Phase Evolution and Surface Morphology of Niobate Hydrate Template Nanoparticles Synthesized by Hydrothermal Method

2016 ◽  
Vol 697 ◽  
pp. 105-108
Author(s):  
Yuan Yu Wang ◽  
Nuo Xin Xu ◽  
Jin Zhuang Liu ◽  
Qi Long Zhang ◽  
Hui Yang
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Surface Morphology ◽  
Hydrothermal Method ◽  
Alkaline Solution ◽  
Phase Structure ◽  
Reaction Rate ◽  
Phase Evolution ◽  
Starting Solution ◽  
Alternative Approach

In this work, an alternative approach to synthesize (K,Na)NbO3 (KNN) particles is investigated. KNN hydrate particles were prepared by hydrothermal method in a mixed alkaline solution with different KOH/(KOH+NaOH) ratios , and phase structure as well as surface morphology of these niobate hydrate particles were systematically studied. For the reaction rate of Na+ is faster than K+, a mixed alkaline solution with K+/Na+ changing from 4/1 to 5/1was required as a starting solution so a to obtain KNN hydrate particles with K/Na=1. Besides, the results show that particle size of KNN hydrate particles synthesized in different starting solution is dependent on K+/Na+ of the starting solution, and grain size of as-sintered KNN ceramics through hydrothermal method decreases sharply.

Effect of Nano-Al2O3 Addition on the Densification of YSZ Electrolytes

2009 ◽  
Vol 6 ◽  
pp. 115-122 ◽  
Author(s):  
Dachamir Hotza ◽  
Adrian Leo ◽  
Jaka Sunarso ◽  
João C. Diniz da Costa
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Sintered Density ◽  
Sintering Temperature ◽  
Phase Segregation ◽  
Phase Evolution ◽  
Second Phase ◽  
Suspension Particle ◽  
Powder Suspension ◽  
Ysz Electrolyte

This work investigates the effect of nanosized Al2O3 addition on the sinterability of YSZ electrolyte. (1−x)YSZ + Al2O3 ceramics with compositions x = 0 to 0.01 were prepared by the conventional mixed oxide route from a commercial powder suspension (particle size <50 nm), and sintered at 1200 to 1500°C for 2 hours in air. Densification, phase evolution, and microstructure were characterized by SEM/EDS and XRD. An improvement in sintered density was observed for the samples with 0.2 to 0.5 mol% Al2O3, though depending on the sintering temperature. Only cubic zirconia was detected as crystalline phase, although XRD features suggested chemical interactions depending upon the amount of Al2O3. The grain size of YSZ was homogeneous and no second phase segregation was detected in the tested range of incorporated nano-Al2O3 and sintering temperatures.

Phase Transformations in Sol-Gel Yag Films

1992 ◽  
Vol 271 ◽  
Author(s):  
R. S. Hay
Keyword(s):  
Grain Size ◽  
Film Thickness ◽  
Reaction Rate ◽  
Yttrium Aluminum Garnet ◽  
Sol Gel ◽  
Phase Evolution ◽  
Transition Alumina ◽  
Heat Treated ◽  
Yttrium Aluminum ◽  
The Matrix

ABSTRACTDiphasic yttrium-aluminum garnet (YAG) sols were gelled across TEM grids to make films. The films were heat-treated up to 300 hours between 800°C to 1150°C. Microstructure and phase evolution were observed by TEM. YAG fraction and grain size, matrix phases and grain size, nuclei/area, and film thickness were measured. Yttrium-aluminum monoclinic and transition alumina appeared at 800°C. YAG nucleated between 800°C and 950°C. Above 850°C nudeation was site-saturated. Final nuclei density averaged 0.3/μm3. Between 850°C and 1000°C YAG growth had ∼t1/2 dependence and Q ∼ 280 kJ/mole. Below 850°C nudeation was continuous and growth had ∼t0.85 dependence. Above 1000°C YAG growth had ∼t1/4 dependence and the matrix grains coarsened with ∼t1/4 dependence. Unreacted areas were more abundant in thinner films because the nuclei/area and reaction rate decreased. YAG growth was often accompanied by formation of 20 – 100 nm subgrains. Above 1100°C there was some readion to YAG by a different process.

Chemical Transformation of Fe, Air & Water to Ammonia: Variation of Reaction Rate with Temperature, Pressure, Alkalinity and Iron

2018 ◽  
Author(s):  
Ping Peng ◽  
Fang-Fang Li ◽  
Xinye Liu ◽  
Jiawen Ren ◽  
jessica stuart ◽  
...  
Keyword(s):  
Particle Size ◽  
Reaction Rate ◽  
Electrolyte Concentration ◽  
Iron Concentration ◽  
Reaction Medium ◽  
Iron Particle ◽  
Intermediate Step ◽  
Ammonia Production ◽  
Pure Nitrogen ◽  
Alkaline Reaction

