Kinetics Study of Crystallization with the Disorder–bcc–fcc Phase Transition of Charged Colloidal Dispersions

Abstract

Structure transformation (disorder-bcc-fcc) in charged colloidal dispersions, as a manifestation of the Ostwald's step rule, was confirmed by means of reflection spectrum (RS) measurements in our previous study. By taking advantage of a reflection spectrum containing plenty of information about the crystallization behaviors, time-dependent changes of parameters associated with the crystal structure and composition during the disorder-bcc-fcc transition are reported by treating the data from RS in this article. In addition, Avrami's model is adopted to analyze the transition process and investigate the transition rate. On the basis of the above investigations, associated kinetic features of crystallization with the disorder-bcc-fcc transition are described.

Influence of the surface charge on the homogeneity of colloidal crystals

“…In PS colloidal dispersions, ν can be estimated from the indices of water and PS and the volume fraction by ν sample = ν water (1 − φ) + ν ps φ. For the measurement of interplanar distance by RS with normal incidence as shown in our previous studies, 33,34 Bragg angle is 90 • , then lattice constant l can be written as…”

“…[31][32][33][34] Based on the Bragg's law, we can get 2dsin θ = mλ/ν, where d is interplanar distance, θ is Bragg angle, m is integer, and ν is refractive index of medium so that λ/ν is the wavelength in medium. In PS colloidal dispersions, ν can be estimated from the indices of water and PS and the volume fraction by ν sample = ν water (1 − φ) + ν ps φ.…”

“…For λ corresponding to the (110) plane of bcc-like structure, which can be determined by reflection spectrum as in our previous studies, 34 D exp is…”

“…Our previous study 33,34 has shown how to use the RS method to identify the types of crystals and also to achieve a series of kinetic parameters during crystallization of charged particles. Typical spectra of bcc and fcc colloidal crystals in our samples are shown in Fig.…”

Experimental and Theoretical Substantiations of Stepwise Mechanism of Crystal Formation From Liquid Phase

“…Однако некоторые метастабильные кристаллические фазы могут далее последовательно претерпевать серию фазовых превращений «твердое -твердое», например, многие полимеры [2,3]. В последние годы это эмпирическое правило нашло дальнейшее теоретическое и экспериментальное обоснование для последовательности фазовых переходов «метастабильное твердое -метастабильная жидкость -стабильная твердая фаза» [4][5][6][7][8][9]. Образование метастабильной жидкой фазы экспериментально доказано во многих работах при контактном плавление двух металлов [10].…”