共查询到20条相似文献,搜索用时 109 毫秒
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H.Y. Mo X.C. Zhong D.L. Jiao Z.W. Liu H. Zhang W.Q. Qiu R.V. Ramanujan 《Physics letters. A》2018,382(25):1679-1684
Gd55Co35Mn10 ribbons were prepared by melt-spinning and subsequent crystallization treatment. Crystallization resulted in the precipitation of the Gd3Co-type and Gd12Co7-type phases in the amorphous matrix. Under a magnetic field change of 0–5 T, a table-like magnetocaloric effect, with a maximum magnetic entropy change of in the temperature range of 137–180 K and enhanced refrigerant capacity (RC) of , was achieved in Gd55Co35Mn10 ribbons crystallized at 600 K for 30 min. The table-like feature and enhanced RC values make Gd55Co35Mn10 crystallized ribbons promising for Ericsson-cycle magnetic refrigeration in the temperature range from 137 to 180 K. 相似文献
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Ram Niranjan R.K. Rout B.S. Tomar P.S. Ramanjaneyulu D.B. Paranjape T.C. Kaushik 《Physics letters. A》2018,382(46):3365-3368
Pulsed neutrons generated in a plasma focus device are used for the thermal neutron activation analysis (TNAA) of selected three elements having widely different half-lives varying from a few seconds to a few days [Dysprosium (Dy), Manganese (Mn) and Gold (Au)]. Neutron pulse having strength of neutrons/pulse with a pulse width of is produced by “MEPF-12” device operated at a filling gas (deuterium + 0.5% krypton) pressure of 3 mbar. The fast 2.45 MeV D–D neutrons are thermalized before irradiating the sample. The decay gammas from the radioisotopes 165mDy (), 56Mn (), and 198Au () produced via reactions, 164Dy()165mDy, 55Mn() 56Mn, and 197Au() 198Au respectively are counted off-line in a lead shielded well type NaI(Tl) detector coupled to a calibrated 2048 channel analyzer. The values of half-lives evaluated from the measured decay gammas, , and respectively for the radioisotopes of Dy, Mn and Au, are seen to be close to the values reported in literature. 相似文献
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D.P. Rojas L. Fernández Barquín C. Echevarria-Bonet J. Rodríguez Fernández 《Solid State Communications》2012,152(19):1834-1837
Measurements of the magnetization and specific heat of YbNi2 binary alloy are reported. The DC magnetic susceptibility displays a ferromagnetic behavior with a Curie temperature TC=10.5 K, one of the highest found in Yb compounds. Moreover, the temperature dependence of the specific heat exhibits a lambda anomaly with a peak of 5.12 J/mol K at 9.4 K. The analysis also shows an additional magnetic contribution around 32 K stemming from the crystalline electric field of a quartet at and a doublet at , according to the splitting of the Yb3+ ion in cubic symmetry. From the magnetic contribution to the specific heat, a relatively high Kondo temperature is estimated. Below the magnetic transition, the specific heat shows a huge value of the electronic coefficient , which is a signature of a heavy fermion behavior. Therefore, this alloy is a fine example of enhanced ferromagnetism and heavy fermion behavior among Yb compounds. 相似文献
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《Radiation measurements》2008,43(1):1-4
Time-resolved luminescence spectra from quartz can be separated into components with distinct principal and secondary lifetimes depending on certain combinations of annealing and measurement temperature. The influence of annealing on properties of the lifetimes related to irradiation dose and temperature of measurement has been investigated in sedimentary quartz annealed at various temperatures up to . Time-resolved luminescence for use in the analysis was pulse stimulated from samples at 470 nm between 20 and . Luminescence lifetimes decrease with measurement temperature due to increasing thermal effect on the associated luminescence with an activation energy of thermal quenching equal to for the secondary lifetime but only qualitatively so for the principal lifetime component. Concerning the influence of annealing temperature, luminescence lifetimes measured at are constant at about for annealing temperatures up to but decrease to about when the annealing temperature is increased to . In addition, it was found that lifetime components in samples annealed at are independent of radiation dose in the range 85–1340 Gy investigated. The dependence of lifetimes on both the annealing temperature and magnitude of radiation dose is described as being due to the increasing importance of a particular recombination centre in the luminescence emission process as a result of dynamic hole transfer between non-radiative and radiative luminescence centres. 相似文献
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Manisha Bajpai Kusum Kumari Ritu Srivastava M.N. Kamalasanan R.S. Tiwari Suresh Chand 《Solid State Communications》2010,150(13-14):581-584
The current density–voltage () behavior of polymer PDY 132 thin films has been investigated in hole-only device configuration, viz., ITO/poly(ethylene-dioxthiophene):polystyrenesulphonate (PEDOT:PSS)/PDY 132/Au, as a function of polymer (PDY) film thickness (150 nm and 200 nm) and temperature (290–90 K). Hole current density was found to follow two distinct modes of conduction, (i) low electric field region I: ohmic conduction where slope , and (ii) intermediate and high electric field region II: non ohmic conduction where slope . Region I has been attributed to the transport of intrinsic background charge carriers while region II has been found to be governed by space charge limited currents (SCLC) with hole mobility strongly dependent on electric field and temperature. The respective hole transport parameters determined from the SCLC regime, is , is , and zero field activation energy () of 0.48 eV is obtained. 相似文献
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Leonardo Campanelli 《Chinese Journal of Physics (Taipei)》2018,56(1):91-95
We study the generation of cosmic magnetic fields during de Sitter inflation in a non-conformally-invariant effective model of massive electrodynamics containing a four-photon interaction term. We show that, if the photon self-coupling is strong enough, comoving magnetic fields correlated on scales of 10kpc and of intensities are produced as excitation of the vacuum. If amplified by galactic dynamo, they naturally explain the existence of galactic magnetic fields. 相似文献
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Recently, micrometer-size patterned magnetic materials have been widely used in MEMS devices. However, the self-demagnetizing action is significantly influencing the performance of the magnetic materials in many MEMS devices. Here, we report an experimental study on the magnetic properties of the patterned micro-scale FeGaB/Al2O3 multilayers. Ferromagnetic hysteresis loop, ferromagnetic resonance (FMR), permeability and domain behavior have been demonstrated by complementary techniques. Magnetic annealing was used to enhance the performance of magnetic multilayers. The comparisons among micro-islands with different sizes in the range of as well as full film show a marked influence of size-effect, the exchange coupling effect, and the different domain structures inside the islands. 相似文献