One Site, Two Cations, Three Environments: s2 and s0 Electronic Configurations Generate Pb-Free Relaxor Behavior in a Perovskite Oxide

New lead-free compositions of AMO3 perovskite type were synthesized in the BaTi 1-x( Nb 1/2 Sc 1/2)x O 3(0 ≤ x ≤ 1) system, with regards to the comparable electronic configurations of the various 6-coordinated cations. Special solid state reaction was used. The effect of the replacement of titanium by scandium and niobium in the B-site on structural and dielectric properties was investigated. For this, we have used X-ray diffraction and dielectric characterizations. Dielectric measurements performed on ceramics with 0 ≤ x ≤ 0.25 composition revealed that the small change in composition from BaTiO3 has a strong influence on the dielectric properties: fast decreasing of the ferroelectric transition temperature for low values of x and evolution from classical ferroelectric for 0 ≤ x ≤ 0.075 to relaxor behavior for 0.075 < x ≤ 0.25.

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Elastic and relaxor behavior in nanocrystalline La-modified PZT-films

Journal de Physique IV (Proceedings) ◽

10.1051/jp4:1998922 ◽

1998 ◽

Vol 08 (PR9) ◽

pp. Pr9-125-Pr9-128 ◽

Cited By ~ 2

Author(s):

M. Marx ◽

J. K. Krüger ◽

R. Birringer ◽

H. Schmitt ◽

R. Holtwick ◽

...

Keyword(s):

Relaxor Behavior ◽

Pzt Films

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Exsolved metal-boosted active perovskite oxide catalyst for stable water gas shift reaction

Journal of Catalysis ◽

10.1016/j.jcat.2021.05.029 ◽

2021 ◽

Author(s):

Rui Huang ◽

Chaesung Lim ◽

Myeong Gon Jang ◽

Ji Young Hwang ◽

Jeong Woo Han

Keyword(s):

Oxide Catalyst ◽

Perovskite Oxide ◽

Water Gas Shift ◽

Water Gas Shift Reaction ◽

Shift Reaction ◽

Water Gas

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Structural tuning of heterogeneous molecular catalysts for electrochemical energy conversion

Science Advances ◽

10.1126/sciadv.abf3989 ◽

2021 ◽

Vol 7 (13) ◽

pp. eabf3989

Author(s):

Jiong Wang ◽

Shuo Dou ◽

Xin Wang

Keyword(s):

Energy Conversion ◽

Model Systems ◽

Structural Variations ◽

Metal Centers ◽

Electrochemical Energy Conversion ◽

Electronic Configurations ◽

Coordination Spheres ◽

The Stability ◽

Molecular Catalysts ◽

Electrochemical Energy

Heterogeneous molecular catalysts based on transition metal complexes have received increasing attention for their potential application in electrochemical energy conversion. The structural tuning of first and second coordination spheres of complexes provides versatile strategies for optimizing the activities of heterogeneous molecular catalysts and appropriate model systems for investigating the mechanism of structural variations on the activity. In this review, we first discuss the variation of first spheres by tuning ligated atoms; afterward, the structural tuning of second spheres by appending adjacent metal centers, pendant groups, electron withdrawing/donating, and conjugating moieties on the ligands is elaborated. Overall, these structural tuning resulted in different impacts on the geometric and electronic configurations of complexes, and the improved activity is achieved through tuning the stability of chemisorbed reactants and the redox behaviors of immobilized complexes.

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Stabilization of Ferroelectric Phase in Highly Oriented Quinuclidinium Perrhenate (HQReO4) Thin Films

Materials ◽

10.3390/ma14092126 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2126

Author(s):

Junyoung Lee ◽

Woojun Seol ◽

Gopinathan Anoop ◽

Shibnath Samanta ◽

Sanjith Unithrattil ◽

...

