Characterization and Alumina Leachability of 12CaO·7Al2O3with Different Holding Times

The effect of synthesis time on phase compositions, lattice constant, average grain size, preferred orientation, and surface morphology of 12CaO·7Al2O3synthesized at 1500°C was analyzed by XRD and SEM. The results indicate that the main phase of samples synthesized is 12CaO·7Al2O3when holding time is over 30 min. The lattice constant increases and the preferred orientation decreases as synthesis time prolongs. The average grain size of samples is about 59 nm calculated by Scherrer formula, and it does not change with synthesis time. The synthesis time affects the micromorphology of samples greatly. There are more and bigger holes in samples synthesized for long time. The aspects mentioned above cause the alumina leaching ratio of 12CaO·7Al2O3to increase with the prolonging of synthesis time, but the rate of increase drops.

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Nanostructured ZrO2 Thin Films Deposited by Spray Pyrolysis Techniques for Ammonia Gas Sensing Application

International Letters of Chemistry Physics and Astronomy ◽

10.18052/www.scipress.com/ilcpa.56.120 ◽

2015 ◽

Vol 56 ◽

pp. 120-130 ◽

Cited By ~ 4

Author(s):

S.B. Deshmukh ◽

R.H. Bari

Keyword(s):

Thin Films ◽

Grain Size ◽

Surface Morphology ◽

Spray Pyrolysis ◽

Gas Sensing ◽

Spray Pyrolysis Technique ◽

Film Surface ◽

Ammonia Gas ◽

Water Solvent ◽

Average Grain Size

The spray pyrolysis deposition technique has number of advantages to produce advance nanostructured oxide films. The film surface morphology and structure depends on the precursor and doping solution and solvents used with their optimized parameters. The surface to volume ratio is achieved is beneficial to gas sensing. Therefore in this paper we report the nanostructured ZrO2 thin films was prepared using spray pyrolysis technique for ammonia gas sensing. There is various precursors such as Zirconium acetylacetonate, Zirconium nitrate, Zirconium tetra chloride etc. In spite of them, the Zirconium oxychloride octohydrate (0.05 M) was chosen as precursor solution and was prepared by dissolving in pure distilled water (Solvent). The films were deposited on heated glass substrate at 350◦C and were annealed at 500◦C for 1 hrs. It was characterized using XRD, FESEM, and TEM technique to examine crystal structure, surface morphology and microstructure properties. The average crystallite and grain size observed to be nanostructured in nature. The different test target gas performances were tested with various concentrations at different operating temperature. The films sprayed for 20 min with optimized spray parameter were observed to be most sensitive (S=58.5) to NH3 for 500 ppm at 150°C. The film thickness dependence parameters: FWHM (0.02678 radians) for peak 111, Inter-planer distance (d=0.2958 nm), lattice parameters Inter-atomic spacing ( a=0.511 nm), atomic volume(a3= 133Å3 ),micro strain (2.8 to 0.76 x 10-2), crystallite size (4-5nm) average grain size (32nm), dislocation density (1.73 x1015 lines/cm2), texture coefficient (>1), specific surface area(31 m2/g), activation energy and band gap were studied. The sensor shows quick response (4 s) and fast recovery (10 s). Reported results are discussed and interpreted

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Microstructural Evolution of AZ31 Mg Wrought Alloy during Partial Remelting for Thixoextrusion

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.116-117.251 ◽

2006 ◽

Vol 116-117 ◽

pp. 251-254

Author(s):

Young Ok Yoon ◽

Shae K. Kim

Keyword(s):

Grain Size ◽

Microstructural Evolution ◽

Liquid Fraction ◽

Isothermal Holding ◽

Holding Time ◽

Interesting Point ◽

Grain Sizes ◽

Partial Remelting ◽

Average Grain Size ◽

Holding Temperature

An attempt has been made to investigate feasibility of thixoextrusion for AZ31 Mg wrought alloy through simple partial remelting. Microstructural evolution of AZ31 Mg wrought alloy for thixoextrusion was investigated as functions of isothermal holding temperature and time in the partially remelted semisolid state. The interesting point of this study was that the thixotropic structures of AZ31 Mg wrought alloy without additional pretreatment could be obtained through simple partial remelting. The uniform average grain size and liquid fraction according to the isothermal holding time were very important for the thixoextrusion. Because, it is must be considered on actual extrusion time. The liquid fraction was increased with increasing isothermal holding temperature and time. But, the liquid fraction was almost uniform after 10 min. The average grain size was decreased with increasing isothermal holding temperature. On the other hand, as the holding time increased, the average grain sizes were uniform at 615 and 622. This phenomenon is very useful for thixoextrusion in terms of process control such as actual extrusion time.

