scholarly journals Formation Mechanisms and Phase Stability of Solid-State Grown CsPbI3 Perovskites

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1823
Author(s):  
Jessica Satta ◽  
Alberto Casu ◽  
Daniele Chiriu ◽  
Carlo Maria Carbonaro ◽  
Luigi Stagi ◽  
...  
Keyword(s):  
Solid State ◽  
Secondary Phase ◽  
Phase Evolution ◽  
Formation Mechanisms ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
Synthesis Time ◽  
Time Length ◽  
Transmission Electron ◽  
Δ Phase

CsPbI3 inorganic perovskite is synthesized by a solvent-free, solid-state reaction, and its structural and optical properties can be deeply investigated using a multi-technique approach. X-ray Diffraction (XRD) and Raman measurements, optical absorption, steady-time and time-resolved luminescence, as well as High-Resolution Transmission Electron Microscopy (HRTEM) imaging, were exploited to understand phase evolution as a function of synthesis time length. Nanoparticles with multiple, well-defined crystalline domains of different crystalline phases were observed, usually surrounded by a thin, amorphous/out-of-axis shell. By increasing the synthesis time length, in addition to the pure α phase, which was rapidly converted into the δ phase at room temperature, a secondary phase, Cs4PbI6, was observed, together with the 715 nm-emitting γ phase.

Observation of solid-state reaction between a thin yttria film and a (0001) α-alumina substrate

1994 ◽  
Vol 52 ◽  
pp. 644-645
Author(s):  
J. R. Heffelfinger ◽  
C. B. Carter
Keyword(s):  
Electron Microscopy ◽  
Solid State ◽  
Solid State Reaction ◽  
Yttrium Aluminum Garnet ◽  
Secondary Phase ◽  
Ceramic Composites ◽  
Alumina Substrate ◽  
Transmission Electron ◽  
Alumina Fibers ◽  
Optical Applications

Transmission-electron microscopy (TEM), scanning-electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS) were used to investigate the solid-state reaction between a thin yttria film and a (0001) α-alumina substrate. Systems containing Y2O3 (yttria) and Al2O3 (alumina) are seen in many technologically relevant applications. For example, yttria is being explored as a coating material for alumina fibers for metal-ceramic composites. The coating serves as a diffusion barrier and protects the alumina fiber from reacting with the metal matrix. With sufficient time and temperature, yttria in contact with alumina will react to form one or a combination of phases shown by the phase diagram in Figure l. Of the reaction phases, yttrium aluminum garnet (YAG) is used as a material for lasers and other optical applications. In a different application, YAG is formed as a secondary phase in the sintering of AIN. Yttria is added to AIN as a sintering aid and acts as an oxygen getter by reacting with the alumina in AIN to form YAG.

scholarly journals A Study of Thin Film Resistors Prepared Using Ni-Cr-Si-Al-Ta High Entropy Alloy

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Ruei-Cheng Lin ◽  
Tai-Kuang Lee ◽  
Der-Ho Wu ◽  
Ying-Chieh Lee
Keyword(s):  
Annealing Temperature ◽  
Phase Evolution ◽  
Amorphous Structure ◽  
High Entropy Alloy ◽  
X Ray Diffraction ◽  
Temperature Coefficient Of Resistance ◽  
X Ray ◽  
High Entropy ◽  
Transmission Electron ◽  
Thin Film Resistors

Ni-Cr-Si-Al-Ta resistive thin films were prepared on glass and Al2O3substrates by DC magnetron cosputtering from targets of Ni0.35-Cr0.25-Si0.2-Al0.2casting alloy and Ta metal. Electrical properties and microstructures of Ni-Cr-Si-Al-Ta films under different sputtering powers and annealing temperatures were investigated. The phase evolution, microstructure, and composition of Ni-Cr-Si-Al-Ta films were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Auger electron spectroscopy (AES). When the annealing temperature was set to 300°C, the Ni-Cr-Si-Al-Ta films with an amorphous structure were observed. When the annealing temperature was at 500°C, the Ni-Cr-Si-Al-Ta films crystallized into Al0.9Ni4.22, Cr2Ta, and Ta5Si3phases. The Ni-Cr-Si-Al-Ta films deposited at 100 W and annealed at 300°C which exhibited the higher resistivity 2215 μΩ-cm with −10 ppm/°C of temperature coefficient of resistance (TCR).