Keyword(s):

Thin Films ◽

Solution Process ◽

Intermediate Temperature ◽

Perovskite Oxide ◽

Temperature Phase ◽

Polar Phase ◽

Practical Applications ◽

Temperature Range ◽

Potential Alternative ◽

Temperature Window

The low-temperature processability of molecular ferroelectric (FE) crystals makes them a potential alternative for perovskite oxide-based ferroelectric thin films. Quinuclidinium perrhenate (HQReO4) is one such molecular FE crystal that exhibits ferroelectricity when crystallized in an intermediate temperature phase (ITP). However, bulk HQReO4 crystals exhibit ferroelectricity only for a narrow temperature window (22 K), above and below which the polar phase transforms to a non-FE phase. The FE phase or ITP of HQReO4 should be stabilized in a much wider temperature range for practical applications. Here, to stabilize the FE phase (ITP) in a wider temperature range, highly oriented thin films of HQReO4 were prepared using a simple solution process. A slow evaporation method was adapted for drying the HQReO4 thin films to control the morphology and the temperature window. The temperature window of the intermediate temperature FE phase was successfully widened up to 35 K by merely varying the film drying temperature between 333 and 353 K. The strategy of stabilizing the FE phase in a wider temperature range can be adapted to other molecular FE materials to realize flexible electronic devices.

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Machine learning aided design of perovskite oxide materials for photocatalytic water splitting

Journal of Energy Chemistry ◽

10.1016/j.jechem.2021.01.035 ◽

2021 ◽

Vol 60 ◽

pp. 351-359

Author(s):

Qiuling Tao ◽

Tian Lu ◽

Ye Sheng ◽

Long Li ◽

Wencong Lu ◽

...

Keyword(s):

Machine Learning ◽

Water Splitting ◽

Perovskite Oxide ◽

Oxide Materials ◽

Photocatalytic Water Splitting ◽

Aided Design

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Single Phase Multi Color Emitting Ca 2 LuTaO 6 : Dy 3+ /Eu 3+ Double Perovskite Oxide Phosphors

Journal of the American Ceramic Society ◽

10.1111/jace.17889 ◽

2021 ◽

Author(s):

Noor Zamin Khan ◽

Sayed Ali Khan ◽

Muhammad Sohail ◽

M.A. Majeed Khan ◽

Jahangeer Ahmed ◽

...

Keyword(s):

Single Phase ◽

Double Perovskite ◽

Perovskite Oxide

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Characterization of Charge States in Conducting Organic Nanoparticles by X-ray Photoemission Spectroscopy

Materials ◽

10.3390/ma14082058 ◽

2021 ◽

Vol 14 (8) ◽

pp. 2058

Author(s):

Jordi Fraxedas ◽

Antje Vollmer ◽

Norbert Koch ◽

Dominique de Caro ◽

Kane Jacob ◽

...

Keyword(s):

Partial Oxidation ◽

Chemical Shifts ◽

Large Family ◽

Photoemission Spectroscopy ◽

Intrinsic Structure ◽

X Ray ◽

Level Lines ◽

Donor And Acceptor ◽

Electronic Configurations

The metallic and semiconducting character of a large family of organic materials based on the electron donor molecule tetrathiafulvalene (TTF) is rooted in the partial oxidation (charge transfer or mixed valency) of TTF derivatives leading to partially filled molecular orbital-based electronic bands. The intrinsic structure of such complexes, with segregated donor and acceptor molecular chains or planes, leads to anisotropic electronic properties (quasi one-dimensional or two-dimensional) and morphology (needle-like or platelet-like crystals). Recently, such materials have been synthesized as nanoparticles by intentionally frustrating the intrinsic anisotropic growth. X-ray photoemission spectroscopy (XPS) has emerged as a valuable technique to characterize the transfer of charge due to its ability to discriminate the different chemical environments or electronic configurations manifested by chemical shifts of core level lines in high-resolution spectra. Since the photoemission process is inherently fast (well below the femtosecond time scale), dynamic processes can be efficiently explored. We determine here the fingerprint of partial oxidation on the photoemission lines of nanoparticles of selected TTF-based conductors.

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