Probing the stability of Pt nanoparticles encapsulated in sol–gel Al 2 O 3 using in situ and ex situ characterization techniques

2014 ◽  
Vol 485 ◽  
pp. 108-117 ◽  
Author(s):  
R.U. Ribeiro ◽  
D.M. Meira ◽  
C.B. Rodella ◽  
D.C. Oliveira ◽  
J.M.C. Bueno ◽  
...  
Keyword(s):  
Sol Gel ◽  
Pt Nanoparticles ◽  
Ex Situ ◽  
Characterization Techniques ◽  
The Stability

In Situ Studies of the Processing of Sol-Gel Produced Amorphous Materials Using Xanes, Saxs and Curved Image Plate XRD

1999 ◽  
Vol 590 ◽  
Author(s):  
DM Pickup ◽  
G Mountjoy ◽  
RJ Newport ◽  
ME Smith ◽  
GW Wallidge ◽  
...  
Keyword(s):  
Amorphous Materials ◽  
Sol Gel ◽  
Heat Treatments ◽  
Silica Gels ◽  
Ex Situ ◽  
High Count ◽  
X Ray ◽  
Image Plate ◽  
Wide Range

ABSTRACTSol-gel produced mixed oxide materials have been extensively studied using conventional, ex situ structural techniques. Because the structure of these materials is complex and dependent on preparation conditions, there is much to be gained from in situ techniques: the high brightness of synchrotron x-ray sources makes it possible to probe atomic structure on a short timescale, and hence in situ. Here we report recent results for mixed titania- (and some zirconia-) silica gels and xerogels. Titania contents were in the range 8–18 mol%, and heat treatments up to 500°C were applied. The results have been obtained from intrinsically rapid synchrotron x-ray experiments: i) time-resolved small angle scattering, using a quadrant detector, to follow the initial stages of aggregation between the sol and the gel; ii) the use of a curved image plate detector in diffraction, which allowed the simultaneous collection of data across a wide range of scattering at high count rate, to study heat treatments; and iii) x-ray absorption spectroscopy to explore the effects of ambient moisture on transition metal sites.

Epoxy networks reinforced with TiO2 generated by nonhydrolytic sol-gel process: A comparison between in situ and ex situ syntheses to obtain filled polymers

2014 ◽  
Vol 55 (7) ◽  
pp. 1689-1697 ◽  
Author(s):  
Davide Morselli ◽  
Federica Bondioli ◽  
Marco Sangermano ◽  
Massimo Messori
Keyword(s):  
Sol Gel ◽  
Ex Situ ◽  
Filled Polymers ◽  
Epoxy Networks ◽  
Sol Gel Process

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.

scholarly journals In Situ Synthesis of Hybrid Inorganic-Polymer Nanocomposites

2018 ◽  
Author(s):  
Mohammed Adnan ◽  
Antoine Dalod ◽  
Mustafa Balci ◽  
Julia Glaum ◽  
Mari-Ann Einarsrud
Keyword(s):  
Polymer Nanocomposites ◽  
Sol Gel ◽  
Inorganic Nanoparticles ◽  
Inorganic Polymer ◽  
Ex Situ ◽  
Synthesis Methods ◽  
Inorganic Oxide ◽  
Synthesis Conditions ◽  
In Situ Techniques

Hybrid inorganic-polymer nanocomposites can be employed in diverse applications due to the potential combination of desired properties from both the organic and inorganic components. The use of novel bottom-up in situ synthesis methods for the fabrication of these nanocomposites is advantageous compared to top-down ex situ mixing methods, as it offers increased control over the structure and properties of the material. In this review, the focus will be on the application of the sol-gel process for the synthesis of inorganic oxide nanoparticles in epoxy and polysiloxane matrices. The effect of the synthesis conditions and the reactants used on the inorganic structures formed, the interactions between the polymer chains and the inorganic nanoparticles, and the resulting properties of the nanocomposites are appraised from several studies over the last two decades. Lastly, alternative in situ techniques and the applications of various polymer-inorganic oxide nanocomposites are briefly discussed.