Brookite titania photocatalytic nanomaterials: Synthesis, properties, and applications

2009 ◽  
Vol 81 (12) ◽  
pp. 2407-2415 ◽  
Author(s):  
Jimin Xie ◽  
Xiaomeng Lü ◽  
Jun Liu ◽  
Huoming Shu
Keyword(s):  
Degradation Products ◽  
Photophysical Properties ◽  
X Ray Diffraction ◽  
Synthesis Time ◽  
Photocatalytic Decolorization ◽  
Transmission Electron ◽  
Precursor Phase ◽  
Phase Pure ◽  
Synthesis Properties ◽  
Nanomaterials Synthesis

Phase-pure brookite TiO2 and its activity has been obscured for its difficulty of synthesis. Hence, we introduced the method of preparation and property of phase-pure brookite TiO2 and prepared phase-pure brookite TiO2 by hydrothermal method using Ti(SO4)2 as precursor. Phase formation was achieved by hydrothermal treatment at 180 °C after different synthesis time. The physical and photophysical properties of samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–vis diffraction (UV–vis/DRS), and Raman spectroscopy. The dependence of the photocatalytic activities on synthesis time and correlations with the physical properties of brookite samples was examined in detail. In the case of mineralization of rhodamine B (Rh B), the sample with the narrowest bandgap and the lowest photoluminescence (PL) intensity (at hydrothermal synthesis time 36 h) showed the best photodecolorization activity. Proposed decolorization mechanism was elucidated in the light of the UV–vis spectra of the analyzed degradation products and frontier electron density (FED) theory. The results indicated that photocatalytic decolorization by brookite TiO2 is a highly effective way to remove Rh B under near-visible light irradiation.

Fabrication of PbO-Type Structure β-FeSe Superconductor Ceramics by Solid State Reaction Method

2013 ◽  
Vol 790 ◽  
pp. 21-24
Author(s):  
Yun Yi Wu ◽  
Jian Gao ◽  
Tao Li ◽  
Zhi Qiang Hua
Keyword(s):  
Solid State ◽  
High Vacuum ◽  
Secondary Phase ◽  
Vacuum State ◽  
Type Structure ◽  
X Ray Diffraction ◽  
Solid State Sinter ◽  
Metallic Behavior ◽  
X Ray ◽  
Sinter Method

PbO-type structure β-FeSe superconductor ceramic were successfully prepared by solid state sinter method in high vacuum state. The structures of the ceramics were investigated by X-ray diffraction and scanning electron microscopy. X-ray diffraction indicates that the sample prepared by two-steps method exhibited a much improved crystallinity. And as sintering temperature increases to 700°C, secondary phase Fe7Se8 phase peak disappear and α-Fe peak weakened. Besides, the ceramic prepared in 700°C exhibited a denser surface morphology in comparison to that prepared in 410°C and its composition is closer to the chemical formula FeSe according to EDX compositional analyses. It was noted that the resistivity of the sample, sintered at 700°C using two-steps sinter method, shows a linear metallic behavior from room temperature and onset is around T = 7.5 K.

