Solid-Solid Transition in Hexamethylbenzene That Depends on Thermal History

Yoshimoto, Yoshikazu; Fujiwara, Takeshi; Ataké, Tooru; Chihara, H.

doi:10.1246/cl.1985.1347

Cited by 5 publications

(3 citation statements)

References 4 publications

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“…Evidence (for HMB-h 18 ; Yoshimoto et al, 1985) for HMBd 18 and the 1:1 h 18 -d 18 solid solution (Fujiwara et al, 1992) has been obtained from calorimetric measurements, showing that each crystallite of a powdered specimen has a specific and different transition temperature or, in other words, each crystallite has a built-in memory as to where it should begin its phase transition. This matches remarks by Mnyukh on nucleation (Mnyukh, 2001, pp.…”

Section: Figure 24mentioning

confidence: 99%

On the mechanism of some first-order enantiotropic solid-state phase transitions: from Simon through Ubbelohde to Mnyukh

Herbstein

2006

Acta Crystallogr B Struct Sci

118

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The first (so-called) lambda transition in solids was found in the specific heat measurements for NH(4)Cl at 242 K by F. Simon in 1922 [Simon (1922). Ann. Phys. 68, 241-280]. Analogous phenomena found in many other solids gave rise to doubts (expressed most clearly by A. R. Ubbelohde some 50 years ago) about the applicability of classical thermodynamics to some phase transitions [Ubbelohde (1956). Brit. J. Appl. Phys. 7, 313-321]. However, Y. Mnyukh's studies of enantiotropic phase transitions in eight organic crystals showed that all proceed by a nucleation-and-growth mechanism [summarized in Mnyukh (2001), Fundamentals of Solid State Phase Transitions, Ferromagnetism and Ferroelectricity. 1st Books]. Nucleation is localized at defects in the parent phase; growth can be epitaxic and oriented if parent and daughter phases have closely similar structures, or random (not oriented) if there are substantial structural differences. This conclusion is supported by a critical review of Mnyukh's eight examples and other results published in the interim. It seems that Ubbelohde's invocation of "hybrid crystals" and "smeared transitions" can mostly be accounted for by lack of equilibrium in the phase-transition studies cited by him. However, the intermediate phase in 4,4'-dichlorobenzophenone appears to have structural resemblances to Ubbelohde's' "hybrid crystal".

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Section: Figure 24mentioning

confidence: 99%

On the mechanism of some first-order enantiotropic solid-state phase transitions: from Simon through Ubbelohde to Mnyukh

Herbstein

2006

Acta Crystallogr B Struct Sci

118

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“…A concealed anomaly at T = 117.5 K in the heat capacity of hexamethylbenzene could be revealed by adiabatic calorimetry [32][33][34][35][36]. Especially, a new adiabatic calorimeter for use of heat capacity measurements in cooling direction [34] was very useful to study peculiar hysteresis and/or memory effects in the heat capacity and phase transition properties [36].…”

Section: Researchers Phasementioning

confidence: 99%

“…Especially, a new adiabatic calorimeter for use of heat capacity measurements in cooling direction [34] was very useful to study peculiar hysteresis and/or memory effects in the heat capacity and phase transition properties [36].…”

Section: Researchers Phasementioning

confidence: 99%