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STRUCTURAL CHARACTERIZATION OF CO-PRECIPITATED Cd1-xZnxS:Cu CRYSTALS

International Journal of Modern Physics B ◽

10.1142/s0217979202008099 ◽

2002 ◽

Vol 16 (03) ◽

pp. 481-496 ◽

Cited By ~ 4

Author(s):

ABDUL NAYEEM ◽

K. YADAIAH ◽

G. VAJRALINGAM ◽

P. MAHESH ◽

M. NAGABHOOSHANAM

Keyword(s):

Grain Size ◽

Dislocation Density ◽

Internal Stress ◽

Lattice Constant ◽

Structural Characterization ◽

Structural Parameters ◽

Size Variation ◽

Preferred Orientation ◽

Average Internal Stress

Structural characterization of Cd 1-x Zn x S : Cu solid solutions were carried out with 0≤x≤1. XRD studies have revealed that the compounds are polycrystalline in nature having either Hexagonal (wurtzite) or Cubic (Zincblende) structure irrespective of their composition. Also the compounds have shown the most preferred reflections due to the plane [101] of CdS(H) and [111] of ZnS(C) in addition to other prominent reflections. The various structural parameters such as lattice constant, average internal stress, micro strain, dislocaion density, grain size, and preferred orientation were correlated with the composition. The lattice constant decreased linearly with the increase in Zn concentration. The sign of internal stress indicated elongational and compressional natures corresponding to hexagonal and cubic phases of CdS respectively. The variation of micro strain appeared to be conjugate when compared to grain size variation, and the variation of dislocation density with the composition showed a higher dislocation density till x=0.4 and then decreased till x=0.8 and then increased. The degree of preferred orientation in mixed Cd 1-x Zn x S : Cu crystals as observed by the maximum peak intensity of CdS(H) and ZnS(C) reflection showed that the degree of preferred orientation remained almost constant till x=0.6 and then increased. The results were explained on the basis of different phases of the compound and the defects related to Zn atoms.

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Effects of Melt Holding Time on as Cast Microstructure and Tensile Properties of Sr-Modified AS31Alloy

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.697.67 ◽

2014 ◽

Vol 697 ◽

pp. 67-71 ◽

Cited By ~ 1

Author(s):

Jin Wei Wang ◽

Ji Xue Zhou ◽

Bai Chang Ma ◽

Shou Qiu Tang ◽

Fu Min Chu ◽

...

Keyword(s):

Grain Size ◽

Elevated Temperature ◽

Ambient Temperature ◽

Tensile Properties ◽

Holding Time ◽

Chinese Script ◽

Modification Effect ◽

Average Grain Size ◽

Polyhedral Shape ◽

Cast Microstructure

Melt holding time has important influences on the modification effect of Sr modified AS31 alloy. Effects of different melt holding time (30min, 60min, 90min and 120min) at 700°C on as cast microstructure and tensile properties both at ambient temperature and elevated temperature of Sr-modified AS31 alloy were studied. There exist polyhedral shape, fine fibers shape and a few Chinese script Mg2Si particles in Sr-modified AS31 alloys. And the average grain size is smallest in Sr-modified AS31 alloys with holding time at 700°C for 30min. The ultimate strength, yield strength and elongation at both ambient temperature and 150°C decrease gradually when the melt holding time increases from 30min to 120min. In the process of smelting of Sr-modified AS31. The burning loss of Sr element becomes more serious with the prolongation of melt holding time, which contributes to the modification effect reducing.

