Synthesis and characterization of the 'beta'-Ba'B IND.2''O IND.4' phase obtained by the polymeric precursor method - Neves, Pérson P.; Maia, Lauro J. Q.; Bernardi, Maria Inês Basso; Zanatta, Antonio Ricardo; Mastelaro, Valmor Roberto; Zanetti, Sônia M.; Leite, Edson R. (Journal of Sol-Gel Science and Technology, 2004)