  Samples of La0.7Ca0.3Mn1-xGaxO3 with x = 0, 0.025, 0.05 and 0.10 were
prepared by standard solid-state reaction. They were first characterized
chemically, including the microstructure. The magnetic properties and various
transport properties, i.e. the electrical resistivity, magnetoresistivity (for
a field below 8T), thermoelectric power and thermal conductivity measured each
time on the same sample, are reported. The markedly different behavior of the x
= 0.1 sample from those with a smaller Ga content, is discussed. The dilution
of the Mn3+/Mn4+ interactions with Ga doping considerably reduces the
ferromagnetic double exchange interaction within the manganese lattice leading
to a decrease of the Curie temperature. The polaron binding energy varies from
224 to 243 meV with increased Ga doping.
