Structural, Microstructural, and Magnetic Properties of Ce and Sr-coSubstituted (La2−xVacx)NiTiO6 (x = 0, 0.1) Perovskites

Abstract

The synthesis of materials in the La2–x(CeSr)mSrn□pNiTiO6-δ series (where □ denotes vacancies, with m, n, and p ranging from 0 to 0.2, and x = 2m + n + p taking values of 0.4 and 0.6) was attempted using a modified Pechini method. A comprehensive chemical, structural, and microstructural characterization was carried out using X-ray diffraction (conventional and synchrotron), neutron powder diffraction, selected area electron diffraction, high-resolution transmission electron microscopy, and X-ray absorption spectroscopy. The results highlight that single-phase samples are obtained for compositions with low cerium and low vacancy contents (m ≤ 0.1 and p ≤ 0.1). The structural study reveals that the compounds present monoclinic symmetry, space groups P21/n or P21, with Ni and Ti cations exhibiting different degrees of disorder or short-range order, influenced by the existence of A-site vacancies and the contents of Ce4+ and Sr2+ ions. The magnetic behavior is closely related to the cationic disorder at the B-site. The presence of antisite defects and short-range Ni–O–Ni interactions contribute to a lack of three-dimensional antiferromagnetic ordering, probably forming instead of random Ni2+ antiferromagnetic clusters at low temperatures.