006 ◽  
Vol 115 ◽  
pp. 63-66
Author(s):  
U. Straube ◽  
Giovanni Mazzolai ◽  
A. Biscarini ◽  
B. Coluzzi ◽  
Fabio M. Mazzolai ◽  
...  
Keyword(s):  
Phase Transition ◽  
Ultrasonic Attenuation ◽  
Shear Stiffness ◽  
Elastic Stiffness ◽  
Elastic Behavior ◽  
Strong Increase ◽  
Propagation Mode ◽  
Stiffness Coefficients ◽  
The One ◽  
Overlap Method

The ultrasound pulse echo overlap method has been used to determine the elastic stiffness coefficients and the corresponding ultrasonic attenuation for a single crystal of the Ni40Ti50Cu10 alloy as a function of temperature. The elastic stiffness coefficients exhibit anomalies near the martensitic phase transition. In the shear stiffness coefficient, corresponding to C44 propagation mode in austenite, a large jump occurs from 36 GPa, above the transition, down to 15 GPa, below the transition. This jump is accompanied by a strong increase in the ultrasonic attenuation. The stiffness coefficients corresponding to C11 and C' = (C11 – C12)/2 modes in austenite show an anomaly at the phase transition, however, these are small effects compared to the one associated with C44 mode. The elastic behavior of this crystal has been characterised down to a temperature of 100 K.

COMPARISON BETWEEN MOLECULAR DYNAMICS AND MONTE CARLO DESCRIPTIONS OF SOLID–LIQUID PHASE-TRANSITION OF LENNARD–JONES FLUIDS

2010 ◽  
Vol 21 (03) ◽  
pp. 349-363 ◽  
Author(s):  
A. S. MARTINS ◽  
C. X. S. SEIXAS ◽  
L. B. dos SANTOS ◽  
P. R. RIOS
Keyword(s):  
Phase Transition ◽  
Molecular Dynamics ◽  
Monte Carlo ◽  
Liquid Phase ◽  
Structural Evolution ◽  
Liquid Phase Transition ◽  
Monte Carlo Techniques ◽  
Lennard Jones ◽  
Liquid Transition ◽  
Solid Liquid

Molecular dynamics and Monte Carlo techniques are employed for the study of Lennard–Jones fluids near the solid–liquid transition region. Systematic comparisons between the predictions of both techniques are discussed, with particular emphasis on the structural evolution and location of the transition (melting) temperature Tm.

Molecular Dynamic Simulation of Zigzag Silicon Carbide Nanoribbon

2021 ◽  
Vol 32 ◽  
Author(s):  
Hang Thi Thuy Nguyen
Keyword(s):  
Phase Transition ◽  
Molecular Dynamics ◽  
Silicon Carbide ◽  
Md Simulation ◽  
Structural Evolution ◽  
Order Type ◽  
Distribution Functions ◽  
Heating Process ◽  
Initial Model ◽  
First Order

The heating process of zigzag silicon carbide nanoribbon (SiCNR) is studied via molecular dynamics (MD) simulation. The initial model contained 10000 atoms is heating from 50K to 6000K to study the structural evolution of zigzag SiCNR. The melting point is defined at 4010K, the phase transition from solid to liquid exhibits the first-order type. The mechanism of structural evolution upon heating is studied based on the radiral distribution functions, coordination number, ring distributions, and angle distributions.

scholarly journals Study of Phase Transition by FTIR/SAXS/WAXD Simultaneous Measurement System

2014 ◽  
Vol 70 (a1) ◽  
pp. C1070-C1070
Author(s):  
Kohji Tashiro ◽  
Hiroko Yamamoto ◽  
Taiyo Yoshioka ◽  
Daisuke Tahara
Keyword(s):  
Phase Transition ◽  
Measurement System ◽  
Simultaneous Measurement ◽  
Isothermal Crystallization ◽  
Structural Phase ◽  
Structural Evolution ◽  
Crystalline Polymer ◽  
Soft Materials ◽  
Order Structure ◽  
Crystalline Polymers

FTIR/SAXS/WAXD simultaneous measurement system has been developed for the study of the structural phase transition behaviors of soft materials including crystalline polymers. The system consists of a transmission-type miniature FTIR spectrometer set around the sample stage and the 2-dimensional detectors for WAXD and SAXS measurements in a synchronized mode, as shown in Figure. The infrared and X-ray beams can pass through the same position of a sample, which is set on the various types of equipments such as a stretcher, a heater, a temperature-jump cell for isothermal crystallization, etc. The system has been successfully applied to the studies of the structural evolution processes of crystalline polymers. For example, an intimate relationship has been clarified between the structural change in the crystal lattice and the change in lamellar stacking mode during the stress-induced phase transition of poly(tetramethylene terephthalate). Another example is the study of phase transition of aliphatic nylons in the heating and cooling processes. So far the aliphatic nylons were considered to show the phase transition at a so-called Brill transition point, but the simultaneous measurement revealed another phase transition occurring in a temperature region immediately below the melting point. The structural evolution has been also studied for the isothermal crystallization process of crystalline polymer from the melt, as seen in the case studies of polyethylene, nylon, polyester, and so on. The concrete description was made for the regularization process viewed from the various hierarchical levels of molecular chain conformation, chain packing mode, and lamellar stacking mode or higher-order structure.

Fluorescence mutation and structural evolution of a π-conjugated molecular crystal during phase transition

2016 ◽  
Vol 4 (6) ◽  
pp. 1257-1262 ◽  
Author(s):  
Yuanxiang Xu ◽  
Kai Wang ◽  
Yujian Zhang ◽  
Zengqi Xie ◽  
Bo Zou ◽  
...  
Keyword(s):  
Phase Transition ◽  
Molecular Crystal ◽  
Structural Evolution ◽  
Crystalline Phases ◽  
Conjugated Molecule

Two thermodynamically stable crystalline phases (B- and G-phases) were found for a twistable π-conjugated molecule, CN-DSB, condensed from its solution.

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