| 1. |
- Ganegoda, Hasitha, et al.
(författare)
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Role of Fe Doping on Local Structure and Electrical and Magnetic Properties of PbTiO3
- 2021
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 125:22, s. 12342-12354
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Tidskriftsartikel (refereegranskat)abstract
- The local structure and multiferroic properties of iron-doped lead titanate (PbTi1-xFexO3-delta) samples was investigated over the entire composition range (x = 0-1). Inherent polarization in PbTiO3 decreases due to Fe3+ incorporation up to the solubility limit (x similar to 0.3), although homogeneous doping persists only up to x = 0.1. Ti prefers highly distorted oxygen octahedra for any x value, while Fe prefers more symmetric O-deficient polyhedra (Fe-O-n). The charge compensating oxygen vacancies induce local tilting of the Fe-O-n polyhedra beyond a critical x value (x >= 0.2), promoting magnetic interaction between two adjacent Fe atoms. The strain induced by local heterogeneity could act as a coupling force between magnetic and ferroelectric properties. Fe-rich clusters evolve into ferromagnetic PbFe12O19 with increased Fe doping. PbTi1-xFexO3-delta ( x >= 0.3) samples therefore have separate origins for the ferroelectric (PbTi1-xFexO3-delta) and magnetic (PbFe12O19) phases.
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| 2. |
- Mukherjee, Soham, et al.
(författare)
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Structure and Electronic Effects from Mn and Nb Co-doping for Low Band Gap BaTiO3 Ferroelectrics
- 2021
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 125:27, s. 14910-14923
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the doping-induced local structural and electronic effects in the recently developed low band gap room temperature ferroelectric Mn-Nb co-doped BaTiO3. Experimental and theoretical Raman spectroscopies are utilized to quantify the Ti off-centering, identified to be the intrinsic origin of ferroelectricity in these systems. Mn and Nb exhibit contrasting doping behaviors that have remarkable effects on BaTiO3 functionality. Jahn-Teller distorted Mn3+ is primarily associated with lowering of the bulk band gap, while charge-compensating Nb5+ off-centers within the O-6 octahedra, creating a polar mode that stabilizes the ferroelectric ground state. The charge neutral aliovalent Mn3+-Nb5+ pair effectively couples to the inherent ferroelectric instability of the BaTiO3 lattice, restoring some spontaneous polarization lost by doping Mn3+ (d(4)) ions at Ti4+ (d(0)) sites.
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| 3. |
- Phuyal, Dibya, 1985-, et al.
(författare)
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Nonlocal Interactions in the Double Perovskite Sr2FeMoO6 from Core-Level X‐ray Spectroscopy
- 2021
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 125, s. 11249-11256
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Tidskriftsartikel (refereegranskat)abstract
- The valence electronic structure of the half-metallicdouble perovskite Sr2FeMoO6 forms from a strongly hybridizedband in the spin-down channel of Fe 3d and Mo 4d states thatprovides metallic conductivity and a gapped spin-up channel. Theground-state description has previously been explored in terms ofmany-body interactions where local and nonlocal interactionsproduce states with a combination of a charge-transferconfiguration and intersite charge fluctuations. Here, we providea qualitative understanding on nonlocal effects in Sr2FeMoO6using a combination of core-level X-ray spectroscopies, specificallyX-ray absorption, emission, and photoelectron spectroscopies. Ourspectroscopic data indicate intersite Fe 4p−O 2p−Mo 4dinteractions to be the origin of these nonlocalized transitions.Close to the Fermi level, this interaction is dominated by Mo 4d−O 2p character. When our data are compared against first- principles electronic structure calculations, we conclude that a full understanding of the nature of these states requires a spin-resolved description of the hybridization functions and that the nonlocal screening occurs predominantly through hybridization in the minority spin channel of the Mo 4d bands.
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