Zeolites due to their structures can be used as molecular sieves for purification of materials and solutions. Zeolites with PHI and SOD structure are so common and applicable for this purpose. Hydroxy sodalite and phillipsite are the more abundant members of zeolites which display good selectivity for very small molecules and some ions such as Sr, Pb, Zn, Cu and Rb. There is not any pure natura...

The anisotropic etching behavior of single-crystal silicon and the behavior of SiO2 and Si3N4 in an ethylenediaminebased solution as well as in aqueous KOH, NaOH, and LiOH were studied. The crystal planes bounding the etch front and their etch rates were determined as a function of temperature, crystal orientation, and etchant composition. A correlation was found between the etch rates and thei...