981 resultados para CU-2
Resumo:
PrBa2 Cu3O7 ,Cu(1 )O 0 .4 1 ,Cu(2 )O 0 .2 8.5 7FePrBa2 Cu3O7M ssbauer ,5 7FePrBa2 Cu3O7 .
Resumo:
RBa2Cu3O7 (R = Pr, Sm, Eu, Gd, Dy, Y, Ho, Er, Tm) has been studied using complex chemical bond theory. The results indicated that with the decreasing of R radius, the ionicities for all considered types of bond decrease. This is in good agreement with the experimental fact that T-c decreases with the decreasing of R radius. PrBa2Cu3O7 with no Ba-site Pr in this calculation is also predicted to be a superconductor. This supports the conclusion obtained by Blackstead et al. The ionicity for each bond obeys the following order: Ba-O > R-O > Cu(2)-O(1) > Cu(2)-O(2,3) > Cu(1)-O(4) similar to Cu(1)-O(1).
Resumo:
Mossbauer spectra of Fe-57 in a thick film YBa2(Cu0.97Fe0.03)(3)O7-x irradiated by a large dose of gamma-rays from Co-60 have been measured. The variation of the relative intensities of some subspectra of Fe-57 in the. Mossbauer spectra of the thick film YBa2(Cu0.97Fe0.03)(3)O7-x after irradiation can be observed. This variation indicates that the change of the coordination environment around some Fe atoms in the lattice occurs due to irradiation. The relative intensity of subspectrum D1(Fe) at the Cu(1) site decreases and that of subspectrum D4(Fe) at the Cu(1) site increases. This may be because of the possible oxygen atom hopping between the coordination environments of D1(Fe) and D4(Fe) in the lattice caused by irradiation. The effect of irradiation on the coordination environment around the Fe atom at the Cu(2) site is not appreciable. (C) 1997 Elsevier Science B.V.
Resumo:
TG and DTA analysis of Y1-xCaxBa2Cu3O7-y suggests that the stability of the 123 phase increases with increasing Ca contents. The O(1) in the Cu(1)-O chain is unstable but O(2) and O(3) in Cu(2)-O planes are very stable. There are hardly any oxygen vacanci
Resumo:
Polyvinyl alcohol amidoxime (PVAAO) chelate fiber prepared in our laboratory is a good adsorbent. Comparing with other adsorbents, it has many advantages, such as higher hydrophilicity, better adsorbability and easier synthesis. In this work, the synthesi
Resumo:
,CuO_4Cu~(2+),Cu~(2+)O~(2-),Cu~(2+)3d~9dx~2-y~2,,
Resumo:
KegginZW_(11)O_(39)M(H_2O)~(n-)(Z=Si,Ge,P;M=Ni~(2+),C~(2+),Cr~(3+),Co~(2+);n=46)DawsonP_2W_(17)O_(61)M(H_2O)~(n-)(M=Ni~(2+),Cu~(2+),Cr~(3+),Co~(2+);n=7,8)(),,.Lewis,,,,ESR.,,,,ZW_(11)O_(39)M(L)~(n-)+PyZW_(11)O_(39)M(Py)~(n-)+L(L=).,,.
Resumo:
YBa2Cu3-xTaxO7-y (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6) superconductors have been prepared, X-ray diffraction shows that the system remains orthorhombic for all compositions studied but. for x > 0.2, Ta2O5 was detected as an impurity phase. Substitution of Ta5+ for Cu2+ occurs in the Cu(2) sites on the Cu(2)O planes. The introduction of the high-valence element tantalum produces extra free electrons. These electrons recombine with the positive carrier of the system, which causes the mobility and the Hall number of YBa2Cu3-xTaxO7-y to decrease and also results in a depression in T(c).
Resumo:
XPS3,Cu~(2+)19%,81%;Pb~(2+)6%,94%,Zn~(2+)17%,83%,Cd~(2+)Cu~(2+)Cu~o
Resumo:
EuBa2(Cu1-xFex)3O7-y has been investigated by the Fe-57 and Eu-151 Mossbauer effect. The Fe-57 Mossbauer spectra of the EuBa2(Cu1xFex)3O7-y without or with DC electric current (the current strength I = 0.5A) around the superconducting transition temperature have been measured. The results indicate that the isomer shift (IS) and the quadrupole splitting (QS) of the Fe replacing the Cu(2) vary neither with increasing the Fe content nor with the small DC eletric current passing the superconductor and that the IS and the QS of the Fe replacing the Cu(1) vary with the Fe content. Especially, the IS and the QS of the Fe (D3) replacing the Cu(1) are changed when the small electric current passes the superconductor at 80K.
Resumo:
Eastman-AQ(AQ-55D,AQ-29D)(),,,,AQ-29DCd~(2+)Cu~(2+)Bi~(3+)Ru(NH_3)_6~(3+),,Cd~(2+)210~(-10)mol/L210~(-9)mol/L
Resumo:
~(57)Fe~(151)EuEuBa_2(Cu_(1-x)Fe_x)_3O_(7-y),~(57)Fe,Cu(2)Fe,Cu(1)FeFe,Fe
Resumo:
:,Cd~(2+)Zn~(2+)1h,Pb~(2+)Cu~(2+)1.5h;:Pb~(2+)>Cu~(2+)>Zn~(2+)>Cd~(2+);[Mg~(2+)]<200mg/L,[Ca~(2+)<400mg/L,[K~+]<350mg/L,Cu~(2+),0.1g(Hg~(2+)),0.15g(Cu~(2+)),pH0.38(Hg~(2+)),38(Cu~(2+))>7mL/min(Hg~(2+)),10mL/min(Cu~(2+)),,320,
Resumo:
Cu~(2+)Mo(V)-SCN~--ERB~+-PVA580nm,=5.610~6Lmol~(-1)cm~(-1)Mo()00.3g/25mL,
