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In this work a detailed analysis of the decomposition behavior of nickel acetylacetonato-propionate with and without additive addition was investigated through thermogravimetry (TG) coupled with differential thermal analyses (DTA) and mass spectrometry (MS), while chemical characterization has been carried out with Fourier transform infrared spectrometry (FTIR), X-ray diffraction analyses (XRD). Electron Spin Resonance and UV–vis measurements were performed to confirm whether the complexation of the precursor with additive occurs. The glycerol addition has effect on decomposition behavior of the precursor powder by shifting the main decomposition temperature with more than 100 °C to lower values. Regarding the intermediate decomposition products, they are similar at lower temperatures, while at final decomposition temperatures high exchanges occurs Ni metallic it is fully oxidized in the case of thermal decomposition of the nickel acetylacetonato-propionate precursor, while in the case of the precursor with glycerol addition, metallic nickel is still observed concomitant with NiO phase. The thermal decomposition mechanism of the precursors has been proposed.

The environmentally friendly fluorine-free propionate chemical solution deposition route has been developed for the epitaxial growth of YBa2Cu3O7−x (YBCO) superconducting films. In the present work, metal acetates are used as reagents to prepare a YBCO fluorine-free precursor solution. In order to determine the thermal decomposition behavior, the precursor powder obtained by drying the precursor solution was investigated by thermogravimetric analysis coupled with mass spectrometry and differential thermal analyses. The precursor films were deposited on SrTiO3 single crystal substrates by spin coating and subjected to a single-step thermal treatment. Fourier Transformed Infrared spectroscopy was used to study the decomposition of the films. The films have been structurally and morphologically characterized by X-ray diffraction and atomic force microscopy, respectively, and the superconducting properties have been measured by SQUID. The film composition was investigated by Auger electron spectroscopy. The as-deposited YBCO films show a sharp texture and good superconducting transport properties with Tc=90 K (R=0) and Jc=0.8 MA/cm2, respectively.

We report on the synthesis and characterization of Eu 3+ -doped Y 2 O 3 nanocrystalline particles prepared by the oxalate (co)-precipitation method. Based on thermogravimetric analyses coupled with mass spectrometry, and correlated with FT-IR analyses and X-ray diffraction (XRD) measurements performed on the Eu 3+ -doped Y 2 O 3 oxalate-type precursor, a thermal decomposition mechanism has been proposed. The yttrium oxy-carbonate formation, as an intermediate product during the decomposition process, was evidenced. The XRD analysis has indicated the formation of crystalline cubic Y 2 O 3 structure at a temperature above 900 K after the complete decomposition of the yttrium oxy-carbonate intermediate. Transmission electron microscopy (TEM) investigations sustain the nanocrystalline nature of the Y 2 O 3 :Eu particles, with spherical and polyhedral shapes, and with an average size in the range of 5–10 nm. The photoluminescence (PL) measurements have revealed a strong red emission peak at 613 nm corresponding to the 5 D 0 → 7 F 2 forced electric dipole transition of the Eu 3+ ions under an excitation wavelength of 254 nm. The emission strongly increased with the increase of the calcination temperature from 773 K, when the yttrium oxy-carbonate decomposition process has been started.

In this paper the thermal decomposition of strontium zirconate metal-organic precursor is investigated by thermal analyses coupled with quadrupole mass spectrometry, Fourier transform infrared spectroscopy and X-ray diffraction measurements. Based on these analyses the decomposition sequence of both individual, and final precursors has been proposed. Starting from this precursor, SrZrO3 (SZO) epitaxial thin films have been deposited on (100)SrTiO3 (STO) single crystalline substrates at a temperature as low as 700 °C, by chemical solution deposition (CSD). The SZO films have a (0 1 0)SZO/(1 0 0)STO out-of-plane epitaxial relationship, and a good surface morphology with a root-mean-square roughness of about 0.8 nm. The structural and morphological properties of the deposited films demonstrate that these precursors are suitable for the deposition by CSD of high quality SZO epitaxial films for applications, e.g. buffer layer for YBa2Cu3O7-x -based coated conductors fabrication.

Gadolinium-doped ceria epitaxial thin films were grown on yttria-stabilized zirconia (YSZ) substrates by polymer-assisted deposition (PAD). PAD utilizes an aqueous polymer to bind a metal or metal complex that serves to encapsulate the metal, in order to prevent chemical reaction in solution and to maintain an even distribution of the metal ions into solution. The structural and morphological properties were investigated by X-ray diffraction (XRD) and atomic force microscopy (AFM). The XRD pattern of the Gd-doped ceria (CGO) films indicated a dramatic improvement of the epitaxial growth with respect to pure CeO 2 films. The CGO thin film morphology changes from rounded to plate-like grains when the annealing temperature increases due to an increase of atom mobility.

