Yb123 Films Research Articles

Optimization of YbBa2Cu3Oy Thick Film Formation on MgO Substrates using Yb2BaO5 and liquid phase

The production of best thick YbBa2Cu3Oy (Yb123) films on MgO substrates are crucial for the utilization of this technology in silver sheeted wire as similar to Bi-2223. In this work, in order to optimize YbBa2Cu3Oy films on MgO substrates, a mixture of alpha-terpineol and 2-ethyl acetate was utilized as a solvent to which 100 nm sized stoichiometric powder mixture of Yb2BaO5, BaCuO2 and CuO was added and grinded for several hours to form a highly dense paste. Thick film precursors were prepared by spreading the paste over MgO substrates with a screen printing technique and various sintered and quench studies are done. Growth temperature is systematically varied between 800 and 950 °C for 30 minutes in air and quenched in liquid nitrogen. Similarly, sintering durations are varied systematically from 15 minutes to 8 hours. XRD reveals conformed that large Yb123 grains are formed when the thick films are sintered at 825 °C for 1 hour on MgO substrate. SEM micrographs are also in congruence with the XRD results depicting the giant Yb123 crystals. The present results clearly demonstrate that optimization of the growth temperature and time is crucial to obtain the large thick YbBa2Cu3Oy films on MgO substrates.

SUPERCONDUCTING PROPERTIES AND ORIENTATION BEHAVIOR OF REBa2Cu3Oy (RE = Yb, Er, Sm, Nd and La) FILMS BY METAL-ORGANIC DEPOSITION

We have investigated superconducting properties and orientation behavior of RE123 ( RE = Yb , Er , Sm , Nd and La ) films on MgO and SrTiO 3 substrates by metal-organic deposition technique using metal naphthenates. On MgO substrates, only Yb123 films showed superconducting transition with Tc( zero ) of 77.0 K and c-axis orientation with in-plane alignment. On SrTiO3 substrates, Yb123 , Er123 , Sm123 , Nd123 and La123 films showed c-axis orientation with in-plane alignment, and Tc( zero ) of 89.5 K, 89.7 K, 80.5 K, 85.0 K and 47.6 K, respectively. Sm123 and La123 films showed square and plate-like grains on MgO substrates, and relatively flat surface covered with well-grown grains on SrTiO 3 substrates.

Low temperature fabrication of epitaxial Yb123 films by coating-pyrolysis process

A novel method for fabrication of epitaxial YbBa 2Cu 3O 7 (Yb123) films at low temperatures by a coating-pyrolysis process is presented. This method comprises precisely controlled heat treatment of prefired films starting with a metal acetylacetonate-based solution according to the following schedule: (1) heated in O 2 atmosphere at 700–750 °C, (2) subsequently, in Ar–O 2 atmosphere with pO 2=10 −4 atm, and (3) postannealed at 300 °C in O 2 atmosphere. We have thus succeeded in preparing c-axis oriented epitaxial Yb123 films at temperatures lower than 750 °C. It was revealed that the initial heating in O 2 atmosphere was effective for lowering crystallization temperature. An epitaxial Yb123 film on 50-mm-diameter LaAlO 3 prepared at 720 °C showed J c∼3.5×10 5 A/cm 2 at 77 K and R s∼3.5 mΩ at 12 GHz and 70 K. While on CeO 2-buffered R-plane sapphire substrates, epitaxial films were fabricated at as low as 700 °C.

Orientation mechanism of REBa/sub 2/Cu/sub 3/O/sub y/ (RE=Nd, Sm, Gd, Y, Yb) thin films prepared by pulsed laser deposition

The orientation behavior and mechanism of REBa/sub 2/Cu/sub 3/O/sub y/ (RE123) films have not been clarified yet. We prepared RE123 films by the pulsed laser deposition method and investigated the orientation behavior and mechanism. We argue that the orientation behavior strongly depends on thermodynamic parameters such as the heat of sublimation. The thickness and surface morphology dependences of the orientation suggest that c-axis oriented thicker films will be obtained in RE123 if the surface remains smooth up to objective thickness. Critical temperatures were around or higher than 90 K and critical current densities were larger than 1 MA/cm/sup 2/ for all RE123 films. From the viewpoint of the orientation, the Yb123 films were the easiest to grow with the c-axis normal to the substrate surface.

The advantages of YbBa 2Cu 3O y thin films for superconducting wire application

We studied YbBa 2Cu 3O y (Yb123) deposited on MgO(1 0 0) and SrTiO 3(1 0 0) substrates by pulsed laser deposition method. In the present work, we discussed thickness dependence of orientation and critical current densities of the Yb123 films. We found that the obtained c-axis oriented Yb123 film with thickness of ∼1 μm showed the excellent superconducting properties, which were T c=89.5 K and J c=1.85 MA/cm 2 at 77.3 K. Additionally, the critical current density has been measured for the Yb123 film on MgO and SrTiO 3 as a function of the angle of the applied magnetic field B . An additional peak occurred in the case of B∥c -axis applied to the film on MgO.

