Selected perovskite oxides: Characterization, preparation and photocatalytic properties—A review

Grabowska, Ewelina

doi:10.1016/j.apcatb.2015.12.035

Cited by 547 publications

(256 citation statements)

References 249 publications

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“…These oxides include TiO2 [5], ZnO [6], ZnS [7], SnO2 [8], molybdates [9][10][11], and tungstates [12,13]. Among the numerous types of perovskite materials (ABO3), alkaline earth metal perovskite oxides are a veritable gold mine of diverse physical and chemical properties with large technological applications [14][15][16][17][18][19][20][21] based on ferroelectricity, piezoelectricity, non-linear optical behavior, and PL emissions, that that arise from the absence of inversion symmetry in a crystal structure [22]. ABO3 perovskite compounds have a large cation at the A-site, a smaller cation at the B-site, and the oxygen O acts as a bridging ligand, linking the Bsite cations to form a three-dimensional cage-like host framework consisting of anionic [BO3] − cages enclosed by 12 B-O-B fragments and filled by A-site guest cations.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of photoluminescence in intrinsically disordered CaZrO3 crystals: First principles modeling of the excited electronic states

Oliveira

Gracia

Assis

et al. 2017

Journal of Alloys and Compounds

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CaZrO3 (CZO) powders were synthesized at different temperatures (400, 600, 800, and 1000 °C) and characterized by X-ray diffraction, Raman and ultraviolet-visible spectroscopic methods, along with photoluminescence (PL) emissions. First principle calculations based on the density functional theory (DFT), using a periodic cell models, provide a theoretical framework for understanding the PL spectra based on the localization and characterization of the ground and electronic excited states.Fundamental (singlet, s) and excited (singlet, s*, and triplet, t*) electronic states were localized and characterized using the ideal and distorted structures of CZO. Their corresponding geometries, electronic structures, and vibrational frequencies were obtained. A relationship between the different morphologies and structural behavior has also been established. Polarized structures were identified by the redistribution of the 4dz2, 4dyz, and 4dxy (Zr) orbitals at the conduction band and the 2pz (O) orbital in the valence band for s, s* and t*. Analysis of the vibrational eigenvector modes of these electronic states reveals a relationship between them via asymmetric bending and stretching modes that arise from Zr atom displacements due to polyhedral [ZrO6] distortion. Furthermore, the results provided an insight into the PL emissions of the as-synthesized CaZrO3 and led to the conclusion that the presence of electronically excited states is strongly related to the structural order-disorder effects (polyhedral distortion) at short range for both [ZrO6] and [CaO8] clusters.

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Section: Introductionmentioning

confidence: 99%

Mechanism of photoluminescence in intrinsically disordered CaZrO3 crystals: First principles modeling of the excited electronic states

Oliveira

Gracia

Assis

et al. 2017

Journal of Alloys and Compounds

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Perovskites are materials with stoichiometry ABX 3 that crystallize in the well-known structure named for crystallographer Lev Perovski. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Perovskites are materials with stoichiometry ABX 3 that crystallize in the well-known structure named for crystallographer Lev Perovski.…”

Section: Introductionmentioning

confidence: 99%

Mix and Match: Organic and Inorganic Ions in the Perovskite Lattice

Gebhardt

Rappe

2018

Advanced Materials

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X-site anions are possible, with only two general requirements that must be fulfilled: i) charge neutrality in the ABX 3 unit (typically, X is a divalent or monovalent anion, hence A and B cations with oxidation states between +1 and +5 can be combined) and ii) the ionic radii of the chosen composition must allow the above coordination, or different phases become more stable. Both of these simple design rules have a certain flexibility.The electronic argument i) can be stretched by allowing the combination of multiple ABX 3 units to form an overall charge neutral unit. For example, this is the case when considering A 2 BB′X 6 or AA′B 2 X 6 systems. Such double perovskite systems are known with B and B′ (A and A′) being the same elemental species (disproportion in oxidation state, e.g., Cs 2 Au + Au 3+ I 6 ) [20] or different ones (e.g., SrBaTi 2 O 6 [21] and SrPbTi 2 O 6 [22] for A-site disproportion or K 2 NbTaO 6 [23] and Bi 2 FeCrO 6 [24] for the B-site). Of course, this concept can also be used to combine three ABX 3 units (e.g., (CaTiO 3 ) n (SrTiO 3 ) l (BaTiO 3 ) m [25-27]) and much more complex stoichiometries with mixed ratios (e.g., (Pb 2 InNbO 6 ) 3/4 (Ba 2 InBiO 6 ) 1/4 [28] or [CaMn 3 3+ ][Mn 3 3+ Mn 4+ ] O 12 ] [29] ). Furthermore, although the bonding character in oxide perovskites is often mainly ionic, some compositions have an increased level of covalency (e.g., halides, sulfides, Bi-and Pbbased oxide perovskites). Thus, the electronic shell configuration and other effects like the steric demands of a metal lonepair will influence the structure and stability of ABX 3 perovskite compounds.In addition, the geometric argument ii) allows for some flexibility. For a perfectly cubic perovskite, the (effective) ionic radii r must fulfill the relation of Goldschmidt's tolerance factor 2( ) 1 A X B X t r r r r = + + = . [30,31] However, perovskites can exist also with t being not ideal, usually in a range of about 0.75 < t < 1.05. [8] Whenever t ≠ 1, the crystal distorts from an ideal cubic lattice, usually in form of off-center displacements, octahedral rotations, or a combination of both. The classification of Glazer [32,33] can be used to describe such distortions from a perfectly cubic perovskite. [34] It is further possible that ABX 3 compounds are stable whose t does not fall into the interval that is required for the perovskite crystal structure. In these cases that are no longer stabilized by deformations and tilting, one observes other phases where the connectivity of BX 6Materials science evolves to a state where the composition and structure of a crystal can be controlled almost at will. Given that a composition meets basic requirements of stoichiometry, steric demands, and charge neutrality, researchers are now able to investigate a wide range of compounds theoretically and, under various experimental conditions, select the constituting fragments of a crystal. One intriguing playground for such materials design is the perovskite structure. While a game of mixing and matching ions has been pla...