Yttrium propionate, Y 2 (CH 3 CH 2 COO) 6 · x H 2 O, has been used as a precursor in the preparation of Y 2 O 3 and YBa 2 Cu 3 O 7− x thin films. The molecular structure of this precursor was determined by X-ray diffraction on single crystals, in good agreement with the formula calculated from the thermogravimetric analysis data. The molecular structure consists of a bimetallic complex with two Y atoms linked by two propionate groups in a bridging bimetallic tridentate fashion, and each metal bearing an extra two monometallic bidentate propionate ligands. The thermal decomposition was studied using the thermogravimetry–differential thermal analysis and mass spectrometry (TG–DTA–MS), in inert atmosphere. The influence of the different heating rates, such as 5, 7.5, 10, 15 and 20 °C/min on the thermal behaviour of yttrium propionate was investigated. The X-ray diffraction pattern on the precursor powder heat treated under nitrogen has shown that the final decomposition product of [Y 2 (CH 3 CH 2 COO) 6 ·4H 2 O]·H 2 O is Y 2 O 3 . The activation energy, as a kinetic parameter, was determined by using both Kissinger and Friedman methods for the decomposition process.

ZnO thin films were prepared by the sol–gel method, using two distinct solvents, ethanol (EtOH) and 1-propanol (1-PrOH). The influence of these two solvents on the crystallographic, morphological and optical properties of ZnO thin films was investigated. Highly c-axis oriented ZnO thin films, having grains with lengthened shapes and good optical absorbance were obtained using 1-PrOH as a solvent in the ZnO precursor sols.

A new copper propionate complex was synthesised and characterized for application as precursor for CuO based oxide thin films deposition. The FT-IR and X-ray diffraction analyses have revealed the formation of a cooper propionate complex [Cu(CH 3 CH 2 COO) 2 ]·2H 2 O. The crystal and molecular structure of a new copper propionate complex was determined by XRD on the copper propionate single crystal. The copper propionate complex has a binuclear structure, connected by bridging bidentate carboxylates groups and a Cu⋯Cu bond of 2.6 A. The thermal decomposition of copper propionate has been investigated by thermal analysis using thermogravimetric (TG) and differential thermal analysis (DTA), differential thermal analysis coupled with quadrupole mass spectrometry-QMS, X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR) techniques. TG and XRD data indicate the reduction of Cu(II)–Cu(I,0) during the decomposition of copper propionate.

The present study reports on a novel barium acetato-propionate complex, obtained by the reaction of barium acetate with propionic acid, used as an oxide precursor with applications in superconducting thin films deposition. The molecular structure has been determined by X-ray diffraction on single crystals and demonstrated to be [Ba 7 (CH 3 CH 2 COO) 10 (CH 3 COO) 4 ·5H 2 O]. The barium acetato–propionate is a three-dimensional channel-type polymer. The thermal decomposition of the barium precursor has been studied by simultaneous differential thermal analysis-thermogravimetry–mass spectrometry (DTA-TG–MS) in air at a heating rate of 10 °C/min. Based on these analyses, infrared spectroscopy was further used to characterize the precursor solution by the step-wise addition of the reagents. The X-ray diffraction on the precursor powder at different temperatures was performed.

Lanthanum acetylacetonate La(C{sub 5}H{sub 7}O{sub 2}){sub 3}.xH{sub 2}O has been used in the preparation of the precursor solution for the deposition of polycrystalline La{sub 2}O{sub 3} thin films on Si(1 1 1) single crystalline substrates. The precursor chemistry of the as-prepared coating solution, precursor powder and precursor single crystal have been investigated by Fourier Transformed Infrared Spectroscopy (FTIR), differential thermal analysis coupled with quadrupole mass spectrometry (TG-DTA-QMS) and X-ray diffraction. The FTIR and X-ray diffraction analyses have revealed the complex nature of the coating solution due to the formation of a lanthanum propionate complex. The La{sub 2}O{sub 3} thin films deposited by spin coating on Si(1 1 1) substrate exhibit good morphological and structural properties. The films heat treated at 800 {sup o}C crystallize in a hexagonal phase with the lattice parameters a = 3,89 A and c = 6.33 A, while at 900 {sup o}C the films contain both the hexagonal and cubic La{sub 2}O{sub 3} phase.

A new chemical solution deposition method for the epitaxial growth of La 0.66 Sr 0.33 MnO 3 (LSMO) thin films from metal acetates, acetylacetonates and propionic acid is presented. Using this method, epitaxial LSMO thin films were grown on (001) SrTiO3 (STO) single crystalline substrates in the temperature range from 800 °C to 1100 °C, both in air and in oxygen atmosphere. The LSMO thin films exhibit good structural and electrical properties. The FWHM of the ω-scan for the (002) peak has a mean value of 0.06°. The Curie temperature of the LSMO thin films is about 320 K and 350 K for the annealed in oxygen and air, respectively.

