Phase Diagram for the RbBr–CuBr System

The phase diagram for the RbBr–CuBr system has been determined. In the system two intermediate compounds are formed: RbCu₂Br₃, melting congruently at 537 K and Rb₃CuBr₄, melting incongruently at 544 K. The coordinates of the two eutectic points are: 501 K, 54 mole% CuBr and 522 K, 74 mole% CuBr. This revised version was published online in July 2006 with corrections to the Cover Date.     

Crystal growth, structure and electrical properties of thorium phosphorosulfide

Single crystals of thorium phosphorosulfide have been grown by the chemical vapour transport method. The X-ray diffraction examination showed that the unit cell of the crystals belongs to a tetragonal system of the PbFCl-type structure. The basal plane resistivity ρ(300 K)=64 μΩ cm and thermoelectric power S(300 K)=−7.7 μV/K, examined between 0.4 and 315 K, show metallic behaviour.     

Remarks on the r and Δ convolutions

In this paper we study the properties of the r–deformation introduced in [B1]. We observe that the associated convolution coming from the conditionally free convolution is associative only for r = 1 and r = 0. We give the realization of some r–Gaussian random variables and obtain Haagerup–Pisier–Buchholz type inequalities. We also study another convolution defined with the use of the r–deformation through a moment–cumulant formula [KY1] and show that it is associative and in general not positive. Partially sponsored with KBN grant no 2P03A00723 and RTN HPRN-CT-2002-00279.     

Magnetic properties of neptunium diarsenide

The magnetic properties of a collection of single crystals of NpAs₂ have been investigated in the temperature range 4.2-300 K and in applied fields up to 100 kOe. For small magnetic fields (3 kOe), NpAs₂ is ferromagnetic up to T_IC=18 K, antiferromagnetic from 28 K to T_N=52 K, then paramagnetic. Both transitions are first order. When the applied field increases T_IC is shifted towards T_N. The antiferromagnetic phase disappears for H#62;30 kOe. The ferromagnetic range is characterized by a very large anisotropy. In the paramagnetic state, NpAs₂ has an effective moment 1.88 μ_B.     

Electronic properties of Th3As4U3As4 solid solutions

(Th_xU_1?x)₃As₄ solid solutions were obtained in the range 1 ≥ x ≥ 0.85 by the modified Van Arkel method. Their resistivity, thermopower and Hall constant were determined in temperatures 4.2—700 K. The condition of impurity band formation, its merging with conduction band, as well as location of the 5?-electron states have been discussed.     

Studies of phase equilibria in the systems ZnCl2-AgCl and ZnBr2-AgBr

Phase equilibria in the systems zinc chloride - silver chloride and zinc bromide - silver bromide were investigated by differential scanning calorimetry, electric conductivity measurements and X-ray diffraction methods. No intermediate compounds were found. Solubility of components in the solid-state is negligible. Both systems are of the eutectic type. The eutectic temperatures in the ZnCl₂-AgCl system and in the ZnBr₂-AgBr system are 504 K and 551 K, respectively, and the compositions of the eutectic point are 53.5 mol% AgCl and 59.4 mol% AgBr, respectively. This revised version was published online in July 2006 with corrections to the Cover Date.     

Bounds for in-progress floating-strike Asian options using symmetry

This paper studies symmetries between fixed and floating-strike Asian options and exploits this symmetry to derive an upper bound for the price of a floating-strike Asian. This bound only involves fixed-strike Asians and vanillas, and can be computed simply given one of the many efficient methods for pricing fixed-strike Asian options. The bound coincides with the true price until after the averaging has begun and again at maturity. The bound is compared to benchmark prices obtained via Monte Carlo simulation in numerical examples. D. Hobson is supported by an Advanced Fellowship from the EPSRC. V. Henderson is partially supported by the NSF under grant DMI 0447990.     

A neutron study of the magnetic ordering in a NpAs2 single crystal

A neutron diffraction study on a small NpAs₂ single crystal is reported. NpAs₂ orders at T_N = 52 K with a pure sine wave modulation propagating along a ≤100≥ direction of the tetragonal unit cell. The value of the wave vector is incommensurate with the lattice (k = ≤0.141,0,0≥) and is temperature independent down to T_IC = 18.5 K where a first-order transition towards a commensurate ferromagnetic state occurs. At all temperatures the magnetic moments are aligned along the c-axis with a value of (1.45±0.1)μ_B at T = 5 K.     

Two-channel Kondo effect in glasslike ThAsSe

We present low-temperature heat and charge transport as well as caloric properties of a ThAsSe single crystal. An extra -AT(1/2) term in the electrical resistivity, independent of magnetic fields as high as 14 T, provides evidence for an unusual scattering of conduction electrons. Additionally, both the thermal conductivity and the specific heat show a glass-type temperature dependence which signifies the presence of tunneling states. These observations apparently point to an experimental realization of a two-channel Kondo effect derived from structural two-level systems.     

Magnetic properties of the uranium sesquichalcogenides

Magnetic measurements on the orthorhombic uranium sesquichalcogenides and orthorhombic U₃Te₄ were performed in the temperature range 4.2–1000 K and in magnetic fields up to 140 kOe. The temperature dependence of the reciprocal susceptibility was found to be curvilinear for all the investigated compounds. At low temperatures U₂Te₃ and U₃Te appeared to be antiferromagnetic below 106 K. U₂Se₃ and U₂S₃ seem to have a more considerable ferromagnetic contribution below 60 and 80 K, respectively. The magnetic properties are discussed in terms of crystal structure and related properties of the investigated compounds.