scholarly journals Facile Synthesis of Monodisperse ZnO Nanocrystals by Direct Liquid Phase Precipitation

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Lan Chen ◽  
Justin D. Holmes ◽  
Sonia Ramírez-García ◽  
Michael A. Morris
Keyword(s):  
Liquid Phase ◽  
Room Temperature ◽  
Surface Defect ◽  
Ex Situ ◽  
Phase Precipitation ◽  
Facile Synthesis ◽  
Zno Nanocrystals ◽  
Defect Control ◽  
Temperature Time

ZnO nanocrystals can be synthesized by a variety of methods. Among them, only a few nonhydrolytic methods have been successful at low synthesis temperatures in terms of size, crystallinity, morphology and surface-defect control. These methods require very careful control of conditions and carefully engineered precursors. A new methodology—direct liquid phase precipitation—is reported here that can produce nanocrystals (NCs) which are a little difficult to obtain for these complex synthesis techniques in a more facile and efficient way (i.e., at room temperature). This technique results in high quality ZnO nanocrystals of diameter 5–12 nm and different morphologies. Characterisation of ZnO products shows that both synthesis and ageing conditions have significant effects on the formation of the nanocrystals. Capping agents and ageing temperature/time can be used to control both size and crystallinity of the products. The use ofin situorex situageing conditions can result in different particle morphologies. Bothin situandex situageing shows that mild ageing conditions (e.g., 60–80∘Cand 24–48 hours) are required to produce the highest quality nanomaterials.

scholarly journals Ion-Irradiation-Induced Amorphization Of Cadmium Niobate Pyrochlore

2000 ◽  
Vol 650 ◽  
Author(s):  
A. Meldrum ◽  
K. Beaty ◽  
L. A. Boatner ◽  
C. W. White
Keyword(s):  
Electron Microscope ◽  
Ambient Temperature ◽  
Transmission Electron Microscope ◽  
Room Temperature ◽  
Ion Irradiation ◽  
Ex Situ ◽  
Temperature Dependent ◽  
Transmission Electron ◽  
Ion Energies

ABSTRACTIrradiation-induced amorphization of Cd2Nb2O7 pyrochlore was investigated by means of in-situ temperature-dependent ion-irradiation experiments in a transmission electron microscope, combined with ex-situ ion-implantation (at ambient temperature) and RBS/channeling analysis. The in-situ experiments were performed using Ne or Xe ions with energies of 280 and 1200 keV, respectively. For the bulk implantation experiments, the incident ion energies were 70 keV (Ne+) and 320 keV (Xe2+). The critical amorphization temperature for Cd2Nb2O7 is ∼480 K (280 keV Ne+) or ∼620 K (1200 keV Xe2+). The dose for in-situ amorphization at room temperature is 0.22 dpa for Xe2+, but is 0.65 dpa for Ne+ irradiation. Both types of experiments suggest a cascade overlap mechanism of amorphization. The results were analyzed in light of available models for the crystalline-to-amorphous transformation and were compared to previous ionirradiation experiments on other pyrochlore compositions.

Phase Transformations in Sol-Gel PZT Thin Films

2000 ◽  
Vol 623 ◽  
Author(s):  
D.P. Eakin ◽  
M.G. Norton ◽  
D.F. Bahr
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Room Temperature ◽  
Structural Changes ◽  
Sol Gel ◽  
Ex Situ ◽  
Ambient Conditions ◽  
Crystalline Films ◽  
In Situ Heating

AbstractThin films of PZT were deposited onto platinized and bare single crystal NaCl using spin coating and sol-gel precursors. These films were then analyzed using in situ heating in a transmission electron microscope. The results of in situ heating are compared with those of an ex situ heat treatment in a standard furnace, mimicking the heat treatment given to entire wafers of these materials for use in MEMS and ferroelectric applications. Films are shown to transform from amorphous to nanocrystalline over the course of days when held at room temperature. While chemical variations are found between films crystallized in ambient conditions and films crystallized in the vacuum conditions of the microscope, the resulting crystal structures appear to be insensitive to these differences. Significant changes in crystal structure are found at 500°C, primarily the change from largely amorphous to the beginnings of clearly crystalline films. Crystallization does occur over the course of weeks at room temperature in these films. Structural changes are more modest in these films when heated in the TEM then those observed on actual wafers. The presence of Pt significantly influences both the resulting structure and morphology in both in situ and ex situ heated films. Without Pt present, the films appear to form small, 10 nm grains consisting of both cubic and tetragonal phases, whereas in the case of the Pt larger, 100 nm grains of a tetragonal phase are formed.

