Immiscibility in the nickel ferrite–zinc ferrite spinel binary

Ziemniak, S.E.; Gaddipati, A.R.; Sander, P.; Rice, Stephen B.

doi:10.1016/j.jpcs.2007.03.025

Cited by 6 publications

(5 citation statements)

References 20 publications

(35 reference statements)

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“…In the inverse Fe 3 O 4 and NiFe 2 O 4 spinels the Fe 3+ ions on tetrahedral sites are anti-ferromagnetically arranged with respect to both the Ni 2+ /Fe 2+ and Fe 3+ ions on the octahedral sites, which agrees with experiments 67,72 and existing DFT studies. 32,36,73 Among the normal spinels, NiCr 2 O 4 and CrFe 2 O 4 exhibit antiferromagnetic alignment between the tetrahedral and octahedral sites, similar to the inverse spinels.…”

Section: Electronic and Magnetic Propertiessupporting

confidence: 89%

“…65 In most of these spinels the spins localized on the metal ions are ordered in an anti-ferromagnetic pattern. [66][67][68][69][70][71][72] Depending on the constituent metal ions, this gives rise to either antiferromagnetism with a zero net magnetic moment or ferrimagnetism with a finite total magnetic moment that arises from unbalanced spin up and down contributions. For each compound all major spin ordering possibilities were investigated, but the formation energy is only reported for the most stable magnetic structure.…”

Section: Electronic and Magnetic Propertiesmentioning

confidence: 99%

“…The calculated positive mixing energies are in fairly good agreement with the measured miscibility gap. 67 In the vicinity of the transition point between normal and inverse spinels one could expect a partially inverse spinel to be preferred, but the DFT calculations show that it is not and either the normal or the inverse spinel is the most stable compound (see Fig. 3).…”

Section: Thermodynamics Of Spinel Mixingmentioning

confidence: 99%

“…In order to analyze the NiFe 2 O 4 -ZnFe 2 O 4 miscibility gap further we calculated the free energy of mixing by adding the mixing entropy to the calculated mixing energies. We used a model that is similar to that derived by Ziemniak et al, 67 should emerge as a stable compound at low temperature according to the calculated mixing energies, at finite temperature entropy will instead favor compositions inside the NiFe 2 O 4 -NiFe 1 Cr 1 O 4 composition range. In order to analyze this behavior further we calculated the free energy of mixing by adding the mixing entropy to the calculated mixing energies.…”

Section: Thermodynamics Of Spinel Mixingmentioning

confidence: 99%

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Mixing and non-stoichiometry in Fe–Ni–Cr–Zn–O spinel compounds: density functional theory calculations

Andersson

Stanek

2013

Phys. Chem. Chem. Phys.

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Density functional theory (DFT) calculations have been performed on A(2+)B2(3+)O4(2-) (where A(2+) = Fe, Ni or Zn, and B(3+) = Fe or Cr) spinel oxides in order to determine some of their thermodynamic properties. Mixing energies were calculated for Fe3O4-NiFe2O4, Fe3O4-ZnFe2O4, Fe3O4-FeCr2O4, NiFe2O4-ZnFe2O4, NiFe2O4-NiCr2O4, FeCr2O4-NiCr2O4, FeCr2O4-ZnCr2O4 and ZnCr2O4-ZnFe2O4 pseudo-binaries based on special quasi random (SQS) structures to account for cationic disorder. The results generally agree with available experimental data and the rule that two normal or two inverse spinel compounds easily form solid solutions, while inverse-normal spinel mixtures exhibit positive deviation from solid solution behavior (i.e. immiscibility). Even though the NiFe2O4-NiCr2O4 and Fe3O4-FeCr2O4 systems obey this rule, they exhibit additional features with implications for the corresponding phase diagrams. In addition to mixing enthalpies, non-stoichiometry was also considered by calculating the energies of the relevant defect reactions resulting in A, B and O excess (or deficiency). The DFT calculations predict close to zero or slightly exothermic reactions for both A and B excess in a number of spinel compounds.

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Section: Electronic and Magnetic Propertiessupporting

confidence: 89%

Section: Electronic and Magnetic Propertiesmentioning

confidence: 99%

Section: Thermodynamics Of Spinel Mixingmentioning

confidence: 99%

Section: Thermodynamics Of Spinel Mixingmentioning

confidence: 99%

See 2 more Smart Citations

Mixing and non-stoichiometry in Fe–Ni–Cr–Zn–O spinel compounds: density functional theory calculations

Andersson

Stanek

2013

Phys. Chem. Chem. Phys.

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“…LiCl and KCl are used as a low-melting flux, the lowest temperature needed for near-complete reaction of NiO and Fe 2 O 3 into trevorite is 350°C, [88]. This flux was heated to several temperatures and held for up to 6 months to achieve reaction.…”

Section: Molten Salt Synthesismentioning

confidence: 99%

Incorporating technetium in minerals and other solids: A review

Luksic

Riley

Schweiger

et al. 2015

Journal of Nuclear Materials

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Technetium (Tc) can be incorporated into a number of different solids including spinel, sodalite, rutile, tin dioxide, pyrochlore, perovskite, goethite, layered double hydroxides, cements, and alloys. Synthetic routes are possible for each of these phases, ranging from high-temperature ceramic sintering to ball-milling of constituent oxides. However, in practice, Tc has only been incorporated into solid materials by a limited number of the possible syntheses. A review of the diverse ways in which Tc-immobilizing materials can be made shows the wide range of options available. Special consideration is given to hypothetical application to the Hanford Tank Waste and Vitrification Plant, such as adding a Tc-bearing mineral to waste glass melter feed. A full survey of solid Tc waste forms, the common synthesis routes to those waste forms, and their potential for application to vitrification processes are presented. The use of tin dioxide or ferrite spinel precursors to reduce Tc(VII) out of solution and into a durable form are shown to be of especially high potential.

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Comments on “Spectroscopic and thermographic study of Ni–Zn ferrites” by J.D. Baraliya and H.H. Joshi, J Therm Anal Calorim. 2015;119:85–90

Drebushchak

2015

J Therm Anal Calorim

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Immiscibility in the nickel ferrite–zinc ferrite spinel binary

Cited by 6 publications

References 20 publications

Mixing and non-stoichiometry in Fe–Ni–Cr–Zn–O spinel compounds: density functional theory calculations

Mixing and non-stoichiometry in Fe–Ni–Cr–Zn–O spinel compounds: density functional theory calculations

Incorporating technetium in minerals and other solids: A review

Comments on “Spectroscopic and thermographic study of Ni–Zn ferrites” by J.D. Baraliya and H.H. Joshi, J Therm Anal Calorim. 2015;119:85–90

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