Zobrazeno 1 - 10
of 200
pro vyhledávání: '"Z.Z. Sheng"'
Publikováno v:
Physica Status Solidi (a). 158:179-182
Tl-M-Sr-Cu-O (M = Cr or V) samples were prepared from ultrafine Cu powder and Tl 2 CO 3 , and studied by TEM, ED, and XRD. The results indicate that the samples consist mainly of 1201 phase and a small amount of a tetragonal phase with larger cell pa
Publikováno v:
Modern Physics Letters B. 10:609-614
The effects of vanadium or chromium on the formation, electric properties and superconductivity of Pb-3212 phase ( Pb 2 Cu ) Sr 2( Ca 0.5 Y 0.5) Cu 2 O z are studied. The sites of V or Cr in PbO–CuO δ– PbO structure unit for Pb -3212 phase is al
Publikováno v:
Solid State Communications. 95:277-280
Nearly-pure 1201-type cuprate HgBa2CuO4+δ was successfully synthesized at ambient pressure in an open system, and was characterized by powder x-ray diffraction analyses and by resistance and ac susceptibility measurements. The lattice parameters are
Publikováno v:
Physica C: Superconductivity. 248:42-48
The crystal structure of the 1212-type cuprate (Tl,Cr)Sr 2 (Ca,Tl)Cu 2 O 7 was investigated using X-ray diffraction data and the Rietveld refinement technique. The refinement was performed using the tetragonal symmetry of space group P4/mmm. It was f
Autor:
Z.Z. Sheng, O. Chmaissem
Publikováno v:
Physica C: Superconductivity. 247:125-132
The (Hg, Pb) based 1212-type cuprate (Hg, Pb)Sr2 (Ca,Y)Cu2O6+δ with Tconset up to 100 K was synthesized. The effect of O annealing on Tc was studied. Rietveld refinements of the structure were carried out with a tetragonal structure of space group P
Autor:
O. Chmaissem, Z.Z. Sheng
Publikováno v:
Zeitschrift für Physik B Condensed Matter. 99:179-184
We have successfully synthesized a new (Hg, V)-based 1212-type cuprate (Hg1−xVx)Sr2(Y1−yCay)Cu2Oz. The electrical resistance measurements showed that some of the as-synthesized materials with proper Hg/V and Y/Ca ratios exhibit weak superconducti
Autor:
O. Chmaissem, Z.Z. Sheng
Publikováno v:
Physica C: Superconductivity. 242:228-232
We synthesized a new 1212-type cuprate (Ga 1− x Hg x )Sr 2 (Y 1− y )Cu 2 O 7 . Partial substitution of divalent Hg for trivalent Ga simplifies the synthesis conditions of the 1212 compound and enhances its T c onset up to 88 K. Similar to GaSr 2
Autor:
Z.Z. Sheng, O. Chmaissem
Publikováno v:
Physica C: Superconductivity. 242:23-29
We have successfully synthesized a new 1212-type (Hg, Cr)-based cuprate (Hg 1− x Cr x )Sr 2 (Ca 1− y Y y )Cu 2 O 6+δ (0.1≤x≤0.5 and 0.1≤ y ≤0.5). According to X-ray diffraction data, the samples with x ≥0.2 and y ≤0.2 are 90–95% pu
Publikováno v:
Physica C: Superconductivity. 232:184-188
Powder of approximate composition Tl0.6V0.5Sr2Ca2Cu3Ox was synthesized in O2 at 970°C from a mixture of oxides of nominal composition Tl2V0.5Sr2Ca2Cu3Ox. The onset Tc was 110 K. Magnetic hysteresis measurements indicated that above ≈ 60 K the irre
Publikováno v:
Materials Research Bulletin. 29:1057-1064
TlBa[sub 2]Ca[sub 2]Cu[sub 3]O[sub x] (Tl-1223) powder was synthesized in O[sub 2] from a mixture of Tl[sub 2]O[sub 3] and Ba[sub 2]Ca[sub 2]Cu[sub 3]O[sub x]. The peritectic melting point of Tl-1223 in O[sub 2] is 905 C. It was found that the maximu