Publisher's Note: Comment on “Conduction states in oxide perovskites: Three manifestations of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>Ti</mml:mi><mml:mrow><mml:mn>3</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:math>Jahn-Teller polarons in barium titanate” [Phys. Rev. B<b>70</b>, 157101 (2004)]

Prosandeev, S. A.; Raevski, I. P.; Bunin, M. A.

doi:10.1103/physrevb.70.199904

Cited by 4 publications

(4 citation statements)

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“…Both TONT films contain the slightly insufficient oxygen ͑Ti 3+ states͒ in the TiO 2 lattice structure, 38 probably causing a slight increase of film conductivity. 39 The structure of anodic TONT films with anatase phase ͑not shown here͒ is modified with depth into TONT, resulting from compositional variation and different annealing conditions. In particular, the interface region between the Ti substrate and the TONT film shows a preferential formation of rutile TiO 2 with compact and dense structure.…”

Section: Resultsmentioning

confidence: 99%

The Effectiveness of Sputtered PtCo Catalysts on TiO[sub 2] Nanotube Arrays for the Oxygen Reduction Reaction

Kang

Sung

2008

J. Electrochem. Soc.

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Pt and PtCo binary catalyst layers were prepared on self-ordered TinormalO2 nanotube (TONT) arrays with the length of 1μm and diameter of 120nm employing a dual-gun sputtering method. The sputtered Pt induced a slight increase of the wall thickness of TONT. With increasing Co content in the alloy catalyst layer, a slight reduction of pore diameter on the TONT was also found. Well-dispersed mixed nanophases of Pt and Co were observed along the inner wall of TONT, and crystalline properties from the crystalline plane of Pt, Co, and TinormalO2 were identified by selective area electron diffraction. Among several compositions of additional Co on Pt, 30at% Co catalyst on Pt showed the best oxygen reduction reaction (ORR) activity with the positive shift (200mV) of onset potential. This is attributed to Pt electronic modification by an alloying effect and the shortening of the Pt–Pt interatomic distance. However, the coverage from the physically deposited sputtering method is incomplete; thus, the uniformity of the catalyst layer could be improved along the inner wall of TONT. Moreover, the influence of the pore size for diffusion of oxygen molecules on the ORR was investigated by increasing the sputtering time for normalPt70normalCo30∕TONT . The normalPt70normalCo30∕TONT sample with the pore diameter of 70nm (sputtering time of 180s ) showed the maximum ORR activity (maximum upshift of half-wave potential), while above that, the ORR activity started to be degraded, resulting from restricted diffusion of oxygen molecules and the reduced surface area of catalyst layer. In order to examine the effect on large surface area of TONT and pore diameter, a compact TinormalO2 film prepared on a Ti substrate was compared for the normalPt70normalCo30 catalyst layer. This compact TinormalO2 support revealed significantly degraded ORR activity.

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Section: Resultsmentioning

confidence: 99%

The Effectiveness of Sputtered PtCo Catalysts on TiO[sub 2] Nanotube Arrays for the Oxygen Reduction Reaction

Kang

Sung

2008

J. Electrochem. Soc.

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“…Sintering trials of the L2 base material under reducing conditions (Ar-5%H 2 ) showed the optimum temperature to be 1700 K. Detailed studies were carried out at 1700 K for times of 8 h to 48 h. While samples of L2 sintered in air 44 were light grey in colour, the samples sintered in Ar-H 2 (this investigation) were black, indicating the presence of Ti 3+ or oxygen deficiency. 53 All sintered samples were of high density (in excess of 90% theoretical), with density increasing with sintering time ( Table 2).…”

Section: Microstructure and Phase Developmentmentioning

confidence: 97%

Tuning the thermoelectric properties of A-site deficient SrTiO₃ ceramics by vacancies and carrier concentration

Srivastava

Norman

Azough

et al. 2016

Phys. Chem. Chem. Phys.

