Synthesis, crystal structure, and magnetic properties of oxynitride perovskites SrMn0.2M0.8O2.6N0.4 (M = Nb, Ta)

Young-Il Kim; Maxim Avdeev

doi:10.1039/d0dt00907e

Synthesis, crystal structure, and magnetic properties of oxynitride perovskites SrMn_0.2M_0.8O_2.6N_0.4 (M = Nb, Ta)

Dalton Trans. 2020 May 19;49(19):6471-6477. doi: 10.1039/d0dt00907e.

Authors

Young-Il Kim¹, Maxim Avdeev²

Affiliations

¹ Department of Chemistry, Yeungnam University, Gyeongsan 38541, Republic of Korea. yikim@ynu.ac.kr.
² Australian Nuclear Science and Technology Organisation, New Illawarra Rd, Lucas Heights, NSW 2234, Australia and School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia.

PMID: 32356852
DOI: 10.1039/d0dt00907e

Abstract

Complex perovskites SrMn0.2Nb0.8O2.6N0.4 and SrMn0.2Ta0.8O2.6N0.4 were synthesized; these are rare examples of octahedral Mn2+ in oxynitride perovskites. Joint Rietveld refinement of neutron and X-ray data revealed that SrMn0.2Nb0.8O2.6N0.4 and SrMn0.2Ta0.8O2.6N0.4 had orthorhombic symmetries, in contrast with those of analogous perovskites SrM'0.2M0.8O3-xNx (M' = Li, Na, Mg; M = Nb, Ta), which are all tetragonal. Both SrMn0.2Nb0.8O2.6N0.4 and SrMn0.2Ta0.8O2.6N0.4 exhibited paramagnetic behavior with effective magnetic moments of 5.60μB and 5.94μB, respectively, consistent with a high-spin Mn2+ (d5, S = 5/2) state. The Weiss constants were -24.7 K for SrMn0.2Nb0.8O2.6N0.4 and -15.4 K for SrMn0.2Ta0.8O2.6N0.4, indicating the presence of weak antiferromagnetic spin-spin interactions. The band gaps of SrMn0.2Nb0.8O2.6N0.4 and SrMn0.2Ta0.8O2.6N0.4 were determined to be 1.75 eV and 2.2 eV, respectively, suggesting that the Mn 3d electrons were essentially localized.