Temperature effects phase transitions

This tells us immediately that, just as for Ising spins, we have a spontaneous magnetization and that there is an effective phase transition for T = 1 stored patterns will only be stable for temperatures T < 1. 

MS2 NiSAl-91 < X < 2.1) Nii j,CUySi.93 (0.03 < y < 0.1) Investigation of structural, electronic, and magnetic properties by means of X-ray diffraction, densitometry, resistivity, susceptibility, and Ni Mossbauer spectroscopy as function of x temperature of phase transition from semimetalhc to metallic state as function of x different Ni sites with different (l/f l) and different angle between H and EFG axis effect of Cu impurities... 

If a temperature-driven phase transition occurs at a temperature Tji ao) in a macroscopically large system, in a finite Lx L geometry this transition will be smeared out over a temperature region AT(L) around a shifted effective transition temperature T L),... 

Figure 10-3. Temperatures of phase transition of the epsilon form of n-alkylammonium bromides, illustrating the odd-even effect...

The effect of s—d hybridization on the relative stability of the structures of metallic Ca and Sr has been studied as a function of temperature and pressure within the context of the pseudopotential theory for metals. The inclusion of hybridization is found to favour the f.c.c. structure at all pressures and, in particular, is necessary to explain the observed f.c.c. structure in these metals at zero temperature and pressure. Phase boundaries are calculated by equating the free energy of the f.c.c. structure to that of the b.c.c. structure. Temperature-induced phase transitions are predicted to occur at 555 K in Ca and 625 K in Sr as compared with the actual temperatures of 721 and 830 K. From the changes in free energy of the reactions of the alkaline-earth metals with gases as a function of temperature, it is confirmed that at 298— 1400 K almost all of the residual gases in electrovacuum devices combine with the metals to form stable compounds. The dehydration of calcium... 

The study of temperature effects (see Section 1.4.2), which has already begun, should continue to explore both the possible existence of temperature-induced phase transitions and surface stability issues in materials of technological importance. 

For the experimentalist, the fundamental point is that the metallic state may not be stable down to very low temperatures. A phase transition might occur, which may or may not be a structural phase transition. In the first case, we will get an electronic Peierls distortion at 2 kp for a free electron gas, or a magnetic analog at 4 kp in the large-U approximation [28] (see Fig. 3). In the second case (AF and SC), there is a cooperative effect, which is manifested through different physical properties. 

Helfnch, W. Effect of electric fields on the temperature of phase transitions of liquid crystals. Phys. Rev. Lett. 24, 201-203 (1970)... 

In order to investigate the viscoelastic behavior of crosslinked EVA, rheological measurements were made to determine at what temperatures the phase transitions occur and their effect on the dynamic mechanical modulus. The complex dynamic modulus E expression is given by Eq. (6). 

Malkin et al. (1993) have plotted the phase diagrams for solid solutions of thulium, terbium, and dysprosium vanadates RpR i pV04, undergoing the low-temperature structural phase transitions. The pseudospin technique has been used. Considering only the lower set of states of Tm + (non-Kramers doublet), Dy (two close Kramers doublets), and Tb " " (singlet-doublet-singlet) ions in the corresponding vanadates (see table 5), the effective Hamiltonian of the R-ions may be presented in the self-consistent field approximation as follows (see eq. 79) ... 

For other usual materials, the critical temperature for phase transition is proportional to the atomic cohesive energy, Tq zE, . with z being the effective atomic CN and E the bond energy of the z-coordinated atom [48]. For water molecules, 7c is proportional to the cohesive energy of the covalent bond E because of the isolation of the H2O molecule by its surrounding four lone pairs. 

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