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Synthesis of Sr4Al14O25:Eu2+, Dy3+ via Using Cyclodextrin as Chelating Agent by Sol-Gel Method

Materials Science Forum ◽

10.4028/www.scientific.net/msf.809-810.702 ◽

2014 ◽

Vol 809-810 ◽

pp. 702-706

Author(s):

Wen Feng Xu ◽

Cheng Li Liao ◽

Fu Hang Xiong ◽

Kui Li ◽

Xiao Ling Liao

Keyword(s):

Grain Size ◽

Surface Morphology ◽

Sol Gel ◽

Chelating Agent ◽

Gel Method ◽

Sol Gel Method ◽

Reducing Atmosphere ◽

Average Grain Size ◽

Pure Phase ◽

First Time

Sr4Al14O25:Eu2+, Dy3+ luminescent phosphor was synthesized for the first time from using cyclodextrin as chelating agent by sol-gel method. The structural characterization, surface morphology and properties of the phosphor were studied. The results revealed that the target phosphor with relatively regular morphology, smaller grain size, pure phase and high crystallinity can be achieved at 1200°C for 4 h in a reducing atmosphere. The average grain size of the Sr4Al14O25:Eu2+, Dy3+ phosphor nanoparticles ranges from 50 to 100 nm . And the phosphorescence in blue-green (483 nm) by Eu2+.

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Effect of Synthesis Time on Microscopic Characteristics of 12CaO·7Al2O3

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.560-561.263 ◽

2012 ◽

Vol 560-561 ◽

pp. 263-266

Author(s):

Bo Wang ◽

Hui Lan Sun ◽

Xue Zheng Zhang

Keyword(s):

Surface Morphology ◽

Lattice Constant ◽

Main Phase ◽

Synthesis Time ◽

Time Changes ◽

Short Time ◽

Micro Morphology

The effect of synthesis time on phase compositions, lattice constant and surface morphology of samples synthesized at 1773K were analyzed by XRD and SEM. The results are: the main phase of sample synthesized for 30min is 12CaO•7Al2O3, besides it also has little quantity of CaO•Al2O3. When prolonging synthesis time the phase tends to be 12CaO•7Al2O3 only. The lattice constant increases as synthesis time prolongs. The micro-morphology of samples synthesized for different time changes greatly. There are more and bigger holes in samples synthesized for longer time than that of short time. The comprehensive influences of phase compositions, lattice constant and surface morphology caused the differences of alumina leaching ratio of 12CaO•7Al2O3 synthesized for different time.

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Polycrystalline Grain Structure of Sputtered Aluminum Nitride Films

MRS Proceedings ◽

10.1557/proc-343-753 ◽

1994 ◽

Vol 343 ◽

Cited By ~ 1

Author(s):

Asher T Matsuda ◽

H. Ming Liaw ◽

Wayne A Cronin ◽

Harland G Tompkins ◽

Peter L Fejes ◽

...

Keyword(s):

Grain Size ◽

Surface Morphology ◽

Aluminum Nitride ◽

Columnar Structure ◽

Preferred Orientation ◽

Grain Structure ◽

Axis Orientation ◽

Force Microscopy ◽

Transmission Electron ◽

Acoustic Wave Devices

ABSTRACTReactively-sputtered, polycrystalline thin film aluminum nitride (AlN) is an attractive material for use in acoustic wave devices, for which it requires a strong preferred orientation, similar to that found in epitaxial films. This investigation evaluated the grain structure including preferred orientation, grain size, and surface morphology of sputtered A1N films. The characterization techniques utilized included x-ray diffraction (XRD), secondary ion mass spectroscopy (SIMS), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The results revealed two types of grain structure: 1) a single-grain columnar structure that is perfectly oriented in the [001] direction throughout the entire film thickness and 2) a multiple-grain columnar structure that possesses a strong [001] orientation at the bottom of the film and a tilted [001] combined with other orientations at the top of the film. Strong correlations between orientation and surface morphology, oxygen content, and grain size were observed, namely higher degrees of c-axis orientation correlated with lower mean surface roughness values, reduced oxygen concentration, and narrower grains.

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NANOSTRUCTURE AND PROPERTIES OF INDIUM TIN OXIDE (ITO) FILMS PRODUCED BY ELECTRON BEAM EVAPORATION

Modern Physics Letters B ◽

10.1142/s0217984906011402 ◽

2006 ◽

Vol 20 (17) ◽

pp. 1049-1058 ◽

Cited By ~ 12

Author(s):

ARTORN POKAIPISIT ◽

NITINAI UDOMKAN ◽

PICHET LIMSUWAN

Keyword(s):

