[en] Influence of Mn substitution on bulk textured Bi₂Sr₂Ca(Cu_1-xMn_x)₂O_8+δ crystals grown by the immersed heater floating zone technique has been studied for the first time. The properties of pure and Mn doped Bi-2212 crystals are compared. X-ray diffraction studies show that the texturing percentage and the c-lattice parameter decrease with increase in Mn concentration. The scanning electron microscope study reveals the cellular growth pattern for x=0.4 Mn concentration. The superconducting transition temperature decreases on increasing Mn concentration

[en] Twelve-thirteen day old rats were given 1-¹⁴C linolenic acid by intraperitoneal injection. Fatty acids were isolated from the brains of animals sacrificed at the end of 8 and 48 hr and 15 and 45 days. Eight hr after the tracer, radioactivity was found neither in 18:3 nor its end-product, 22:6, and palmitate was the most highly radioactive component. At longer intervals, 22:6 seemed to retain much of the radioactivity, whereas palmitate showed a precipitous decline in radioactivity. Initial oxidation of linolenate and sparing of the linolenate complexed with polar lipids are discussed

[en] Metabolism of 1-¹⁴C linolenic acid was studied in growing animals by injecting the tracer intraperitoneally into 12-13 day old suckling rats and following up the results by sacrificing groups of animals at 8 hr, 48 hr, 15 day, and 45 day intervals. In the first 15 days, there was a greater decrease in radioactivity of brain total lipids compared to the later period, although the earlier age period is characterized by lipid deposition rather than breakdown. Results showed that 8 hr after the tracer phosphatidyl choline had the highest specific radioactivity. When the total phosphatidyl ethanolamine fraction was resolved into diacyl and alk-l-enyl species, it was found that radioactivity was not distributed evenly between the two species. There was a progressive increase in radioactivity of the alkenyl and a decrease in the diacyl species. Forty-eight hr after the tracer, however, the radioactivity of phosphatidyl ethanolamine increased and at 45 days remained slightly higher than phosphatidyl choline. Radioactivity of cholesterol, a result of synthesis from acetate undoubtedly derived from the breakdown of tracer linolenate, was also high 48 hr after tracer and remained high until 45 days

[en] Bulk textured crystals of Bi₂Sr₂Ca(Cu_1-xMn_x)₂O₈ have been grown by immersed heater floating zone (IHFZ) technique. The crystal size is influenced by Mn doping and for higher doping concentration the growth interface becomes narrow and no melt flow is observed. The melting sequence, microstructure, lattice parameter and chemical composition of the grown crystals have been studied. The growth parameters such as seed rotation, pulling rate and interface temperature have been optimized to grow phase pure bulk textured crystals of Mn-doped Bi-2212

[en] Single crystals of superconducting Eu_1.5Ce_0.5Sr₂Cu₂TiO_10-δ (Ti-1222) have been grown from excess CuO and SrCO₃-CuO mixed fluxes by slow cooling technique. The growth temperature was determined by studying the thermal behaviour of polycrystalline Eu_1.5Ce_0.5Sr₂Cu₂TiO_10-δ with different fluxing agents. Morphology studies by SEM reveals the layer growth pattern, indicative 2D nucleation mechanism. Stoichiometric Ti-1222 crystals were obtained for CuO flux, whereas composition of SrCO₃-CuO mixed flux is different from the starting composition. Ti-1222 crystals possess tetragonal structure with a superconducting transition at 22 K. Growth aspects and phase formation of Ti-1222 for both CuO and SrCO₃-CuO flux systems have been studied in detail

[en] A strip heater floating zone apparatus was used for the growth of bulk textured crystals of Bi-2212 superconductors of size 3 cm length x 1 cm diameter. Samples with a composition of Bi_2.2Sr_1.9CaCu₂O₈ and Bi_xY_0.1Sr_1.9CaCu₂O₈ (x=1.9, 2.1 and 2.3) were used for the crystal growth. Optimal growth conditions were adopted to get crack free crystals. The grown crystals were annealed at 650 C for 24 h and the superconducting property was studied. The X-ray diffraction studies confirmed the Bi-2212 phase formation and texturing were quantified. The compositional analysis of the as grown and annealed crystals were done by inductively coupled plasma (ICP) analysis. AC susceptibility data of thecrystals reveal the change of superconducting volume fraction with different initial Bi ratio. Chemical etching studies were carried out for the grown crystals using chemical etchants. (orig.)

[en] The growth kinetics of YBCO single crystal from high temperature solution of YBCO-BaO/CuO solute-solvent system has been studied. Based on regular solution model and classical nucleation theory the thermodynamical data investigated for the system are used to determine the nucleation parameters: interfacial energy, metastable zone-width (supercooling temperature), free energy change, critical nucleation radius etc, which leads to the understanding of the nucleation phenomena of YBCO. (orig.)

[en] Growth of lead-doped textured Bi-cuprate, using an immersed heater floating zone (TSFZ) apparatus, from a narrow supercooled melt created an essentially dense structure consisting of locally aligned long platelet crystal grains. The extended grains have their long axes parallel to the growth axis with a low angle misorientation. The effect of gas bubbles and the pulling rates on the microstructure and superconducting transition temperature of the textured boules have been studied. The decomposing nature of the 2223 phase on melting leads to form the energetically favourable low T_c 2212 phase. (orig.)

[en] The growth of single crystals of Y-Ba-Cu-O has been performed from two different starting compositions of Y₂O₃, BaCO₃, and CuO. The presence of twins, flux inclusions and the growth spirals are observed on the surface by optical and scanning electron microscopy. (author)

[en] Textured crystals of Bi_2.2Sr_1.9Ca_1-xY_xCu₂O_8+δ (0 ≤ x ≤ 0.6) have been grown by the platinum strip heater-floating zone technique. Texturing ratio and phase purity (Bi-2212) of the grown crystals were calculated from the x-ray diffraction data. Chemical compositions of the grown crystals were quantified from the inductively coupled plasma analysis. T_c was found to be increased by 2 K for a lower level of substitution and a superconductor to semiconductor transition was observed for the higher order Y substitution. Oxygen stoichiometries of the Y substituted crystals were quantified from the iodometry titration method. Micro-twinning along the growth axis was revealed during etching studies for the cleaved crystals. (author)