A self-consistent model for the electronic component of a thin current sheet in the Earth’s magnetosphere

A self-consistent model for the electronic component of a thin current sheet (TCS) of the Earth’s magnetosphere based on the concept of the tension of lines of force is proposed and studied analytically and numerically. It has been shown that the model has a certain range of applicability, beyond which the results may be incorrect; within the range of correctness the model allows for a quite significant increase in the rate of convergence of the iterative algorithm for solving the total self-consistent model of the TCS, which also includes the Boltzmann equations for the ionic component.     

Reactions of sodium tetrahydroborate with alkyl and aryl halides: A new approach to the synthesis of B3H 8 − and B12H 12 2− anions

A new method for the synthesis of the B₃H ₈ ^? anion based on the reactions of alkyl and aryl halides (C₂H₄Cl₂, C₆H₅CH₂Cl, C₄H₉Br, (C₆H₅)₃CCl, C₁₀H₇CH₂Cl, CH₂I₂, C₂HCl₃) with sodium tetrahydroborate in diglyme was proposed. The method is characterized by high (up to quantitative) yields and easy isolation of the target products, (n-C₄H₉)₄N)[B₃H₈] and Cs[B₃H₈], and also easy preparation of a salt of higher hydroborate anion, B₁₂H ₁₂ ^2? , without multistage purification from impurities of other anions of this series.     

Synthesis,structure, and properties of Schiff base iodobismuthate and its alteration in DMSO solution

New hybrid iodobismuthates (C₁₂H₁₈N₂)(BiI₄)₂ (1, C₁₂H₁₈N₂ is N,N´-bis(1- methylethylidene)-1,4-benzоdiammonium dication) and (C₆H₄(NH₃)₂) [Bi₂I₈?2DMSO]?4DMSO (2, C₆H₄(NH₃)₂ is p-phenylenediammonium dication) were synthesized and their crystal structures were established. Compound 1 crystallizes in the space group P2₁/n, a = 7.632(4), b = 13.471(6), c = 14.556(5) Å, β = 93.57(4)°; compound 2 crystallizes in the space group P\(\overline 1 \), a = 9.208(4), b = 12.203(5), c = 13.600(5) Å, α = 110.20(3)°, β = 97.28(4)°, γ = 110.04(4)°. In the crystal structure of compound 1, one-dimensional infinite BiI ₄ ^– polyanions are linked into a three-dimensional structure by N,N'-bis(1-methylethylidene)- 1,4-benzоdiammonium dications through N–H…I and C–H…I hydrogen bonds. Compound 1 is stable up to 200 °С, optical studies showed that it has a band gap of 2.15 eV. The recrystallization of compound 1 from DMSO is accompanied by the transformation of chain BiI ₄ ^– anions to binuclear [Bi₂I₈?2DMSO]^2– anions, while the azomethine cation decomposes to form a p-phenylenediammonium dication.     

Stishovite's Relative: A Post‐Coesite Form of Phosphorus Oxonitride

Phosphorus oxonitride (PON) is isoelectronic with SiO₂ and may exhibit a similar broad spectrum of intriguing properties as silica. However, PON has only been sparsely investigated under high‐pressure conditions and there has been no evidence on a PON polymorph with a coordination number of P greater than 4. Herein, we report a post‐coesite (pc) PON polymorph exhibiting a stishovite‐related structure with P in a (5+1) coordination. The pc‐PON was synthesized using the multianvil technique and characterized by powder X‐ray diffraction, solid‐state NMR spectroscopy, TEM measurements and in situ synchrotron X‐ray diffraction in diamond anvil cells. The structure model was verified by single‐crystal X‐ray diffraction at 1.8 GPa and the isothermal bulk modulus of pc‐PON was determined to K₀=163(2) GPa. Moreover, an orthorhombic PON polymorph (o‐PON) was observed under high‐pressure conditions and corroborated as the stable modification at pressures above 17 GPa by DFT calculations.     

The thermodynamic properties of rare-earth metal binuclear acetates and pivalates

The temperature dependence of the heat capacities of binuclear acetates M₂(η¹,η²-OOCCH₃)₂(η²-OOCCH₃)₄(H₂O)₄ · xH₂O (M = La(1), Sm(2), Eu(3), and Tm(4)) (113?330 K); pivalates M₂(μ₂-OOCCMe₃)₄(OOCCMe₃)₂(HOOCCMe₃)₄·HOOCCMe₃ (M=La(5), Sm(6), and Eu(7)) (113?320 K); and intermediate products of their thermal decomposition M₂(OOCCH₃)₆(113–330 K) and M₂(OOCCMe₃)₆ (113–500 K) and enthalpy changes at particular decomposition stages were determined by differential scanning calorimetry. The composition of the solid phase formed in decomposition was determined experimentally. The complete set of thermodynamic data was obtained, including C _p (T), S°(298), Δ_f H°(298), and Δ_f G°(298), for binuclear lanthanide acetates and pivalates specified above. The composition of the gas phase formed in decomposition was determined, which allowed us to suggest a resultant scheme of the thermal destruction of pivalates. The reliability of this scheme was demonstrated.     

Single-electron charging of triangular quantum dots in a ring interferometer

Small-size semiconductor ring interferometers operating in the Coulomb blockade regime have been experimentally and theoretically studied. The conductance as a function of the gate voltage exhibits narrow quasiperiodic peaks, which are further split into doublets. Based on the experimental structural data, a three-dimensional electrostatic potential, the energy spectrum, and the single-electron transport in the interferometer were modeled. The electron system can be divided into two triangular quantum dots connected by single-mode microcontacts to each other and to the reservoirs. A model of quantum dot charging in this system is proposed that explains the appearance of doublets in the conductance-gate voltage characteristics.     

Magnetorefractive effect in magnetic nanocomposites

The magnetorefractive effect in ferromagnetic metal-insulator granular nanostructures (CoFeZr)-SiO_n, Co-Al-O, FeSiO_n, and (CoFe)-(Mg-F) is investigated in the infrared spectral region in a wavelength range from 5 to 20 μm. The magnitude of the effect varies from 0.1 to 1.5% for different nanocomposites and strongly depends on the frequency of light and magnetoresistance. It is shown that the reflection coefficient changes in a magnetic field not only due to the magnetorefractive effect, but also due to the even magnetooptical effect. Simple relations describing this effect are given for the case when the reflection from the substrate is insignificant and in the case of a three-layer (insulator-film-substrate) system. The expression for the frequency dependence of the magnetorefractive effect in nanocomposites is derived and its features in the case of high-frequency spin-dependent tunneling are analyzed.