Microstructural properties and formation mechanisms of GaN nanorods grown on Al2O3 (0001) substrates

2009 ◽  
Vol 24 (8) ◽  
pp. 2476-2482
Author(s):  
Kyu H. Lee ◽  
Jeong Y. Lee ◽  
Y.H. Kwon ◽  
Tae W. Kang ◽  
Dong H. Kim ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Hydride Vapor Phase Epitaxy ◽  
Formation Mechanisms ◽  
Gas Mixing ◽  
X Ray Diffraction ◽  
One Dimensional ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
Increasing Temperature ◽  
Microscopy Images

X-ray diffraction patterns, scanning electron microscopy images, and transmission electron microscopy images showed that one-dimensional GaN nanorods with [0001]-oriented single-crystalline wurtzite structures were grown on Al2O3 (0001) substrates by hydride vapor-phase epitaxy without a catalyst. The tip morphology of the GaN nanorods became flat with increasing temperature difference between the gas mixing and the substrate zones. The gas mixing temperature significantly affected the formation of the nanorods, and the substrate temperature influenced the morphology and the strain of the GaN nanorods near the GaN/Al2O3 heterointerface. The strain and the stress existing in the GaN layer near the heterointerface were decreased with increasing growth rate. The formation mechanisms of the GaN nanorods grown on the Al2O3 (0001) substrates are described on the basis of the experimental results.

Preparation of PVC/Kaolin Nanocomposites through Solid State Shear Compounding Based on Pan-Milling

2011 ◽  
Vol 694 ◽  
pp. 350-354 ◽  
Author(s):  
Kan She Li ◽  
Ying Hong Chen ◽  
Hong Mei Niu ◽  
Jian Jun Chen
Keyword(s):  
Electron Microscopy ◽  
Tensile Strength ◽  
Solid State ◽  
Impact Strength ◽  
Ambient Temperature ◽  
Mechanical Tests ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Filled Composite

Solid state shear compounding technology (S3C) based on pan-milling is an effective method to prepare polymer/layered mineral composites with nano intercalating structure. The PVC/Kaolin compounding powders were successfully prepared by pan-milling at ambient temperature, and then the PVC/Kaolin nanocomposites were processed by moulding The structure and properties of PVC/Kaolin compounding powder and nanocomposites were investigated by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and mechanical tests. The results showed that the mechanical properties of PVC/Kaolin nanocomposites prepared through S3C based on pan-milling 30 cycles at ambient temperature including elongation, tensile strength and notched impact strength were remarkably improved compared with conventional filled composites. The elongation of PVC / Kaolin nanocomposites with 4 %wt. Kaolin was 274.6%, which is 187.3 % higher than that for a conventional filled composite. The tensile strength was 54.0 MPa, which is 6.3 MPa higher than that for a conventional filled composite. The tensile strength of the nanocomposites with 8 %wt. Kaolin was 57.5 MPa, which is 9.1 MPa higher than that for a conventional filled composite. At the same time, the notched impact strength was 4.9 kJ/m2, which is 1.0 kJ/m2 higher than a conventional filled composite. Strengthening and toughening for PVC were synchronously realized. XRD, SEM and TEM verified that S3C based on pan-milling realized synchronously pulverizing, dispersion and compounding of PVC with kaolin Through 25-30 cycles pan-milling, PVC and Kaolin powders imbedded each other and made into uniform PVC/Kaolin compounding powders and nanocomposites. The strip flake of Kaolin particles with thickness less than 50 nanometer and the aspect ratio of 10 times dispersed homogeneously in the PVC matrix.

Structure and Photoluminescent Properties of Microstructural YBO3 : Eu3+ Nanocrystals

2007 ◽  
Vol 7 (2) ◽  
pp. 593-601 ◽  
Author(s):  
Guohui Pan ◽  
Hongwei Song ◽  
Lixin Yu ◽  
Zhongxin Liu ◽  
Xue Bai ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Luminescent Properties ◽  
Radiative Transition ◽  
Surface Site ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
Hydrothermal Temperature ◽  
Transmission Electron ◽  
Site Selective ◽  
Radiative Transition Rate

YBO3 : Eu3+ nanocrystals (NCs) were prepared by a hydrothermal method and characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy. The results demonstrate that morphology and structure of the NCs varied strongly with hydrothermal temperature. Their luminescent properties were investigated in comparison to the bulk. A large number of NO&minus3 groups were adsorbed at the surface of hydrothermal products, which acted as luminescent killers; Two symmetry sites of Eu3+ ions in NCs, the interior and the surface sites, were identified by the site-selective excitation and time-resolved emission experiments; The intensity ratio of 5D0–7F2 to 5D0–7F1 of Eu3+ at the surface site increased greatly than that at the interior site; as a result, the chromaticity was improved; The total radiative transition rate of 5D0–ΣJ7Fj for Eu3+ at the surface site was 3–5 times larger than that at the interior.

