The decomposition, shrinkage and evolution of aligned gel fibres with the s
toichiometric compositions for BaM, SrM and CO(2)Z were investigated over a
range of temperatures. SrM and Ba-M began to form by 750 and 800 degreesC
respectively, giving pure SrM and BaM phases at 900 and 1000 degreesC. The
Z phase formed at 1250 degreesC, and only after the full crystallisation of
the M and Y phases at 1000 degreesC. Pure phase fibres of all ferrites wer
e produced from stoichiometric mixes, unlike standard ceramic preparations.
The fibres shrank by up to 22-23% at 1200 degreesC, with no loss of alignm
ent, and were appeared sintered (similar to 97%) by this point. The formati
on of the M ferrite phases seemed to occur at unexpectedly high temperature
s compared to previous work on bulk sol-gel M ferrites. Halides were retain
ed in the fibre over 800 degreesC, and ferrite formation was delayed until
the halides were lost. (C) 2001 Acta Materialia Inc. Published by Elsevier
Science Ltd. All rights reserved.