(Cu,Tl)Ba2Ca3Cu4Ox compositions: I. The influence of synthesis time and temperature on the phase formation and evaporation$ndash$condensation mechanism

Badica, P.; Iyo, A.; Crisan, A.; Ishiura, Y; Sundaresan, A.; Ihara, Hideo

doi:10.1088/0953-2048/15/6/323

Cited by 11 publications

(10 citation statements)

References 37 publications

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“…For our experiments in a closed system (sealed Au tubes) a relatively good measure of the pressure inside the capsule is the weight loss and weight loss rate. Our data have shown that weight loss increases with time for any given temperature following a sigmoid-type curve [1]. Increase in synthesis temperature for the same synthesis time leads to an increase in weight loss.…”

Section: Introductionmentioning

confidence: 50%

“…Special attention is paid to Cpurification of the oxides. Details are presented in [1]. In fact, for the synthesis of the samples discussed here we have used heat-treated oxides from the same batches as in [1].…”

Section: Methodsmentioning

confidence: 99%

“…Details are presented in [1]. In fact, for the synthesis of the samples discussed here we have used heat-treated oxides from the same batches as in [1]. Oxygen content in some situations was adjusted by using Cu 2 O in the starting mixture instead of CuO, or a pellet of Ag 2 O was placed in the Au capsule.…”

Section: Methodsmentioning

confidence: 99%

“…In the first part of this paper [1] we demonstrate the vapour phase transport mechanism for the formation of superconducting phases in (Cu,Tl)-1234 compositions. Several problems are related to this mechanism: (i) Although the vapour phase may transport enough material to produce some connectivity between grains, it cannot result in increased density [2].…”

Section: Introductionmentioning

confidence: 94%

“…All samples consist of several superconducting phases and non-superconducting phases. Another important piece of information is that the content of the main residual phase, the crystallized Ba(Ca,Tl)-Cu-O liquid phase [1], was lower at lower temperatures and synthesis times. All these results suggest that instead of a synthesis at a constant temperature one should make, for example, a synthesis with the controlled heating rate.…”

Section: Introductionmentioning

confidence: 99%

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(Cu,Tl)Ba2Ca3Cu4Ox compositions: II. Heating rate applied to synthesis of superconducting ceramics

Badica

Iyo

Crisan

et al. 2002

Supercond. Sci. Technol.

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Superconducting samples with a starting composition Cu0.5TlxBa2Ca3Cu4O12 (x = 1–0.35) were prepared in Au tubes from oxides by using different heating rates. The optimum heating rate was 0.11 °C min−1 applied between 860 and 880 °C. These samples show the highest content of 1234 phase and the lowest of Ba–Cu–O phases as well as the highest critical temperatures. The highest values were Tc = 119.2 K and Tc0 = 115.1 K. All samples show Jc values around 6 × 105 A cm−2, at 60 K and 0.5 T. In the rest of the samples, heated by using lower or higher heating rates, a high concentration of 1223 and/or 1245 phases is detected. The content of the 1234 phase and of Ba(Ca,Tl)–Cu–O residual liquid phase, in the samples synthesized for the optimum heating rate, depends on the Tl content in the starting mixture. The influence of the oxygen content in the starting mixture on phase composition is not as strong as of Tl, but it has a major role in establishing the superconducting behaviour of the 1234 grains. Some arguments that suggest the dependence of the transport properties of the non-superconducting matrix on oxygen content will be discussed. In our technological arrangement the determined optimum heating rate can be applied to the synthesis of other single-layered superconducting phases, e.g. 1212 phase from a Cu0.25Tl0.75Ba2CaCu2O8.115 starting composition.

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Section: Introductionmentioning

confidence: 50%

Section: Methodsmentioning

confidence: 99%