Structural phase transition temperature

We present the results of a study related to phase transformation of chemically synthesized FePt nanoparticles under high pressure from face-centered cubic into face-centered tetragonal structure. As-synthesized nanoparticles are around 4.5 nm and show superparamagnetic behavior at 300 K. After annealing under 60 bar pressure of hydrogen at 400◦C for 2 h, nanoparticles exhibit strong ferromagnetic behavior with 5391 Oe coercivity.

7p tudichquannguyet 29-11-2021 12 3   Download

A variety of experimental realizations of binary atomic Bose-Fermi mixtures have brought opportunities for studying composite quantum systems with different spin-statistics. The binary atomic mixtures can exhibit a structural transition from a mixture into phase separation as the boson-fermion interaction increases.

18p vioregon2711 19-02-2021 8 1   Download

The stable phase of Gd, Tb, Sc, Y and Yb metals can be determined by examining the Helmholtz free energy at a given temperature, i.e. the phase that gives the lowest free energy will be stable. These findings on the structural phase transition temperature are in agreement with previous experiments.

6p tamynhan9 02-12-2020 14 1   Download

he effect of the ZnO addition in pure perovskite PZT−PMnN−PSbN ceramics sintered from 950 to 1200oC has been investigated. The phase structure of ceramics changes from rhombohedral to tetragonal and the temperature decreases with the increase of the ZnO content. The limitation of Zn2+ concentration for the solubility in PZT–PMnN–PSbN systems is about 0.25% wt., at which the ceramic shows some good physical properties such as the density of 8.20 g/cm3 , some dielectric constants including εr = 1,555 and εmax = 32,900.

9p nguaconbaynhay9 03-12-2020 7 0   Download

The Tb3+ rare-earth-ion-doped Ca2Al2SiO7 material has a tetragonal phase structure that was successfully synthesized using the solid-state reaction method under optimal conditions: sintering temperature: 1280 °C; time: 60 minutes; and the B2O3 flux agent content: 4% wt. The photoluminescence spectrum of Tb3+ doped Ca2Al2SiO7 phosphor consists of narrow lines with peaks at 545, 440, 462, 494, 590, and 622 nm that correspond to 4f electronic transitions of the Tb3+ ion. The peak at 545 nm has the highest luminescent intensity.

4p nguaconbaynhay9 03-12-2020 7 1   Download

The α - β (fcc-hcp) phase transition temperature under pressure can be investigated theoretically by combining the self-consistent field method and the statistical moment method and only the statistical moment method which was developed by the authors. Theoretical results are applied to N2 and CO molecular cryocrystals and our calculated results are compared with the experimental data and other calculations.

8p tamynhan8 04-11-2020 13 1   Download

In this paper, continuing the research direction done in we consider further on phase structure of Reissner-Nordstr¨om charged black hole. The results show that there is a transition between small and large black holes (with horizonal radius change), the system share the same oscillatory behavior in pressure-volume graph, in temperature-entropy graph.

8p koxih_kothogmih5 04-09-2020 11 1   Download

Influence of substitution of 3d metals for Mn on properties of La0.67Ca0.33Mn0.9 TM0.1O3 (TM = Fe, Co, Ni) compounds was studied. Ferromagnetic – paramagnetic and metals – insulator transitions were significantly affected by Mn-site substitution. However, no observable difference was found in their crystal structure from X-ray diffraction analysis. At room temperature the structure characterization of these compounds gave the single phase and structure is the distortion orthorhombic cell with space group symmetry Pnma.

12p 12120609 01-06-2020 12 1   Download

A series of composite materials of general molecular formula (1 x) Na2SO4 (x) LDT was prepared by solid state reaction method. The phase structure and functionalization of these materials were defined by X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR) respectively. Differential thermal analysis (DTA) revealed that the hump of phase transition at 250 C has decreased while its thermal stability was enhanced.

7p kequaidan1 16-11-2019 28 0   Download

Triblock copolymers were polymerised by the ringopening reaction of D,L-lactide in the presence of poly(ethylene glycol) (PEG), with number-average molecular weight (Mn ) of 1500 and 2050 g/mol, using Sn(Oct)2 as a catalyst. The influences of the reaction time, the ratio of PEG and Poly(D,L-lactic acid) (PLA), and PEG types on structure and sol-gel phase transition of PLA-PEG-PLA triblock copolymers were investigated. Optimal polymerisation parameters were obtained, such as reaction time of 18 hours, a catalyst amount of 1.3%, and PEG/PLA ratio of 1/1.

5p caygaocaolon1 13-11-2019 23 3   Download

The analytic expressions of the Helmholtz free energy, the Gibbs thermodynamic potential the mean nearest neighbor distance between two atoms, the crystal parameters for bcc, fcc and hcp phases of defective and perfect substitutional alloys AB with interstitial atoms C and structural phase transition temperatures of these alloys at zero pressure and under pressure are derived by the statistical moment method.

11p viedison2711 03-09-2019 19 0   Download

The TbTSn compounds (T = Pt, Rh) have been prepared by arc-melting in purified Ar atmosphere. Crystal structures were studied by X-ray powder diffraction. The Rietveld analysis shows the single phase in hexagonal ZrNiAl-type structure for TbPtSn and TbRhSn compounds. Magnetic properties and specific heat measured by mean of Physical Properties Measurement System (PPMS) demonstrated the phase magnetic transition at Néel temperature TN.

5p cathydoll4 21-02-2019 17 0   Download

Magnetic properties and giant magnetocaloric effect (GMCE) of Mn-based Heusler compounds such as Co-Mn-Si, Ni-Mn-Sn, Ni-Mn-Sb have been investigated. The results show that the structure strongly influences on magnetic properties and GMCE of these alloys. The coexistence of ferromagnetic (FM) and antiferromagnetic (AFM) orders is observed. The magnetic phase transitions can be controlled by changing composition and annealing condition of the alloys.

8p thuyliebe 12-10-2018 26 2   Download

The Bose - Einstein condensation of ultra - cold Bose gases is studied by means of the Cornwall - Jackiw - Tomboulis effective potential approach in the improved double - bubble approximation which preserves the Goldstone theorem. The phase structure of Bose - Einstein condensate associating with two different types of phase transition is systematically investigated. Its main feature is that the symmetry which was broken at zero temperature gets restored at higher temperature.

9p thuyliebe 09-10-2018 21 0   Download

The temperature is increased from 50 K to 5500 K in order to observe the change of the structure during heating process. Various thermodynamic quantities related to the change of structure are calculated such as the radial distribution functions the Lindemann criterion, the occurrence/growth of liquidlike atoms, the formation of clusters, and the ring statistics. The melting point is defined. The phase transition from solid to liquid states exhibits first order behavior.

10p thuyliebe 08-10-2018 20 1   Download

The interaction of bacterial endotoxins [lipopolysaccharide (LPS) and the
endotoxic principle lipid A], with high-den-sity lipoprotein (HDL) from serum was investigated with a variety of physical techniques and biological assays. HDL exhibited an increase in the gel to liquid crystalline phase transition temperature Tc and a rigidification of the acyl chains of the endotoxins as measured by Fourier-transform infrared spectroscopy and differential scanningcalorimetry.

10p tumor12 22-04-2013 36 1   Download