scholarly journals Overlooked cation-ordered brownmillerite in Ba2(In1-xGax)2O5

2014 ◽  
Vol 70 (a1) ◽  
pp. C51-C51
Author(s):  
Christophe Didier ◽  
John Claridge ◽  
Matthew Rosseinsky
Keyword(s):  
Crystal Structure ◽  
Photocatalytic Activity ◽  
Ionic Conductivity ◽  
Structural Disorder ◽  
Size Difference ◽  
X Ray ◽  
Oxygen Interstitial ◽  
Interstitial Defects ◽  
Combined Structure ◽  
Brownmillerite Structure

As Goodenough showed 20 years ago, [1] Ba2In2O5 undergoes a transition from brownmillerite to cubic perovskite at higher temperatures, where it becomes a good oxygen ionic conductor. Past studies on doping gallium onto the indium sites [2] showed that higher Ga contents decrease the temperature required for the disordering to occur, in accordance with a higher structural disorder on the B site. In this work, we have showed that past studies on Ba2(In1-xGax)2O5 have overlooked a special ordering for the Ba2InGaO5 composition. Combined structure refinements of neutron and X ray powder diffraction show that this material adopts a brownmilleite structure below 1200°C with a layered ordering of In and Ga. This is one of a few examples of such an ordering in the brownmillerite structure only due to size difference between the B cations. This ordering further stabilizes the brownmillerite crystal structure compared to other compositions at smaller Ga contents. As could be expected, such stronger ordering is detrimental to ionic conductivity. At 1300°C, the material disorders into a cubic perovskite structure, which was already observed in past studies. However this polymorph has an unreported red colour, which was unexpected for a material with no incompletely filled orbitals. Incorporation of oxygen interstitial defects, on the basis of conductivity versus variable oxygen experiments and spectroscopic measurements, could be at the origin of this colouration much like in TiO2. [3] Unfortunately photocatalytic activity for water splitting could not be tested due to the strong instability of this material towards water.

scholarly journals Influence of Cu(NO3)2 content used in thermal shock method on the photocatalytic activity of Cu-Modified ZnO nanoparticles

2021 ◽  
Vol 5 (3) ◽  
pp. first
Author(s):  
Thế Luân Nguyễn ◽  
Tiến Khoa Lê ◽  
Châu Ngọc Hoàng ◽  
Hữu Khánh Hưng Nguyễn ◽  
Thị Kiều Xuân Huỳnh
Keyword(s):  
Crystal Structure ◽  
Methylene Blue ◽  
Photocatalytic Activity ◽  
Thermal Shock ◽  
Photoelectron Spectroscopy ◽  
Copper Content ◽  
Uv Light ◽  
Copper Nitrate ◽  
X Ray ◽  
Doped Zno

The Cu doped ZnO photocatalysts were prepared on ZnO substrate modified with copper nitrate by thermal shock method with different ratio % molar Cu : Zn = 0.3, 0.5, 1.0, 2.0 and 5.0 in order to study the impacts of copper content on the photocatalytic activity of ZnO under both UV and Vis light irradiation. The crystal structure, morphology bulk and surface were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Their photocatalytic activities were studied via time-dependent degradation of methylene blue in aqueous solution. The results exhibit that crystal structure and morphology of Cu doped ZnO photocatalysts is not modified significally than ZnO original but surface charateristicschanged greatly. The photocatalyst was doped with copper content under 2% showed formation of Cu species. These samples perform photocatalytic activity higher than ZnO. The CuNZO-0.05-500 had the highest rate constants for methylene blue degradation (kUV = 6,901 h-1, kVIS = 0,224 h-1), which are about 2.2 times and 1.3 times higher than unmodified ZnO under UV light and Vis light, respectively. However, the CuNZO-5.0-500 which had the formation of CuO phase and unchangeable ZnO's surface has photocatalytic activity similar to pure ZnO.

