Isomorphous substitution method to fabricating pure phase Al‐doped zinc malachite: defects driven promotion improvement and enhanced synergy between Cu−ZnO

Two series of doped coordination polymers (EuxY1−x and TbxY1−x) through isomorphous substitution method utilizing Y3+ in place of partial Eu3+/Tb3+ were obtained. The doped materials could detect Fe3+, Cr3+, and acetone selectively and sensitively.

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Isomorphous replacement in electron diffraction of wet crystals of rat hemoglobin

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100075968 ◽

1983 ◽

Vol 41 ◽

pp. 446-447

Author(s):

William F. Tivol ◽

Murray Vernon King ◽

D. F. Parsons

Keyword(s):

Electron Diffraction ◽

Heavy Atom ◽

Isomorphous Substitution ◽

X Ray Diffraction ◽

Salt Solutions ◽

X Ray ◽

Isomorphous Replacement ◽

Structure Factors ◽

Diffraction Structure ◽

The Mean

Feasibility of isomorphous substitution in electron diffraction is supported by a calculation of the mean alteration of the electron-diffraction structure factors for hemoglobin crystals caused by substituting two mercury atoms per molecule, following Green, Ingram & Perutz, but with allowance for the proportionality of f to Z3/4 for electron diffraction. This yields a mean net change in F of 12.5%, as contrasted with 22.8% for x-ray diffraction.Use of the hydration chamber in electron diffraction opens prospects for examining many proteins that yield only very thin crystals not suitable for x-ray diffraction. Examination in the wet state avoids treatments that could cause translocation of the heavy-atom labels or distortion of the crystal. Combined with low-fluence techniques, it enables study of the protein in a state as close to native as possible.We have undertaken a study of crystals of rat hemoglobin by electron diffraction in the wet state. Rat hemoglobin offers a certain advantage for hydration-chamber work over other hemoglobins in that it can be crystallized from distilled water instead of salt solutions.

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The role of differential phase contrast in electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100108027 ◽

1978 ◽

Vol 36 (1) ◽

pp. 176-177

Author(s):

E.M. Waddell ◽

J.N. Chapman ◽

R.P. Ferrier

Keyword(s):

Phase Contrast ◽

Practical Method ◽

Position Vector ◽

Differential Phase ◽

Pure Phase ◽

Differential Phase Contrast ◽

The Difference ◽

Image Position ◽

First Moment

Dekkers and de Lang (1977) have discussed a practical method of realising differential phase contrast in a STEM. The method involves taking the difference signal from two semi-circular detectors placed symmetrically about the optic axis and subtending the same angle (2α) at the specimen as that of the cone of illumination. Such a system, or an obvious generalisation of it, namely a quadrant detector, has the characteristic of responding to the gradient of the phase of the specimen transmittance. In this paper we shall compare the performance of this type of system with that of a first moment detector (Waddell et al.1977).For a first moment detector the response function R(k) is of the form R(k) = ck where c is a constant, k is a position vector in the detector plane and the vector nature of R(k)indicates that two signals are produced. This type of system would produce an image signal given bywhere the specimen transmittance is given by a (r) exp (iϕ (r), r is a position vector in object space, ro the position of the probe, ⊛ represents a convolution integral and it has been assumed that we have a coherent probe, with a complex disturbance of the form b(r-ro) exp (iζ (r-ro)). Thus the image signal for a pure phase object imaged in a STEM using a first moment detector is b2 ⊛ ▽ø. Note that this puts no restrictions on the magnitude of the variation of the phase function, but does assume an infinite detector.

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Magnetic and dielectric properties of BiFeO3 nanoparticles

JOURNAL OF ADVANCES IN PHYSICS ◽

10.24297/jap.v7i2.1697 ◽

2015 ◽

Vol 7 (2) ◽

pp. 1393-1403

Author(s):

Dr R.P VIJAYALAKSHMI ◽

N. Manjula ◽

S. Ramu ◽

Amaranatha Reddy

Keyword(s):

