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The phases present in FeS2 electrodes operated in normalLiCl‐normalKCl eutectic electrolyte were determined by x‐ray diffraction and by metallographic examination. The phases were FeS2 , KFeS2 , Li3Fe2S4 , Li2.33Fe0.67S2 , Fe1−xS , Li2FeS2 , LiK6Fe24S26normalCl , Li2S , and Fe. The metallographic and crystallographic characteristics of these phases are presented. The sequence of Li‐Fe‐S phases in the FeS2 electrode was in accord with the sequence predicted from the equilibrium Li‐Fe‐S phase diagram. Two of the Li‐Fe‐S phases found at room temperature ( Li2.33Fe0.67S2 and Li2FeS2 ) result from decomposition on cooling of a solid solution phase: Li2+xFe1−xS2 false(0≤x≤0.33false) .

Anhydrous double nitrates of the lanthanides with potassium have been obtained in crystalline form. Crystallographic and spectroscopic studies are reported. K3Pr2(N03)9 is cubic, with a = 13.52 (1) A and space group 06-/>4332. The experimental density is 2.53 (3) g cm"3 and the computed value is 2.57 (1) g cm"3 for four formula weights. The structure was solved with 529 independent reflections recorded with an automatic diffractometer utilizing the -2 scan method. A least-squares refinement based on all reflections and with isotropic temperature factors for all atoms gave R = 0.058. Each Pr atom is surrounded by twelve oxygen atoms belonging to six nitrate groups which form a distorted icosahedron. The nitrates form two nonequivalent sets, each with its distinct bonding characteristics to the Pr and K atoms. Infrared and Raman studies confirm a strong interaction between the oxygen atoms and the lanthanide ion and indicate typical bidentate bonding. The optical spectrum of K3Nd2(N03)9 was investigated at ambient and at high pressure. The enhancement of hypersensitive transitions was noted and discussed in comparison to other crystals in which the Nd3+ exists in low site symmetries.

The composition and microstructural evolution of nonsuperconducting phases during the course of formation of (Bi,Pb)2Sr2Ca2Cu3Ox (Bi-2223) in a silver sheath have been investigated by x-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), and digital image analysis. Wire samples fabricated by the oxide-powder-in-tube technique were heat-treated under a variety of conditions (time, temperature, and oxygen pressure). Backscattered images taken on polished but unetched transverse cross sections were subjected to computerized image processing, which allowed determination of the stoichiometry and quantification of microstructural characteristics (such as area fraction, size distribution, position, and orientation) of each nonsuperconducting particle. The dominant nonsuperconducting phases observed by SEM/EDX were CuO, (Ca,Sr)2CuO3 (2/1), and (Ca, Sr)14Cu24O41 (14/24) in amounts that varied depending on the annealing temperature, time, and oxygen partial pressure. Time evolution studies performed at 825 °C in 0.075 atm O2 showed that the area fraction of 2/1 decreased with reaction time, while that for 14/24 increased. In all cases, a substantial amount (>10% area fraction) of nonsuperconducting phases was detected even after all the Bi2Sr2CaCu2Oy (Bi-2212) in the as-rolled composite conductor was fully converted to Bi-2223, as determined by XRD. High aspect ratio nonsuperconducting particles were initially randomly oriented in the composite conductor core but gradually aligned parallel to the silver/(Bi,Pb)-Sr-Ca-Cu-O interface after extended annealing. They tended to segregate and exhibited a much broader size distribution when processing was carried out at temperatures and oxygen partial pressures on the high end of the normal processing range, most likely as a result of the occurrence of partial melting in the system.

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