Colloidal dispersions and phase transitions in charged colloids

Sterically stabilized as well as charge-stabilized colloidal dispersions mi mic most of the phases of condensed matter and serve as excellent model sys tems to study the cooperative behaviour at micrometer length scales in equi librium and non-equilibrium conditions, Charged-stabilized suspensions have the advantage of exhibiting structural ordering at much lower volume fract ions as compared to sterically stabilized suspensions and is mainly due to the strong electrostatic interaction between the particles, The easy tunabi lity of the interparticle interaction makes these systems ideally suited fo r studies of ordering phenomenon and the phase transitions under ambient co nditions. Apart from novel applications of their ordered structures, it is the richness of the phase behaviour that makes the colloidal systems intere sting from a fundamental point of view. Under certain conditions charge-sta bilized suspensions are found to become inhomogeneous or undergo macroscopi c phase separation. The underlying phase transitions have been identified. The phase separation phenomena observed in bulk suspensions of like-charged particles as well as microscopic investigations under confined geometries have generated considerable interest in reexamining the interparticie inter action in suspension of like-charged particles, This article reviews the st ructural ordering and phase transitions brought about by parameters such as particle volume fraction, surface charge density, salt concentration and p olydispersity. In addition, the recent investigations of a two-dimensional system of charged large size metal balls, which has commonness with the cha rged colloidal system, are also discussed.