Lattice effects related to metal–insulator and charge-ordered transitions in La0.7Ca0.3Mn0.9Cr0.1O3 and La0.4Ca0.6Mn0.99Cr0.01O3

Lattice effects related to metal–insulator (M–I) and charge-ordered (CO) transitions have been studied through the thermal expansion and the thermal conductivity measurements from 77 to 450 K in La0.7Ca0.3Mn0.9Cr0.1O3 and La0.4Ca0.6Mn0.99Cr0.01O3. Thermal-expansion coefficient shows an obvious contraction near the M–I transition temperature TMI, but a sharp increase around the CO transition temperature TCO. Thermal conductivity is enhanced below both TMI and TCO. These findings are attributed to the strong charge–lattice coupling associated with the different electron states in manganites.