D. Suvorov et al., MICROWAVE DIELECTRIC-PROPERTIES OF CERAMICS WITH COMPOSITIONS ALONG THE LA2 3TIO3(STAB)-LAALO3 TIE LINE/, Journal of Materials Science, 33(1), 1998, pp. 85-89
The stabilization of La2/3TiO3 in the perovskite structure by 4 mol% L
aAlO3 resulted in maximum values for the relative permittivity (k'appr
oximate to 72) and temperature coefficient of resonant frequency (tau(
f) = 123 ppmK(-1)). The Q-value (quality factor) of these ceramics wer
e over 5300 measured at 4.5 GHz. Higher contents of LaAlO3 cause a dec
rease in both the permittivity and tau(f) values, accompanied by an in
crease in the Q-value. Typical values measured at 6.0 GHz for ceramics
with the composition 70 mol% La2/3TiO3-30 mol% LaAlO3 are k' > 44, ta
u(f) = +7 ppmK(-1) and Q > 5500. The results depend on the processing
parameters. The sintering temperature increases with increasing LaAlO3
content. An oxidizing sintering atmosphere improves the Q-value, wher
eas the permittivity and tau(f) are not significantly affected.