Y-type Ba-hexaferrites (Ba2Zn2Fe12O22), which have been identified as electromagnetic wave absorbers, were prepared by the glass-ceramic method. Glasses with the composition 0.1 ZnO center dot 0.9(xB(2)O(3) center dot gamma BaO center dot (1-x-y)Fe2O3) were prepared, and the precipitation of Y-type Ba-hexaferrite from the glass matrix was investigated. Y-type Ba-hexaferrite were precipitated by heating glass specimens with roughly the composition 0.1ZnO center dot 0.9 (0.2B(2)O(3) center dot 0.5BaO center dot 0.3Fe(2)O(3)) at temperatures above about 1073 K. The lower temperature limit at which single-phase Y-type powder was obtained after leaching with a dilute HCl solution was about 1093 K. The low-temperature formation of Y-type Ba-hexaferrite was linked to the generation of a liquid phase. The shape of Y-type crystals depended strongly on the heating temperature and changed from a plate-like hexagon to a complex polyhedron with increasing heating temperature.