G. K. Marasinghe

University of North Dakota

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W. J. James

Schott (Germany)

W. B. Yelon

Missouri University of Science and Technology

O. A. Pringle

Missouri University of Science and Technology

Gary J. Long

Missouri University of Science and Technology

M. Karabulut

Gebze Technical University

Delbert E. Day

Missouri University of Science and Technology

Chandra S. Ray

Missouri University of Science and Technology

Fernande Grandjean

Missouri University of Science and Technology

P. C. Ezekwenna

Missouri University of Science and Technology

Naushad Ali

Southern Illinois University Carbondale

Cooperative Institutions

Missouri University of Science and Technology

The Graduate Center, CUNY

University of Missouri

Centre National de la Recherche Scientifique

University of California, Berkeley

Lawrence Berkeley National Laboratory

Argonne National Laboratory

American Ceramic Society

Lawrence Livermore National Laboratory

Massachusetts Institute of Technology

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Structural features of hafnium iron phosphate glasses

Journal of Non-Crystalline Solids (2009)

M. Karabulut Mustafa Yüksek G. K. Marasinghe Delbert E. Day

Iron phosphate

Phosphate glass

Hafnium

10.1016/j.jnoncrysol.2009.06.005

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Citations (24)

Mechanical and structural properties of phosphate glasses

Journal of Non-Crystalline Solids (2001)

M. Karabulut Е И Мельник Rǎzvan Ştefan G. K. Marasinghe Chandra S. Ray

Phosphate glass

10.1016/s0022-3093(01)00615-9

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Citations (125)

Polymer Assisted Synthesis of FeNi Nanoparticles

arXiv (Cornell University) (2012)

Sanjay Karna Sachin Mishra E. Gunapala Igor Dubenko V. Malagareddy

Polymer assisted spherical FeNi nanoparticles were prepared via wet chemical method using hydrazine as a reducing agent and polymers (PVP and PEG) as reducing and stabilizing agent. Structural studies performed using XRD and TEM shows uniform dispersion of fine FeNi nanocrystallites in nanocomposite particles. The size and thermal stability of FeNi nanoparticles prepared under same reaction condition was found to be dependent on the type and the molecular weight of the polymer used. However, the magnetic properties of nanocomposite particles were not influenced by the polymers. The study highlights subtle differences in using polymers during the synthesis of alloyed nanocomposite particles.

Thermal Stability

Polymer nanocomposite

Hydrazine (antidepressant)

Dispersion stability

Source

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Citations (6)

Neutron diffraction and magnetic studies of Nd/sub 2/Fe/sub 17-x/T/sub x/ (T=Si, Mn) alloys

IEEE Transactions on Magnetics (1996)

W. B. Yelon Z.Q. Hu M. Chen Hongxi Luo P. C. Ezekwenna

We have carried out neutron and magnetic studies on Nd/sub 2/Fe/sub 17-x/T/sub x/ (T=Si, Mn) alloys. The unit cell of the compounds contracts with both Si and Mn substitution. Si atoms avoid the 6c site, prefer the 18h site strongly, fill the 9d site steadily and fill the 18f site only at relatively high Si concentration. Mn atoms avoid the 9d sites but prefer the 6c site strongly, while the 18f site and 18h site fill slowly. The Si site occupancies appear to be dominated by the crystal environment while the Mn site occupancies are dominated by steric considerations. The Curie temperature of the compound Nd/sub 2/Fe/sub 17/ increases significantly with Si substitution but is only affected slightly by the Mn substitution. Although the unit cell contracts with increasing Si concentration, the average length of bonds to the Fe(6c) and the Fe(18f) sites increase slightly at x<4.

10.1109/20.538891

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Citations (32)

Magnetic and crystallographic properties of SmMn/sub 6-x/Fe/sub x/Ge/sub 6/ intermetallics

IEEE Transactions on Magnetics (2000)

J. Han G. K. Marasinghe W. J. James M. Chen W. B. Yelon

The magnetic and crystallographic properties of induction-melted SmMn/sub 6-x/Fe/sub x/Ge/sub 6/ compounds, where x is 0, 0.5, 1.0, and 1.5, have been studied using X-ray diffraction and bulk magnetic measurements between 30 and 490 K. All of the samples crystallized in the YCo/sub 6/Ge/sub 6/-type structure with the space group P6/mmm. A small amount, less than 9 mol%, of Sm(MnFe)/sub 2/Ge/sub 2/ was present as an impurity in all samples. The unit cell volume decreases with increasing iron content at an average rate of 2.4% per substituted atom at room temperature. The a and c lattice parameters decrease at an average rate of 1.1 and 0.1% per substituted atom at room temperature, respectively. The magnetic properties deteriorate rapidly as the iron concentration increases beyond x=0.5. Magnetic behavior of SmMn/sub 5/Fe/sub 1/Ge/sub 6/ and SmMn/sub 4.5/Fe/sub 1.5/Ge/sub 6/ is indicative of antiferromagnetic or ferrimagnetic coupling. According to X-ray diffraction patterns of magnetically aligned powders, the easy direction of magnetization at room temperature for all of the samples lies close to the basal plane of the unit cell.