The rate of ammonia production by the <u>chemical </u>oxidation of iron, N<sub>2</sub>(from air or as pure nitrogen) and water is studied as a function of (1) iron particle size, (2) iron concentration, (3) temperature, (4) pressureand (5) concentration of the alkaline reaction medium. The reaction meduium consists of an aqueous solution of equal molal concentrations of NaOH and KOH (Na<sub>0.5</sub>K<sub>0.5</sub>OH). We had previously reported on the <u>chemical </u>reaction of iron and nitrogen in alkaline medium to ammonia as an intermediate step in the <u>electrochemical </u>synthesis of ammonia by a nano-sized iron oxide electrocatlyst. Here, the intermediate <u>chemical </u>reaction step is exclusively explored. The ammonia production rate increases with temperature (from 20 to 250°C), pressure (from 1 atm to 15 atm of air or N<sub>2</sub>), and exhibits a maximum rate at an electrolyte concentration of 8 molal Na<sub>0,5</sub>K<sub>0,5</sub>OH in a sealed N<sub>2</sub>reactor. 1-3 µm particle size Fe drive the highest observed ammonia production reaction rate. The Fe mass normalized rate of ammonia production increases with decreasing added mass of the Fe reactant reaching a maximum observed rate of 2.2x10<sup>-4</sup>mole of NH<sub>3</sub>h<sup>-1</sup>g<sup>-1</sup>for the reaction of 0.1 g of 1-3 µm Fe in 200°C 8 molal Na<sub>0.5</sub>K<sub>0.5</sub>OH at 15 atm. Under these conditions 5.1 wt% of the iron reacts to form NH<sub>3</sub>via the reaction N<sub>2</sub>+ 2Fe + 3H<sub>2</sub>O ®2NH<sub>3</sub>+ Fe<sub>2</sub>O<sub>3</sub>.

Isolasi Dan Karakterisasi Bentonit Alam Menjadi Nanopartikel Monmorillonit

2018 ◽  
Vol 3 (1) ◽  
pp. 12 ◽  
Author(s):  
Zaimahwati Zaimahwati ◽  
Yuniati Yuniati ◽  
Ramzi Jalal ◽  
Syahman Zhafiri ◽  
Yuli Yetri
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Particle Size ◽  
Surface Morphology ◽  
Average Diameter ◽  
Particle Size Analyzer ◽  
Ft Ir ◽  
Scanning Electron ◽  
Sedimentation Processes

<p>Pada penelitian ini telah dilakukan isolasi dan karakterisasi bentonit alam menjadi nanopartikel montmorillonit. Bentonit alam yang digunakan diambil dari desa Blangdalam, Kecamatan Nisam Kabupaten Aceh Utara.  Proses isolasi meliputi proses pelarutan dengan aquades, ultrasonic dan proses sedimentasi. Untuk mengetahui karakterisasi montmorillonit dilakukan uji FT-IR, X-RD dan uji morfologi permukaan dengan Scanning Electron Microscopy (SEM). Partikel size analyzer untuk menganalisis dan menentukan ukuran nanopartikel dari isolasi bentonit alam. Dari hasil penelitian didapat ukuran nanopartikel montmorillonit hasil isolasi dari bentonit alam diperoleh berdiameter rata-rata 82,15 nm.</p><p><em>In this research we have isolated and characterized natural bentonite into montmorillonite nanoparticles. Natural bentonite used was taken from Blangdalam village, Nisam sub-district, North Aceh district. The isolation process includes dissolving process with aquades, ultrasonic and sedimentation processes.  The characterization of montmorillonite, FT-IR, X-RD and surface morphology test by Scanning Electron Microscopy (SEM). Particle size analyzer to analyze and determine the size of nanoparticles from natural bentonite insulation. From the research results obtained the size of montmorillonite nanoparticles isolated from natural bentonite obtained an average diameter of 82.15 nm.</em></p>

The effect of particle size on the reactivity of active sodium carbonate towards sulfur dioxide

1979 ◽  
Vol 44 (12) ◽  
pp. 3419-3424
Author(s):  
Karel Mocek ◽  
Erich Lippert ◽  
Dušan Husek ◽  
Emerich Erdös
Keyword(s):  
Particle Size ◽  
Sulfur Dioxide ◽  
Sodium Carbonate ◽  
Reaction Rate ◽  
Active Form ◽  
Controlling Factor ◽  
Active Sodium ◽  
Effect Of Particle Size ◽  
Integral Reactor

The effect of particle size (0.33-1.0 mm) of the sodium carbonate on the reactivity of the active sodium carbonate prepared therefrom towards the sulfur dioxide was studied in a fixedbed integral reactor at a temperature of 150 °C. The found dependence of the reaction rate on the particle size exhibits an unexpected course; at sizes of about 0.65 mm, a distinct minimum appears. The reaction rate decreases approximately ten times in the first branch of this dependence. The controlling factor of the reactivity of sodium carbonate, however, remains to be the method of preparing the active form.

scholarly journals Mining Wastes of an Albite Deposit as Raw Materials for Vitrified Mullite Ceramics

