  In this article, we report the synthesis, magneto transport features, and
magnetization of polycrystalline La2/3Ca1/3MnO3:Agx/Inx composites with x = 0,
0.1, 0.2, 0.3 and 0.4. In case of Ag the temperature coefficient of resistance
(TCR) near ferromagnetic (FM) transition enhances significantly with addition
of Ag. The FM transition temperature (TFM) is also increased slightly with Ag
doping. Magneto-transport measurements revealed that magneto-resistance (MR) is
found to be maximum near TFM. Very sharp TCR is seen near TFM with highest
value of up to 15 % for Ag (0.4) sample, which is an order of magnitude higher
than as for pristine sample and is the best value yet reported for any
polycrystalline LCMO compound. Increased TCR, TFM and significant above room
temperature MR of La2/3Ca1/3MnO3:Agx composites is explained on the basis of
improved grains size. Interestingly the La2/3Ca1/3MnO3:Inx composites behaved
exactly in opposite way resulting in decreased TFM, and TCR compared to
pristine LCMO compound. In fact the grains morphology of LCMO:Inx composites is
seen inferior to pristine LCMO which is opposite to the LCMO:Agx case.
