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21.
Sudhish Kumar S. K. Paranjpe Bipin K. Srivastava Anjali Krishnamurthy V. C. Sahni 《Pramana》1999,52(1):111-120
Magnetic behaviour of di-metal iron phosphide with a small substitution of iron by chromium, (Fe0.97Cr0.03)2P, has been studied using SQUID magnetometry and powder neutron diffraction. It is paramagnetic at temperatures above ∼180
K with persisting short range ferromagnetic (FM) order. At lower temperatures three different regions of magnetic behaviour
are identified. FM order evolves in the region 180 K-120 K but much more slowly and with much less magnetic moments than in
Fe2P. In the region 120 K-50 K negative exchange interactions gain some importance leading to a loss of FM order. Below 50 K
FM interactions again dominate. Pinning centres influence the behaviour at low temperature up to ∼100 K. 相似文献
22.
An analytical iterative procedure has been established to determine the amplitude of a laser beam propagating through an active
medium. The treatment is valid for both homogeneous and inhomogeneous broadening, and for arbitrary inhomogeneities of the
parameters characterizing the active medium, namely, the refractive index, the small-signal gain and the saturation intensity.
After a supplementary approximation, a thin-sheet gain approach is derived from the first iteration. The formalism enables
us to provide analytical criteria for evaluating both the accuracy of each iteration and the propagation distances for which
the thin-sheet solution can be used.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
23.
EPR investigations using Cu2+ ion as a probe have been performed on supersaturated sucrose solution with percent concentration c = 66 as a function of temperature T, and at room temperature as a function of c. The motionally averaged spectrum of [Cu(H2O)6]2+ was used to monitor the changes in intermolecular interactions that occur as a function of [c, T]. A drastic increase in the line width, symptomatic of increase in the rotational correlation time of [Cu(H2O)6]2+, is observed between 293 and 288 K. The motionally averaged spectrum disappears below 281 K. The motionally averaged spectrum is also absent in the room temperature spectra of the solution with c= 85. Even in the [c, T] range where [Cu(H2O)6]2 is found to be nearly static, these molecules appear to have an orientational fluctuation manifesting in the m 1 dependence of the line width of the parallel component. 相似文献
24.
N S Satya Murthy S K Paranjpe Marsongkohadi Kurniadi Sumaamidjaja M R L N Murthy 《Pramana》1985,24(1-2):311-316
The magnetic structures of Fe4N and Mn4N have been redetermined using neutron diffraction. The magnetic form factors, obtained from polarised neutron data have been
shown to be different for the face-centred and corner atoms. A qualitative explanation of the structures of Fe4N and Mn4N has been provided from the shapes of the magnetic form factors.
Since deceased. 相似文献
25.
Paranjpe AS 《Physical review letters》2002,89(7):075504
A sequence of morphological transitions in two-dimensional dehydration patterns of aqueous solutions of ascorbic acid is observed with humidity as a control parameter. Change in morphology occurs due to humidity induced variation in the concentration of the metastable supersaturated solution phase formed after initial solvent evaporation. As percent humidity is varied from 40 to 80, patterns change from compact circular --> radial --> density modulated radial (a new morphology) --> density modulated circular --> density modulated dendritic (a new morphology) --> dense branching. 相似文献
26.
Sudhish?KumarEmail author Anjali?Krishnamurthy Bipin?K.?Srivastava A.?Das S.?K.?Paranjpe 《Pramana》2004,63(2):199-205
Crystal structure and magnetic behaviour of FeCrP have been investigated using magnetization and neutron diffraction measurements.
FeCrP crystallizes in orthorhombic FeZrP type structure (Pnma space group,Z = 4) in which Cr atoms occupy the pyramidal site and Fe atoms occupy the tetrahedral site with total preference. Structural
parameters including positional parameters have been refined. The refined values of positional parameters for Fe and Cr are
quite different from those in FeZrP. The nature of magnetization-temperature curve is suggestive of antiferromagnetic nature
withT
N = 280 (±10) K. Preliminary analysis of neutron diffraction pattern at 13 K is indicative of a rather complicated magnetic
structure. 相似文献
27.
Kalpesh H. Jani K. B. Modi H. H. Joshi P. D. Babu S. K. Paranjpe 《Journal of magnetism and magnetic materials》2004,280(2-3):334-345
The spinel oxide system ZnzTizFe2−x−zCrx−zCoO4; z=x2; x=0.60, 0.65, 0.70 and 0.80, was studied using neutron diffraction technique, low field DC magnetization measurements (ZFC–FC measurements), magnetic hysterisis, Mössbauer spectroscopy and low field AC susceptibility measurements. All the compositions show significantly less B-site magnetic moments at 10 K temperature derived from neutron diffraction data than the free ions site moments deduced assuming collinear arrangement of spins. This combined with some other features seen in the low temperature neutron diffraction patterns suggest localized canting of spins (LCS) type of magnetic ordering in the present system where a long range order of longitudinal component of moments co-exists along with totally disordered transverse component of moments. The conclusion is also supported by the features seen in the other measurements. The magnetic moments derived from 10 K neutron diffraction data are explained using the LCS approach for different exchange integrals ratios. 相似文献
28.
MARTI´NEZ C. Encinas-Sanz F. Serna J. MEJI´AS P. M. MARTI´NEZ-HERRERO R. 《Optical and Quantum Electronics》1997,29(9):923-931
A simple analytical model is proposed to describe the transversal spatial structure of a tridimensional rotationally symmetric
pulsed beam. The spatial behaviour of the pulse amplitude is shown to be linked to its (measurable) second- and higher-order
intensity moments, namely, beam width, quality parameter and kurtosis. As an illustrative experimental example, this model
has been applied to high-quality TEA CO2 laser pulses.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
29.
S. K. Jain A. Das Bipin K. Srivastava Anjali Krishnamurthy S. K. Paranjpe 《Pramana》2004,63(2):207-212
Magnetization and neutron diffraction measurements have been made on the title pseudo-binary of tetragonal anti-ferromagnets
Fe2 As and Cr2 As. In this system antiferromagnetic (AFM) ordering appears below 310 K. The moments are confined in theab plane but unlike in the end members they are tilted off thea-axis. In addition to the AFM structure a weak ferromagnetic behaviour shows up below∼80 K with a rather low moment of ∼0.07
μB per formula unit at 5 K and under a field of 3 T. 相似文献
30.