Related Research Articles
In physics and materials science,the Curie temperature (TC),or Curie point,is the temperature above which certain materials lose their permanent magnetic properties,which can (in most cases) be replaced by induced magnetism. The Curie temperature is named after Pierre Curie,who showed that magnetism was lost at a critical temperature.
Coercivity,also called the magnetic coercivity,coercive field or coercive force,is a measure of the ability of a ferromagnetic material to withstand an external magnetic field without becoming demagnetized. Coercivity is usually measured in oersted or ampere/meter units and is denoted HC.
Maghemite (Fe2O3,γ-Fe2O3) is a member of the family of iron oxides. It has the same formula as hematite,but the same spinel ferrite structure as magnetite (Fe3O4) and is also ferrimagnetic. It is sometimes spelled as "maghaemite".
A magnon is a quasiparticle,a collective excitation of the spin structure of an electron in a crystal lattice. In the equivalent wave picture of quantum mechanics,a magnon can be viewed as a quantized spin wave. Magnons carry a fixed amount of energy and lattice momentum,and are spin-1,indicating they obey boson behavior.
Dynamic nuclear polarization (DNP) results from transferring spin polarization from electrons to atomic nuclei,thereby aligning the nuclear spins to the extent that electron spins are aligned. Note that the alignment of electron spins at a given magnetic field and temperature is described by the Boltzmann distribution under the thermal equilibrium. It is also possible that those electrons are aligned to a higher degree of order by other preparations of electron spin order such as:chemical reactions,optical pumping and spin injection. DNP is considered one of several techniques for hyperpolarization. DNP can also be induced using unpaired electrons produced by radiation damage in solids.
Iron(II,III) oxide,or black iron oxide,is the chemical compound with formula Fe3O4. It occurs in nature as the mineral magnetite. It is one of a number of iron oxides,the others being iron(II) oxide (FeO),which is rare,and iron(III) oxide (Fe2O3) which also occurs naturally as the mineral hematite. It contains both Fe2+ and Fe3+ ions and is sometimes formulated as FeO ∙ Fe2O3. This iron oxide is encountered in the laboratory as a black powder. It exhibits permanent magnetism and is ferrimagnetic,but is sometimes incorrectly described as ferromagnetic. Its most extensive use is as a black pigment (see:Mars Black). For this purpose,it is synthesized rather than being extracted from the naturally occurring mineral as the particle size and shape can be varied by the method of production.
Electron paramagnetic resonance (EPR) or electron spin resonance (ESR) spectroscopy is a method for studying materials that have unpaired electrons. The basic concepts of EPR are analogous to those of nuclear magnetic resonance (NMR),but the spins excited are those of the electrons instead of the atomic nuclei. EPR spectroscopy is particularly useful for studying metal complexes and organic radicals. EPR was first observed in Kazan State University by Soviet physicist Yevgeny Zavoisky in 1944,and was developed independently at the same time by Brebis Bleaney at the University of Oxford.
Imperfections in the crystal lattice of diamond are common. Such defects may be the result of lattice irregularities or extrinsic substitutional or interstitial impurities,introduced during or after the diamond growth. The defects affect the material properties of diamond and determine to which type a diamond is assigned;the most dramatic effects are on the diamond color and electrical conductivity,as explained by the electronic band structure.
Multiferroics are defined as materials that exhibit more than one of the primary ferroic properties in the same phase:
Cobalt(II) oxide is an inorganic compound that has been described as an olive-green or gray solid. It is used extensively in the ceramics industry as an additive to create blue-colored glazes and enamels,as well as in the chemical industry for producing cobalt(II) salts. A related material is cobalt(II,III) oxide,a black solid with the formula Co3O4.
Helimagnetism is a form of magnetic ordering where spins of neighbouring magnetic moments arrange themselves in a spiral or helical pattern,with a characteristic turn angle of somewhere between 0 and 180 degrees. It results from the competition between ferromagnetic and antiferromagnetic exchange interactions. It is possible to view ferromagnetism and antiferromagnetism as helimagnetic structures with characteristic turn angles of 0 and 180 degrees respectively. Helimagnetic order breaks spatial inversion symmetry,as it can be either left-handed or right-handed in nature.
