An unexpected dichotomic long time aging behaviour is observed in a glassy colloidal clay suspension investigated by X-ray photon correlation spectroscopy and dynamic light scattering. In the long time aging regime the intensity autocorrelations are non-exponential, following the Kohlrausch-Williams-Watts functional form with an exponent beta(Q). We show that for spontaneously aged samples a stretched behaviour (beta(Q) < 1) is always found. Surprisingly a compressed exponent (beta(Q) > 1) appears only when the system is rejuvenated by application of a shear field. In both cases the relaxation times scale as Q(-1). These observations shed light on the origin of compressed exponential behaviour and help in classifying previous results in the literature on anomalous dynamics.
Dichotomic aging behaviour in a colloidal glass / Angelini, Roberta; Laura, Zulian; Andrei, Fluerasu; Anders, Madsen; Ruocco, Giancarlo; Ruzicka, Barbara. - In: SOFT MATTER. - ISSN 1744-683X. - 9:46(2013), pp. 10955-10959. [10.1039/c3sm52173g]
Dichotomic aging behaviour in a colloidal glass
ANGELINI, ROBERTA;RUOCCO, Giancarlo;RUZICKA, BARBARA
2013
Abstract
An unexpected dichotomic long time aging behaviour is observed in a glassy colloidal clay suspension investigated by X-ray photon correlation spectroscopy and dynamic light scattering. In the long time aging regime the intensity autocorrelations are non-exponential, following the Kohlrausch-Williams-Watts functional form with an exponent beta(Q). We show that for spontaneously aged samples a stretched behaviour (beta(Q) < 1) is always found. Surprisingly a compressed exponent (beta(Q) > 1) appears only when the system is rejuvenated by application of a shear field. In both cases the relaxation times scale as Q(-1). These observations shed light on the origin of compressed exponential behaviour and help in classifying previous results in the literature on anomalous dynamics.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