Structure and ionic conductivity of the octahydrate of tetralithium salt of calix[4]arenesulfonic acid

2021 ◽  
Author(s):  
Anna Pisareva ◽  
Gennady V. Shilov ◽  
Alexander Karelin ◽  
Rostislav Pisarev ◽  
Nadezhghda Bukun ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Ionic Conductivity ◽  
Diffraction Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Arenesulfonic Acid ◽  
First Time

Octahydrate of tetralithium salt of calix[4]sarenesulfonic acid was isolated for the first time The crystal structure of salt was determined by X-ray diffraction analysis. Compound crystallized in triclinic syngony, P-1,...

scholarly journals Crystal structure, magneto-structural correlation, thermal and electrical studies of an imidazolium halometallate molten salt: (trimim)[FeCl4]

RSC Advances ◽  
2020 ◽  
Vol 10 (19) ◽  
pp. 11200-11209 ◽  
Author(s):  
Palmerina González-Izquierdo ◽  
Oscar Fabelo ◽  
Garikoitz Beobide ◽  
Israel Cano ◽  
Idoia Ruiz de Larramendi ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Ionic Conductivity ◽  
Low Temperature ◽  
Neutron Diffraction ◽  
Molten Salt ◽  
Magnetic Structure ◽  
Imidazolium Cation ◽  
X Ray ◽  
Electrical Studies ◽  
Structural Correlation

We present a novel halometallate molten salt based on imidazolium cation with two structural transitions from 100 to 400 K which has been studied by X-ray and neutron diffraction techniques. Furthermore, the magnetic structure at low temperature and the ionic conductivity is also described.

Structure and Ionic Conductivity of Ln2Zr2O7-Type Rare Earth Zirconates

2007 ◽  
Vol 336-338 ◽  
pp. 420-423 ◽  
Author(s):  
Rui Zhang ◽  
Qiang Xu ◽  
Wei Pan ◽  
Chun Lei Wan ◽  
Long Hao Qi ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Rare Earth ◽  
Solid State ◽  
Ionic Conductivity ◽  
Single Phase ◽  
Complex Impedance ◽  
Pyrochlore Structure ◽  
Fluorite Structure ◽  
X Ray Diffraction ◽  
X Ray

Three rare earth zirconates (Sm2Zr2O7, Gd2Zr2O7 and Er2Zr2O7) were prepared by solid state reaction. The crystal structure and ionic conductivity of these zirconates were characterized by X-ray diffraction (XRD) and complex impedance spectroscopy. The results show that Sm2Zr2O7 exhibits single-phase pyrochlore structure and Er2Zr2O7 exhibits single-phase fluorite structure, while Gd2Zr2O7 has pyrochlore and fluorite structure. Among three zirconates, the ionic conductivity of Sm2Zr2O7 is highest, while that of Er2Zr2O7 is lowest.

scholarly journals Carrier concentration dependence of structural disorder in thermoelectric Sn1−xTe

IUCrJ ◽  
2016 ◽  
Vol 3 (5) ◽  
pp. 377-388 ◽  
Author(s):  
Mattia Sist ◽  
Ellen Marie Jensen Hedegaard ◽  
Sebastian Christensen ◽  
Niels Bindzus ◽  
Karl Frederik Færch Fischer ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Rock Salt ◽  
Theoretical Calculations ◽  
Rhombohedral Phase ◽  
Structural Disorder ◽  
Entropy Method ◽  
Salt Crystal ◽  
X Ray ◽  
Two Samples

SnTe is a promising thermoelectric and topological insulator material. Here, the presumably simple rock salt crystal structure of SnTe is studied comprehensively by means of high-resolution synchrotron single-crystal and powder X-ray diffraction from 20 to 800 K. Two samples with different carrier concentrations (sampleA= high, sampleB= low) have remarkably different atomic displacement parameters, especially at low temperatures. Both samples contain significant numbers of cation vacancies (1–2%) and ordering of Sn vacancies possibly occurs on warming, as corroborated by the appearance of multiple phases and strain above 400 K. The possible presence of disorder and anharmonicity is investigated in view of the low thermal conductivity of SnTe. Refinement of anharmonic Gram–Charlier parameters reveals marginal anharmonicity for sampleA, whereas sampleBexhibits anharmonic effects even at low temperature. For both samples, no indications are found of a low-temperature rhombohedral phase. Maximum entropy method (MEM) calculations are carried out, including nuclear-weighted X-ray MEM calculations (NXMEM). The atomic electron densities are spherical for sampleA, whereas for sampleBthe Te electron density is elongated along the 〈100〉 direction, with the maximum being displaced from the lattice position at higher temperatures. Overall, the crystal structure of SnTe is found to be defective and sample-dependent, and therefore theoretical calculations of perfect rock salt structures are not expected to predict the properties of real materials.

