Rb2CaCu6(PO4)4O2, a novel oxophosphate with a shchurovskyite‐type topology: synthesis, structure, magnetic properties and crystal chemistry of rubidium copper phosphates. Issue 5 (25th September 2019)

• Record Type: Journal Article
• Authors: Aksenov, Sergey M.; Borovikova, Elena Yu.; Mironov, Vladimir S.; Yamnova, Natalia A.; Volkov, Anatoly S.; Ksenofontov, Dmitry A.; Gurbanova, Olga A.; Dimitrova, Olga V.; Deyneko, Dina V.; Zvereva, Elena A.; Maximova, Olga V.; Krivovichev, Sergey V.; Burns, Peter C.; Vasiliev, Alexander N.
• Is Part Of: Acta crystallographica. Volume 75:Issue 5(2019:Oct.)
• Page Start: 903
• Page End: 913
• Publication Date: 2019-09-25
• Subjects: hydrothermal synthesis -- copper oxophosphate -- shchurovskyite -- single‐crystal X‐ray diffraction -- IR spectroscopy -- structural complexity -- magnetic properties
• DOI: 10.1107/S2052520619008527
• Languages: English
• ISSNs: 2052-5206

Abstract

Abstract : A novel compound, Rb2 CaCu6 (PO4 )4 O2, was synthesized by a hydrothermal method and characterized as the shchurovskyite‐type structure, based upon a heteropolyhedral copper phosphate framework. Microscopic calculations are indicative of possible low‐dimensional magnetic behavior, as they confirm weak magnetic coupling between the copper‐based layers mediated by the Cu–Cu pairs. Abstract : Single crystals of Rb2 CaCu6 (PO4 )4 O2 were synthesized by a hydrothermal method in the multicomponent system CuCl2 –Ca(OH)2 –RbCl–B2 O3 –Rb3 PO4 . The synthesis was carried out in the temperature range from 690 to 700 K and at the general pressure of 480–500 atm [1 atm = 101.325 kPa] from the mixture in the molar ratio 2CuO:CaO:Rb2 O:B2 O3 :P2 O5 . The crystals studied by single‐crystal X‐ray analysis were found to be monoclinic, space group C 2, a = 16.8913 (4), b = 5.6406 (1), c = 8.3591 (3) Å, β = 93.919 (3)°, V = 794.57 (4) Å 3 . The crystal structure of Rb2 CaCu6 (PO4 )4 O2 is similar to that of shchurovskyite and dmisokolovite and is based upon a heteropolyhedral open framework formed by polar layers of copper polyhedra linked via isolated PO4 tetrahedra. The presence of well‐isolated 2D heteropolyhedral layers in the title compound suggests low‐dimensional magnetic behavior which is masked, however, by the fierce competition between multiple ferromagnetic and antiferromagnetic exchange interactions. At T C = 25 K, Rb2 CaCu6 (PO4 )4 O2 reaches a magnetically ordered state with large residual magnetization.