Diffuse Reflectance Spectrum ◽

Precipitation Method ◽

Secondary Phases ◽

X Ray Diffraction ◽

Bifeo3 Nanoparticles ◽

Transmission Electron ◽

Multiferroic Bifeo3 ◽

Pure Phase ◽

Simple Chemical ◽

Co Precipitation

Single crystalline nano-sized multiferroic BiFeO3 (BFO) powders were synthesized through simple chemical co-precipitation method using polyethylene glycol (PEG) as capping agent. We obtained pure phase BiFeO3 powder by controlling pHand calcination temperature. From X-ray diffraction studies the nanoparticles were unambiguously identified to have a rhombohedrally distorted perovskite structure belonging to the space group of R3c. No secondary phases were detected. It indicates single phase structure. EDX spectra indicated the appearance of three elements Bi, Fe, O in 1:1:3. From the UV-Vis diffuse reflectance spectrum, the absorption cut-off wavelength of the BFO sample is around 558nm corresponding to the energy band gap of 2.2 eV. The size (60-70 nm) and morphology of the nanoparticles have been analyzed using transmission electron microscopy (TEM). Â Â Linear Mâˆ’H behaviour and slight hysteresis at lower magnetic field is observed for BiFeO3 nanoparticles from Vibrating sample magnetometer studies. It indicates weak ferromagnetic behaviour at room temperature. From dielectric studies, the conductivity value is calculated from the relation s = L/RbA Sm-1 and it is around 7.2 x 10-9 S/m.

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ION Exchange Characterisation of Modified Zeolite

Water Science & Technology ◽

10.2166/wst.1992.0713 ◽

1992 ◽

Vol 26 (9-11) ◽

pp. 2269-2272 ◽

Cited By ~ 3

Author(s):

Š Cerjan-Stefanovic ◽

M. Kaštelan-Macan ◽

T. Filipan

Keyword(s):

Drinking Water ◽

Ion Exchange ◽

Anion Exchange ◽

Natural Zeolite ◽

Deionized Water ◽

Isomorphous Substitution ◽

Waste Waters ◽

Modified Zeolite ◽

Water Drinking

Isomorphous substitution of phosphorus into a natural zeolite affords the possibility to change the overall framework charge from negative to positive. The substances so created should be used for purification of waste waters. The work describes the preparation of phosphated zeolite, their characterisation and examples of their anion exchange of NO3 on observed in deionized water, drinking water and in the solution containing varying amounts of nitrate.

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Structural/Texture Evolution During Facile Substitution of Ni into ZSM-5 Nanostructure vs. its Impregnation Dispersion Used in Selective Transformation of Methanol to Ethylene and Propylene

Combinatorial Chemistry & High Throughput Screening ◽

10.2174/1386207323666200825144543 ◽

2020 ◽

Vol 23 ◽

Cited By ~ 1

Author(s):

Parisa Sadeghpour ◽

Mohammad Haghighi ◽

Mehrdad Esmaeili

Keyword(s):

High Temperature ◽

Physicochemical Properties ◽

Active Sites ◽

Catalytic Performance ◽

Fixed Bed Reactor ◽

Light Olefins ◽

Isomorphous Substitution ◽

Impregnation Method ◽

Hydrothermal Temperature ◽

X Ray

Aim and Objective: Effect of two different modification methods for introducing Ni into ZSM-5 framework was investigated under high temperature synthesis conditions. The nickel successfully introduced into the MFI structures at different crystallization conditions to enhance the physicochemical properties and catalytic performance. Materials and Methods: A series of impregnated Ni/ZSM-5 and isomorphous substituted NiZSM-5 nanostructure catalysts were prepared hydrothermally at different high temperatures and within short times. X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Energy dispersive X-ray (EDX), Brunner, Emmett and Teller-Barrett, Joyner and Halenda (BET-BJH), Fourier transform infrared (FTIR) and Temperature-programmed desorption of ammonia (TPDNH3) were applied to investigate the physicochemical properties. Results: Although all the catalysts showed pure silica MFI–type nanosheets and coffin-like morphology, using the isomorphous substitution for Ni incorporation into the ZSM-5 framework led to the formation of materials with lower crystallinity, higher pore volume and stronger acidity compared to using impregnation method. Moreover, it was found that raising the hydrothermal temperature increased the crystallinity and enhanced more uniform incorporation of Ni atoms in the crystalline structure of catalysts. TPD-NH3 analysis demonstrated that high crystallization temperature and short crystallization time of NiZSM-5(350-0.5) resulted in fewer weak acid sites and medium acid strength. The MTO catalytic performance was tested in a fixed bed reactor at 460ºC and GHSV=10500 cm3 /gcat.h. A slightly different reaction pathway was proposed for the production of light olefins over impregnated Ni/ZSM-5 catalysts based on the role of NiO species. The enhanced methanol conversion for isomorphous substituted NiZSM-5 catalysts could be related to the most accessible active sites located inside the pores. Conclusion: The impregnated Ni/ZSM-5 catalyst prepared at low hydrothermal temperature showed the best catalytic performance, while the isomorphous substituted NiZSM-5 prepared at high temperature was found to be the active molecular sieve regarding the stability performance.

