Structural study and physical properties of a new phosphate KCuFe(PO 4) 2

• Published in: Journal of solid state chemistry 2011-04, Vol.184 (4), p.937-944
• Main Authors: Badri, Abdessalem, Hidouri, Mourad, López, María Luisa, Pico, Carlos, Wattiaux, Alain, Amara, Mongi Ben
• Format: Article
• Language: English
• Subjects: Chemical Sciences; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Electrical measurements; Exact sciences and technology; Growth from melts; zone melting and refining; Magnetic susceptibility; Material chemistry; Materials science; Methods of crystal growth; physics of crystal growth; Mössbauer spectroscopy; Phosphate; Physics; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; X-ray diffraction
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2011.02.021

Single crystals of a new phosphate KCuFe(PO 4) 2 have been prepared by the flux method and its structural and physical properties have been investigated. This compound crystallizes in the monoclinic system with the space group P2 1/ n and its parameters are: a=7.958(3) Å, b=9.931(2) Å, c=9.039(2) Å, β=115.59(3)° and Z=4. Its structure consists of FeO 6 octahedra sharing corners with Cu 2O 8 units of edge-sharing CuO 5 polyhedra to form undulating chains extending infinitely along the b-axis. These chains are connected by the phosphate tetrahedra giving rise to a 3D framework with six-sided tunnels parallel to the [101] direction, where the K + ions are located. The Mössbauer spectroscopy results confirm the exclusive presence of octahedral Fe 3+ ions. The magnetic measurements show the compound to be antiferromagnetic with C m =5.71 emu K/mol and θ=−156.5 K. The derived experimental effective moment μ ex =6.76 μ B is somewhat higher than the theoretical one of μ th =6.16 μ B, calculated taking only into account the spin contribution for Fe 3+ and Cu 2+ cations. Electrical measurements allow us to obtain the activation energy (1.22 eV) and the conductivity measurements suggest that the charge carriers through the structure are the potassium cations. A projection along the [101] direction of the structure showing the six-edged tunnels, occupied by the K + ions. [Display omitted] ► The reported structure is of a new type. ► The structural model is supported by a Mössbauer spectroscopy study. ► The magnetic susceptibility results are reported. ► The electrical properties are discussed.