Hybrid Perovskite/Polymer Materials: Preparation and Physicochemical Properties

The aim of this work is to investigate the preparation, the optical properties, and the stability over time of a colloidal organic–inorganic hybrid perovskite (CH3NH3PbBr3)/random copolymer P(MMA-co- DMAEMA) system. Different ratios of perovskite to copolymer were used to study its effect on stability and properties. The optical properties were investigated by UV-Vis and fluorescence spectroscopy. Dynamic light scattering was used to determine the size, and the size polydispersity of the colloidal hybrid particles; while morphology was investigated by transmission electron microscopy. Photoluminescence decay studies revealed the interaction of the random copolymer with the perovskite. Finally, thin-films were prepared, to investigate the optical properties of the samples in the absence of the solvent. High temporal stability of the optical properties of thin hybrid films was observed under certain conditions.

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Laser-Based Synthesis of Au Nanoparticles for Optical Sensing of Glyphosate: A Preliminary Study

Micromachines ◽

10.3390/mi11110989 ◽

2020 ◽

Vol 11 (11) ◽

pp. 989 ◽

Cited By ~ 1

Author(s):

Antonella Laura Sortino ◽

Maria Censabella ◽

Gabriella Munzi ◽

Simona Boninelli ◽

Vittorio Privitera ◽

...

Keyword(s):

Optical Properties ◽

Au Nanoparticles ◽

Synthesis Methods ◽

Colloidal Solutions ◽

Nanosecond Pulsed Laser ◽

Transmission Electron ◽

Vis Spectroscopy ◽

Fine Control ◽

The Stability ◽

Simple Economic

Nowadays, Au nanoparticles (AuNPs) capture great interest due to their chemical stability, optical properties, and biocompatibility. The success of technologies based on the use of AuNPs implies the development of simple synthesis methods allowing, also, the fine control over their properties (shape, sizes, structure). Here, we present the AuNPs fabrication by nanosecond pulsed laser ablation in citrate-solution, that has the advantage of being a simple, economic and eco-sustainable method to fabricate colloidal solutions of NPs. We characterized the stability and the absorbance of the solutions by Ultraviolet-Visible (UV-Vis) spectroscopy and the morphology of the AuNPs by Transmission Electron Microscopy. In addition, we used the AuNPs solutions as colorimetric sensor to detect the amount of glyphosate in liquid. Indeed, glyphosate is one of the most widely used herbicides which intensive use represents a risk to human health. The glyphosate presence in the colloidal AuNPs solutions determines the aggregation of the AuNPs causing the change in the color of the solution. The variation of the optical properties of the colloidal solutions versus the concentration of glyphosate is studied.

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Nano-assembling and optical properties of sub-100 nm raspberry-like nanoparticles

The European Physical Journal Applied Physics ◽

10.1051/epjap/2018180065 ◽

2018 ◽

Vol 82 (2) ◽

pp. 20401

Author(s):

Chouaib Daoudi ◽

Mahmoud Ould Metidji ◽

Mohamed Remram ◽

Anne-Marie Jurdyc ◽

Matteo Martini ◽

...

Keyword(s):

Optical Properties ◽

Self Assembly ◽

Hot Spots ◽

Silica Particles ◽

Assembly Method ◽

Dispersed Particles ◽

Transmission Electron ◽

Scattering Measurements ◽

Monodisperse Silica ◽

The Stability

The optical properties of sub-100 nm raspberry-like nano-systems composed of highly monodisperse silica particles and large gold nanoparticles (GNPs) is studied experimentally. The nanoparticles (NPs) were prepared by a self-assembly method, and the pH of each solution was determined by measuring the ζ-potential to ensure the stability of the nano-systems. Dynamic light scattering measurements show a narrow size distribution of NPs, and fairly dispersed particles in solution. The obtained nanoraspberries was also studied by transmission electron microscopy, which shows that the GNPs closely packed on the surface of silica particles. This effect induced a broadening and a shift of the absorption band to higher wavelengths, with an increase in GNPs density. It was also observed that the reduced size of silica particles resulted in a shortening of the inter-particles distance, which has favoured the generation of many hot spots in the gaps between GNPs. The tenability of obtained plasmon bands may have benefits in SERS probe, photocatalysis and fluorescence-based bioimaging.