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Ceramics based on SrLaTiNbO have been prepared by the mixed oxide route. The LaNbO component generates ∼13.4% A-site vacancies; this was fixed for all samples. Powders were sintered under air and reducing conditions at 1450 to 1700 K; products were of high density (>90% theoretical). Processing under reducing conditions led to the formation of a TiNbO second phase, core-shell structures and oxygen deficiency. X-ray diffraction (XRD) confirmed a simple cubic structure with space group Pm3[combining macron]m. Transmission electron microscopy revealed a high density of dislocations while analytical scanning transmission electron microscopy at atomic resolution demonstrated a uniform distribution of La, Nb and vacancies in the lattice. X-ray photoemission spectroscopy and thermogravimetry showed the oxygen deficiency (δ value) to be ∼0.08 in reduced samples with enhanced carrier concentrations ∼2 × 10 cm. Both carrier concentration and carrier mobility increased with sintering time, giving a maximum figure of merit (ZT) of 0.25. Selective additional doping by La or Nb, with no additional A site vacancies, led to the creation of additional carriers and reduced electrical resistivity. Together these led to enhanced ZT values of 0.345 at 1000 K. The contributions from oxygen vacancies and charge carriers have been investigated independently.

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“…The large charge difference between Zn 2+ and Nb 5+ is expected to lead to a strong ordering tendency on the B site. This is the case in the relaxor systems Pb(Zn,Nb)O 3 , Pb(Mg,Nb)O 3 , and Pb(Sc,Nb)O 3 . − Theory has demonstrated that this is a direct consequence of the electrostatic interactions between the A - and B -site ions. , Note, there is a considerable size difference between the radius of Zn ( r Zn = 0.74 Å) and Nb/Ti ( r Nb = 0.64 Å, r Ti = 0.605 Å) which also contributes to ordering. Hence, B -cations were arranged such that the Zn and Nb/Ti were on separate rocksalt-ordered sublattices placing excess cations on the deficient site.…”

Section: Methodsmentioning

confidence: 98%

La-Driven Morphotrophic Phase Boundary in the Bi(Zn_1/2Ti_1/2)O₃–La(Zn_1/2Ti_1/2)O₃–PbTiO₃ Solid Solution

et al. 2012

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We explore the Bi(Zn1/2Ti1/2)O3–La(Zn1/2Ti1/2)O3–PbTiO3 pseudoternary phase diagram using density functional theory and a solid solution model. We find a region of stability against phase segregation that contains a morphotropic phase boundary. On the basis of the results, we identify a ferroelectrically active composition-dependent region that is likely to show strong electro-mechanical response. Furthermore, we find that La replacement for Bi not only lowers the polarization as might be expected, but also shifts the balance from tetragonality toward rhombohedral distortions. This may be of general use in modifying phase diagrams of A-site driven perovskite ferroelectric solid solutions to generate new morphotropic phase boundary systems.

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Publisher's Note: Comment on “Conduction states in oxide perovskites: Three manifestations ofTi3+Jahn-Teller polarons in barium titanate” [Phys. Rev. B70, 157101 (2004)]

Cited by 4 publications

References 0 publications

The Effectiveness of Sputtered PtCo Catalysts on TiO[sub 2] Nanotube Arrays for the Oxygen Reduction Reaction

The Effectiveness of Sputtered PtCo Catalysts on TiO[sub 2] Nanotube Arrays for the Oxygen Reduction Reaction

Tuning the thermoelectric properties of A-site deficient SrTiO₃ ceramics by vacancies and carrier concentration

La-Driven Morphotrophic Phase Boundary in the Bi(Zn_1/2Ti_1/2)O₃–La(Zn_1/2Ti_1/2)O₃–PbTiO₃ Solid Solution

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Publisher's Note: Comment on “Conduction states in oxide perovskites: Three manifestations ofTi3+Jahn-Teller polarons in barium titanate” [Phys. Rev. B70, 157101 (2004)]

Cited by 4 publications

References 0 publications

The Effectiveness of Sputtered PtCo Catalysts on TiO[sub 2] Nanotube Arrays for the Oxygen Reduction Reaction

The Effectiveness of Sputtered PtCo Catalysts on TiO[sub 2] Nanotube Arrays for the Oxygen Reduction Reaction

Tuning the thermoelectric properties of A-site deficient SrTiO3 ceramics by vacancies and carrier concentration

La-Driven Morphotrophic Phase Boundary in the Bi(Zn1/2Ti1/2)O3–La(Zn1/2Ti1/2)O3–PbTiO3 Solid Solution

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Tuning the thermoelectric properties of A-site deficient SrTiO₃ ceramics by vacancies and carrier concentration

La-Driven Morphotrophic Phase Boundary in the Bi(Zn_1/2Ti_1/2)O₃–La(Zn_1/2Ti_1/2)O₃–PbTiO₃ Solid Solution