K2Mn3O(OH)(VO4)(V2O7) with Sawtooth Chains of Multivalent Manganese Triangular Trimer Units: Magnetic Susceptibility Shrouding a Long-Range Antiferromagnetic Order of Ferromagnetic Triangles

Olga V Yakubovich; Larisa V Shvanskaya; Galina V Kiriukhina; Sergey V Simonov; Anatoly S Volkov; Olga V Dimitrova; Vasiliy N Glazkov; Andrey N Ignatenko; Seung Hwan Chung; Hyun-Joo Koo; Myung-Hwan Whangbo; Alexander N Vasiliev

doi:10.1021/acs.inorgchem.3c01100

K₂Mn₃O(OH)(VO₄)(V₂O₇) with Sawtooth Chains of Multivalent Manganese Triangular Trimer Units: Magnetic Susceptibility Shrouding a Long-Range Antiferromagnetic Order of Ferromagnetic Triangles

Inorg Chem. 2023 Sep 4;62(35):14180-14190. doi: 10.1021/acs.inorgchem.3c01100. Epub 2023 Aug 18.

Authors

Olga V Yakubovich¹, Larisa V Shvanskaya^{1

2}, Galina V Kiriukhina^{1

3}, Sergey V Simonov⁴, Anatoly S Volkov⁵, Olga V Dimitrova¹, Vasiliy N Glazkov^{6

7}, Andrey N Ignatenko⁸, Seung Hwan Chung⁹, Hyun-Joo Koo⁹, Myung-Hwan Whangbo^{9

10}, Alexander N Vasiliev^{1

2}

Affiliations

¹ Lomonosov Moscow State University, Moscow 119991, Russia.
² National University of Science and Technology "MISiS", Moscow 119049, Russia.
³ Korzhinskii Institute of Experimental Mineralogy RAS, Chernogolovka 142432, Russia.
⁴ Institute of Solid State Physics RAS, Chernogolovka 142432, Russia.
⁵ Skolkovo Institute of Science and Technology, Moscow 121205, Russia.
⁶ Kapitza Institute for Physical Problems, RAS, Moscow 119334, Russia.
⁷ HSE University, Moscow 101000, Russia.
⁸ M.N. Mikheev Institute of Metal Physics, Yekaterinburg 620108, Russia.
⁹ Department of Chemistry and Research Institute for Basic Sciences, Kyung Hee University, Seoul 02447, Republic of Korea.
¹⁰ Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States.

PMID: 37595259
DOI: 10.1021/acs.inorgchem.3c01100

Abstract

ortho-Pyrovanadate (or ortho-diorthovanadate) K₂Mn₂³⁺Mn²⁺O(OH)(VO₄)(V₂O₇) synthesized hydrothermally crystallizes in the orthorhombic space group Pnma with a = 17.9155(5), b = 5.8940(2), c = 10.9971(3) Å, V = 1161.23(6) Å³, and Z = 4. Its crystal structure features linear chains of edge-sharing Mn³⁺O₆ octahedra with every second pair of Mn³⁺O₆ octahedra condensed with a Mn²⁺O₆ octahedron on one side of a chain in a sawtooth pattern so that each sawtooth chain consists of a triangular trimer. These sawtooth chains, running parallel to the b axis and linked by the VO₄ and V₂O₇ groups, form a framework with channels populated by K atoms. The new compound is a structural analogue of the mineral zoisite Ca₂Al₃O(OH)(SiO₄)(Si₂O₇), showing a striking example of very different chemical compositions. K₂Mn₃O(OH)(VO₄)(V₂O₇) undergoes a phase transition into an ordered antiferromagnetic (AFM) state at T_N = 14.4 K, which was detected by high-frequency electron spin resonance as well as by both specific heat C_p and Fisher's specific heat d(χT)/dT measurements. However, this phase transition was not detected by magnetic susceptibility measurements. The origin of this puzzling observation was resolved by evaluating the spin exchanges of K₂Mn₃O(OH)(VO₄)(V₂O₇), which revealed that each triangular trimer is a ferromagnetically coupled cluster, and the observed ordering involves an AFM ordering between the ferromagnetic (FM) clusters. This ordering is shrouded in magnetic susceptibility measurements due to the susceptibility contributions from the individual FM triangular trimers even below T_N. We showed that the magnetic susceptibility of K₂Mn₃O(OH)(VO₄)(V₂O₇) between ∼30 K and room temperature is satisfactorily described by an AFM chain made up of ferromagnetically coupled triangular clusters, as described by a few spin-exchange parameters.