Role of Li in the low temperature synthesis of monoclinic celsian from (Ba, Li)-exchanged zeolite-A precursor

A sample of exhaustively Ba-exchanged zeolite-A was subjected to Li-exchange to obtain four samples of zeolite Ba-A bearing different Li amounts. These samples were subjected to thermal treatments at temperatures ranging from 200 to 1100 ◦C for times up to 28 hours. Samples of fully monoclinic celsian bearing an amount of impurities of 0.62 weight % Na2O and 0.17 weight % Li2O, 0.60 Na2O weight % and 0.29 Li2O weight %, and 0.67 Na2O weight % and 0.55 Li2O weight % were obtained after thermal treatments lasting 10 hours at 1100 ◦C, 4 hours at 1100 ◦C, and 4 hours at 1000 ◦C, respectively.