Microstructural characterization of ball-milled α-Al2O3: bimodal size distribution and shape anisotropy

2007 ◽  
Vol 40 (1) ◽  
pp. 33-39 ◽  
Author(s):  
Apurba Kanti Deb ◽  
Partha Chatterjee ◽  
Siba Prasad Sen Gupta
Keyword(s):  
Size Distribution ◽  
Goodness Of Fit ◽  
Microstructural Characterization ◽  
Rietveld Analysis ◽  
X Ray Diffraction ◽  
Bimodal Size Distribution ◽  
X Ray ◽  
Diffraction Patterns ◽  
Α Al2o3

α-Al2O3prepared by combustion technique was ball-milled in a planetary ball-mill for several hours. A detail microstructural characterization of the ball-milled samples was performed by X-ray line broadening analysis. X-ray diffraction patterns from the milled materials showed super-Lorentzian peak shapes for the α-Al2O3peak profiles, attributed to a bimodal size distribution of the α-Al2O3crystallites, one type of crystallites having spherical and the other having cylindrical morphology. Rietveld analysis using two different phase fractions of α-Al2O3with different microstructural features yielded a low goodness-of-fit of the X-ray data, indicating the suitability of the assumed model.

Structural Transformations of Boron Nitride Powders Obtained by Mechanical Milling Process

2009 ◽  
Vol 68 ◽  
pp. 101-108
Author(s):  
Rodrigo A. Esparza ◽  
J. Ayala ◽  
C. Ángeles-Chávez ◽  
G. Rosas ◽  
Ramiro Pérez
Keyword(s):  
Boron Nitride ◽  
Microstructural Characterization ◽  
Structural Transformations ◽  
Milling Process ◽  
X Ray Diffraction ◽  
Microstructural Characteristics ◽  
X Ray ◽  
Diffraction Patterns ◽  
Milled Powders

Mechanical milled powders of boron nitride were obtained. The microstructural characterization of these milled powders was carried out using X-ray diffraction technique. Insights on the nature of the crystalline phases obtained in these milled powders were obtained between comparisons of theoretical and experimental X-ray diffraction patterns. Observations on the phase transformations have been carried out using calorimetry and thermogravity experiments. Morphological and microstructural characteristics of nanocrystals are obtained using SEM and HRTEM instruments.

Microstructure Formation of Al-Fe-Mn-Si Aluminides by Pressure-Assisted Reactive Sintering of Elemental Powder Mixtures

2009 ◽  
Vol 68 ◽  
pp. 21-33 ◽  
Author(s):  
Alfredo Flores ◽  
J.A. Toscano ◽  
S. Rodríguez ◽  
A. Salinas R. ◽  
Enrique Nava-Vázquez
Keyword(s):  
Microstructural Characterization ◽  
Rietveld Analysis ◽  
Reactive Sintering ◽  
X Ray Diffraction ◽  
Microstructure Formation ◽  
Powder Mixtures ◽  
X Ray ◽  
Intermediate Phases ◽  
Diffraction Patterns ◽  
Metallurgical Reactions

This paper presents the results of an investigation aimed at understanding microstructure formation of Al-Fe-Mn-Si intermetallics during pressure-assisted reactive sintering of elemental powders. The proportion of elements was selected such that the composition of the product was 55 wt % Al, 17 wt % Si, 14 wt % Mn, and 14 wt % Fe. Experiments were conducted at temperatures between 600 and 800°C, using compaction stresses of up to 20 MPa. Rietveld analysis of x-ray diffraction patterns of fully processed samples showed that the powders were transformed into a mixture of Al9FeMnSi and Al9FeMn2Si phases. However, as temperature and pressure were increased, the Al9FeMnSi phase was transformed into the Al9FeMn2Si phase. Differential Thermal Analysis, as well as microstructural characterization by scanning electron microscopy and x-ray diffraction, showed that these intermetallics do not form directly from the powder mixtures. Rather, they are the result of metallurgical reactions between a molten Al-Si solution and various intermediate phases formed during reactive sintering.