Bismuth ferrite (BiFeO3,also commonly referred to as BFO in materials science) is an inorganic chemical compound with perovskite structure and one of the most promising multiferroic materials. The room-temperature phase of BiFeO3 is classed as rhombohedral belonging to the space group R3c. It is synthesized in bulk and thin film form and both its antiferromagnetic (G type ordering) Néel temperature (approximately 653 K) and ferroelectric Curie temperature are well above room temperature (approximately 1100K). Ferroelectric polarization occurs along the pseudocubic direction () with a magnitude of 90–95 μC/cm2.
Superferromagnetism is the magnetism of an ensemble of magnetically interacting super-moment-bearing material particles that would be superparamagnetic if they were not interacting. Nanoparticles of iron oxides,such as ferrihydrite,often cluster and interact magnetically. These interactions change the magnetic behaviours of the nanoparticles and lead to an ordered low-temperature phase with non-randomly oriented particle super-moments.
Melting-point depression is the phenomenon of reduction of the melting point of a material with a reduction of its size. This phenomenon is very prominent in nanoscale materials,which melt at temperatures hundreds of degrees lower than bulk materials.
Magnetic nanoparticles (MNPs) are a class of nanoparticle that can be manipulated using magnetic fields. Such particles commonly consist of two components,a magnetic material,often iron,nickel and cobalt,and a chemical component that has functionality. While nanoparticles are smaller than 1 micrometer in diameter,the larger microbeads are 0.5–500 micrometer in diameter. Magnetic nanoparticle clusters that are composed of a number of individual magnetic nanoparticles are known as magnetic nanobeads with a diameter of 50–200 nanometers. Magnetic nanoparticle clusters are a basis for their further magnetic assembly into magnetic nanochains. The magnetic nanoparticles have been the focus of much research recently because they possess attractive properties which could see potential use in catalysis including nanomaterial-based catalysts,biomedicine and tissue specific targeting,magnetically tunable colloidal photonic crystals,microfluidics,magnetic resonance imaging,magnetic particle imaging,data storage,environmental remediation,nanofluids,optical filters,defect sensor,magnetic cooling and cation sensors.
DPPH is a common abbreviation for the organic chemical compound 2,2-diphenyl-1-picrylhydrazyl. It is a dark-colored crystalline powder composed of stable free radical molecules. DPPH has two major applications,both in laboratory research:one is a monitor of chemical reactions involving radicals,most notably it is a common antioxidant assay,and another is a standard of the position and intensity of electron paramagnetic resonance signals.
Iron oxide nanoparticles are iron oxide particles with diameters between about 1 and 100 nanometers. The two main forms are composed of magnetite and its oxidized form maghemite. They have attracted extensive interest due to their superparamagnetic properties and their potential applications in many fields including molecular imaging.
Zinc ferrites are a series of synthetic inorganic compounds of zinc and iron (ferrite) with the general formula of ZnxFe3−xO4. Zinc ferrite compounds can be prepared by aging solutions of Zn(NO3)2,Fe(NO3)3,and triethanolamine in the presence and in the absence of hydrazine,or reacting iron oxides and zinc oxide at high temperature. Spinel (Zn,Fe) Fe2O4 appears as a tan-colored solid that is insoluble in water,acids,or diluted alkali. Because of their high opacity,zinc ferrites can be used as pigments,especially in applications requiring heat stability. For example,zinc ferrite prepared from yellow iron oxide can be used as a substitute for applications in temperatures above 350 °F (177 °C). When added to high corrosion-resistant coatings,the corrosion protection increases with an increase in the concentration of zinc ferrite.
In acoustics,acoustic paramagnetic resonance (APR) is a phenomenon of resonant absorption of sound by a system of magnetic particles placed in an external magnetic field. It occurs when the energy of the sound wave quantum becomes equal to the splitting of the energy levels of the particles,the splitting being induced by the magnetic field. APR is a variation of electron paramagnetic resonance (EPR) where the acoustic rather than electromagnetic waves are absorbed by the studied sample. APR was theoretically predicted in 1952,independently by Semen Altshuler and Alfred Kastler,and was experimentally observed by W. G. Proctor and W. H. Tanttila in 1955.
