Abstract
To obtain comprehensive materials with both high temperature coefficient of resistivity (TCR) and magnetoresistance (MR) at low magnetic fields, polycrystalline La0.72Ca0.28Mn1−xCrxO3 (x = 0, 0.02, 0.04, 0.06) ceramics were prepared herein by sol–gel method. Electronic configuration of Cr3+ ions is similar to that of Mn4+ ions, therefore, successive substitution of Mn with Cr increases electrical resistivity and decreases metal–insulator transition temperature of ceramics, even yielding hump-like feature for Cr-rich (x = 0.06) samples. The best TCR (28.50%·K−1) and MR (72.37%) values were obtained simultaneously at Cr dopant content of 0.02 (La0.72Ca0.28Mn0.98Cr0.02O3). Strong response of the material to temperature and magnetic field was caused by minimal symmetry of orthorhombic structure and the most robust Jahn–Teller distortion. With increasing Cr content, Mn3+/Mn4+ or Mn3+/Cr3+ double exchange was diluted, and Cr3+/Cr3+ or Cr3+/Mn4+ superexchange was promoted. However, the internal competition effect was not conducive to the improvement of material properties.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