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“…Green catalytic chemistry and resource efficiency are at the heart of a minimum waste circular economy. 39 It has long been thought that ABO 3 perovskites 40 had an advantage in a circular economy over precious metals, provided that their surface areas could be raised above a very modest 1. They showed a similar light-off temperature (LOT) for CO oxidation (870 K) to commercial platinum-group metal three-way catalysts (TWCs) (812 K) in a stoichiometric gas stream.…”

Section: Introductionmentioning

confidence: 99%

Nanoengineering ABO₃active sites from low-energy routes (TX100-stabilised water-in-oil microemulsions, surface segregation and surface complexation on colloidal AlOOH/sol–gel Al₂O₃surfaces) for pollution control catalysis

et al. 2018

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It is shown that water-in-oil microemulsions (m/e or mE) can produce BaCeO 3 (BCO) and LaCoO 3 (LCO) precursors. The nanoparticles (NPs) adsorb on AlOOH sols, in much the same way as Turkevich previously immobilised platinum group metal sols. BCO is active in CO and propane oxidation and NO removal under stoichiometric exhaust conditions, but LCO is a better oxidation catalyst. Activity was also seen when Ba,Ce and La,Co are inserted into/segregate at the surface of AlOOH/Al 2 O 3 . However, there is only formation of low levels of BCO, CAIO 3 (CAO), LCO and LaAIO 3 (LAO) perovskites, along with aluminates and separate oxides. The complexing of cations by AlOOH surface-held oxalate ions, albeit with different efficiencies, has also been explored. All three routes yield active catalysts with micro-domains of crystallinity; microemulsions produce the best defined perovskite NPs, but even those from surface segregation have higher turnover numbers than traditional Pt catalysts. Perovskite NPs may open up green chemistry for air pollution control that is consistent with a circular economy.

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Selected perovskite oxides: Characterization, preparation and photocatalytic properties—A review

Cited by 547 publications

References 249 publications

Mechanism of photoluminescence in intrinsically disordered CaZrO3 crystals: First principles modeling of the excited electronic states

Mechanism of photoluminescence in intrinsically disordered CaZrO3 crystals: First principles modeling of the excited electronic states

Mix and Match: Organic and Inorganic Ions in the Perovskite Lattice

Nanoengineering ABO₃active sites from low-energy routes (TX100-stabilised water-in-oil microemulsions, surface segregation and surface complexation on colloidal AlOOH/sol–gel Al₂O₃surfaces) for pollution control catalysis

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Selected perovskite oxides: Characterization, preparation and photocatalytic properties—A review

Cited by 547 publications

References 249 publications

Mechanism of photoluminescence in intrinsically disordered CaZrO3 crystals: First principles modeling of the excited electronic states

Mechanism of photoluminescence in intrinsically disordered CaZrO3 crystals: First principles modeling of the excited electronic states

Mix and Match: Organic and Inorganic Ions in the Perovskite Lattice

Nanoengineering ABO3active sites from low-energy routes (TX100-stabilised water-in-oil microemulsions, surface segregation and surface complexation on colloidal AlOOH/sol–gel Al2O3surfaces) for pollution control catalysis

Contact Info

Product

Resources

About

Nanoengineering ABO₃active sites from low-energy routes (TX100-stabilised water-in-oil microemulsions, surface segregation and surface complexation on colloidal AlOOH/sol–gel Al₂O₃surfaces) for pollution control catalysis