Trigonal Phases in YBa2Cu306.5
نویسندگان
چکیده
Trigonal ordering is evident from electron microscopy of quenched powders of composition YBa#Zu, 0, 5. The powders are a mixture of phases, some of which are based upon two trigonal phases with (I = 0.54 and c = 0.66 nm. In the first the yttrium and barium atoms order on the (I 11) planes of the parent perovskite structure rather than the (001) while in the second stacking sequence the yttrium layer of this structure is interchanged with one of the copper layers. 0 19X9 Academic Press, Inc.
منابع مشابه
The effect of alkaline earth metals (Magnesium and Calcium) on Hydrogen storage efficiency of alanate nanopowders
Different Aluminum: alkaline earth metal atomic weight ratios effects on structure transformations in alanates nanopowders were studied. Changes in crystal structures from alane to alanates by increasing alkaline earth metals dopants in the mixture with slight changes in crystal structures from rhombohedral centered – trigonal (alane) to trigonal (magnesium alanate), and monoclinic (calcium ala...
متن کاملThe effect of alkaline earth metals (Magnesium and Calcium) on Hydrogen storage efficiency of alanate nanopowders
Different Aluminum: alkaline earth metal atomic weight ratios effects on structure transformations in alanates nanopowders were studied. Changes in crystal structures from alane to alanates by increasing alkaline earth metals dopants in the mixture with slight changes in crystal structures from rhombohedral centered – trigonal (alane) to trigonal (magnesium alanate), and monoclinic (calcium ala...
متن کاملElectric-Field-Induced Triplet to Singlet Transition in Size-2 Trigonal Zigzag Graphene Nanoflake
Using Hartree-Fock Su-Sheriffer-Heeger (HF-SSH) model, we have studied the dependence of the energies of the ground (magnetic triplet state) and the first exited (nonmagnetic singlet state) states of the size-2 trigonal zigzag graphene nanoflake (size-2 NF) on the intensity of an external in plane static electric field at zero temperature. We identify a transition from the magnetic triplet stat...
متن کاملStructural study of A2CuTiO6 (A=Y, Tb–Lu) compounds
The A2CuTiO6 (A=Y, Tb–Lu) series has been reinvestigated in light of the recent discovery of cation order in structurally similar La4Cu3MoO12 and La3Cu2VO9. The crystal structure has been determined by electron and powder X-ray diffraction. The phases crystallize in an hexagonal symmetry, space group P63cm with cell parameters a ≈ 6.2 Å; c ≈ 11.5 Å. In this series of compounds, the Cu(II) and T...
متن کاملFar-Infrared and Raman Spectroscopy Investigation of Phonon Modes in Amorphous and Crystalline Epitaxial GeTe-Sb2Te3 Alloys
A combination of far-infrared and Raman spectroscopy is employed to investigate vibrational modes and the carrier behavior in amorphous and crystalline ordered GeTe-Sb2Te3 alloys (GST) epitaxially grown on Si(111). The infrared active GST mode is not observed in the Raman spectra and vice versa, indication of the fact that inversion symmetry is preserved in the metastable cubic phase in accorda...
متن کامل