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TEM Analysis of Long-Period Polytypes in SiC—S

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100093110 ◽

1976 ◽

Vol 34 ◽

pp. 630-631

Author(s):

S. Shinozaki ◽

J. W. Sprys

Keyword(s):

Electron Diffraction ◽

Isothermal Annealing ◽

Tem Analysis ◽

Long Period ◽

Transmission Electron ◽

Average Grain Size ◽

High Resolution Tem ◽

Structural Lattice ◽

The Stability ◽

Continuous Curves

In reaction sintered SiC (∽ 5um average grain size), about 15% of the grains were found to have long-period structures, which were identifiable by transmission electron microscopy (TEM). In order to investigate the stability of the long-period polytypes at high temperature, crystal structures as well as microstructural changes in the long-period polytypes were analyzed as a function of time in isothermal annealing.Each polytype was analyzed by two methods: (1) Electron diffraction, and (2) Electron micrograph analysis. Fig. 1 shows microdensitometer traces of ED patterns (continuous curves) and calculated intensities (vertical lines) along 10.l row for 6H and 84R (Ramsdell notation). Intensity distributions were calculated based on the Zhdanov notation of (33) for 6H and [ (33)3 (32)2 ]3 for 84R. Because of the dynamical effect in electron diffraction, the observed intensities do not exactly coincide with those intensities obtained by structure factor calculations. Fig. 2 shows the high resolution TEM micrographs, where the striped patterns correspond to direct resolution of the structural lattice periodicities of 6H and 84R structures and the spacings shown in the figures are as expected for those structures.

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A transmission electron microscopic study of structural transitions in fast ionic conductors

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100125713 ◽

1987 ◽

Vol 45 ◽

pp. 156-157

Author(s):

R. B. Queenan ◽

P. K. Davies

Keyword(s):

Optical Properties ◽

Ionic Conduction ◽

Recent Observation ◽

Ionic Conductivities ◽

Sodium Aluminate ◽

Two Dimensions ◽

Ionic Conductors ◽

Electron Microscopic ◽

Transmission Electron ◽

Trivalent Cations

Na ß“-alumina (Na1.67Mg67Al10.33O17) is a non-stoichiometric sodium aluminate which exhibits fast ionic conduction of the Na+ ions in two dimensions. The Na+ ions can be exchanged with a variety of mono-, di-, and trivalent cations. The resulting exchanged materials also show high ionic conductivities.Considerable interest in the Na+-Nd3+-ß“-aluminas has been generated as a result of the recent observation of lasing in the pulsed and cw modes. A recent TEM investigation on a 100% exchanged Nd ß“-alumina sample found evidence for the intergrowth of two different structure types. Microdiffraction revealed an ordered phase coexisting with an apparently disordered phase, in which the cations are completely randomized in two dimensions. If an order-disorder transition is present then the cooling rates would be expected to affect the microstructures of these materials which may in turn affect the optical properties. The purpose of this work was to investigate the affect of thermal treatments upon the micro-structural and optical properties of these materials.

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Electron spectroscopic imaging (ESI) on multiphase polymer materials

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100153713 ◽

1989 ◽

Vol 47 ◽

pp. 348-349

Author(s):

H.-J. Cantow ◽

M. Kunz ◽

M. Möller

Keyword(s):

Energy Loss ◽

Melt Spinning ◽

Chromatic Aberration ◽

Element Distribution ◽

Polymer Materials ◽

Specific Energy Loss ◽

Transmission Electron ◽

Multicomponent Polymer ◽

Diffraction Patterns ◽

Image Planes

In transmission electron microscopy the natural contrast of polymers is very low. Thus the contrast has to be enhanced by staining with heavy metals. The resolution is limited by the size of the staining particles and by the fact that electrons with different energy are focused in different image planes due to the chromatic aberration of the magnetic lenses. The integration of an electron energy loss spectrometer into the optical coloumn of a transmission electron microscope offers the possibility to use monoenergetic electrons and to select electrons with a certain energy for imaging. Thus contrast and resolution are enhanced. By imaging only electrons with an element specific energy loss the element distribution in the sample can be obtained. In addition, elastic bright field images and diffraction patterns yield excellent resolution. Some applications of the method on multicomponent polymer materials are discussed.Bulk polymer samples were prepared by ultramicrotoming at room temperature or well below the glass transition temperature. Very thin films for the direct observation of the structure in semicrystalline polymers were obtained by melt-spinning. Specimens were examined with a ZEISS CEM 902 operated at 80 kV.

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TEM characterization of Au/Polysilicon interactions

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100176381 ◽

1990 ◽

Vol 48 (4) ◽

pp. 650-651

Author(s):

N. David Theodore ◽

Leslie H. Allen ◽

C. Barry Carter ◽

James W. Mayer

Keyword(s):

Solid Phase ◽

Single Crystal Silicon ◽

Chemical Vapor ◽

Electrical Contacts ◽

Silicon Substrates ◽

Crystal Silicon ◽

Transmission Electron ◽

Polysilicon Films ◽

The Stability

Metal/polysilicon investigations contribute to an understanding of issues relevant to the stability of electrical contacts in semiconductor devices. These investigations also contribute to an understanding of Si lateral solid-phase epitactic growth. Metals such as Au, Al and Ag form eutectics with Si. reactions in these metal/polysilicon systems lead to the formation of large-grain silicon. Of these systems, the Al/polysilicon system has been most extensively studied. In this study, the behavior upon thermal annealing of Au/polysilicon bilayers is investigated using cross-section transmission electron microscopy (XTEM). The unique feature of this system is that silicon grain-growth occurs at particularly low temperatures ∽300°C).Gold/polysilicon bilayers were fabricated on thermally oxidized single-crystal silicon substrates. Lowpressure chemical vapor deposition (LPCVD) at 620°C was used to obtain 100 to 400 nm polysilicon films. The surface of the polysilicon was cleaned with a buffered hydrofluoric acid solution. Gold was then thermally evaporated onto the samples.

