Theory of the Magnetic Properties of the Ilmenites<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>M</mml:mi><mml:mi mathvariant="normal">Ti</mml:mi><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>

Goodenough, John B; Stickler, J J

doi:10.1103/physrev.164.768

Cited by 55 publications

(37 citation statements)

References 16 publications

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“…[6,7,12,13] This is in contrast to other 3d ilmenites such as FeTiO3, CoTiO3, and NiTiO3, but the difference in behaviour is largely accounted for by a modification of the Goodenough-Kanamori rules [14] using an excitonsuperexchange mechanism. [15] But, over the last eight years MnTiO3 has once again been the subject of scientific scrutiny for its strong magnetoelectric properties. [16][17][18][19][20][21][22] Mufti et al [16] showed that the application of electric and magnetic fields along the c-axis results in a strong dielectric anomaly and pyroelectric current up until the spin flop transition.…”

Section: -Introductionmentioning

confidence: 99%

Incommensurate crystal supercell and polarization flop observed in the magnetoelectric ilmeniteMnTiO3

Silverstein¹,

Skoropata²,

Sarte³

et al. 2016

Phys. Rev. B

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MnTiO3 has been studied for many decades, but it was only in the last few years that its strong magnetoelectric behavior had been observed. Here, we use neutron scattering on two separately grown single crystals and two powder samples to show the presence of a supercell that breaks R-3 symmetry. We also present the temperature and field dependence of the dielectric constant and pyroelectric current, and show evidence of non-zero off-diagonal magnetoelectric tensor elements (forbidden by R-3 symmetry) followed by a polarization flop accompanying the spin flop transition at μ0HSF = 6.5 T. Mössbauer spectroscopy on MnTiO3 gently doped with 57 Fe was used to help shed light on the impact of the supercell on the observed behavior. Although the full supercell structure could not be solved at this time due to a lack of visible reflections, the full-scope of the results presented here suggest that the role of local spin-lattice coupling in the magnetoelectric properties of MnTiO3 is likely more important than previously thought.

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Section: -Introductionmentioning

confidence: 99%

Incommensurate crystal supercell and polarization flop observed in the magnetoelectric ilmeniteMnTiO3

Silverstein¹,

Skoropata²,

Sarte³

et al. 2016

Phys. Rev. B

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confidence: 99%

“…Since the electronic transfer occurs along Fe-O-Fe chains, a disruption of these chains by oxygen vacancies hinders the hopping of the electronic charge carriers. 25,[33][34][35] As a result, in reducing atmospheres the electronic conductivity is much smaller than in air. 2 The decreased electronic conductivity of LSF and other acceptor doped perovskite-type oxides in reducing atmosphere can be a problem for their use as electrode materials as it causes resistive losses from the outer current collector to the reaction site.…”

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confidence: 99%

Comparison of Electrochemical Properties of La_0.6Sr_0.4FeO_3-δThin Film Electrodes: Oxidizing vs. Reducing Conditions

