Phase transition temperatures neutron-diffraction

Interlayer c/-Values and Phase Transition Temperatures Tc at 16 r,c Points Obtained by Neutron Diffraction Experiments... [Pg.82]

TABLE 5.5 Phase Transition Temperatures (°C) Obtained by Three Methods (a) Neutron Diffraction ... [Pg.89]

Fig. 20. Left panel Neutron diffraction intensity in CeCu2Si2 at temperatures above and below the A-phase transition temperature Incommensurate peak corresponds to Q = (0.215,0.215,0.53) (Stockert et al., 2004). Right panel Nesting of heavy FS columns (fig. 18) leads to a peak in the static susceptibility x(

$Fig. 20. Left panel Neutron diffraction intensity in CeCu2Si2 at temperatures above and below the A-phase transition temperature Incommensurate peak corresponds to Q = (0.215,0.215,0.53) (Stockert et al., 2004). Right panel Nesting of heavy FS columns (fig. 18) leads to a peak in the static susceptibility x(<l) at q = Q. The intensity map of X (q) (value increasing from dark to bright) in the reciprocal h, h, /)-plane as calculated for the renormalized bands at T = 100 mK. The experimental Q at 50 mK from the left panel shows perfect agreement with the calculated...$

The FM phase is also stabilized by pressure. In an x = 0.15 sample, we [199] found a transition from vibronic to itinerant electronic behavior in the pressure range 5 < P < 6 kbar and the temperature range Tco < T < Tc it marks the FV-FM transition. A neutron-diffraction study [220] of an x = 0.165 sample showed that pressure stabilizes the R-rhombohedral phase relative to the O phase. We have also found that Tc jumps discontinuously by about 15-20 °C not only at the first-order O —O transition, but also at the FV-FM and the 0 -R transitions [199, 220a]. In addition, the slope dTc/dP drops discontinuously on crossing each transition. [Pg.84]

Also known for some time is a phase transition at low temperature (111K), observed in studies with various methods (NQR, elasticity measurement by ultrasound, Raman spectrometry) 112 temperature-dependent neutron diffraction showed the phase transition to be caused by an antiphase rotation of adjacent anions around the threefold axis ([111] in the cubic cell) and to lower the symmetry from cubic to rhombohedral (Ric). As shown by inelastic neutron scattering, this phase transition is driven by a low-frequency rotatory soft mode (0.288 THz 9.61 cm / 298 K) 113 a more recent NQR study revealed a small hysteresis and hence first-order character of this transition.114 This rhombohedral structure is adopted by Rb2Hg(CN)4 already at room temperature (rav(Hg—C) 218.6, rav(C—N) 114.0 pm for two independent cyano groups), and the analogous phase transition to the cubic structure occurs at 398 K.115... [Pg.1261]

Neutron diffraction studies under pressure [84] on the 70/30 composition have revealed that transitions in this copolymer are displaced towards higher temperature with increasing pressure, as can be seen in the phase diagram of Fig. 11. In addition, it is worth noting the non-linear increase of the Curie temperature with pressure. By considering the Clausius-Clapeyron relation dTc/dP = TCAVC/Ahc, this effect can be related to a decrease in the volume... [Pg.19]

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