A microstructural characterization of Co-Zr type permanent-magnet materials

1991 ◽  
Vol 49 ◽  
pp. 782-783
Author(s):  
K. R. Lawless ◽  
G. C. Hadjipanayis
Keyword(s):  
Melt Spinning ◽  
Microstructural Characterization ◽  
X Ray Diffraction ◽  
Ion Milling ◽  
X Ray ◽  
Heat Treated ◽  
Diffraction Patterns ◽  
Rapidly Solidified ◽  
Hard Magnetic Properties

Considerable interest has been shown recently in the hard magnetic properties of Co-Zr, Co-Zr-B, and Co-Hf-B alloys, but as yet no detailed microstructural studies have been published. The Co-Zr phase diagram seems to be reasonably well known, although the crystal structure of the Co11Zr2 phase is only partially determined. This paper will report on some preliminary studies of rapidly solidified Co-Zr-B-Si and Co-Hf-B-Si alloys and binary Co-Zr alloys.All specimens used in this study were prepared by melt spinning. Specific alloys were heat treated at temperatures from 650 to 900°C. TEM specimens were prepared from ribbon material by ion milling.X-ray diffraction studies of these alloys all showed a characteristic broad peak centered around d = 0.205nm. Although it was obvious that this was a complex peak, attempts to deconvolute it were unsuccessful. SAD patterns revealed that major phases in the alloys were very heavily faulted, thus giving rise to the very confusing X-ray diffraction patterns.

Influence of the Residue of Casting by Lost Wax in the Modulus of Elasticity and Porosity of Concretes

2014 ◽  
Vol 805 ◽  
pp. 343-349
Author(s):  
Carine F. Machado ◽  
Weber G. Moravia
Keyword(s):  
Construction Industry ◽  
Modulus Of Elasticity ◽  
Chemical Characterization ◽  
Microstructural Characterization ◽  
Cement Matrix ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hardened State ◽  
Material Powder

This work evaluated the influence of additions of the ceramic shell residue (CSR), from the industries of Lost Wax Casting, in the modulus of elasticity and porosity of concrete. The CSR was ground and underwent a physical, chemical, and microstructural characterization. It was also analyzed, the environmental risk of the residue. In the physical characterization of the residue were analyzed, the surface area, and particle size distribution. In chemical characterization, the material powder was subjected to testing of X-ray fluorescence (XRF). Microstructural characterization was performed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The residue was utilized like addition by substitution of cement in concrete in the percentages of 10% and 15% by weight of Portland cement. It was evaluated properties of concrete in the fresh and hardened state, such as compressive strength, modulus of elasticity, absorption of water by total immersion and by capillarity. The results showed that the residue can be used in cement matrix and improve some properties of concrete. Thus, the CSR may contribute to improved sustainability and benefit the construction industry.

scholarly journals Perbaikan Kelarutan Albendazol Melalui Pembentukan Kristal Multikomponen dengan Asam Malat

2020 ◽  
Vol 6 (1) ◽  
pp. 114-123
Author(s):  
Fikri Alatas ◽  
Fahmi Abdul Azizsidiq ◽  
Titta Hartyana Sutarna ◽  
Hestyari Ratih ◽  
Sundani Nurono Soewandhi
Keyword(s):  
Phase Solubility ◽  
Crystal Formation ◽  
Solubility Curve ◽  
X Ray Diffraction ◽  
Ethanol Mixture ◽  
X Ray ◽  
Grinding Method ◽  
Diffraction Patterns ◽  
Phase Solubility Curve

An effort to improve the solubility of albendazole (ABZ), an anthelmintic drug has been successfully carried out through the formation of multicomponent crystal with dl-malic acid (MAL). Construction of phase solubility curve of ABZ in MAL solution and crystal morphological observations after recrystallization in the acetone-ethanol (9:1) mixture were performed for initial prediction of multicomponent crystal formation. ABZ-MAL multicomponent crystal was prepared by wet grinding or also known as solvent-drop grinding (SDG) with acetone-ethanol (9:1) mixture as a solvent followed by characterization of the multicomponent crystal formation by powder X-ray diffraction and Fourier transform infrared (FTIR) methods. The solubility of ABZ-MAL multicomponent crystal was tested in water at ambient temperature and in pH 1.2, 4.5 and 6.8 of buffered solutions at 37°C. The phase solubility curve of the ABZ in the MAL solution showed type Bs. The ABZ-MAL mixture has a different crystalline morphology than pure ABZ and MAL after recrystallization in the acetone-ethanol mixture (9:1). The powder X-ray diffraction pattern and the FTIR spectrum of ABZ-MAL from SDG different from intact ABZ and MAL powder X-ray diffraction patterns and these results can indicate the ABZ-MAL multicomponent crystal formation. The ABZ-MAL multicomponent crystal has better solubility than pure ABZ in all media used. These results can be concluded that ABZ-MAL multicomponent crystal can be prepared by solvent-drop grinding method with acetone-ethanol (9:1) mixture as a solvent and can increase the solubility of albendazole.

