New Mixed-Valent Iron (II/III) Phosphates, Cu3−xFe4+x(PO4)6

Spectroscopic and magnetic properties of Fe3IIFe4III(AsO4)6

“…Besides, the (a) population is about half that of (b), which would be the case if all the (a) probes are sited at the special Fe(3) site. Considering these results and the findings of Belik et al [3,4], we assign the hyperfine site (a) to Fe(III) ions located only at site Fe(3). The very narrow value of the line width (G ¼ 0:24 mm=s, close to the 0.23 mm/s yielded by the a-Fe calibration foil) is also an indication that all the probes belonging to this site are located at the same structural site and, therefore, sensing the same hyperfine fields.…”

“…Using this criterion and other experimental evidences, Belik et al [3,4] determined that in Fe 7 (PO 4 ) 6 and in a series of mixed cation M(II)/Fe(III) phosphates isotypic to Fe 7 (AsO 4 ) 6 , the Fe(II) cations are always located at the pentacoordinated crystallographic Fe(2) site, while Fe(III) always occupies the hexacoordinated Fe(3) site, employing Weil's nomenclature [7]. Often, the combined analysis of the magnitudes of the isomer shift and the quadrupole splitting helps in the determination of the Fe occupation of any site.…”

“…Since the preparation and determination of the crystal structure of Fe 7 (PO 4 ) 6 [1], a multitude of isotypic compounds of general formula M 3 II M 4 III (XO 4 ) 6 (where M ¼ first-row transition metal, and X ¼ P, V) has been prepared and characterized [2][3][4][5][6]. Some molybdates of the type M 2 I M 5 II (MoO 4 ) 6 and others with different mono-and divalent cationic ratios are also known to adopt the same structure [3,5,6].…”

Study of one-dimensional nature ofS=1∕2(Sr,Ba)2Nath1, Mahajan2, Büttgen3 et al. 2005Phys. Rev. B7018581View full textAdd to dashboardCite

“…A Cu target was used in the diffractometer with av = 1.541 82 Å. Lattice parameters were calculated using a least-squares fit procedure. [17][18][19] Magnetization ͑M͒ data were measured as a function of temperature T ͑1.8 K ഛ T ഛ 400 K͒ and applied field H ͑0 ഛ H ഛ 50 kG͒ using a superconducting quantum interference device ͑SQUID͒ magnetometer.…”

The Adaptable Lyonsite Structure

“…As suggested above, the Fe 7 A C H T U N G T R E N N U N G (PO 4 ) 6 structure type represents another large class of materials, [45] and could itself be the focus of new solid-state chemistry. For a short explanation of how various elemental compositions and structures are related within the Fe 7 A C H T U N G T R E N N U N G (PO 4 ) 6 structure type, the reader is referred to reference [41].…”