Ground state and the metal-insulator transition in (Pr1-yYy)1-xCaxCoO3 (0.45 ≤ x ≤ 0.55) cobaltites

Abstract

Pr0.5Ca0.5CoO3 exhibits a non-conventional metal-insulator transition (MIT) in which the insulating state is due toa volume contraction (∼2%) and electron transfer from Pr to Co sites. Pr1-xCaxCoO3cobaltites 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 Pr3+/Pr4+ transformation at the MIT in Pr0.45Y0.05Ca0.50CoO3[0.25(5) e-/Pr ion and T MI = 120 K] with respect to Pr0.5Ca0.5CoO3[0.15(5) e-/ Pr ion and T MI = 75 K]. © 2013 The Korean Physical Society.