Surface Morphologies and Interfaces of TiSi2 Formed from UHV Deposited Ti on Si

1989 ◽  
Vol 160 ◽  
Author(s):  
Hyeongtag Jeon ◽  
R. J. Nemanich ◽  
J.W. Honeycutt ◽  
G. A. Rozgonyi
Keyword(s):  
Room Temperature ◽  
Ex Situ ◽  
Island Formation ◽  
Surface And Interface ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
Liquid Model ◽  
Surface Morphologies ◽  
Substrate Temperatures

AbstractThe island formation of TiSi2 and the surface morphologies and interfaces of TiSi2 on Si have been examined and related to the surface and the interface energies. Ti (200Å and 400Å) films were deposited on clean, reconstructed Si(100) and Si(111) substrates at room temperature and also at high substrate temperatures (500°C~800°C). The TiSi2 formation process is monitored with in-situ LEED and AES and the surface morphologies and interfaces are examined with ex-situ SEM and TEM. For annealing to temperatures such that the C54 phase forms, the results indicate island formation with clean reconstructed substrate regions between the islands. The TiSi2 islands show different morphology on the (100) and (111) oriented substrates. The mechanism of TiSi2 island formation is described in terms of a liquid-liquid model, and the surface and interface energies for the TiSi2 island are determined from contact angle measurements.

scholarly journals Nanoscopic and in-situ cross-sectional observations of Li-based conversion coating formation using liquid-phase TEM

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
A. Kosari ◽  
F. Tichelaar ◽  
P. Visser ◽  
P. Taheri ◽  
H. Zandbergen ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Protective Coatings ◽  
Conversion Process ◽  
Ex Situ ◽  
Lithium Salts ◽  
Detailed Knowledge ◽  
Cross Sectional ◽  
Coating Formation ◽  
Phase Transmission

AbstractLithium salts have been proposed as promising environmentally friendly alternatives to carcinogenic hexavalent chromium-based inhibitors for the corrosion protection of aerospace aluminium alloys (AAs). Incorporated into organic coatings, lithium salts are released at damaged locations to establish a conversion layer in which distinct sublayers have different barrier characteristics. Thus, detailed knowledge on the sequence of formation events from the early stages of nucleation towards the final multi-layered arrangement is essential for developing and optimising lithium-leaching technology for protective coatings. Here, liquid-phase-transmission electron microscopy (LP-TEM) is employed to observe nanoscopic morphological evolutions in situ during the lithium-based conversion process of AA2024-T3. Thanks to dedicated preparation of delicate sandwiched TEM specimens allowing us to explore the events cross-sectionally, we provide real-time direct mechanistic information on the conversion process from the initiation to an advanced growth stage. In parallel, we perform supplementary ex situ SEM and TEM investigations to support and validate the LP-TEM findings. The unprecedented experimental approach developed and executed in this study provides an inspiring base for studying also other complicated surface conversion processes in situ and at the nanoscopic scale.

scholarly journals Phase Evolution from Volborthite, Cu3(V2O7)(OH)2·2H2O, upon Heat Treatment

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1312
Author(s):  
Rezeda M. Ismagilova ◽  
Elena S. Zhitova ◽  
Sergey V. Krivovichev ◽  
Anastasia V. Sergeeva ◽  
Anton A. Nuzhdaev ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Room Temperature ◽  
Analytical Data ◽  
Phase Evolution ◽  
Ex Situ ◽  
Fast Cooling ◽  
In Situ Heating ◽  
Structure Complexity ◽  
Increasing Temperature

In the experiments on volborthite in situ and ex situ heating, analogues of all known natural anhydrous copper vanadates have been obtained: ziesite, pseudolyonsite, mcbirneyite, fingerite, stoiberite and blossite, with the exception of borisenkoite, which requires the presence of As in the V site. The evolution of Cu-V minerals during in situ heating is as follows: volborthite Cu3(V2O7)(OH)2·2H2O (30–230 °C) → X-ray amorphous phase (230–290 °C) → ziesite β-Cu2(V2O7) (290–430 °C) → ziesite + pseudolyonsite α-Cu3(VO4)2 + mcbirneyite β-Cu3(VO4)2 (430–510 °C) → mcbirneyite (510–750 °C). This trend of mineral evolution agrees with the thermal analytical data. These phases also dominate in all experiments with an ex situ annealing. However, the phase compositions of the samples annealed ex situ are more complex: fingerite Cu11(VO4)6O2 occurs in the samples annealed at ~250 and ~480 °C and quickly or slowly cooled to room temperature, and in the sample annealed at ~850 °C with fast cooling. At the same time, blossite and stoiberite have been found in the samples annealed at ~480–780 and ~780–850 °C, respectively, and slowly cooled to room temperature. There is a trend of decreasing crystal structure complexity in the raw phases obtained by the in situ heating with the increasing temperature: volborthite → ziesite → mcbirneyite (except of pseudolyonsite). Another tendency is that the longer the sample is cooled, the more complex the crystal structure that is formed, with the exception of blossite, most probably because blossite and ziesite are polymorphs with identical crystal structure complexities. The high complexity of fingerite and stoiberite, as well as their distinction by Cu:V ratio, may explain the uncertain conditions of their formation.