Superparamagnetic relaxometry (SPMR) is a technology combining the use of sensitive magnetic sensors and the superparamagnetic properties of magnetite nanoparticles (NP). For NP of a sufficiently small size,on the order of tens of nanometers (nm),the NP exhibit paramagnetic properties,i.e.,they have little or no magnetic moment. When they are exposed to a small external magnetic field,on the order of a few millitesla (mT),the NP align with that field and exhibit ferromagnetic properties with large magnetic moments. Following removal of the magnetizing field,the NP slowly become thermalized,decaying with a distinct time constant from the ferromagnetic state back to the paramagnetic state. This time constant depends strongly upon the NP diameter and whether they are unbound or bound to an external surface such as a cell. Measurement of this decaying magnetic field is typically done by superconducting quantum interference detectors (SQUIDs). The magnitude of the field during the decay process determines the magnetic moment of the NPs in the source. A spatial contour map of the field distribution determines the location of the source in three dimensions as well as the magnetic moment.
References
- 1 2 3 4 "Professor Mohindar Singh Seehra Retires". 20 January 2017.
- ↑ "APS Fellow Archive".
- ↑ "Mohinder Seehra - Google Scholar".
- ↑ "From Partition of the Indian Subcontinent, a hard-won wholeness". Archived from the original on 2020-11-09. Retrieved 2021-03-26.
- ↑ Punnoose, A.; Magnone, H.; Seehra, M. S.; Bonevich, J. (2001). "Bulk to nanoscale magnetism and exchange bias in CuO nanoparticles". Physical Review B. 64 (17): 174420. Bibcode:2001PhRvB..64q4420P. doi:10.1103/PhysRevB.64.174420.
- ↑ Dutta, P.; Pal, S.; Seehra, M. S.; Shi, Y.; Eyring, E. M.; Ernst, R. D. (2006). "Concentration of Ce3+ and Oxygen Vacancies in Cerium Oxide Nanoparticles". Chemistry of Materials. 18 (21): 5144–5146. doi:10.1021/cm061580n.
- ↑ Park, Wan Kyu; Ortega-Hertogs, Ricardo J.; Moodera, Jagadeesh S.; Punnoose, Alex; Seehra, M. S. (2002). "Semiconducting and ferromagnetic behavior of sputtered Co-doped TiO2 thin films above room temperature". Journal of Applied Physics. 91 (10): 8093. Bibcode:2002JAP....91.8093P. doi:10.1063/1.1452650.
- ↑ Dutta, P.; Seehra, M. S.; Thota, S.; Kumar, J. (2008). "A comparative study of the magnetic properties of bulk and nanocrystalline Co3O4". Journal of Physics: Condensed Matter. 20 (1): 015218. Bibcode:2008JPCM...20a5218D. doi:10.1088/0953-8984/20/01/015218. S2CID 55609724.
- ↑ Dutta, P.; Manivannan, A.; Seehra, M. S.; Shah, N.; Huffman, G. P. (2004). "Magnetic properties of nearly defect-free maghemite nanocrystals". Physical Review B. 70 (17): 174428. Bibcode:2004PhRvB..70q4428D. doi:10.1103/PhysRevB.70.174428.
- ↑ "Neutron scattering and magnetic studies of ferrihydrite nanoparticles".
- ↑ Punnoose, A.; Phanthavady, T.; Seehra, M. S.; Shah, N.; Huffman, G. P. (2004). "Magnetic properties of ferrihydrite nanoparticles doped with Ni, Mo, and Ir". Physical Review B. 69 (5): 054425. Bibcode:2004PhRvB..69e4425P. doi:10.1103/PHYSREVB.69.054425. S2CID 120219874.
- ↑ Neeleshwar, S.; Chen, C. L.; Tsai, C. B.; Chen, Y. Y.; Chen, C. C.; Shyu, S. G.; Seehra, M. S. (2005). "Size-dependent properties of CdSe quantum dots". Physical Review B. 71 (20): 201307. Bibcode:2005PhRvB..71t1307N. doi:10.1103/PhysRevB.71.201307.
- ↑ "Size-dependent magnetic parameters of fcc FePt nanoparticles: Applications to magnetic hyperthermia".
- ↑ Pisane, K. L.; Singh, Sobhit; Seehra, M. S. (2017). "Unusual enhancement of effective magnetic anisotropy with decreasing particle size in maghemite nanoparticles". Applied Physics Letters. 110 (22): 222409. arXiv: 1702.08378 . Bibcode:2017ApPhL.110v2409P. doi:10.1063/1.4984903. S2CID 119487428.
- ↑ Seehra, Mohindar S. (1968). "New Method for Measuring the Static Magnetic Susceptibility by Paramagnetic Resonance". Review of Scientific Instruments. 39 (7): 1044–1047. Bibcode:1968RScI...39.1044S. doi: 10.1063/1.1683559 .
