The surface properties of a Ba-beta-alumina sample (Ba : Al ratio 1 :
12) very stable to sintering (15 m(2)/g after calcination at 1670 K fo
r 10 h) have been investigated by FT-IR spectroscopy of adsorbed probe
molecules (water, pyridine and CO2) and by measuring the isoelectric
point. The surface has a medium-strong basic character,justified by th
e preferential exposition of Ba-O-containing ''mirror planes'', parall
el to 0001 planes, on the surface of plate-like particles. This behavi
or has been associated to the resistance to sintering, typical of this
material, possibly originated by the difficulty of the very big Ba2ions to migrate into the spinel-type alumina blocks. This should imply
the blocking of the crystal growth along the crystallographic c axis.