High TCR (temperature coefficient of resistance) La 2/3 Ca 1/3 MnO 3 :Ag x polycrystalline composites

Abstract

La 2/3 Ca 1/3 MnO 3 :mol%Ag x (LCMO:Ag x ) ceramics with x = 0, 0.2 and 0.4 were prepared by chemical coprecipitation. The TCR (temperature coefficient of resistance) is increased significantly with Ag addition. Large TCR is observed around T MI (metal-insulator transition temperature) with the highest value of 28%/K at 271.3 K for LCMO:Ag x (x = 0.4) sample, which can be used as a candidate of bolometer or infrared detector around room temperature. Furthermore, the increased magneto-resistance (MR) of 79% is seen at 276 K for higher silver added samples in an applied field of 5 T. Ag substitution A site ion and gathering at grain boundaries (GBs) were proposed to describe the existence of Ag. All of evidences suggest that the electrical and magnetic properties enhancement is due to silver-doping improving Mn 4+ concentration, grain size and connectivity. © 2013 Elsevier B.V. All rights reserved.