(NH{sub 4})[V{sub 1-x}{sup III}V{sub x}{sup IV}(AsO{sub 4})F{sub 1-x}O{sub x}]: A new mixed valence vanadium(III,IV) fluoro-arsenate with ferromagnetic interactions and electronic conductivity

Journal Article · Thu Jan 15 04:00:00 EST 2009 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2008.10.002· OSTI ID:21212157

Berrocal, Teresa ^[1]; Pizarro, Jose L; Bazan, Begona ^[1]; Ruiz de Larramendi, Idoia ^[2]; Arriortua, Maria I ^[1]; Rojo, Teofilo ^[2]

---

1. Departamento de Mineralogia y Petrologia, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco/EHU, Apdo. 644, E-48080 Bilbao (Spain)
2. Departamento de Quimica Inorganica, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco/EHU, Apdo. 644, E-48080 Bilbao (Spain)

A new mixed valence vanadium(III,IV) fluoro-arsenate compound, with formula (NH{sub 4})[V{sub 1-x}{sup III}V{sub x}{sup IV}(AsO{sub 4})F{sub 1-x}O{sub x}] and KTP structure-type, has been synthesized by mild hydrothermal techniques. The crystal structure has been solved from single crystal X-ray diffraction data in the Pna2{sub 1} orthorhombic space group. The unit-cell parameters are a=13.196(2) A, b=6.628(1) A and c=10.7379(7) A with Z=8. The final R factors were R1=0.0438 and wR2=0.0943 [all data]. The crystal structure consists of a three-dimensional framework formed by (V{sup III,IV}O{sub 4}F{sub 2}) octahedra and (AsO{sub 4}){sup 3-} tetrahedra arsenate oxoanions. The vanadium(III,IV) cations, from the (V{sup III,IV}O{sub 4}F{sub 2}) octahedra, are linked through the fluorine atoms giving rise to zigzag chains. The ammonium cations are located in the cavities of the structure compensating the anionic charge of the [V{sub 1-x}{sup III}V{sub x}{sup IV}(AsO{sub 4})F{sub 1-x}O{sub x}]{sup -} inorganic skeleton. The thermal stability limit of the phase is 345 deg. C, around to this temperature the ammonium cation and fluoride anion are lost. The IR spectrum shows the characteristic bands of the (NH{sub 4}){sup +} and (AsO{sub 4}){sup 3-} ions. Magnetic measurements indicate the existence of weak ferromagnetic interactions. Electronic conductivity, via a hopping mechanism, occurs with an activation energy of 0.66 eV. - Graphical abstract: Polyhedral view of the crystal structure of (NH{sub 4})[V{sup III}{sub 1-x}V{sup IV}{sub x}(AsO{sub 4})F{sub 1-x}O{sub x}].

• OSTI ID: 21212157
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 1 Vol. 182; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ACTIVATION ENERGY
ARSENATES
ELECTRON SPIN RESONANCE
FERROMAGNETISM
FLUORIDES
HYDROTHERMAL SYNTHESIS
INFRARED SPECTRA
MILLI EV RANGE
MONOCRYSTALS
ORTHORHOMBIC LATTICES
R FACTORS
SPACE GROUPS
TEMPERATURE RANGE 0400-1000 K
VANADIUM COMPOUNDS
X-RAY DIFFRACTION