A Novel Mineral-like Copper Phosphate Chloride with a Disordered Guest Structure: Crystal Chemistry and Magnetic Properties

Galina Kiriukhina; Olga Yakubovich; Larisa Shvanskaya; Anatoly Volkov; Olga Dimitrova; Sergey Simonov; Olga Volkova; Alexander Vasiliev

doi:10.3390/ma15041411

A Novel Mineral-like Copper Phosphate Chloride with a Disordered Guest Structure: Crystal Chemistry and Magnetic Properties

Materials (Basel). 2022 Feb 14;15(4):1411. doi: 10.3390/ma15041411.

Authors

Galina Kiriukhina^{1

2}, Olga Yakubovich¹, Larisa Shvanskaya^{1

3}, Anatoly Volkov¹, Olga Dimitrova¹, Sergey Simonov⁴, Olga Volkova^{3

5

6}, Alexander Vasiliev^{3

5

6}

Affiliations

¹ Faculty of Geology, Lomonosov Moscow State University, 119991 Moscow, Russia.
² Institute of Experimental Mineralogy RAS, 142432 Chernogolovka, Russia.
³ Quantum Functional Materials Laboratory, National University of Science and Technology "MISiS", 119049 Moscow, Russia.
⁴ Institute of Solid State Physics RAS, 142432 Chernogolovka, Russia.
⁵ Faculty of Physics, Lomonosov Moscow State University, 119991 Moscow, Russia.
⁶ Institute of Physics and Technology, Ural Federal University, 620002 Ekaterinburg, Russia.

Abstract

Novel copper phosphate chloride has been obtained under middle-temperature hydrothermal conditions. Its crystal structure was established based on the low-temperature X-ray diffraction data: Na₂Li_0.75(Cs,K)_0.5[Cu₅(PO₄)₄Cl]·3.5(H₂O,OH), sp. gr. C2/m, a = 19.3951(8) Å, b = 9.7627(3) Å, c = 9.7383(4) Å, β = 99.329(4)°, T = 150 K, MoK_α (λ = 0.71073 Å), R = 0.049. The crystal structure includes tetrameric copper clusters as the main building blocks, which are built of four CuO₄Cl pyramids sharing apical Cl vertices. The clusters are combined through phosphate groups and additional copper-centered polyhedra to form two mostly ordered periodic layers. Between the layers and inside the framework channels, alkali ions, H₂O molecules, or OH groups are statistically distributed. Na₂Li_0.75(Cs,K)_0.5[Cu₅(PO₄)₄Cl]·3.5(H₂O,OH) is a synthetic modification of a sampleite-polymorph of the lavendulan mineral group and represents a new member in a mero-plesiotype series of copper phosphates and arsenates, for which the crystal structures contain two-periodic [Cu₄X(TO₄)₄]_∞ modules (T = As, P; X = Cl, O). Magnetically, this phase exhibits the phase transition at T_C = 6.5 K, below which it possesses a weak ferromagnetic moment.

Keywords: crystal chemistry; crystal structure; hydrothermal synthesis; low temperature; magnetic properties; phosphates.