SILICATE ANION STRUCTURE AND DEHYDRATION PROCESSES OF OKENITE

The silicate anion structure and thermal decomposition behavior of oke nite were studied mainly using solid Si-29 NMR. The silicate anion str ucture of okenite is very close to some parts of the sheet structure o f gyrolite. Dehydration occurs at around 119 and 315-degrees-C which a re caused by the decomposition of the double-chain and sheet structure , and the sheet structure, respectively. Although, the dehydration is caused by the water in the interlayer of okenite, and the main silicat e anion structure remains untill around 350-degrees-C. From 350 to 700 -degrees-C, the silicate anion structure decompose gradually as the te mperature increases and many kinds of silicate anions are formed from the double-chain and the sheet structure of okenite. By the thermal tr eatment above 800-degrees-C, wollastonite, pseudo-wollastonite and amo rphous silica are formed and pseudo-wollastonite, cristobalite, quartz and silica glass are formed over 1200-degrees-C.