Rotational structures in the 125Cs nucleus

The collective band structures of the ¹²⁵Cs nucleus have been investigated by in-beam γ-ray spectroscopic techniques following the ¹¹⁰Pd ( ¹⁹F, 4n) reaction at 75MeV. The previously known level scheme, with rotational bands built on πg_7/2, πg_9/2 and πh_11/2 orbitals, has been extended and evolves into bands involving rotationally aligned ν(h_11/2)² and π(h_11/2)² quasiparticles. A strongly coupled band has been reassigned a high-K πh_11/2 ⊗ νg_7/2 ⊗ νh_11/2 three-quasiparticle configuration and a new side band likely to be its chiral partner has been identified. Configurations assigned to various bands are discussed in the framework of Principal/Tilted Axis Cranking (PAC/TAC) model calculations.     

Ion acoustic solitons in a relativistic warm plasma with densitygradient

Modified Korteweg-deVries equation (mK-dV), which governs the behavior of ion acoustic solitons in a relativistic warm plasma with density gradient, is derived. The electron inertia is also taken into account which is important when the streaming ions are present in the plasma. A solution of the mK-dV equation is obtained for the constant density gradient. When the ion acoustic soliton propagates into the lower plasma density region, its amplitude and energy increase, but the width decreases; the same is the case for the stronger density gradients     

Magnetization and specific heat studies of RNi4Ga (RSm,Gd and Tb)

In order to elucidate the anomalous magnetic properties in the ferromagnetically ordered state of SmNi₄Ga GdNi₄Ga and TbNi₄Ga, we have carried out a detailed study with magnetization and specific heat (SH) measurements. GdNi₄Ga shows the possibility of a filled 3d band and a helical spin arrangement below the ordering temperature. TbNi₄Ga shows a dominant crystal field effect resulting in a deviation of T_C from the de-Gennes scaling and possible Schottky anomalies in the SH. SmNi₄Ga shows a large coercivity at low temperatures. A rough estimate of the domain wall thickness in SmNi₄Ga gives a value of 8 Å.     

Spectroelectrochemical identity of Prussian blue films in various electrolytes: comparison of time-derivative voltabsorptometric responses with conventional cyclic voltammetry

Using Prussian blue (PB) electrodeposited on gold-covered foil as a model system, we have demonstrated the usefulness of the time-derivative measurements of absorbance versus potential (linear potential-scan voltabsorptometry) for spectroelectrochemical characterization of thin electrochromic films. The time-derivative signals were monitored for PB at 680 and 420 nm in potassium, sodium and lithium electrolytes. Information obtained from cyclic voltabsorptometry is equivalent or complementary to that from conventional cyclic voltammetry. In the case of PB films investigated in lithium electrolyte, the voltabsorptometric time-derivative peaks are better defined than the respective voltammetric peaks. The combination of voltabsorptometry with voltammetry enables molar absorptivity and/or film loading to be determined. Also, concentration changes of differently colored mixed-valence redox centers can be monitored as a function of applied potential. Received: 16 January 1997 / Accepted: 11 March 1997     

57Fe and 166Er Mössbauer and magnetic studies of RFe4B (R = Er,Tm, Lu) compounds

Magnetic and Mössbauer studies have been carried out on a series of ternary borides RFe₄B (R = Er, Tm, Lu) which have the hexagonal CeCo₄B type structure. These compounds are found to be magnetically ordered at room temperature. Magnetization studies in the temperature range from 5 to 300 K reveal the presence of compensation temperatures in Er and Tm compounds and indicate antiferromagnetic coupling between the rare earth and Fe moments. Room temperature ⁵⁷Fe Mössbauer studies yield values of hyperfine fields at the two Fe sites as 246 and 185 kOe in ErFe₄B and TmFe₄B, and 204 and 145 kOe in LuFe₄B. The ¹⁶⁶Er Mössbauer studies give nearly free-ion hyperfine field at the Er sites which indicates that the exchange interaction in ErFe₄B is much stronger than crystal field interaction.     

Crystal field effects on the saturation magnetic moment of Sm3+ ion in ferronagnetic samarium compounds

The effects of cubic crystal fields on the saturation magnetic moment of Sm³⁺ ion in ferromagnetic compounds have been investigated. In samarium compounds with magnetic elements, the exchange fieldH _ex acting on Sm³⁺ ion is taken to be proportional to the sublattice magnetization of the magnetic element, while in compounds with nonmagnetic elementsH _ex is taken to be proportional to the spin average of the Sm³⁺ ion and is determined self-consistently. In both types of compoundsH _ex is assumed to be along [001] direction. The saturation magnetic moment is calculated by taking into account the admixture of excited (J=7/2 andJ=9/2) levels into the ground (J=5/2) level of Sm³⁺ ion by crystal fields and exchange fields. It is shown that depending upon the strength, the crystal fields quench or enhance the magnetic moment from the free ion value, and in some cases force Sm³⁺ ion to behave effectively like an (L+S) ion rather than an (L−S)ion. The crystal fields may have important bearing on the performance of samarium compounds as permanent magnet materials.     

Magnetization studies on ErCo3-hydride and TmCo3-hydride

The compounds ErCo₃ and TmCo₃ are ferrimagnetic with Curie temperatures of 401 K and 370 K, respectively. These absorb hydrogen to form ErCo₃H_4.3 and TmCo₃H_3.3. From magnetization studies on these as well as other RCo₃ hydrides in the temperature interval 4.2 to 300 K, it is inferred that hydrogen absorption leads to a reduction in magnetic moment on cobalt and a weakening of the R-Co interaction (R = rare earth). Except in the case of the GdCo₃-hydride, saturation in magnetization is not achieved at 4.2 K in applied fields up to 21 kOe. This suggests the possibility of fanning of rare earth moments. The RCo₃-hydrides investigated earlier with R = Gd, Dy and Ho and the ErCo₃-hydride and TmCo₃-hydride all appear to be magnetically ordered at room temperature.