Abstract
Neutron powder diffraction experiments at high temperature (300-1600 K) were performed at BENSC (Berlin, D), on synthetic Zn0.97Fe2.02O4, to investigate the cation partitioning of Zn and Fe over the tetrahedral and octahedral sites as a function of T. The data analysis combined Rietveld structure refinements with minimization techniques. The thermodynamic behavior of the thermally activated order-disorder transformation occurring in Zn-ferrite was interpreted by the O’Neill- Navrotsky model (α = 49.3 ± 0.4 and β = -31.6 ± 2.0 kJ/mol) and by the equilibrium Landau theory. We obtain λ2 = 2.813 ± 0.002/K, Tc = 1022 ± 37 K using a “pure” Landau approach, and h = -1.164 ± 0.002 kJ/mol, c = 9.868 ± 0.06 kJ/mol, Tc = -742 ± 10 K, if the configurational contribution to entropy is explicitly accounted. The results are in agreement with the earlier powder XRD work of O’Neill (1992) on quenched specimens, but extend the temperature over which measurements were obtained to 1600 K.
© 2015 by Walter de Gruyter Berlin/Boston
Artikel in diesem Heft
- Nucleation and growth kinetics of analcime from precursor Na-clinoptilolite
- Viscosities of granitic (sensu lato) melts: Influence of the anorthite component
- Geochemistry of pyroxene inclusions from the Warrumbungle Volcano, New South Wales, Australia
- Supersilicic clinopyroxene and silica exsolution in UHPM eclogite and pelitic gneiss from the Kokchetav massif, Kazakhstan
- Experimental study of intracrystalline Fe2+-Mg exchange in three augite crystals: Effect of composition on geothermometric calibration
- Transmission electron microscopy and differential thermal studies of lazurite polymorphs
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- Letter. Fivefold-coordinated aluminum in tectosilicate glasses observed by triple quantum MAS NMR
Artikel in diesem Heft
- Nucleation and growth kinetics of analcime from precursor Na-clinoptilolite
- Viscosities of granitic (sensu lato) melts: Influence of the anorthite component
- Geochemistry of pyroxene inclusions from the Warrumbungle Volcano, New South Wales, Australia
- Supersilicic clinopyroxene and silica exsolution in UHPM eclogite and pelitic gneiss from the Kokchetav massif, Kazakhstan
- Experimental study of intracrystalline Fe2+-Mg exchange in three augite crystals: Effect of composition on geothermometric calibration
- Transmission electron microscopy and differential thermal studies of lazurite polymorphs
- Re-equilibration of glass and CO2 inclusions in xenolith olivine: A TEM study
- Origin and structural character of haüyness in spinel dunite xenoliths from La Palma, Canary Islands
- Pyrrhotite varieties from the 9.1 km deep borehole of the KTB project
- Mineralogy and magnetic behavior of pyrrhotite from a 260 °C section at the KTB drilling site, Germany
- Surface defects and self-diffusion on pyrite {100}: An ultra-high vacuum scanning tunneling microscopy and theoretical modeling study
- Rare-earth elements in chlorapatite [Ca10(PO4)6Cl2]: Uptake, site preference, and degradation of monoclinic structure
- Thermal pressure in MgO and MgSiO3 perovskite at lower mantle conditions
- Electron energy-loss spectroscopy of silicate perovskite-magnesiowüstite high-pressure assemblages
- Magnesium coordination environments in glasses and minerals: New insight from high-field magnesium-25 MAS NMR
- In situ powder diffraction study of titanite (CaTiOSiO4) at high pressure and high temperature
- Surinamite: A high-temperature metamorphic beryllosilicate from Lewisian sapphirine-bearing kyanite-orthopyroxene-quartz-potassium feldspar gneiss at South Harris, N.W. Scotland
- Single-crystal X-ray diffraction study of FeGeO3 high-P clinopyroxene (C2/c) up to 8.2 GPa
- High-pressure Ca4Al6O13: An example of a calcium aluminate with three different types of coordination polyhedra for aluminum
- Cation distribution in synthetic zinc ferrite (Zn0.97Fe2.02O4) from in situ high-temperature neutron powder diffraction
- Infrared study of OH sites in tourmaline from the elbaite-schorl series
- Second occurrence of okayamalite, Ca2SiB2O7: chemical and TEM characterization
- Rietveld refinement of okayamalite, Ca2SiB2O7: Structural evidence for the B/Si ordered distribution
- Tumchaite Na2(Zr,Sn)Si4O11·2H2O—A new mineral from carbonatites of the Vuoriyarvi alkali-ultrabasic massif, Murmansk Region, Russia
- The crystal structure of thornasite, Na12Th3[Si8O19]4(H2O)18: A novel interrupted silicate framework
- Symesite, Pb10(SO4)O7Cl4(H2O), a new PbO-related sheet mineral: Description and crystal structure
- Na2Ca2(P2O7)F2, the first diphosphate of the cuspidine family
- Amphibole asbestos from Libby, Montana: Aspects of nomenclature
- Thermodynamics of multicomponent olivines and the solution properties of (Ni,Mg,Fe)2SiO4 and (Ca,Mg,Fe)2SiO4 olivines—Comment
- Thermodynamics of multicomponent olivines and the solution properties of (Ni,Mg,Fe)2SiO4 and (Ca,Mg,Fe)2SiO4 olivine—Reply
- Letter. Fivefold-coordinated aluminum in tectosilicate glasses observed by triple quantum MAS NMR