The influence of nonstoichiometric additions of ReO3 in HgBa2Ca2Cu3O8+delta (Hg-1223) has been examined with respect to microstructure and superconducting properties. Grain size and shape depend significantly on the Re content whereas the intragranular defect structure does not change. EDX examinations suggest the existance of a limit of solubility of Re in Hg-1223. The critical temperature, T-c,, of the as prepared (Hg,Re)-1223 samples is above 130 K and could not be improved by O-2-/N-2- annealing. A maximum of magnetical hysteresis versus Re content has been observed for 15% Re which might be caused simply by a grain size maximum.

The relaxation of the irreversible magnetization has been measured by a Faraday magnetometer for the weakly anisotropic polycrystalline Tl0.5Pb0.5Sr2Ca2Cu3O9 (Tl-1223) and a highly anisotropic Tl2Ba2Ca2 Cu3O10 (Tl-2223) single crystal. From these data, the effective activation energy, U eff(j)=U l(j c /j)μ, is determined by the method of Maley. A comparison of the irreversibility data at 77 K for different high-temperature superconductors (HTSC) indicates that the irreversibility field is quickly decreasing with increasing distance between the superconducting CuO2-layers. In agreement with this tendency, U eff is higher for the one-intermediatelayer compound Tl-1223 than for the highly anisotropic two-intermediate-layer Tl-2223 compound. The exponent μ≡d log(U eff)/d log(j) saturates for Tl-1223 at a value of μ≈1.4 near j c and decreases with decreasing current down to 0.3. On the other hand μ increases for Tl-2223 with increasing current from 0.1 up to 2.5 and shows no tendency to saturate. A comparison with data for Y-123 and Bi-2212 taken from literature, indicates that the flux creep in Tl-1223 is 3-dimensional like in Y-123. Therefore it can be explained by the 3D collective creep model for not too small currents. For Tl-2223, 2-dimensional behaviour is observed.

A Tl2Ca2Ba2Cu3O10 single crystal of platelet shape with Tc=121.5 K was investigated by SQUID magnetometry. Zero field cooled (=ZFC) and field cooled (=FC) measurements were carried out in different fields with the applied field parallel to the crystallographic c-axis. Taking the fluctuations of the vortices in Josephson-coupled layered superconductors into account, the temperature dependent penetration depth λab, the Ginzburg Landau parameter κ, and the upper critical field Hc2 are calculated from the reversible ZFC/FC magnetization data. The Hc2-data (Hc) can be fitted linearly at higher temperatures. The temperature dependent penetration depth does not follow the empirical law λ(T)=λ(0)/(1−(T/Tc)4)12.

A Tl2Ca2Ba2Cu3O10 single crystal with a transition temperature of 117.5 K was subjected to fast neutron irradiation to fluences of 2·1021, 4·1021, 8·1021, and 1.6·1022 m2 (E>0.1 MeV). The superconducting transition temperatures Tc, the hysteresis loops and the irreversibility lines were measured before and after each irradiation step. The critical current densities Jc were calculated from the magnetization loops using an anisotropic Bean model. With increasing fluence we find a decrease of Tc, as observed in YBCO-123 and other high temperature superconductors, and an increase of Jc. The irreversibility line is shifted to higher fields and temperatures.

We Present measurements of the resistivity tensor components rho(a)(T) and rho(c)(T) of high-quality Tl2Ba2Ca2Cu3O10 single crystals wit T(c) = 118 ... 121 K. The in-plane resistivity rho(a) as well as the out-of-plane resistivity rho(c) show a metal-like temperature dependence with an anisotropy ratio rho(c)/rho(a) of Up to 10(3). The coherence length xi(c) (0) = 0.15 nm could be determined from an analysis of the fluctuation conductivity above T(c). From measurements of the ac-susceptibility in magnetic fields up to 10 Tesla the temperature dependence of the depinning line could be obtained. The diffusion coefficient of the flux lines obtained from the frequency dependence of the depinning temperature shows a thermally activated behaviour of the flux motion in the field range 0.1 T less-than-or-equal-to B less-than-or-equal-to 10 T

Cristallisation dans I4 avec affinement jusqu'a 0,030. Structure polymerique bidimensionnelle=l'atome de zinc a une coordination octaedrique (avec quatre atomes d'oxygene des groupements propionate et deux molecules d'eau); l'atome d'or est coordine a quatre atomes d'oxygene des groupements propionate dans une structure plan carre

Le complexe de Zn cristallise dans le systeme triclinique, groupe d'espace P1 et sa structure est affinee jusqu'a R=0,039. Le complexe de Pb cristallise dans le systeme monoclinique, groupe d'espace C2/c avec R=0,060

Cristallisation dans P2 1 /n avec affinement jusqu'a 0,034. Zn a une structure octaedrique deformee; Au a une structure plan carre. Les molecules d'eau ont une structure cis. Deux atomes de chlore de chaque groupement AuCl 4 − sont pontes sur Zn

Cristallisation dans P2 1 /n avec affinement jusqu'a 0,077. Les anions ont une structure plan carre. Chaque atome de sodium est relie a 7 atomes de chlore

The superconducting, structural and magnetic properties of YiBa 2 ( Cu 100− z − Fe z ) 0.03 O 7−δ (O ⩽ x ⩽ 18) were determined by resistive and magnetic measurements as well as by X-ray diffraction experiments and thermogravimetrical analysis. Four Fe-concentration regimes can be distinguished: Below x = 2 T c remains constant, above 2.3 % Fe contents T c decreases linearly with x, first with 5.4 K jat% Fe and above x 10 with 9.0 Kiat% Fe. Above 15 at% Fe no superconductivity could be detected. This behaviour of T coincides with changes in the structure and the oxygen contents of the Y 1 Ba 2 ( Cu 100− x − Fe x ) 0.03 O 7−δ . Below 2.3 at% the orthorhombic perovskite structure is retained. At larger Fe concentration a tetragonal structure is attained with a = b /3 below x = 10 and with a = b = c /3 above x = 15. Between 10 and 15 at% Fe c /3 approaches the value of a = b . Magnetic measurements show an anomaly below T c , which indicates antiferromagnetic ordering. The magnetic ordering temperature increases with Fe concentration.

