The phase transformation and densification behavior of (Pb2+1-XLa3+2X/3)5 Nb10O30 (X=0 .00-0.20) tungsten bronze (TB) -type compounds were studied with respect to La3+ ion substitution for Pb2+ ion in Pb5Nb10O30 . Analysis of the phase identification shows that the phase transformation temperature (low temperature rhombohedral form _??_ high temperature tetragonal form) decreases along with the increase of La3+ amount . The decrease of phase transformation temperature limits excessive grain

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... th , which usually occurs from the co-proceeding of phase transformation and sintering in Pb5Nb10O30 and, as a result , the density after sin tering is effectively improved. Furthermore, two different densification models for Pb5Nb10O30 and (Ph La2X/33+)5 Nb10O30 were described and discussed. [