Ferrimagnetism

10.1109/20.908786

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Citations (44)

Neutron diffraction studies of ErNi/sub 5-x/Co/sub x/ (x=0.68, 1.68, 2.26) alloys

IEEE Transactions on Magnetics (1995)

Zhongliang Zu W. B. Yelon G. K. Marasinghe W. J. James

ErNi/sub 5-x/Co/sub x/ alloys were prepared by RF induction melting and analyzed using neutron powder diffraction. Rietveld analysis neutron diffraction data indicates the unit cell volume increases with Co content while the a and c lattice parameters show different dependencies on the composition. The Co atoms show higher affinity for the 3g sites than for the 2c sites. The Co sublattice tends to couple antiferromagnetically to the Er sublattice. The easy magnetization direction is along the c axis.

Rietveld Refinement

Lattice constant

Powder Diffraction

10.1109/20.489601

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Citations (5)

Nanoscale effects of silica particle supports on the formation and properties of TiO2 nanocatalysts

Nanoscale (2013)

Aize Li Yuhui Jin Darrin S. Muggli David T. Pierce Hemantha Aranwela

Small TiO2 crystals in the anatase phase are in high demand as photocatalysts. Stable TiO2 crystals in the anatase phase were obtained using a silica nanoparticle as a support. The focus of this study was to investigate the nanoscale effect of the silica support on the formation and properties of small anatase crystals. The experiments were carried out using powder X-ray diffraction, differential thermal analysis, transmission electron microscopy, and energy dispersion spectroscopy. The results showed that the size of the silica support played a crucial role in crystallization of TiO2 and regulation of TiO2 properties, including phase transition, crystal size, thermodynamic property and catalytic activity. A nanoscale curvature model of the spherical silica support was proposed to explain these size effects. Finally, the developed TiO2 catalysts were applied to the oxidation of methanol using a high-throughput photochemical reactor. The size effect of the silica supports on the TiO2 catalytic efficiency was demonstrated using this system.

Nanomaterial-based catalyst

Crystal (programming language)

10.1039/c3nr01287e

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Citations (38)

The atomic and magnetic structure of NdMn(6−x)FexGe6 solid solutions

Journal of Applied Physics (2000)

J. Han G. K. Marasinghe W. J. James M. Chen W. B. Yelon

The magnetic and crystallographic properties of induction-melted NdMn(6−x)FexGe6 intermetallics (x=0, 1.0, and 1.5) in the temperature range of 30–475 K have been studied by x-ray and neutron diffraction techniques and SQUID measurements. All of the samples crystallized in the YCo6Ge6-type structure (P6/mmm). A small amount (<5 mol%) of Nd(MnFe)2Ge2 is present as an impurity. As expected, iron replaces manganese at the 3g site. The unit cell volume decreases slightly with increasing iron content at an average rate of 1.3% per substituted atom. Lattice parameters a and c contract at a rate of 0.6% and 0.2% per substitution atom, respectively. The net magnetization of these samples decreases rapidly with increasing iron content. According to neutron diffraction data, the magnetic moment of the iron sublattice couples negatively with ferromagnetically coupled manganese and neodymium moments. Addition of iron suppresses the spin reorientation processes observed in NdMn6Ge6. Whereas the net moment in NdMn5Fe1Ge6 slowly cants away from the c-axis with increasing temperature, the easy direction of NdMn4.5Fe1.5Ge6 is approximately parallel to the c-axis in the temperature range mentioned above.

Magnetic structure

Formula unit

10.1063/1.373321

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Citations (9)

A neutron diffraction study of the atomic ordering in Er(Fe1 − xCox)3

Journal of the Less Common Metals (1989)

Dwayne E. Tharp O. A. Pringle W.J. James G. K. Marasinghe Gary J. Long

Magnetic structure

Curie

10.1016/0022-5088(89)90513-4

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Citations (3)

Electronic structures and magnetism of LaNi5–xFex compounds

Journal of Applied Physics (2001)

Jinbo Yang C. Y. Tai G. K. Marasinghe G. D. Waddill O. A. Pringle

A systematic study of the magnetic moments and hyperfine interactions of the LaNi5–xFex compounds was performed using the spin-polarized tight-binding-linear-muffin-tin-orbital methods (TBLMTO). The calculated results were compared with neutron diffraction and Mössbauer experimental data and found to be in good agreement. Fe atoms exhibit more localized magnetic moments in LaNi5–xFex when the Fe content x is lower than 1.0. The calculated magnetic moments of the Fe atoms approach values as large as 2.5μB due to the dilution effect. The strong s–d hybridization between the Ni and La atoms and the neighboring Fe in the Fe-substituted samples results in a large transferred valence contribution to the total hyperfine field. It is found that the Fe and Ni magnetic moments decrease abruptly at a unit cell volume which is 5% smaller than the observed volume in LaNi4Fe due to the instability of the Fe magnetic moment. LaNi5 becomes ferromagnetic when the unit cell volume is larger than its original volume.

Magnetism

10.1063/1.1357854

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Citations (12)