A Study of the MBE Growth of MGO on The FE(001) Surface

1994 ◽  
Vol 357 ◽  
Author(s):  
J.L. Vassent ◽  
M. Dynna ◽  
G. Patrat ◽  
B. Gilles ◽  
A. Marty
Keyword(s):  
Room Temperature ◽  
Lattice Parameter ◽  
Electron Beam Evaporation ◽  
Ex Situ ◽  
Misfit Dislocations ◽  
Mbe Growth ◽  
Plane Lattice ◽  
Pseudomorphic Growth ◽  
Bulk Parameter

AbstractThe deposition of MgO on the Fe(001) surface has been carried out using electron beam evaporation. MgO is observed to grow epitaxially with a 45° rotation between the Fe(001) and MgO(001) unit cell axes. Oscillations in the intensity of the RHEED specular beam are observed at room temperature showing that growth is two-dimensional. The relaxation of the in-plane lattice parameter during the growth at room temperature has been investigated in-situ by measuring the position of the RHEED streaks and ex-situ with GIXD experiments. Pseudomorphic growth is observed up to about five monolayers. Then the in-plane lattice parameter starts to evolve towards the MgO bulk parameter. HREM shows that the relaxation of MgO occurs via the generation of 1/2<011> misfit dislocations which are non-uniformly spaced at the Fe/MgO interface.

In situ and Ex situ Measurements of Stress Evolution in the Cobalt-Silicon System

2000 ◽  
Vol 611 ◽  
Author(s):  
G. Lucadamo ◽  
C. Lavoie ◽  
C. Cabral ◽  
R. A. Carruthers ◽  
J.M.E. Harper
Keyword(s):  
Room Temperature ◽  
Biaxial Stress ◽  
Ex Situ ◽  
Silicide Formation ◽  
Stress Evolution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Bending Force ◽  
Constant Heating

ABSTRACTThe biaxial stress in Co thin-films has been investigated in situ by measuring changes in substrate curvature that occurred during deposition and annealing.Films of Co, 35 to 500 nm in thickness, were deposited by UHV magnetron sputtering at room temperature on Si (100) and poly-Si substrates.Results show that during Co deposition the bending force increased linearly with film thickness; a signature of constant stress.In addition, the stress evolution during silicide formation was measured under constant heating rate conditions from room temperature up to 700°C. The stress-temperature curve was correlated with Co2Si, CoSi, and CoSi2 phase formation using in situ synchrotron X-ray diffraction measurements.The room temperature stress for the CoSi2 phase was found to be ∼0.8 GPa (tensile) in the films deposited on Si (100) and ∼1 GPa (tensile) on the films deposited on poly-Si.The higher tensile stress in the poly-Si sample could be a result of Si grain growth during annealing.

Silver nanoparticles: facile synthesis and their catalytic application for the degradation of dyes

RSC Advances ◽  
2015 ◽  
Vol 5 (33) ◽  
pp. 25781-25788 ◽  
Author(s):  
Kamaldeep Sharma ◽  
Gurpreet Singh ◽  
Gurpreet Singh ◽  
Manoj Kumar ◽  
Vandana Bhalla
Keyword(s):  
Room Temperature ◽  
Dye Degradation ◽  
Catalytic Efficiency ◽  
Organic Dye ◽  
Facile Synthesis ◽  
Catalytic Application ◽  
Degradation Of Dyes ◽  
Organic Dye Degradation ◽  
Aldehyde Groups

The aggregates of pentacenequinone, HPB and PDI derivatives 3, 5 and 7 having aldehyde groups bind strongly with Ag+ and serve as reactors and stabilizers for the preparation of AgNPs at room temperature. In situ generated AgNPs show high catalytic efficiency for industrially important organic dye degradation.

One-Pot Preparation of Stable Organoboronate Reagents for the Functionalization of Unsaturated Four- and Five-Membered Carbo­- and Heterocycles

Synthesis ◽  
2018 ◽  
Vol 50 (16) ◽  
pp. 3149-3160 ◽  
Author(s):  
Dorian Didier ◽  
Andreas Baumann ◽  
Michael Eisold ◽  
Arif Music
Keyword(s):  
Room Temperature ◽  
Functional Group ◽  
Building Blocks ◽  
Boronic Acids ◽  
Ex Situ ◽  
One Pot ◽  
Potential Applicability ◽  
Facile Preparation

Combining a facile preparation of organoboronates with their remarkable stability and functional group tolerance allows for the straightforward synthesis of four- and five-membered carbo- and hetero­cycles. While most strategies rely on the ex situ preparation of boronic acids as isolated intermediates, we demonstrate that in situ transmetalation of sensitive organometallics with boron alkoxides can lead to great stabilization of such species at room temperature. A considerable extension of the library of unsaturated strained structures is achieved through these sequences, expanding the potential applicability of such unusual building blocks.

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