scholarly journals Microstructure Characterization of Nanocrystalline Magnesium Ferrite Annealed at Elevated Temperatures by Rietveld Method

ISRN Ceramics ◽  
2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Swapan Kumar Pradhan ◽  
Sumanta Sain ◽  
Hema Dutta
Keyword(s):  
Spinel Structure ◽  
Elevated Temperatures ◽  
High Energy ◽  
Nanocrystalline Powder ◽  
Magnesium Ferrite ◽  
Continuous Change ◽  
Inverse Spinel ◽  
Inverse Spinel Structure ◽  
Spinel Lattice ◽  
Mixed Spinel

Nanocrystalline magnesium ferrite is synthesized at room temperature by high energy ball milling the MgO and α-Fe2O3 (1 : 1 mol fraction) powders. The Rietveld structure and microstructure refinements of X-ray powder diffraction data of 9 h milled sample reveal the presence of mixed and nearly inverse spinel nanocrystalline Mg-ferrite phases. Postannealing of nanocrystalline powder within 873–1473 K reveals continuous change in cation distribution among the tetrahedral and octahedral sites of mixed spinel lattice leading to nearly inverse spinel structure with increasing temperature. Mixed spinel structure finally transformed into inverse spinel structure after 1 h of annealing at 1073 K. The ferrite phase becomes completely stoichiometric by solid-state diffusion of unreacted (∼0.3 mol fraction) α-Fe2O3 into spinel lattice after 1 h of annealing at 1273 K. Interestingly, particle sizes of ferrite phases do not increase considerably up to 1073 K and increase suddenly after transformation of mixed spinel into nearly inverse spinel structure.

Some chlorides with the inverse spinel structure

1975 ◽  
Vol 31 (10) ◽  
pp. 2549-2550 ◽  
Author(s):  
C. J. J. van Loon ◽  
J. de Jong
Keyword(s):  
Spinel Structure ◽  
Inverse Spinel ◽  
Inverse Spinel Structure

The Effect of the Fe2+B/Fe3+B Ratio on Electric Conductivity and Corrosion Resistance of Anodes

2017 ◽  
Vol 896 ◽  
pp. 72-77
Author(s):  
Han Bing He ◽  
Yuan Wang ◽  
Pei Yu Huang ◽  
Xu Peng Niu
Keyword(s):  
Electrical Conductivity ◽  
Corrosion Resistance ◽  
Electric Conductivity ◽  
Spinel Structure ◽  
Experimental Results ◽  
Trivalent Iron ◽  
Iron Ion ◽  
Inverse Spinel ◽  
Inverse Spinel Structure

The effect of the Fe2+B/Fe3+B ratio (the ratio of divalent and trivalent iron ion in B position of the inverse spinel structure) in cermets on the electric conductivity and corrosion resistance of anodes was investigated. The experimental results showed that both the electrical conductivity and corrosion resistance are proportional to the Fe2+B/Fe3+B ratio on the surface of anodes because FeAl2O4 and NiAl2O4 are produced on the surface of the anode and Fe3+ in the NiFe2O4 is corroded preferentially during electrolysis.

Synthesis and Luminescence Properties of Non-Doped Long Persistent Phosphors : Mg2SnO4

2009 ◽  
Vol 421-422 ◽  
pp. 352-355 ◽  
Author(s):  
Akiko Torisaka ◽  
Hiroaki Kaneko ◽  
Kentaro Nomizu ◽  
Sho Abe ◽  
Tadashi Ishigaki ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Reaction ◽  
Spinel Structure ◽  
Single Phase ◽  
Broad Band ◽  
Photoluminescence Intensity ◽  
Inverse Spinel ◽  
Inverse Spinel Structure ◽  
Broad Band Emission ◽  
Band Emission

A white long persistence phosphor was synthesized in a single-phase of Mg2SnO4 which was synthesized by a solid-state reaction. This phosphor crystallized in an inverse spinel structure and showed a broad-band emission from 350nm to 700nm. The afterglow was observed upon the excitation by 254nm. A Li-doped Mg2SnO4 sample showed a higher photoluminescence intensity and a longer lifetime than the non-doped one.

Neutronenbeugungsmessungen an Li2CrCl4 / Neutron Diffraction Studies of Li2CrCl4

1989 ◽  
Vol 44 (10) ◽  
pp. 1203-1205 ◽  
Author(s):  
Peter Kuske ◽  
Jeremy Karl Cockcroft ◽  
Heinz Dieter Lutz
Keyword(s):  
Neutron Diffraction ◽  
Elevated Temperatures ◽  
Inverse Spinel ◽  
Lithium Ions ◽  
Teller Distortion ◽  
Inverse Spinel Structure ◽  
Jahn Teller ◽  
Jahn Teller Distortion ◽  
High Temperature Polymorph ◽  
Large Disorder

Neutron diffraction studies of Li2CrCl4 at 350 °C are presented. The cubic high-temperature polymorph of Li2CrCl4 (space group Fd3̅m, Z = 8, R = 3.26%) crystallizes in an inverse spinel structure (cF56) with large Frenkel disorder of the tetrahedrally coordinated lithium ions. The occupation of the interstitial octahedral 16c sites by lithium ions is 38%, that of the tetrahedral 8a lattice sites only 24%. This large disorder is obviously the reason of the high ionic conductivity of Li2CrCl4 at elevated temperatures. There are some indications of a dynamic Jahn-Teller distortion of the CrCl6 units.

Study of the Inorganic Ion Exchanger Li3Mn0.25Ti0.5O3

2012 ◽  
Vol 178-181 ◽  
pp. 471-474
Author(s):  
Jin He Jiang
Keyword(s):  
Ion Exchange ◽  
Spinel Structure ◽  
Exchange Capacity ◽  
Ion Exchanger ◽  
Inverse Spinel ◽  
Ion Exchange Capacity ◽  
Inorganic Ion Exchanger ◽  
Inverse Spinel Structure ◽  
Inorganic Ion ◽  
Crystallization Method

Inorganic ion exchanger (Li3Mn0.25Ti0.5O3) with an inverse spinel structure was synthesized by solid state reaction crystallization method. The results showed that the Li+ extraction/insertion be progressed mainly by an ion-exchange mechanism. The acid treated samples had an ion exchange capacity of 9.2mmol/g for Li+.

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