AbstractThe title compound, prepared by heating Au, Te, and Br2 in a sealed glass tube to 1600 °C for 7 d, crystallizes in the triclinic system, space group P1, Z=2.

Cristallisation dans C 2/C avec affinement jusqu'a 0,051. La structure est constituee de deux types de couches: les trois atomes de plomb independants sont coordinnes aux ions chlorures et acetates en formant des couches qui sont reliees par les ions AuCl 4 −

C 36 H 31 As 2 O 2 + .AuCl 4 − cristallise dans P2 1 /n avec a=13,659, b=9,955 et c=14,481 A, β=110,98 o , Z=2; affinement jusqu'a R=0,072. Les anions sont associes au centre de symetrie a 0, 0,5, 0,5 avec Au-Cl=2,270, 2,280 A. Les moities Ph 3 AsO du cation sont apparentees autour du centre de symetrie 0, 0, 0. Le proton qui les connecte par une liaison hydrogene de 2,39 A n'est pas localise, mais repose probablement sur l'origine

AuCI{P(C6H5)(C10HgFe)2}), M r= 710.5, monoclinic, P21/n, a = 10.205 (2), b = 18.014 (4), c=12.680(3)A, fl=98.29(2) ° , V=2306.5A 3, Z --- 4, Dx= 2.04 Mg m -3, 2(Mo Ka) = 0.71069/~, # = 7.8 mm -1, F(000) = 1368, T= 293 K. The structure was refined to R 0.035 for 3523 unique observed reflections. The coordination geometry at the Au atom is linear, with Au-C1 2.289 (2), Au-P 2.234 (2)/~, C1-Au-P 176.1 (1)% There are no unusually short intermolecular contacts. The Fe-C distances lie in the range 2.025 (8)-2.058 (8)/~, mean 2.041 (8)./k. The C5H 4 rings of the ferrocene moieties are approximately ecliosed (rotated by 12, 14 °, respectively). Experimental. The title compound was obtained as a brown powder from the reaction of carbonylgold(I) chloride with diferrocenyl(phenyl)phosphine in benzene, and recrystallized from dichloromethane/petrol ether as orange to red plates. A full elemental analysis con- firmed the expected composition. A crystal 0.55 x 0.35 x 0.15 mm was mounted in a glass capillary. 5761 profile-fitted intensities (Clegg, 1981) were registered on a Stoe-Siemens four-circle diffractometer using monochromated Mo Ka radiation (20ma x 50 °, quadrant -h+k+l and some +h equiv- alents). An absorption correction based on ~, scans was applied, with transmission factors 0.34 to 0.99. The intensities of 3 check reflections showed no significant variation. Merging equivalents gave 4045 unique reflections (Rin t 0026, index ranges h-12 to + 12, k 0 to 21, 10 to 15), 3530 with F > 4a(F). Cell constants were refined from 20 values of 40 reflections in the range 20-23 o. The structure was solved by the heavy-atom method and subjected to full-matrix least-squares refinement on F. All non-H atoms were refined anisotropically; H atoms were included using a riding model. The final R value was 0.0352, wR 0.0412 for 280 parameters, 3523 reflections (seven low-angle reflections were omitted because of extinction effects). The weighting scheme was w-i= tr2(F)+ 0.0004F 2. Max. shift/e.s.d. = 0.003, max. residual electron density within +1.0 e A -3 near Au, S = 1.52. The program system was SHELX (Sheldrick, 1986), locally modified by its

Abstract The reaction between elemental gold, tellurium and bromine leads to a crystalline product of empirical formula AuBr8Te. The crystal structure determination of AuBr8Te shows that it is composed of dimeric [TeBr3 · AuBr4]2 units with secondary Te···Br interactions and of isolated Br2 molecules.

[PCl 4 ][AuCl 4 ] cristallise dans le systeme orthorhombique avec le groupe d'espace Imma. Affinement de la structure jusqu'a 0,045. La structure se compose d'ions isoles PCl 4 + et AuCl 4 − de symetrie cristallographique 2 et mm 2 respectivement

Abstract Two calcium aurate phases have been obtained as single crystals, phase 1 from H AUC1 4 + Ca(OH) 2 and phase 2 from NaAu(OH) 4 + Ca(C10 4) 2 . An X-ray structure determination of 1 shows its composition to be Ca 2 (0H) 3 (H 2 0) 4 [Au(0H) 4 ]. The apparent space group is Cmcm, but this corresponds to a sub-cell of the true structure. The disordered Cmcm structure was refined to R 0.032 for 813 reflections. The coordination geometry is square planar at gold (Au-O 1.97, 1.99 Ä), cubic at Ca(l) and octahedral at Ca(2). Phase 2 crystallizes in a primitive tetragonal cell with a 6.94, c 7.71 Ä; it is probably Ca[Au(OH) 4 ] 2 , but this has not yet been confirmed by a full structure determination.

AbstractThe title compound, which has been prepared by reaction of TeCl4 and Au2Cl6 dissolved in AsCl3 with dry Cl2 passing through the solution (40‐45 °C, 1 h), crystallizes in the triclinic system (P1, Z=2).