The ordering of cations in the B sublattice remains a challenging issue in double perovskites. In this work, a combined experimental and theoretical approach was employed to investigate the Co/Nb distribution in Ca2CoNbO6 and its influence on magnetic and transport properties. The density functional theory, supported by magnetic susceptibility measurements, indicates that Co adopts a high-spin Co3+ state. No long-range magnetic ordering was observed down to low temperatures; however, the presence of short-range correlations points to the partial disorder in the Co/Nb sublattice. This interpretation is further supported by electron paramagnetic resonance, which also reveals slight oxygen nonstoichiometry. Electrical transport follows a small-polaron hopping mechanism with an activation energy of 0.25 eV. The Seebeck coefficient reaches 0.4 mV/K at 600 K.
@article{arxiv.2605.23558,
title = {Ambiguity in B-Site cation ordering: A Case study of the double perovskite Ca$_2$CoNbO$_6$},
author = {Svetlana A. Artiukova and Ivan V. Yatsyk and Ruslan G. Batulin and Yulia A. Deeva and Tatiana I. Chupakhina and Vladislav V. Bazhal and Alexandr I. Balitskiy and Rushana M. Eremina and Dina I. Fazlizhanova},
journal= {arXiv preprint arXiv:2605.23558},
year = {2026}
}