Structural and crystallochemical characterization of thermal tretment of ion exchange natural zeolites

Abstract

There has been intense activity over the last three decades in the area of preparation of various ceramic materials using synthetic or natural zeolites as a precursors. Aqueous ion exchange can be preformed to incorporate a variety of other metals, typically alkali and alkaline earth for the Rn+ cation. For this investigation was used the two naturale HEU type zeolite from different deposit. Thermally induced phase transformation of Pb, Ca and K-exchange is followed in the range from room temperature to 1300 ºC. The frameworks collapse into amorphous intermediate products after heating between 600 and 650 °C. Prolonged heating of the intermediate product over 900 °C results directly in formation of alumosilicate phases anorthite or structure of celsian. The crystale phases of alumosilicate in temperature range between 700 and 1300 °C was investigated by X-ray powder analyses.