Perspectives and limitations of symmetric X-ray Bragg reflections for inspecting polytypism in nanowires

2016 ◽  
Vol 23 (2) ◽  
pp. 487-500 ◽  
Author(s):  
Martin Köhl ◽  
Philipp Schroth ◽  
Tilo Baumbach
Keyword(s):  
Statistical Significance ◽  
Large Set ◽  
X Ray Diffraction ◽  
Free Standing ◽  
Time Resolved ◽  
X Ray ◽  
Transmission Electron ◽  
Gaas Nanowires ◽  
High Statistical Significance ◽  
Proper Interpretation

X-ray diffraction, possibly time-resolved during growth or annealing, is an important technique for the investigation of polytypism in free-standing nanowires. A major advantage of the X-ray diffraction approach for adequately chosen beam conditions is its high statistical significance in comparison with transmission electron microscopy. In this manuscript the interpretation of such X-ray intensity distribution is discussed, and is shown to be non-trivial and non-unique given measurements of the [111]cor [333]creflection of polytypic nanowires grown in the (111)cdirection. In particular, the diffracted intensity distributions for several statistical distributions of the polytypes inside the nanowires are simulated and compared. As an example, polytypic GaAs nanowires are employed, grown on a Si-(111) substrate with an interplanar spacing of the Ga (or As) planes in the wurtzite arrangement that is 0.7% larger than in the zinc blende arrangement along the (111)cdirection. Most importantly, ambiguities of high experimental relevance in the case of strongly fluctuating length of the defect-free polytype segments in the nanowires are demonstrated. As a consequence of these ambiguities, a large set of deviations from the widely used Markov model for the stacking sequences of the nanowires cannot be detected in the X-ray diffraction data. Thus, the results here are of high relevance for the proper interpretation of such data.

LASER-INDUCED PHOTOLUMINESCENT STUDIES OF Al-DOPED ZINC OXIDE NANOPARTICLES

2010 ◽  
Vol 09 (05) ◽  
pp. 439-445
Author(s):  
DHIRAJ KUMAR ◽  
SUNIL KUMAR ◽  
H. S. BHATTI
Keyword(s):  
Zinc Oxide ◽  
Zinc Oxide Nanoparticles ◽  
Oxide Nanoparticles ◽  
Nitrogen Laser ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
Time Resolved ◽  
X Ray ◽  
Aluminum Ions ◽  
Transmission Electron

In this paper, addition of aluminum in zinc oxide is incorporated using low-temperature chemical synthesis route. Aluminum ions help in crystallization of zinc oxide nanoparticles. Characterization of the synthesized nanoparticles of zinc oxide has been done using Transmission electron microscope (TEM), and X-ray diffraction (XRD) analysis, Energy-resolved photoluminescence (PL) spectra and Time-resolved laser-induced photoluminescence (TRPL) at room temperature. Transmission electron microscopic observations and X-Ray diffraction studies indicate highly crystalline nature and particle size of the order of 20 nm in ZnO:Al . Time-resolved laser-induced photoluminescence measurements have been done using pulsed nitrogen laser as an excitation source, operated at wavelength 337.1 nm and having high peak output power of 1 MW. The results show that at higher concentrations of Al doping in host ZnO phosphor, emission intensity is more by several orders of magnitude and lifetime shortening indicates that these nanoparticles are more efficient as compared with lower concentrations of dopant.

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