The first layer potassium–bismuth-nickel oxophosphate KBi{sub 4}Ni{sub 2}(PO{sub 4}){sub 3}O{sub 4}: Synthesis, crystal structure, and expected magnetic properties

• Published in: Crystallography reports 2017-05, Vol.62 (3)
• Main Authors: Yamnova, N. A., Aksenov, S. M., Mironov, V. S., Volkov, A. S., Borovikova, E. Yu, Gurbanova, O. A., Dimitrova, O. V., Deyneko, D. V.
• Format: Article
• Language: English
• Subjects: ANTIFERROMAGNETISM; APPROXIMATIONS; ATOMIC DISPLACEMENTS; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; EXCHANGE INTERACTIONS; HYDROTHERMAL SYNTHESIS; INFRARED SPECTRA; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; LAYERS; MAGNETIC PROPERTIES; NICKEL; NICKEL CARBONATES; NICKEL IONS; ORTHORHOMBIC LATTICES; PARAMAGNETISM; POTASSIUM; POTASSIUM CARBONATES; POTASSIUM PHOSPHATES; RAMAN SPECTROSCOPY; SPACE GROUPS; SPIN; X-RAY DIFFRACTION
• ISSN: 1063-7745; 1562-689X
• DOI: 10.1134/S1063774517030245

The new potassium–bismuth–nickel oxophosphate obtained by hydrothermal synthesis in the Bi(OH){sub 3}–NiCO{sub 3}–K{sub 2}CO{sub 3}–K{sub 3}PO{sub 4} system is studied by X-ray diffraction, IR spectroscopy, and Raman spectroscopy. Parameters of the orthorhombic cell are as follows: a = 13.632(1) Å, b = 19.610(2) Å, and c = 5.4377(3) Å; V = 1452.64(2) Å{sup 3}; and space group Pnma. The structure is solved and refined to the final discrepancy factor R{sub 1} = 5.76% in the anisotropic approximation of atomic displacements using 3606 reflections with I > 2σ(I). The crystal-chemical formula (Z = 4) is KBi{sub 4}{Ni_2O_4(PO_4)_3}, where the composition of the layer nickel–phosphate polyanion is enclosed in braces. Theoretical calculations show that all exchange spin interactions between Ni{sup 2+} ions are antiferromagnetic and very weak (J < 0.1 cm{sup –1}) because of the polyatomic character of bridging Ni–O–P–O–Ni and Ni–O–Bi–O–Ni groups. Thus, this compound is expected to be paramagnetic with very weak antiferromagnetic exchange interactions and appreciable energy of zero-field splitting of the spin levels of Ni{sup 2+} ions.