Microstructures of Tl 2 Ba 2 Cuo 6 Thin ®lms with Dierent Doping Levels
نویسندگان
چکیده
Microstructures of Tl 2 Ba 2 CuO 6 (Tl-2201) thin ®lms with dierent doping levels grown on SrTiO 3 substrates were studied by transmission electron microscopy. It is found that Tl-2201 ®lms are epitaxial single phase over large area. A new three-dimensional modulation structure was observed for the heavily overdoped ®lms. With decrease of doping level from heavily overdoped to optimally doped, the modulation structure becomes weaker and weaker and ®nally disappears at T c of about 50 K. The structural symmetry of the optimally doped Tl-2201 ®lms was con®rmed to be tetragonal I4/mmm by convergent-beam electron diraction. The tetragonal symmetry is broken into orthorhombic due to the modulation structure and consequently orthogonal twinning bands along h1 1 0i directions were observed. The modulation was found to be mainly localized in the CuO 2 plane.
منابع مشابه
Contributions of CuO planes and CuO chains on the transport
We have investigated the contributions of CuO planes and CuO chains on the transport properties of YBa Cu O by 2 2 4 8 Ž . Ž . measuring the electrical resistivity and thermoelectric power S of Y Pr Ba Cu Zn O , Y Ca Ba Cu O and 1yx x 2 1yy y 4 8 1yx x 2 4 8 Ž . YBa Cu Ga O . Pr reduces the mobile carrier concentration in the CuO planes in YBa Cu O , as a consequence, the 2 1yx x 4 8 2 2 4 8 Ž ...
متن کاملV2O5 NanoElectrodes with High Power and Energy Densities for Thin Film LiIon Batteries
Nanostructured V 2 O 5 thin fi lms have been prepared by means of cathodic deposition from an aqueous solution made from V 2 O 5 and H 2 O 2 directly on fl uorine-doped tin oxide coated (FTO) glasses followed by annealing at 500 ° C in air, and studied as fi lm electrodes for lithium ion batteries. XPS results show that the as-deposited fi lms contained 15% V 4 + , however after annealing all t...
متن کاملE!ect of Si doping on the strain and defect structure of GaN thin "lms
The amount of strain was measured in GaN "lms using X-ray di!raction, Raman, and curvature techniques as a function of "lm thickness and the Si doping concentration. It was found that for a doping concentration of 2]1019, the threshold thickness for crack formation was about 2.5 lm. Transmission electron microscopy observations showed that cracking proceeds without plastic deformation (i.e., no...
متن کاملSystematic (63)Cu NQR and (89)Y NMR study of spin dynamics in Y(1-z)Ca(z)Ba(2)Cu(3)O(y) across the superconductor-insulator boundary.
We demonstrate that the spin dynamics in underdoped Y(1-z)Ca(z)Ba(2)Cu(3)O(y) for y approximately equal to 6.0 exhibit qualitatively the same behavior to underdoped La(2-x)Sr(x)CuO(4) for an equal amount of hole concentration p = z/2 = x< or =0.11. However, a spin gap appears as more holes are doped into the CuO(2) plane by increasing the oxygen concentration to y approximately equal to 6.5 for...
متن کاملCorrelation of the local and the macroscopic properties of high-temperature superconductors: EXAFS data analysis.
Based on temperature-dependent EXAFS studies of Ba(1-x)K(x)BiO(3) superconducting oxide, a model of the relationship between the local crystal and the local electronic structures has been proposed. Oxygen ions were found to vibrate in a double-well potential and their vibrations are correlated with the local electron pair transfer due to the dynamical exchange BiO(6) <--> BiL(2)O(6), where L(2)...
متن کامل