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CM Thaker S Rayaprol Krushna Mavani DS Rana MS Sahasrabudhe SI Patil DG Kuberkar 《Pramana》2002,58(5-6):1035-1039
The effect of simultaneous substitution of a fluctuating cation and a divalent cation in LaMnO3 perovskite modifies the properties of the material to exhibit large valence colossal magnetoresistance (CMR) effect. A good
example of these properties is (La1−2x
Pr
x
Ca
x
)MnO3 (LPCMO) type CMR material. In this communication it is reported that, with the increase in x (for x=0.1, 0.15, 0.2), the T
c varies between 100 and 120 K with improvisation in metal-insulator transition. Interestingly, resistance increases with x from few hundred ohms to few kilo ohms with corresponding decrease in the unit cell volume. The results of the studies using
X-ray diffraction (XRD), electrical resistivity, magnetoresistance and ac susceptibility measurements on LPCMO samples for
understanding the structural, transport and magnetic properties are discussed in detail. 相似文献
3.
A simple pseudoexternal cavity with a commerically available broad-area laser diode, standard optics, and a thin FabryPerot etalon provides single-mode emission with 1-W optical power and a tuning range of ~0.5nm . The linewidth is estimated at 200MHz. Such high-power semiconductor laser systems are promising light sources for atomic physics, in which narrow-band high-power light is necessary, for example, for optical pumping of alkali metal vapor. Methods for expanding the tuning range and achieving higher narrow-band optical power are discussed. 相似文献
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D. Fink J. Krauser D. Nagengast T. Almeida Murphy J. Erxmeier L. Palmetshofer D. Bräunig A. Weidinger 《Applied Physics A: Materials Science & Processing》1995,61(4):381-388
Depth profiles of hydrogen implanted into crystalline silicon in random direction at different fluences have been measured by the15N technique and by SIMS. Whereas hydrogen implanted at a fluence of 1015 ions/cm2 shows some limited mobility, no such mobility is observed for higher implantation fluences. In these cases, ballistic computer codes describe the depth distributions well, within the ranges of both experimental and theoretical accuracy. Annealing up to 510 K does not change the hydrogen distributions.Furthermore, high-fluence hydrogen implantation into silicon dioxide has been examined. There is some indication for radiation-enhanced diffusion during the implantation process. Upon subsequent thermal annealing, the hydrogen is found to diffuse, probably via a trapping/detrapping mechanism associated with an OH/H2 transformation of the hydrogen bonding. 相似文献
5.
Kul Ismail Bhat Krishna Nagengast Alexis Azarewicz Julianne 《Journal of solution chemistry》2021,50(8):1051-1064
Journal of Solution Chemistry - Several thermodynamic parameters for trans-resveratrol have been experimentally determined or calculated at different temperatures. The capability of... 相似文献
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§ 1.Introduction WearegivenkindependentWishartdensitiesofthe (p +q)× (p +q)randomsymmetricpositivedefinitematricesG1,… ,Gktobeg(Gi) =Kexp -12 trR- 1i Gi Gi12 (ni- q-p- 1) ,(1 )wherei=1 ,… ,k,andRidenotesthepopulationcorrelationmatrixofthei thpopulationandKasagenericletterdenote… 相似文献
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S Rayaprol Krushna Mavani CM Thaker DS Rana Keka Chakravorty SK Paranjape M Ramanadham Nilesh A Kulkarni DG Kuberkar 《Pramana》2002,58(5-6):877-880
A new series of mixed oxide superconductors with the stoichiometric composition La2−x
Dy
x
Ca
y
Ba2Cu4+y
O
z
(x=0.0 − 0.5, y=2x) has been studied for structural and superconductiong properties. Our earlier studies on La2−x
(Y/Er)
x
Ca
y
Ba2Cu4+y
O
z
series, show a strong dependence of T
c on hole concentration (p
sh). In the present work, the results of the analysis of the neutron diffraction measurements at room temprerature on x=0.3 and 0.5 samples are reported. It is interesting to know that Ca substitutes for both La and Ba site with concomitant
displacement of La onto Ba site. Superconductivity studies show that maximum T
c is obtained for x=0.5, y=1.0 sample (T
c ∼ 75 K), for La1.5Dy0.5Ca1Ba2Cu5O
z
(La-2125). 相似文献
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