[en] A review of the structural existing date on Hg-1201 shows evidence of non stoichiometry of the sample. In this compound not only oxygen but also Hg seems to be released or, perhaps, substituted. So, the production of bulk samples with optimal oxygen doping and homogeneous Hg content could be profitable for the study of the effect of the Hg solubility, allowing to confirm its existence, and to test the effect of Hg impoverishment on other critical superconducting parameters different from Tc

[en] A systematic study on the heat capacity of high T_c superconducting oxides RBa₂Cu₃O_7-x (R = Y, Ln) is in progress. In this paper, the authors report some results on Yttrium, Europium, Holmium and Erbium-based compounds with well determined amount of oxygen and measured in zero field. The specific heat jump of YBa₂cu₃O_7-x and ErBa₂Cu₃O_7-x measured in low magnetic fields (20 and 90 Oe) is also discussed so as preliminary results on YBa₂Cu₃O_7-x with different amount of oxygen and sintered under different conditions

[en] The Gd-Cu system was examined by differential thermal analysis, X-ray diffraction analysis and metallography. Six intermediate phases were found: GdCu, GdCu₂, Gd₂Cu₇, Gd₂Cu₉, GdCu₅ and GdCu₆. The existence of the previously reported GdCu₇ phase was not confirmed. Only GdCu (830⁰C), GdCu₂ (860⁰C) and Gd₂Cu₉ (930⁰C) melt congruently. The remaining three phases are formed peritectically: Gd₂Cu₇ (870⁰C), GdCu₅ (925⁰C) and GdCu₆ (865⁰C). Eutectic points occur at about 30 at.% Cu (675⁰C), 56.5 at.% Cu (770⁰C), 71.0 at.% Cu (820⁰C) and 90.5 at.% Cu (860⁰C). The solubility of gadolinium in copper was negligible whereas about 15 at.% Cu dissolved in β-Gd and about 2 at.% Cu dissolved in α-Gd. (Auth.)

[en] The Nd-Cu phase diagram was established by differential thermal analysis, metallography and X-ray analysis. A microprobe analysis was performed, and the microhardness and resistivity of the intermediate phases were determined. The following phases were observed: NdCu (670⁰C), NdCu₂ (840⁰C), Nd₂Cu₇ (825⁰C), NdCusub(approx. 4) (745⁰C), NdCu₅ (870⁰C) and NdCu₆ (920⁰C). Only NdCu₂ and NdCu₆ melt congruently. The compound Nd₂Cu₇ has a limited stability range. Eutectics occur at 30 at.% Cu (520⁰C), 73 at.% Cu (770⁰C) and about 90 at.% Cu (865⁰C). The presence of a thermal anomaly around the 1:1 composition caused by a first-order transition is pointed out. (Auth.)

[en] This paper reports on the binary sections YBa₂Cu₃O_7-δ - CuO and YBa₂Cu₃O_7-δ - Y₂O₃ in the system Y₂O₃ - BaO - CuO that were studied by differential thermal analysis, X-ray powder diffraction and micrographic examination, in order to test the stability of YBCO phase. A linear dependence of the peritectic decomposition temperature of RBa₂Cu₃O_7-δ on different rare earths was found. On the contrary, the low-melting reactions were practically independent on the rare earth. The influence of the partial oxygen pressure on the equilibria reactions was determined. X-ray diffraction was also employed to recognize the chemical equilibria occurring at different well determinated temperatures

[en] In this paper the problems of the preparation of ETSC by melting are examined. Results of the thermal properties of the total substitution of Y by a rare earth are reported. The process of fabrication of HTSC both textured in thermal gradient or only locally textured for effect of the natural gradient of the furnace is indicated. The results of the physical characteristics of the specimen cooled in the natural gradient of the furnace resulting in only locally textured sample are also reported

[en] A stability study of perovskitic LaREO₃ oxides (RE = Dy, Ho, Er, Tm, Yb, Lu) as a function of temperature was undertaken. A correlation between the Goldschmidt t value and the perovskitic stability field amplitude was found: the latter widens as t increases. Magnetic measurements, performed on all the perovskitic samples, showed that t is also related to the exchange interactions. LaREO₃ oxides were synthesized by thermal decomposition of the corresponding coprecipitated oxalates at temperatures ranging between 600 and 1800 ^oC. Simultaneous differential thermal and thermogravimetric analyses showed that all the La-RE mixed oxalates decompose similarly. All the oxides, except LaDyO₃, crystallize in the perovskitic form in a temperature range that depends on the ionic size difference between La and the smaller rare earth; above and below the perovskitic stability field, the B or C form, typical of rare earth sesquioxides, is present. Rietveld refinements, carried out on all the LaREO₃ samples synthesized at 1200 ^oC, showed the occurrence of an orthorhombic distorted perovskitic structure belonging to the Pnma space group.

[en] Highlights: ► A novel synthesis route is proposed and discussed to synthesize phase pure RuSr₂Gd_1.4Ce_0.6Cu₂O₁₀ samples. ► Phase purity is analyzed and discussed via structural, Raman and magnetic measurements. - Abstract: Two different synthetic routes to synthesize the magnetic superconductor RuSr₂Gd_1.4Ce_0.6Cu₂O_10−δ (Ru-1222) have been reported as an alternative method to the solid state reaction starting from the oxides of Ru, Gd, Ce, Cu and SrCO₃. The 1222-phase has been namely prepared by mixing and reacting proper amounts of: (a) the 1212-phase (RuSr₂GdCu₂O₈) with the mixed oxide Ce_0.6Gd_0.4O_1.8; (b) the 1212-phase with the separate oxides Gd₂O₃ and CeO₂. The possibility to obtain a pure Ru-1222 phase has been discussed and the effect of the different synthetic paths on the purity, structural and physical properties of the compound has been presented.