Pretransition in ethanol–water mixtures

Abstract

Ultrasonic velocity data are reported for the ethanol-water mixture of 23 mole% at frequencies between I and 5 MHz in the temperature range from -80· to + 20' C. Velocities in a crystalline state are far lower than that of ice. The mixtures in the concentration ranging from 9.4 to 23 mole% ethanol indicate a maximum density in a saturated liquid state. The 23 mole% ethanol mixture. among others. grows into a layered hexagonal crystalline structure. Temperature dependency of limiting shear modulus is found to obey the Hirai-Eyring equation. deviating down at high temperatures. The deviation is interpreted in terms of the structural decay process due to the decomposition of the cluster containing 10-15 molecules.

Particle size effects in thermoluminescent lithium fluoride

“…This suggests a competing trapping mechanism, possibly related to increased surface effects as the particle size decreases (Zanelli 1968). Previous work (King 1974, Zanelli 1968, Yamaoka 1978) confirms the general observations. Coupled with the sensitivity decreases, the observed reduction in particle size with annealing may partly explain observed decreases in the sensitivity of lithium fluoride powders and discs with repeated thermal treatment during routine re-use.…”

Comment on 'Particle size effects in LiF'

“…Zanelli (1968) considered tentatively the existence of an 'inactive surface layer'. The shapes of the curves of thermoluminescent light yield as a function of particle size as reported by Yamaoka (1978) for air and nitrogen annealed samples are not identical, being described by separate equations. These equations have both volume and surface contributions which determine the shape and position of the maximum of the thermoluminescence yield.…”