Preceramic Polymer Route to Amorphous and Crystalline Potassium Aluminosilicate Powders and Their Electrorheological Properties

Abstract

The oxide one‐pot synthesis (OOPS) process was used to synthesize a polymer precursor to potassium aluminosilicate, KAlSiO 4 (KASp). A KAlSiO 4 gel (KASg) also was produced via a solgel route using the same precursor. The two routes to KAlSiO 4 were explored to compare the effects of the two processing methods on powder properties. The KASp and KASg powders both transformed on heating (.500°C) to amorphous, high‐surface‐area powders with narrow pore‐size distributions (4–24 nm). These anhydrous, amorphous powders were intrinsic electrorheological (ER) materials. Both materials crystallized at } 1070°C, and thermogravimetric analysis, differential thermal analysis, and X‐ray diffractometry suggested that they were identical. Diffuse reflectance infrared Fourier transform spectroscopy and scanning electron microscopy proved that the KASp powders were homogeneous, whereas the KASg powders were heterogeneous and segregated. The KASg powders exhibited better ER properties that were associated with the segregated phases.