Mineral derived lithium solid electrolyte

MRS Advances ◽  
2017 ◽  
Vol 3 (23) ◽  
pp. 1301-1307 ◽  
Author(s):  
Bo Wang
Keyword(s):  
Crystal Structure ◽  
Solid Solution ◽  
Ionic Conductivity ◽  
Solid Electrolyte ◽  
Room Temperature ◽  
Low Cost ◽  
Nasicon Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Order Of Magnitude

ABSTRACTLithium solid electrolyte with NASICON structure in the form of Li1+2xAlxTi2−xSixP3−xO12 solid solution has been prepared by high temperature solid state reaction using low cost kaolin as the starting material. The crystal structure of the solid solution was investigated by powder X-ray diffraction. The AC impedance measurements indicate that ionic conductivity increased by more than one order of magnitude when a small amount of Al3+ and Si4+ ions were incorporated into the LiTi2(PO4)3 crystal structure. The significant improvement on ionic conductivity can be attributed to the increased interstitial Li+ ions in the crystal structure. The highest ionic conductivity was found in Li1.2Al0.1Ti1.9Si0.1P2.9O12: 8.3 x 10-5 S·cm-1 at room temperature (21°C) and 1.5 x 10-3 S·cm-1 at 100°C.

Unveiling the atomic defects and electronic structure of Cu2.2Zn0.8SnSe4−xTex (x = 0 to 0.04) by X-ray absorption fine structure spectroscopy

2020 ◽  
Vol 22 (17) ◽  
pp. 9362-9367
Author(s):  
Weifeng Huang ◽  
Yingcai Zhu ◽  
Yong Liu ◽  
Lijuan Liu ◽  
Changchun Yang ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Fine Structure ◽  
Quaternary Compound ◽  
X Ray ◽  
Absorption Fine ◽  
Oxygen Interstitial ◽  
Interstitial Defects ◽  
X Ray Absorption

CuZn anti-site defects and oxygen interstitial defects in a quaternary compound, Cu2.2Zn0.8SnSe4, are revealed by X-ray absorption fine structure spectroscopy.

RGO/BiVO4 with Photocatalytic Activity by a Hydrothermal Method

2014 ◽  
Vol 809-810 ◽  
pp. 912-915
Author(s):  
Dan Li ◽  
Lian Wei Shan ◽  
Li Min Dong ◽  
Gui Lin Wang ◽  
Ze Wu ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Photocatalytic Activity ◽  
Electron Microscope ◽  
Hydrothermal Method ◽  
Photogenerated Electron ◽  
X Ray Diffraction ◽  
Electron Hole ◽  
X Ray ◽  
Micro Morphology ◽  
Scanning Electron

RGO/BiVO4powders were prepared by a hydrothermal method. The crystal structure of RGO/BiVO4was investigated by X-ray diffraction (XRD). Scanning electron microscope (SEM) was used to characterize the micro-morphology of RGO/BiVO4. The recombination rate of photogenerated electron-hole pairs were investigated by fluorescence spectrophotometer. Photocatalytic properties of the prepared samples were examined by studying the degradation of model dyes magenta.

Defect Chemistry of " BaCuO2" I. Oxygen Non -Stoichiometry, Cation Molecularity and X-ray Diffraction Determinations

1995 ◽  
Vol 50 (11) ◽  
pp. 1050-1058 ◽  
Author(s):  
G. Spinolo ◽  
U. Anselmi-Tamburini ◽  
M. Arimondi ◽  
P. Ghigna ◽  
G. Flor
Keyword(s):  
Single Phase ◽  
Large Change ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxygen Interstitial ◽  
Maximum Value ◽  
Profile Fitting ◽  
Complex Crystal Structure ◽  
Interstitial Defects ◽  
Complex Crystal

Abstract “BaCuO2” is the key intermediate in the synthesis of the Ba2YCu3O7−δ superconductor. Its very complex crystal structure is able to accommodate a large change in oxygen content. Oxygen non-stoichiometry of "BaCuO2" materials with 1:1 and 88:90 (Ba :Cu) molecularity has been investigated by polythermal X-ray powder diffraction coupled with isobaric-isothermal gravimetry determinations under different temperature and oxygen partial pressure conditions [300≤ T≤ 820 °C, 1 ≥ P(O2) ≥ 3 • 10-3 atm]. The 1:1 composition does not give well reproducible results, thus suggesting its polyphasic nature, at least in part of the investigated range. The results for the 88:90 ≅ 0.98 (Ba :Cu) composi­ tion are well reproducible and show that the material is single phase. Ba0.98CuO1.98 + δ is oxygen over-stoichiometric in the whole investigated [T, P(O2)] range, with a maximum value δ∼0.21. A Rietveld X-ray profile fitting is in agreement with previous single-crystal data. The trend of δ vs. P(O2) is consistent with the presence of oxygen interstitial defects on (possibly different) crystallographic sites.

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