Kogler

Nenning

Rupp

et al. 2015

J. Electrochem. Soc.

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Owing to its mixed ionic and electronic conductivity and high thermochemical stability, La 0.6 Sr 0.4 FeO 3-δ (LSF64) is an attractive electrode material in solid oxide fuel/electrolysis cells (SOFCs/SOECs). Well defined thin film microelectrodes are used to compare the electrochemical properties of LSF64 in oxidizing and reducing conditions. The high electronic sheet resistance in hydrogen can be overcome by the use of an additional metallic current collector. With the sheet resistance being compensated, the area specific electrode resistance is similar in humidified hydrogen and oxygen containing atmospheres. Analysis of the chemical capacitance and the electrode resistance for current collectors on top and beneath the LSF64 thin film allow mechanistic conclusions on active zones and bulk defect chemistry. Cyclic gas changes between reducing and oxidizing conditions, performed on macroscopic LSF64 thin film electrodes with top current collector, reveal a strong degradation of the surface kinetics in synthetic air with very fast recovery in reducing atmosphere. Additional in-situ high-temperature powder XRD on LSF64 demonstrates the formation of small amounts of iron oxides in humidified hydrogen at elevated temperatures. Solid oxide fuel cells (SOFCs) are in the process of gaining more and more commercial success as highly efficient power generation systems. They transform the chemically bound energy of a fuel to electrical energy. Solid oxide electrolysis cells (SOECs) are the counter parts of SOFCs as they use electrical energy, e.g. excess energy from the grid, to form fuel by electrolysis. Owing to their very high efficiencies, also SOECs are promising devices in future energy technologies. 1Currently Ni/YSZ cermet electrodes are the standard electrodes in SOF/ECs for reducing conditions, but they are known to suffer from several problems, like sulfur poisoning (in SOFC operation), sintering, redox cycle stability etc.2 To find an alternative to Ni/YSZ could therefore be favorable for both SOFCs and SOECs.Electrodes in SOE/FCs have to meet numerous requirements: thermochemical stability over a wide oxygen partial pressure range, high catalytic activity for oxygen exchange reactions, compatibility with adjacent cell components, sufficiently high electronic and ionic conductivity, etc. Perovskite-type oxides such as LaMnO 3 , LaCoO 3 and LaFeO 3 based materials are used in state-of-the-art SOF/EC electrodes in oxygen atmosphere. Often they are mixed ionic and electronic conductors (MIECs), which is advantageous in SOF/ECs as the whole electrode surface area may become active in the oxygen exchange reaction. Employing such MIECs also in reducing atmosphere could be highly attractive. However, Sr-doped LaMnO 3 and LaCoO 3 are only stable under comparatively high oxygen partial pressures and thus not suited for the use in hydrogen. Fe 4+ states can be interpreted as electron holes (h • ) and those determine the electronic conductivity at high oxygen partial pressure as they are the majority mobile charge carrie...

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“…1(a,b)). The electrostatic repulsion between Mn 2+ and Ti 4+ leads to them being alternately displaced above and below the hexagonal layers in the ab-plane 25,26 . The Mn-O octahedra undergo a slight trigonal distortion, and the Mn 2+ cations are in the high spin 3d 5 state as confirmed by electron energy loss spectroscopy (EELS) [25][26][27][28] .…”

Section: Structure and Properties Of Mntio3mentioning

confidence: 99%

“…They were paramagnetic at room temperature ( Fig. 1(e) inset) and belong to the non-magnetic, centrosymmetric point group 3 25,27,[29][30][31] . Magnetic susceptibility (Fig.…”

Section: Structure and Properties Of Mntio3mentioning

confidence: 99%

Electronic structure and magnetic symmetry in MnTiO3analyzed by second harmonic generation

et al. 2013

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Second harmonic generation (SHG) and linear absorbance spectra of MnTiO3 were measured and the 1.88, 2.41, 2.63, and 3.06 eV SHG features were identified as d-d optical transitions from 6 A1g to 4 T1g( 4 G), 4 T2g( 4 G), { 4 Eg, 4 A1g( 4 G)}, and 4 Eg( 4 D) respectively. These zero-phonon transitions were used to calculate the octahedral crystal field splitting energy (∆0) and the Racah parameters B and C. The SHG spectra showed significant distinctions between the antiferromagnetic and the paramagnetic or spin-flop phases. The polarization dependence of the SHG in the spin-flop phase provided optical evidence that the spins canted from the c-axis toward the a-axis. These distinctions between the three magnetic phases could be useful for mapping 180 • antiferromagnetic domains in MnTiO3.2

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Theory of the Magnetic Properties of the IlmenitesMTiO3

Cited by 55 publications

References 16 publications

Incommensurate crystal supercell and polarization flop observed in the magnetoelectric ilmeniteMnTiO3

Incommensurate crystal supercell and polarization flop observed in the magnetoelectric ilmeniteMnTiO3

Comparison of Electrochemical Properties of La_0.6Sr_0.4FeO_3-δThin Film Electrodes: Oxidizing vs. Reducing Conditions

Electronic structure and magnetic symmetry in MnTiO3analyzed by second harmonic generation

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Theory of the Magnetic Properties of the IlmenitesMTiO3

Cited by 55 publications

References 16 publications

Incommensurate crystal supercell and polarization flop observed in the magnetoelectric ilmeniteMnTiO3

Incommensurate crystal supercell and polarization flop observed in the magnetoelectric ilmeniteMnTiO3

Comparison of Electrochemical Properties of La0.6Sr0.4FeO3-δThin Film Electrodes: Oxidizing vs. Reducing Conditions

Electronic structure and magnetic symmetry in MnTiO3analyzed by second harmonic generation

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Comparison of Electrochemical Properties of La_0.6Sr_0.4FeO_3-δThin Film Electrodes: Oxidizing vs. Reducing Conditions