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 232
Author(s):  
Pedro J. Sánchez-Soto ◽  
Eduardo Garzón ◽  
Luis Pérez-Villarejo ◽  
George N. Angelopoulos ◽  
Dolores Eliche-Quesada
Keyword(s):  
Particle Size ◽  
Raw Materials ◽  
Phase Evolution ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Mining Wastes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Maximum Value

In this work, an examination of mining wastes of an albite deposit in south Spain was carried out using X-ray Fluorescence (XRF), X-ray diffraction (XRD), particle size analysis, thermo-dilatometry and Differential Thermal Analysis (DTA) and Thermogravimetric (TG) analysis, followed by the determination of the main ceramic properties. The albite content in two selected samples was high (65–40 wt. %), accompanied by quartz (25–40 wt. %) and other minor minerals identified by XRD, mainly kaolinite, in agreement with the high content of silica and alumina determined by XRF. The content of Na2O was in the range 5.44–3.09 wt. %, being associated with albite. The iron content was very low (<0.75 wt. %). The kaolinite content in the waste was estimated from ~8 to 32 wt. %. The particle size analysis indicated values of 11–31 wt. % of particles <63 µm. The ceramic properties of fired samples (1000–1350 °C) showed progressive shrinkage by the thermal effect, with water absorption and open porosity almost at zero at 1200–1250 °C. At 1200 °C, the bulk density reached a maximum value of 2.38 g/cm3. An abrupt change in the phase evolution by XRD was found from 1150 to 1200 °C, with the disappearance of albite by melting in accordance with the predictions of the phase diagram SiO2-Al2O3-Na2O and the system albite-quartz. These fired materials contained as main crystalline phases quartz and mullite. Quartz was present in the raw samples and mullite was formed by decomposition of kaolinite. The observation of mullite forming needle-shape crystals was revealed by Scanning Electron Microscopy (SEM). The formation of fully densified and vitrified mullite materials by firing treatments was demonstrated.

Microstructure Characterization of Ag Nanoparticles Prepared by Hydrothermal Method

2012 ◽  
Vol 476-478 ◽  
pp. 1138-1141
Author(s):  
Zhi Qiang Wei ◽  
Qiang Wei ◽  
Li Gang Liu ◽  
Hua Yang ◽  
Xiao Juan Wu
Keyword(s):  
Crystal Structure ◽  
Particle Size ◽  
Hydrothermal Method ◽  
Ag Nanoparticles ◽  
Average Particle Size ◽  
Average Particle ◽  
Face Centered Cubic ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Face Centered

Ag nanoparticles were successfully synthesized by hydrothermal method under the polyol system combined with traces of sodium chloride, Silver nitrate(AgNO3) and polyvinylpyrrolidone (PVP) acted as the silver source and dispersant respectively. The samples by this process were characterized via X-ray powder diffraction (XRD), Brunauer–Emmett–Teller (BET) adsorption equation, transmission electron microscopy (TEM) and the corresponding selected area electron diffraction (SAED) to determine the chemical composition, particle size, crystal structure and morphology. The experiment results indicate that the crystal structure of the samples is face centered cubic (FCC) structure as same as the bulk materials, The specific surface area is 24 m2/g, the particle size distribution ranging from10 to 50 nm, with an average particle size about 26 nm obtained by TEM and confirmed by XRD and BET results.

Intact Ultrathin Ni Films Fabricated by Electroplating with Supercritical CO2 Emulsion

2013 ◽  
Vol 284-287 ◽  
pp. 147-151
Author(s):  
Tso Fu Mark Chang ◽  
Takashi Nagoshi ◽  
Chiemi Ishiyama ◽  
Tatsuo Sato ◽  
Masato Sone
Keyword(s):  
Grain Size ◽  
Surface Morphology ◽  
Grain Refinement ◽  
Deposition Time ◽  
Reactive Species ◽  
Complete Coverage ◽  
Transport Efficiency ◽  
Working Electrode ◽  
Incomplete Coverage

Ultrathin (2 emulsion (SCE). Incomplete coverage of the Cu plate, the working electrode, by electroplated Ni and non-uniform Ni films with defects were obtained when conventional electroplating at 1 A/dm2 with 30 sec of deposition time was used. When electroplating with SCE (ESCE) was applied, complete coverage, defect-free and uniform UTNFs were obtained. SEM and AFM showed surface morphology of the UTNFs was covered by spherical-shaped particles with ~10 nm in diameter, which was expected to be individual Ni grains because the size was consistent with grain size of Ni films reported when ESCE was applied. High H2 solubility in CO2, periodic-plating-characteristic after applying ESCE, and improved transport efficiency of the reactive species are believed to be the main reasons to cause effects of grain refinement and suppression in formation of the defects. Thickness of the UTNFs was 11.97±1.82 nm when the deposition time was 15 sec, and the thickness increased to 38.45±1.71 nm when the deposition time was increased to 45 sec.

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