Grain Size ◽

Electron Beam ◽

Surface Morphology ◽

Tin Oxide ◽

Indium Tin Oxide ◽

Electron Beam Evaporation ◽

Visible Range ◽

Average Crystalline Size ◽

Average Grain Size ◽

Ito Films

Nanocrystal indium tin oxide (ITO) thin films were grown by electron beam evaporation (e-beam). The ITO films were fabricated at substrate temperatures ranging from 100 to 400°C in O 2 partial pressure ranging from 0.10 to 100 mTorr. The surface morphology was monitored using atomic force microscopy (AFM). The charge in the surface morphology of ITO films was discussed in terms of grain size and crystallographic orientations. Grain size measurements of the solid dispersed and the AFM study for nanostructure showed that the oxides were in the nano range (20–30 nm). In general, the values of the optical bandgap for the films are consistently blue-shifted as compared with the crystal size. The average crystalline size determined from the shift of the optical gap were found to be in the range 20–30 nm, which is in excellent agreement with the data obtained from AFM. All ITO films average grain size was ~ 20 nm deposited by e-beam evaporation. The average optical transmittance was 90.50% in the visible range (400–700 nm) and the average bandgap was 3.98 eV. ESR spectrum of ITO film showed random oxygen vacancies which arise due to the changing crystal field effects.

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Effect of Nanosized Particles on the Mechanical Properties of Y2O3

Materials Science Forum ◽

10.4028/www.scientific.net/msf.750.44 ◽

2013 ◽

Vol 750 ◽

pp. 44-47

Author(s):

Hadi Razavi Khosroshahi ◽

Xin Liu ◽

Noritaka Saito ◽

Kunihiko Nakashima ◽

Kenji Kaneko

Keyword(s):

Mechanical Properties ◽

Grain Size ◽

Relative Density ◽

Holding Time ◽

Second Step ◽

Nanosized Particles ◽

Firing Schedule ◽

Average Grain Size ◽

Optimum Firing ◽

Series Of Experiments

A systematic series of experiments was performed to determine the optimum firing schedule of Y2O3. A two-step sintering with subsequent profile succeeded to fabricate Y2O3 ceramic with the relative density of 97.6% and the average grain size of 0.46 μm: first step and second step temperature of T1 = 1490 °C and T2 = 1350 °C, respectively and second step holding time of t2 = 20 h. After the firing schedule of pure Y2O3 was determined, two types of TiO2/Y2O3 and ZrO2/Y2O3 composites were fabricated for the further improvement of mechanical properties. According to results, ZrO2/Y2O3 composite showed a dramatic increase in strength and toughness as 417 MPa and 4.4 MPa.m1/2, respectively.

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SPRAY FORMING OF FINEMET ALLOY FE73.5CU1NB3SI13.5B9

International Journal of Modern Physics B ◽

10.1142/s0217979209060828 ◽

2009 ◽

Vol 23 (06n07) ◽

pp. 1282-1287

Author(s):

SHA YANG ◽

BIAO YAN ◽

PENG DONG ◽

LEDING GUAN

Keyword(s):

Grain Size ◽

Amorphous Alloys ◽

Melt Spinning ◽

Optical Microscope ◽

Spray Forming ◽

Nominal Composition ◽

Transmission Electron ◽

Average Grain Size ◽

Median Diameter ◽

Scherrer Formula

Fe -based amorphous alloys are widely used in the magnetic apparatus and generally produced by the single-roller copper-wheel melt spinning method. Spray forming is one of the rapid solidification techniques as the spinning method is, seldom used to fabricate Fe -based amorphous alloys. However in this paper, a Fe -based alloy with the nominal composition of Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 ( at .%) alloy was fabricated by spray forming technique with the aim of investigating the formation of amorphous phases and novel microstructures by the high cooling rate involved in this process. The gas/metal mass flow rate used was 0.15, and nitrogen was used as the atomization gas. The resulting deposit and the overspray powder had a median diameter of about 50 μm with a total weight of about 2.2 kg. The microstructure of the deposit was observed by utilizing the X-Ray Diffraction (XRD) and Optical Microscope (OM), as well as Transmission Electron Microscope (TEM), which revealed a heterogeneous varying with the thickness, presenting at center region 15 mm and at border 8 mm with porosities 4 and 9%, respectively. The thicker region showed a fully crystalline microstructure with grain size of about 250nm, whereas the thinner region had a partially amorphous phase with an average grain size of 40nm. The overspray powder was fully crystallized with the grain size of 80nm which was calculated from XRD spectra using the Scherrer formula. The magnetic properties were measured through VSM, giving a poor magnetic saturation value of about 0.3~0.6 T . The coercive force was increased significantly.

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