Effect of sodium on crystallite size and surface area of zirconia powders at elevated temperatures

Fine ZrO2 powders were synthesized by an aqueous precipitation method using zirconyl nitrate. By adding the precursor salt to NaOH, single-phase ZrO2 powders were formed, and the monoclinic phase did not appear upon heat trea tment up to 1000 degrees C. The samples were digested in NaOH for different amounts of time, Different levels of washing of digested samples produced surface area at 900 degrees C for 4 h ranging from 8 to 100 m(2)/g. It was found that the properties of the powders at elevated temperatures were sens itive to the sodium content. The surface area decreased while the crystalli te size and pore size of the samples Increased with increased sodium conten t. Our results indicated that sodium is detrimental to the stabilization of surface area at elevated temperatures.