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Post-illumination activity of Bi2WO6 in the dark from the photocatalytic “memory” effect

Journal of Advanced Ceramics ◽

10.1007/s40145-020-0448-8 ◽

2021 ◽

Vol 10 (2) ◽

pp. 355-367

Author(s):

Weiyi Yang ◽

Yan Chen ◽

Shuang Gao ◽

Licheng Sang ◽

Ruoge Tao ◽

...

Keyword(s):

Memory Effect ◽

Reduction Process ◽

Production Performance ◽

Intrinsic Activity ◽

Light Illumination ◽

Two Phase ◽

Photogenerated Electrons ◽

Composite Photocatalysts ◽

Pure Phase ◽

Activity Loss

AbstractPhotocatalysts with the photocatalytic “memory” effect could resolve the intrinsic activity loss of traditional photocatalysts when the light illumination is turned off. Due to the dual requirements of light absorption and energy storage/release functions, most previously reported photocatalysts with the photocatalytic “memory” effect were composite photocatalysts of two phase components, which may lose their performance due to gradually deteriorated interface conditions during their applications. In this work, a simple solvothermal process was developed to synthesize Bi2WO6 microspheres constructed by aggregated nanoflakes. The pure phase Bi2WO6 was found to possess the photocatalytic “memory” effect through the trapping and release of photogenerated electrons by the reversible chemical state change of W component in the (WO4)2− layers. When the illumination was switched off, Bi2WO6 microspheres continuously produced H2O2 in the dark as those trapped photogenerated electrons were gradually released to react with O2 through the two-electron O2 reduction process, resulting in the continuous disinfection of Escherichia coli bacteria in the dark through the photocatalytic “memory” effect. No deterioration of their cycling H2O2 production performance in the dark was observed, which verified their stable photocatalytic “memory” effect.

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Controlled synthesis of pure-phase metastable tetragonal Nb2O5 anode material for high-performance lithium batteries

Journal of Solid State Chemistry ◽

10.1016/j.jssc.2021.122136 ◽

2021 ◽

Vol 299 ◽

pp. 122136

Author(s):

Huibin Ding ◽

Zihan Song ◽

Kai Feng ◽

Hongzhang Zhang ◽

Huamin Zhang ◽

...

Keyword(s):

Anode Material ◽

Lithium Batteries ◽

High Performance ◽

Controlled Synthesis ◽

Pure Phase

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Controlled Synthesis of CuS and Cu9S5 and Their Application in the Photocatalytic Mineralization of Tetracycline

Catalysts ◽

10.3390/catal11080899 ◽

2021 ◽

Vol 11 (8) ◽

pp. 899

Author(s):

Murendeni P. Ravele ◽

Opeyemi A. Oyewo ◽

Damian C. Onwudiwe

Keyword(s):

Electron Microscopy ◽

Visible Light ◽

Blue Shift ◽

X Ray Diffraction ◽

X Ray ◽

Copper Sulfides ◽

Transmission Electron ◽

Single Source Precursor ◽

Pure Phase ◽

Pure Phases

Pure-phase Cu2−xS (x = 1, 0.2) nanoparticles have been synthesized by the thermal decomposition of copper(II) dithiocarbamate as a single-source precursor in oleylamine as a capping agent. The compositions of the Cu2−xS nanocrystals varied from CuS (covellite) through the mixture of phases (CuS and Cu7.2S4) to Cu9S5 (digenite) by simply varying the temperature of synthesis. The crystallinity and morphology of the copper sulfides were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), which showed pure phases at low (120 °C) and high (220 °C) temperatures and a mixture of phases at intermediate temperatures (150 and 180 °C). Covellite was of a spherical morphology, while digenite was rod shaped. The optical properties of these nanocrystals were characterized by UV−vis–NIR and photoluminescence spectroscopies. Both samples had very similar absorption spectra but distinguishable fluorescence properties and exhibited a blue shift in their band gap energies compared to bulk Cu2−xS. The pure phases were used as catalysts for the photocatalytic degradation of tetracycline (TC) under visible-light irradiation. The results demonstrated that the photocatalytic activity of the digenite phase exhibited higher catalytic degradation of 98.5% compared to the covellite phase, which showed 88% degradation within the 120 min reaction time using 80 mg of the catalysts. The higher degradation efficiency achieved with the digenite phase was attributed to its higher absorption of the visible light compared to covellite.

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