Double and double double perovskites in the RMnMnTaO6 series

• Published in: Journal of solid state chemistry 2022-09, Vol.313, p.123329, Article 123329
• Main Authors: Ji, K., Yuan, Y., Moyo, G.T., Ritter, C., Attfield, J.P.
• Format: Article
• Language: English
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2022.123329

A new family of perovskites RMnMnTaO6 has been synthesised at high pressure for representative R ​= ​La, Nd, Sm, Eu, Gd, Y and Lu that span the whole rare earth series. The structure type changes from tetragonal P42/n double double perovskite (DDPv) type with columnar R3+/Mn2+ cation order (R ​= ​La, Nd, Sm) to monoclinic P21/n double perovskite (DPv) (R0.5Mn0.5)2MnTaO6 (R ​= ​Sm, Gd, Y, Lu) as R3+ cation size decreases. No antisite disorder or nonstoichiometry is observed. Spin ordering transitions are observed below 70 ​K and a neutron diffraction study of DDPv NdMnMnTaO6 reveals ferrimagnetic orders at TC1 ​= ​65 ​K and TC2 ​= ​40 ​K with Mn-spin reorientation due to Nd moment order at TC2 leading to magnetoelastic coupling. Exploration of RMnMnTaO6 perovskites at high pressure shows that the structure type changes from double double perovskite (DDPv) to double perovskite (DPv) type as R3+ cation size decreases, with a narrow coexistence region for R ​= ​Sm. [Display omitted] •A new family of perovskites RMnMnTaO6 has been synthesised at high pressure for R ​= ​La, Nd, Sm, Eu, Gd, Y and Lu.•Structure type changes from double double perovskite (DDPv) type (R ​= ​La, Nd, Sm) to double perovskite (DPv) (R0.5Mn0.5)2MnTaO6 (R ​= ​Sm, Gd, Y, Lu).•Ferrimagnetic spin ordering transitions are discovered in all phases below 70 ​K.•A neutron diffraction study of DDPv NdMnMnTaO6 reveals ferrimagnetic orders at TC1 ​= ​65 ​K and TC2 ​= ​40 ​K.