A large entropy variation (magnetocaloric effect) has been discovered
in ceramic perovskites with the formulas La0.65Ca0.35Ti1-xMnxO3-z and
La0.5+x+yLi0.5-3yTi1-3xMn3xO3-z. Both Curie temperature and entropy ch
ange were studied from 4.2 to 400 K for different stoichiometric compo
sitions and applied magnetic fields. Our conclusion is that these mate
rials are excellent candidates for working materials in magnetic refri
geration and liquefaction devices in a wide temperature range. (C) 199
8 American Institute of Physics.