Topic: Superconductors After reading the provided article, Describe in detail le

Question

Topic: Superconductors

After reading the provided article,

Describe in detail least two new ideas,concepts,relationships,methods that you have learned from this paper.

Since the discovery of high-temperature superconduc- Our synthetic strategy for the new single-layer Cu-O ) in copper oxide compounds by Bednor and Mller, unprecedented extensive efforts have been well-known examples of copper oxide compounds with devoted to synthesizing new superconducting copper oxide single-layer shee compounds with higher Te. Some The K2NiF4 structure in I known, realizing higher-T c La2Cuo and the Nd CuO4 structure or the so-called T ductors, e.g., Y-Ba-Cu-O (Ref. 2) and Bi(TID-Sr(Ba) Sm, Eu, and Gd. Whether rare-earth metal copper oxides sheets structure seems to be critically dependent on the ionic r which comprise Cu-O pyramidal quentially dius of constituent rare-earth on. In particular ordered noncopper cations along the normal to the CuO2 planes. In this Brief Report, we describe the design and phase is only stabilized for the largest La ion among rare earth trivalent ions. The relatively large Pr (and Nd) ions form the solid solution with the largest I pounds, partially Sr-substituted L La Cuo4, where L La2-Pr,Cuo and Laz-Nd,Cu, over the whole stands for Sm, Eu, and Gd: The new compounds are com- posed of the single-layer sheets of Cu-O pyramids, as shown in Fig. 1(a), and show the sequential ordering of the cations in such a way as -La-La-L-L-1. We found that the Sr-doping into the mother compound LLaCuo4 stabilizes the new structure, which we w call the T phase hereafter, and makes the compounds metal lic (and possibly superconducting, if we can diminish oxy gen vacancies). The new compounds form essentially the same Cu-O network as the 30-K superconductor Ndz-x-Ce,Sr, Cu04 discovered by Akimitsu et al., which shows the partial ordering of Nd and Sr as shown in Fig. b). The T* phase compound is possibly the sim plest system among the Cu-O pyramidal sheet compounds ducting) copper oxide compounds with single-layer CuO2 sheets: and, hence, will provide a unique opportunity for investi gating multisheet compounds with higher Te but with more com phase); and (d) Lz-Ce,Cuo (T pha FIG. . Crystal structures of metallic (and possibly supercon- basic physical properties relating to the existing NdCeSr CuO (T* phase): (c La-Sr,Cu4 C7 u,

Explanation / Answer

This article describes 4 types of superconductors i.e; single layered CuO2 sheets.

1) LaSrCuO4 which is doped with Sr to make it superconducting.

2) Fig2 LLaCuO4 ( T* phase)

3) LaCeCuO4

4) NdCeSrCuO4

While the synthesis, testing the properties of LLaCuO4 is described briefly.

Synthesis:

Since La hardly dissolves in Eu ,Sm, Gd sites,

La2O3 is mixed with either (Eu2O3 or Sm2O3 or Gd2O3 these three are mutually insolinsoluble CuO and SrCuO3 the mixture is calcined at 950? in air for 10 hours then pressed into pellets, and finally sintered at 1130? in air for 15 hours, the pellets are quenched to room temperature in air and subsequently annealed at 550? with various oxygen pressures up to 18 atm.

Testing methods:

X ray diffraction : X-ray diffraction is based on constructive interference of monochromatic X-rays and a crystalline sample. Here , it is used to test the new compound and the diffraction pattern is different from that of T phase and T' phase.

LLaCuO4 acts as a superconductor if the oxygen vacancy is diminished .The oxygen in the newly made sample is measured by iodometric titrations. The occupancy of L atom is greater. Hence it is a hybrid model between T and T* phase and acts as a superconductor.

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