Controlled Deposition of Calcite Crystals on Yttria-Stabilized Zirconia Ceramic Electrets

Abstract

We demonstrated the crystallization of calcite on yttria-stabilized zirconia (YSZ) ceramic electrets using diffusion of (NH 4 ) 2 CO 3 vapor into a CaCl 2 solution with and without poly(acrylic acid) (PAA). On both negatively and positively charged surfaces in the absence of PAA, the precipitates were calcite crystals with the rhombohedra {10.4} plane oriented parallel to the electrets. This oriented growth was explained by the nucleation theory in the presence of an electric field. The calcite thin films with a fan-like fracture in a cross section formed on the electrets in the presence of PAA. The calcite aggregates consisting of the thin films were made of bundles of calcite needles either having a rough (00.1) top face with a triangular shape or having a faceted rhombohedral {10.4} top face. These calcite needles grew radially from PAA-Ca 2+ complex assemblies attached to the electrets with the growth direction being the c-axis. The effects of PAA addition and a surface electric field due to the electrets on calcite crystallization were apparent most remarkably on a negatively charged surface of the electrets. The surface electric field regulates not only CaCO 3 supersaturation in its vicinity but also the morphology of the PAA-Ca 2- complex assemblies anchored on the surface of the electret.