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Abstract
The temperature dependences of the resistivity of La0.7Ca0.3Mn1−xFexO3 and La0.7Ca0.3Mn1−xFexO3 (0 < × < 0.04) mixed crystals were studied under hydrostatic pressures up to 15kbar. The substitution of Fe for Mn results in an increase of the resistivity and a continuous decrease of the metal-insulator transition temperature Tmi while the substitution of Ge for Mn leads to a more complicated Tmi(x)-curve. In all cases Tmi shifts under pressure with a rate between 1.6 and 2.9K/kbar and a correlation between Tmi and its pressure derivative dTmi/dP is observed which is in accordance with the general trend of dTmi/dP versus Tmi as derived for other manganites and is discussed in terns of a competition between superexchange and double exchange.