- ↑ Castner, T. G.; Seehra, Mohindar S. (1971). "Antisymmetric Exchange and Exchange-Narrowed Electron-Paramagnetic-Resonance Linewidths". Physical Review B. 4 (1): 38–45. Bibcode:1971PhRvB...4...38C. doi:10.1103/PhysRevB.4.38.
- ↑ Seehra, Mohindar S. (1971). "Frequency Dependence of the EPR Linewidth in MnF2 Near the Critical Point". Journal of Applied Physics. 42 (4): 1290–1292. Bibcode:1971JAP....42.1290S. doi: 10.1063/1.1660219 .
- ↑ Hùber, D. L.; Seehra, M. S. (1976). "Electron Paramagnetic Resonance in Anisotropic Magnets". Physica Status Solidi B. 74 (1): 145–149. Bibcode:1976PSSBR..74..145H. doi:10.1002/pssb.2220740114.
- ↑ Seehra, Mohindar S.; Ibrahim, Manjula M.; Babu, V Suresh; Srinivasan, G. (1996). "The linear temperature dependence of the paramagnetic resonance linewidth in the manganate perovskites". Journal of Physics: Condensed Matter. 8 (50): 11283–11289. doi:10.1088/0953-8984/8/50/048. S2CID 250872679.
- ↑ Dalal, N. S.; Millar, J. M.; Jagadeesh, M. S.; Seehra, M. S. (1981). "Paramagnetic resonance, magnetic susceptibility, and antiferromagnetic exchange in a Cr5+ paramagnet: Potassium perchromate (K3CrO8)". The Journal of Chemical Physics. 74 (3): 1916–1923. Bibcode:1981JChPh..74.1916D. doi:10.1063/1.441284.
- ↑ "Magnetic properties of Mn3O4 and a solution of the canted-spin problem".
- ↑ Das, S. R.; Choudhary, R. N. P.; Bhattacharya, P.; Katiyar, R. S.; Dutta, P.; Manivannan, A.; Seehra, M. S. (2007). "Structural and multiferroic properties of La-modified BiFeO3 ceramics". Journal of Applied Physics. 101 (3): 034104–034104–7. Bibcode:2007JAP...101c4104D. doi:10.1063/1.2432869.
- ↑ Seehra, M. S.; Helmick, R. E.; Srinivasan, G. (1986). "Effect of temperature and antiferromagnetic ordering on the dielectric constants of MnO and MnF2". Journal of Physics C: Solid State Physics. 19 (10): 1627–1635. Bibcode:1986JPhC...19.1627S. doi:10.1088/0022-3719/19/10/016.
- ↑ Thota, Subhash; Shim, J. H.; Seehra, M. S. (2013). "Size-dependent shifts of the Néel temperature and optical band-gap in NiO nanoparticles". Journal of Applied Physics. 114 (21): 214307–214307–4. Bibcode:2013JAP...114u4307T. doi:10.1063/1.4838915.
- ↑ Kou, William W.; Seehra, Mohindar S. (1978). "Optical absorption in iron pyrite (FeS2)". Physical Review B. 18 (12): 7062–7068. Bibcode:1978PhRvB..18.7062K. doi:10.1103/PhysRevB.18.7062.
- ↑ Babu, V.Suresh; Seehra, M.S. (1996). "Modeling of disorder and X-ray diffraction in coal-based graphitic carbons". Carbon. 34 (10): 1259–1265. doi:10.1016/0008-6223(96)00085-1.
- ↑ Seehra, Mohindar S.; Narang, Vishal; Geddam, Usha K.; Stefaniak, Aleksandr B. (2017). "Correlation between X-ray diffraction and Raman spectra of 16 commercial graphene–based materials and their resulting classification". Carbon. 111: 380–385. doi:10.1016/j.carbon.2016.10.010. PMC 5497829 . PMID 28690336.
- ↑ Seehra, M.S.; Bollineni, S. (2009). "Nanocarbon boosts energy-efficient hydrogen production in carbon-assisted water electrolysis". International Journal of Hydrogen Energy. 34 (15): 6078–6084. doi:10.1016/j.ijhydene.2009.06.023.
- 1 2 "Mohindar Singh Seehra, PhD, Presented with the Albert Nelson Marquis Lifetime Achievement Award by Marquis Who's Who".
- ↑ "Past Mary Catherine Buswell Award Winners".
- ↑ "Roll of the Order of Vandalia".
| Authority control databases: Academics |
|---|
