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61.
We have investigated the superconducting properties of the Bi1.7 Pb0.3Sr2Ca2−xCe
x
Cu3O10+δ system with x=0.00, 0.02, 0.04, 0.08 and 0.1 by X-ray diffraction and magnetic susceptibility. The substitution of Ce for Ca has been found
to drastically change the superconducting properties of the system. X-ray diffraction studies on these compounds indicate
decrease in the c-parameter with increased substitution of Ce at Ca site and volume fraction of high T
c (2 : 2 : 2 : 3) phase decreases and low T
c phase increases. The magnetic susceptibility of this compound shows that the diamagnetic on set superconducting transition
temperature (onset) varies from 109 K to 51 K for x=0.00, 0.02, 0.04, 0.08 and 0.1. These results suggest the possible existence of Ce in a tetravalent state rather than a trivalent
state in this system; that is, Ca2+ → Ce4+ replacement changes the hole carrier concentration. Hole filling is the cause of lowering T
c of the system. 相似文献
62.
P. S. Radhakrishna Murti B. M. Sasmal D. P. Patnaik 《Reaction Kinetics and Catalysis Letters》1985,28(2):455-461
Kinetics of iodination ofp-aminobenzoic acid ando-aminobenzoic acid at different pH and solvent media has been studied. The order of the reaction with respect to the iodinating agent and substrates was established. Reactions were carried out with buffer mixtures of primary and secondary phosphates and catalytic constants were evaluated. Effect of temperature and dielectric constant of solvents used were studied. Suitable mechanism and composite rate law have been suggested.
- - . . . . .相似文献
63.
R. Vijaya Y. V. G. S. Murti T. A. Vijayaraj G. Sundararajan 《Optical and Quantum Electronics》1993,25(10):723-731
Conjugated polymers with sidegroups such as methyl, trimethylsilyl, p-methoxy phenyl, o-methoxy phenyl, and hexyl groups on a polyphenylacetylene chain are studied in an attempt to understand the contribution of factors such as the backbone, conformation of the chain, sidegroups and polymerization catalyst on the optical nonlinearities. The results of degenerate four-wave mixing experiments at 532 nm with nanosecond pulses indicate that the substitution of an electron-donating group away from the backbone can enhance the third-order susceptibility. Some of the polymers show optical limiting action at this wavelength. The thermal contribution to the measured susceptibility is also determined. 相似文献
64.
The NaCl → CsCl structural pressure transformation is studied using a new interionic potential. The theoretical transition pressures are in good agreement with experiment. 相似文献
65.
In this paper, we establish several inequalities for some differantiable mappings that are connected with the Riemann-Liouville fractional integrals. The analysis used in the proofs is fairly elementar... 相似文献
66.
D. V. Ramana Murti P. Venkatacharyulu D. Premaswarup 《Magnetic resonance in chemistry : MRC》1980,13(2):143-147
Two resonance lines were observed in 2,6-dichlorobenzamide, both in liquid nitrogen and at room temperatures, using a self quenched super-regenerative NQR spectrometer. Analysis of the Zeeman effect on the two lines using an uncut crystal grown from solution reveals: (1) the crystal belongs to the orthorhombic system; (2) there are two crystallographically equivalent but physically non-equivalent directions for the principal field gradient making an angle of 71° for the low frequency line, and four such directions for the high frequency line; (3) the directions of the crystalline axes a, b and c are tentatively fixed as (90°, 90°), (90°, 90°) and (0°,—); (4) from morphological studies a: b: c are estimated as 0.959 ± 0.005: 1:1,402 ± 0.005 and, from the estimated density (1.440 gms/cc) of the crystal, the absolute values a, b, c are calculated, on the basis of four molecules per unit cell, as a = 8.33 Å, b = 8.68 Å and c = 12.18 Å; (5) there are a mininium of four molecules per unit cell; the four molecules lie in four different planes which are, however, connected by symmetry operations. There is an inplane bending by 6.5° between the two C? Cl bonds away from one another and (6) the ionic, single bond and double bond characters for both chlorines are almost equal and are in the ratio 25:72:3. 相似文献
67.
68.
Thiobenzoylacetone in benzene is used for the extraction and spectrophotometric determination of cobalt at pH 8.4-9.1. The orange-yellow complex is measured at 460 nm. The system conforms to Beer's law over the range 0.20-4.58 microg ml of extract. The colour of the complex is stable for at least 144 hr. Cobalt(II) is quantitatively extracted and determined in the presence of 200:1 (w w ratios) of various ions. The method is made selective by using common sequestering agents such as thiourea or fluoride or by selective extraction with mesityl oxide, tributylphosphate and acetylacetone. It is possible to determine cobalt in the presence of nickel by simultaneous spectrophotometry. The method is rapid, simple, selective and sensitive. 相似文献
69.
H. P. Nawada P. Srirama Murti G. Seenivasan S. Anthonysamy C. K. Mathews 《Journal of Thermal Analysis and Calorimetry》1989,35(4):1145-1155
Systematic studies were carried out on the oxidation behaviour of uranium dicarbide in air in the temperature range 25 °C to 700 °C employing thermogravimetry, evolved gas detection X-ray diffraction and chemical analysis. The mechanistic aspects were investigated and the oxidation was found to proceed through reaction processes involving oxidation of uranium to-UO3 with release of chemically bound carbon, reaction of released carbon leading to the formation of CO2 which gets liberated stepwise, decomposition of-UO3 to U3O8 and oxidation of free carbon to CO2. Examination of the thermoanalytical behaviour of sintered graphite, UO3, mixtures of graphite with UO3 and with U3O8 supported the above findings.
The authors wish to thank Dr. M. K. Ahmed for his help in O/U measurements and Dr. P. R. Vasudeva Rao for useful advices during the course of the work. 相似文献
Zusammenfassung Das Oxydationsverhalten von Urandikarbid in Luft im Temperaturbereich zwischen 25 und 700 °C wurde mittels Thermogravimetrie, Gasprodukteanalyse, Röntgendiffraktion und chemischer Analyse systematisch untersucht. Studien des Mechanismus ergaben, daß die Oxydation über Teilschritte abläuft, die folgende Schritte beinhalten: Oxydation von Uran zu-UO3 unter Freisetzung chemisch gebundenen Kohlenstoffes, Reaktion des freigesetzten Kohlenstoffes unter Bildung von CO2, das schrittweise entweicht, Zerfall von-UO3 zu U3O8 und Oxydation von freiem Kohlenstoff zu CO2. Diese Feststellungen wurden durch Untersuchung des thermoanalytischen Verhaltens gesinterter Graphit- und UO3-Proben sowie Mischproben von Graphit mit UO3 bzw. U3O8 bekräftigt.
, , 25–700°. , , -UO3 , , , -UO3 U3O8 . ë , UO3, UO3 U3O8 .
The authors wish to thank Dr. M. K. Ahmed for his help in O/U measurements and Dr. P. R. Vasudeva Rao for useful advices during the course of the work. 相似文献
70.
M. V. R. Murti S. S. Raju B. Seetharami Reddy V. Koteswara Rao L. S. Mombaswala T. Seshi Reddy S. Lakshminarayana K. Premachand 《Pramana》2008,70(4):747-752
K X-ray emission spectra of Ti, V, Cr and Mn generated by photon excitation have been studied with a crystal spectrometer.
The measured energy shifts of Kα satellite relative to the diagram line are compared with values obtained by electron excitation and with different theoretical
estimates. The present experimental values of KαL1/KαL0 relative intensities are compared with values obtained by electron excitation.
相似文献