Growth and Characterization of YbBCO Films on Textured Gd2O3 Buffer-Layered Ni Tapes: All Sol–Gel Process

YbBa2Cu3O7−x (YbBCO) thick films were grown on buffered, cube-textured Nickel tapes by sol–gel dip-coating method. Yb-123 films were prepared using solutions of Yb, Ba, and Cu organometallic compounds. A solution-based Gd2O3 buffer layer was deposited by dip-coating process with excellent texture and uniformity. The texture development and surface morphology of the buffer-layer films were examined by X-ray diffraction, pole figures, and ESEM analysis. Microstructure and characterization of Yb-123 films were done by ESEM, EDS, and XRD analysis. Tc and Jc were conducted by four-wire measurement method

Effects of the Heat-Treatment Conditions on Microstructures of YbBa2Cu3O7-σ Superconducting Films Formed by the Dipping-Pyrolysis Process

AbstractYbBa2Cu3O7-σ(Yb123) films were formed on SrTiO3(STO)(001) and LaAlO3(LAO)(001) substrates by the dipping-pyrolysis process. Using transmission electron microscopy, we investigated effects of the heat-treatment conditions in the processes of the dipping-pyrolysis method on microstructures of these films. As a result, we found that the high heating rates at the initial and final heat-treatments are necessary for achieving the epitaxial growth of the superconducting films.

Characterization of the YbBa2Cu3O7-y and YBa2Cu3O7-y thin superconducting films prepared by chemical solution deposition on MgO(001) substrate.

Thin superconducting films of the YbBa2Cu3O7-y (Yb123) and YBa2Cu3O7-y (Y123), prepared by post-deposition annealing of the metal naphthenates gels spin-coated on MgO(001) substrate, have been characterized by cross-sectional high-resolution electron microscopy and X-ray diffraction. It was found that the c-axis Yb123 films were epitaxially grown on the MgO(001) substrate at the temperature range from 700 degrees C to 775 degrees C in a gas mixture containing Ar and O2 with the oxygen partial pressure of p(O2) = 10(-4) atm. In contrast to the Yb123 films, it was found that Y123 films could be derived at a wider temperature range from 750 degrees C to 950 degrees C. Randomly oriented Y123 films were also grown on the MgO(001) substrate besides the majority of in-plane c-axis oriented growth.

The influence of calcination processes on the superconducting properties of Yb123 films prepared by chemical solution deposition

In-plane aligned c-axis oriented YbBa 2Cu 3O 7− δ (Yb123) films were successfully prepared on SrTiO 3 substrates by chemical solution deposition (CSD) using metal naphthenates under low oxygen partial pressure. The homogeneously coated films on SrTiO 3(100) were calcined by different heat-treatment profiles to decompose their organic components. These calcined films were fired at 750°C under 10 −4 atm of oxygen partial pressure (pO 2). The microstructures and the superconducting properties of the final Yb123 films are highly dependent on the heat-treatment profiles of calcination to obtain a uniform amorphous state. It has been confirmed by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) measurements that the heat-treatment of rapid heating and quenching is effective to prepare good calcined precursor film.

Structural and superconducting properties of biaxially aligned Yb123 films prepared by chemical solution deposition

We have succeeded in preparing in-plane aligned YbBa 2Cu 3O 7− δ (Yb123) films by chemical solution deposition (CSD) processing. A homogeneous coating solution having a molar ratio of Yb:Ba:Cu=1:2:3 was prepared by dissolving metal naphthenates in toluene. This solution was spin-coated onto the SrTiO 3(100) and MgO(100) substrates. The coated films were calcined at 425°C to decompose their organic components. The precursor films were fired under low oxygen partial pressure ( pO 2). The Yb123 films showed strong (00 n) peaks which correspond to c-axis orientation perpendicular to the substrates and their a/b-axis were in-plane aligned. The T c,zero values of the films prepared on SrTiO 3(100) were over 89 K, which are comparable to the results on typical YBa 2Cu 3O 7− δ (Y123) films. Typical J c values were about 10 5 A/cm 2 at 77 K, 0 T.

Growth of high quality YbBa2Cu3O7−δ thin films by pulsed laser deposition

Abstract YbBa2Cu3O7−δ (Yb-123) films are deposited for the first time using Pulsed Laser Deposition (PLD) method at three different substrate temperatures, viz. 675°C, 700°C and 725°C. Films are characterized using XRD, dc electrical resistivity, critical current density (Jc) and microstructural study by Atomic Force Microscopy (AFM) techniques. It is found that 700°C is the optimum growth temperature for growing high quality Yb-123 films. The best Tc and Jc values obtained at optimum growth conditions are 88 K and 2.6×106 A cm−2 at 77 K, respectively. AFM photographs provide evidence in confirming the relation between growth temperature and superconducting properties.