scholarly journals In-Situ Kinetic Investigation of Calcium Aluminate Formation

Ceramics ◽  
2018 ◽  
Vol 1 (1) ◽  
pp. 175-197 ◽  
Author(s):  
John Salasin ◽  
Claudia Rawn
Keyword(s):  
Calcium Aluminate ◽  
Sol Gel ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
Direct Crystallization ◽  
Crystalline Materials ◽  
The Stability ◽  
First Time ◽  
Kinetic Equilibrium

Rapid in-situ non-ambient X-ray diffraction represents a powerful tool for characterizing the evolution of crystalline materials in real time. The calcium aluminate system and formation of Ca12Al14O33 (C12A7) is particularly sensitive to processing conditions. This report characterizes the kinetic pathways to thermodynamic equilibrium as a function of atmosphere (ambient, dry, and vacuum) and reactant heterogeneity (as-received, milled, and sol-gel reactants). When reactants are heterogenous (as-received and milled), intermediary phases of Ca3Al2O6 (C3A) and CaAl2O4 (CA) are observed as the route to C12A7 formation and Ca5Al6O14 (C5A3) is only observed as a decomposition product of C12A7. When reactants are heterogenous, C12A7 is only thermodynamically favorable under ambient conditions due to the stability provided by hydration. When reactants are homogenous (sol-gel), direct crystallization of C12A7 from an amorphous precursor is observed at low temperature regardless of atmosphere defining C12A7 as the kinetic equilibrium. These findings accurately define the heterogenous formation pathways and report for the first time the formation of C12A7 under a carbon-free vacuum environment.

Targeted filling of silica in Nafion by a modified in situ sol–gel method for enhanced fuel cell performance at elevated temperatures and low humidity

2019 ◽  
Vol 55 (38) ◽  
pp. 5499-5502 ◽  
Author(s):  
Guoxiao Xu ◽  
Shuai Li ◽  
Jing Li ◽  
Zhao Liu ◽  
Ying Li ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Sol Gel ◽  
Silica Network ◽  
Fuel Cell Performance ◽  
Term Operation ◽  
Ionic Cluster ◽  
Low Humidity ◽  
The Stability

By facilely utilizing an ionic cluster as a nano-reactor, a silica network can be targeted filled in Nafion to increase the PEMFC performance at elevated temperatures and low humidity. Moreover, the stability of Nafion can be improved for the long-term operation of PEMFC under harsh conditions.

Observation of the structural changes of sol-gel formed Li2MnTi3O8 during electrochemical reaction by in-situ and ex-situ studies

2015 ◽  
Vol 152 ◽  
pp. 187-194 ◽  
Author(s):  
Wei Chen ◽  
Hanfeng Liang ◽  
Lianyi Shao ◽  
Jie Shu ◽  
Zhoucheng Wang
Keyword(s):  
Structural Changes ◽  
Electrochemical Reaction ◽  
Sol Gel ◽  
Ex Situ

scholarly journals Structure-Dependent CO2 Gas Sensitivity of La2O2CO3 Thin Films

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Margus Kodu ◽  
Tea Avarmaa ◽  
Hugo Mändar ◽  
Rando Saar ◽  
Raivo Jaaniso
Keyword(s):  
Thin Films ◽  
Partial Pressure ◽  
Low Cost ◽  
Sol Gel ◽  
Working Environment ◽  
Ex Situ ◽  
Potential Candidate ◽  
Gas Sensitivity ◽  
Sensor Structure

Rare earth oxycarbonates are potential candidate materials for constructing simple and low-cost chemiresistive sensors for monitoring carbon dioxide (CO2) gas in the living and working environment for personal comfort and health reasons. Also, measurement of CO2 concentrations is needed in many industrial processes. Specifically, sol-gel made nanoparticles of Nd and La oxycarbonates have been studied previously as novel CO2 gas sensor materials. In this paper, pulsed laser deposition of La oxycarbonate (La2O2CO3) thin films was studied and structural properties of obtained thin films were characterized. Also, CO2 gas sensing ability of synthesized films was evaluated. The films deposited under CO2 partial pressure in various conditions were all Raman amorphous. In situ or ex situ annealing procedure at high CO2 partial pressure was needed for obtaining crystalline La2O2CO3 films, whereby hexagonal and monoclinic polymorphs were obtained in ex situ and in situ processes, respectively. Sensor structure, made using in situ process, was sensitive to CO2 gas and showed relatively fast response and recovery characteristics.

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