scholarly journals PECHINI SYNTHESIS AND CHARACTERIZATION OF Eu3+ DOPED ZnCo2O4 SPINELS

2005 ◽  
Vol 03 (2) ◽  
pp. 24-29
Author(s):  
P.M. PIMENTEL ◽  
A.M.G. PEDROSA ◽  
H.K.S. SOUZA ◽  
C.N.S. JÚNIOR ◽  
R.C.A. PINTO ◽  
...  
Keyword(s):  
Spinel Structure ◽  
Pechini Method ◽  
Synthesis Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Spinel Oxides ◽  
Diffraction Patterns ◽  
Pechini Synthesis ◽  
Spinel Structures

Spinel oxides with the composition ZnCo2O4 and ZnCo2O4:Eu3+ have been synthesized by the Pechini method and characterized by X-ray diffraction, infrared spectroscopy, thermal analysis and scanning electron microscopy. IR spectroscopy revealed the presence of n1 and n2 bands, typical of spinel structures. The formation of monophase cubic spinel structure was confirmed by X-ray diffraction patterns. Extra lines corresponding to other phase has been observed in the powders calcined at 900 ºC. The results showed the extremely lower synthesis temperature than those presents in conventional methods.

The Synthesis of Ce-Filled CoSb3 and Characterization of its Magnetic and Structural Properties

2003 ◽  
Vol 793 ◽  
Author(s):  
Arwyn L. E. Smalley ◽  
Brandon Howe ◽  
David C. Johnson
Keyword(s):  
Low Temperatures ◽  
Magnetic Measurements ◽  
Rietveld Analysis ◽  
X Ray Diffraction ◽  
Electrical Measurements ◽  
X Ray ◽  
Ferromagnetic Component ◽  
Phase Pure ◽  
Powder Samples

ABSTRACTA series of cerium-containing CoSb3 samples were synthesized, with cerium quantities varying from 0 to 2 stoichiometric equivalents. These samples were annealed at low temperatures to crystallize the kinetically stable phases CexCo4Sb12 (x = 0–0.5). X-ray diffraction showed that these samples were phase pure, and Rietveld analysis on x-ray diffraction data from powder samples indicated that these samples were 25–88% crystalline. Electrical measurements showed that these samples are n-type, which was previously unknown in CexCo4Sb12. Magnetic measurements showed that the samples were paramagnetic due to the cerium being incorporated into the diamagnetic CoSb3 compound. In addition, they contained a ferromagnetic component that was attributed to the amorphous, cerium-containing phase.

Growth and Characterization of bulk GaN by Ga Vapor Transport

2004 ◽  
Vol 831 ◽  
Author(s):  
Phanikumar Konkapaka ◽  
Huaqiang Wu ◽  
Yuri Makarov ◽  
Michael G. Spencer
Keyword(s):  
Growth Rates ◽  
Vapor Transport ◽  
Spiral Growth ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Bulk Gan ◽  
Diffraction Patterns

ABSTRACTBulk GaN crystals of dimensions 8.5 mm × 8.5 mm were grown at growth rates greater than 200μm/hr using Gallium Vapor Transport technique. GaN powder and Ammonia were used as the precursors for growing bulk GaN. Nitrogen is used as the carrier gas to transport the Ga vapor that was obtained from the decomposition of GaN powder. During the process, the source GaN powder was kept at 1155°C and the seed at 1180°C. Using this process, it was possible to achieve growth rates of above 200 microns/hr. The GaN layers thus obtained were characterized using X-Ray diffraction [XRD], scanning electron microscopy [SEM], and atomic force microscopy [AFM]. X-ray diffraction patterns showed that the grown GaN layers are single crystals oriented along c direction. AFM studies indicated that the dominant growth mode was dislocation mediated spiral growth. Electrical and Optical characterization were also performed on these samples. Hall mobility measurements indicated a mobility of 550 cm2/V.s and a carrier concentration of 6.67 × 1018/cm3

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