Ground state and the metal-insulator transition in (Pr1-yYy)1-xCaxCoO3 (0.45≤x≤0.55) cobaltites
نویسنده
چکیده
Pr0.5Ca0.5CoO3 exhibits a non-conventional metal-insulator transition (MIT) in which the insulating state is due to a volume contraction (~2%) and electron transfer from Pr to Co sites. Pr1-xCaxCoO3 cobaltites with Ca doping around x 0.5 (0.45≤x≤0.55) have been investigated. Different ground states and phase transitions are reported in samples at both sides of the half-doped composition. The relevance of the Pr/Ca ratio around half-doping and the amplitude of the changes observed at the MIT are analyzed. Besides the expected variation in the transition temperature, we report an enhanced Pr 3+ /Pr 4+ transformation at the MIT in Pr0.45Y0.05Ca0.50CoO3 [0.25(5) e / Pr ion and TMI=120 K] with respect to Pr0.5Ca0.5CoO3 [0.15(5) e / Pr ion and TMI=75 K].
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