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Implications of Person Fluctuation for the Stability and Validity of Test Scores

Methodology ◽

10.1027/1614-2241.2.4.142 ◽

2006 ◽

Vol 2 (4) ◽

pp. 142-148 ◽

Cited By ~ 1

Author(s):

Pere J. Ferrando

Keyword(s):

Item Response ◽

Test Scores ◽

Temporal Stability ◽

Person Fit ◽

Item Parameters ◽

Individual Trait ◽

The Stability ◽

The Individual ◽

Different Levels ◽

Fluctuation Model

In the IRT person-fluctuation model, the individual trait levels fluctuate within a single test administration whereas the items have fixed locations. This article studies the relations between the person and item parameters of this model and two central properties of item and test scores: temporal stability and external validity. For temporal stability, formulas are derived for predicting and interpreting item response changes in a test-retest situation on the basis of the individual fluctuations. As for validity, formulas are derived for obtaining disattenuated estimates and for predicting changes in validity in groups with different levels of fluctuation. These latter formulas are related to previous research in the person-fit domain. The results obtained and the relations discussed are illustrated with an empirical example.

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Temperature Dependence of Stress and Optical Properties in AlN Films Grown by MOCVD

Nanomaterials ◽

10.3390/nano11030698 ◽

2021 ◽

Vol 11 (3) ◽

pp. 698

Author(s):

Wenwang Wei ◽

Yi Peng ◽

Jiabin Wang ◽

Muhammad Farooq Saleem ◽

Wen Wang ◽

...

Keyword(s):

Optical Properties ◽

Compressive Stress ◽

Sapphire Substrate ◽

Light Transmission ◽

Chemical Vapor ◽

Biaxial Stress ◽

X Ray Diffraction ◽

Patterned Sapphire Substrate ◽

Transmission Electron ◽

Nano Patterning

AlN epilayers were grown on a 2-inch [0001] conventional flat sapphire substrate (CSS) and a nano-patterned sapphire substrate (NPSS) by metalorganic chemical vapor deposition. In this work, the effect of the substrate template and temperature on stress and optical properties of AlN films has been studied by using Raman spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible spectrophotometer and spectroscopic ellipsometry (SE). The AlN on NPSS exhibits lower compressive stress and strain values. The biaxial stress decreases from 1.59 to 0.60 GPa for AlN on CSS and from 0.90 to 0.38 GPa for AlN on NPSS sample in the temperature range 80–300 K, which shows compressive stress. According to the TEM data, the stress varies from tensile on the interface to compressive on the surface. It can be deduced that the nano-holes provide more channels for stress relaxation. Nano-patterning leads to a lower degree of disorder and stress/strain relaxes by the formation of the nano-hole structure between the interface of AlN epilayers and the substrate. The low crystal disorder and defects in the AlN on NPSS is confirmed by the small Urbach energy values. The variation in bandgap (Eg) and optical constants (n, k) with temperature are discussed in detail. Nano-patterning leads to poor light transmission due to light scattering, coupling, and trapping in nano-holes.

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Facile Organometallic Synthesis of Fe-Based Nanomaterials by Hot Injection Reaction

Nanomaterials ◽

10.3390/nano11051141 ◽

2021 ◽

Vol 11 (5) ◽

pp. 1141

Author(s):

Georgia Basina ◽

Hafsa Khurshid ◽

Nikolaos Tzitzios ◽

George Hadjipanayis ◽

Vasileios Tzitzios

Keyword(s):

Room Temperature ◽

Colloidal Particles ◽

Iron Pentacarbonyl ◽

Vibrating Sample Magnetometer ◽

X Ray Diffraction ◽

Organometallic Synthesis ◽

X Ray ◽

Transmission Electron ◽

Hot Injection ◽

The Stability

Fe-based colloids with a core/shell structure consisting of metallic iron and iron oxide were synthesized by a facile hot injection reaction of iron pentacarbonyl in a multi-surfactant mixture. The size of the colloidal particles was affected by the reaction temperature and the results demonstrated that their stability against complete oxidation related to their size. The crystal structure and the morphology were identified by powder X-ray diffraction and transmission electron microscopy, while the magnetic properties were studied at room temperature with a vibrating sample magnetometer. The injection temperature plays a very crucial role and higher temperatures enhance the stability and the resistance against oxidation. For the case of injection at 315 °C, the nanoparticles had around a 10 nm mean diameter and revealed 132 emu/g. Remarkably, a stable dispersion was created due to the colloids’ surface functionalization in a nonpolar solvent.

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