A STUDY OF HOMOGENEOUS NUCLEATION AND GROWTH IN AQUEOUS SOLUTION GLASSES BY CONDUCTIMETRIC AND CALORIMETRIC TECHNIQUES (ICE, CRYSTALLIZATION)
Abstract
The nucleation and growth of ice Ic in aqueous LiCl solutions and of crystalline Ni(NO(,3))(,2).6H(,2)O from its emulsified melt have been studied using a novel conductimetric technique. The conductance is found to exhibit a sigmoidal fall off in time during crystallization, as expected theoretically, while the capacitance passes through a maximum during the nucleation of ice. Analysis of the conductance-time curves for ice crystallization yields values for the growth morphology of the ice nuclei and also values of the nucleation rate which, with other data, allow us to lay out the complete nucleation behavior of these solutions as a function of concentration and temperature. Similarly the TTT curve for Ni(NO(,3))(,2).6H(,2)O is mapped out. A study of the conductivity relaxation in hydrates near T(,9) indicates that the celebrated return to Arrhenius behavior of the conductivity is only partially manifested in Ca(NO(,3))(,2).4H(,2)O and not at all in Na(,2)S(,2)O(,3).5H(,2)O. In a series of calorimetric experiments on vapor deposited water the samples failed to show a glass transition at the expected 140 K but continued to crystallize at 166 K, again as expected. This behavior and other evidence presented leads us to believe that the glass transition temperature of water is (TURN) 162 K.
Degree
Ph.D.
Subject Area
Chemistry
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.