This work reports on the low temperature preparation and characterization of BaZrO3 (BZO) epitaxial thin films by chemical solution deposition (CSD). The X-ray θ–2θ scan and φ-scan measurements have demonstrated that the BZO films exhibit cube-on-cube epitaxy on (100) MgO substrates, with the full width at half maximum (FWHM) for the ω-scan and φ-scan of 0.35° and 0.46°, respectively. The SEM and AFM analyses revealed that the morphology of the films is strongly correlated with annealing temperature. The root mean square roughness for the film annealed at 600 °C is 3.63 nm, while for the film grown at 1000 °C is 5.25 nm.

We report on the superconducting properties of epitaxial thin films Y/sub 1-x/Ca/sub x/Ba/sub 2/Cu/sub 3/O/sub 7-y/ with 0/spl les/x/spl les/0.2, grown on SrTiO/sub 3/ [001] by Pulsed Laser Deposition (PLD) technique. The partial substitution of Ca/sup 2+/ at the Y/sup 3+/site in YBCO leads to a monotonic decrease of the zero resistance critical temperature, T/sub c/. The oxygen stoichiometry is varied by means of post-deposition thermal treatment varying the oxygen partial pressure. The dependence of T/sub c/ on annealing oxygen pressure can be attributed to an overdoping effect and/or to a cation disorder.

The introduction of artificial pinning sites in YBa(2)Cu(3)O(7-delta) (YBCO) epitaxial thin films has been obtained by pulsed laser deposition (PLD) technique from YBCO-BaZrO(3) (BZO) composite targets with BZO concentration ranging from 2.5 to 7 mol %. The typical critical temperature, T(c), drop observed in YBCO-secondary phase films grown by PLD has been successfully recovered by increasing the deposition temperature. Transport properties analyses revealed improved pinning force values for YBCO-BZO films for BZO concentration above 5 mol %. These films exhibited an anomalous dual peak structure which has been ascribed to the presence of two pinning contributions. The crossover field, B(m), separating these two pinning regimes has been observed to be temperature independent suggesting the occurrence of the matching field effect. The measured value of B(m) agreed with the matching field value, B(Phi)=Kn(d)Phi(0), as evaluated from transmission electron microscopy investigations. The mark of this phenomenon is retained down to 10 K, making YBCO-BZO more performing than pristine YBCO films at applied magnetic fields below B(m) in all the temperature range inspected. On the contrary, in the high magnetic field range (above B(m)), the effectiveness of correlated pinning is progressively reduced on lowering the temperature suggesting that at low temperatures the dominant pinning contribution arises from isotropic pinning centers. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3477451]

In the present paper, we analyze the role of in situ grown BaZrO3 (BZO) inclusions in YBa2Cu3O7−x (YBCO) thin films prepared by chemical solution deposition using a low fluorine coating solution, on the field angle dependence of the critical current density, J c (𝜃), data using the vortex path model. In order to form a coherent picture on the BZO doping influence on the pinning properties of the YBCO matrix, detailed structural analyses performed by X-ray diffraction techniques and microstructural evaluation by transmission electron microscopy are also presented. The evaluation of different contributions to the overall, J c , permitted us to prove the effectiveness of the BZO inclusions acting as isotropic pinning centers, reflected in a uniform component of high relative value with respect to other components. For the studied 10 mol % BZO doping concentration, a threefold increase in the critical current density, J c , of the YBCO host is measured, in self-field at 77 K, corresponding to a value of J c =2.9MA/cm2, whereas a factor 10 is measured at 1 T (J c =0.35 MA/cm2).

We present measurements of the microwave complex surface impedance at 47.7 GHz in YBa2Cu3O7Àd (YBCO) films deposited by pulsed laser deposition with the explicit goal to introduce BaZrO3 (BZO) nanoinclusions. Composite targets obtained by addition of BZO powder in molar percents ranging from 2.5 to 7 mol.% have been prepared and characterized. Measurements of the microwave surface impedance indicate a broadened transition in zero field, however compensated by a very large pinning frequency, indicating that while intergrain properties are still to be optimized the effect of nanometric inclusions substantially enhances the intragrain vortex pinning.

The addition of artificially induced defects improves the pinning efficiency of magnetic flux vortices in YBa2Cu3O7 (YBCO) films. In YBCO films by pulsed laser ablation (PLD) technique this goal can be pursued by the introduction of epitaxial second phase nanoinclusions in the YBCO matrix. In the present work, the effect of BaZrO3 (BZO) inclusions in stoichiometric YBCO films on transport properties has been studied. Composite targets obtained by addition of BZO powder in molar percents ranging from 2.5 to 7 mol.% have been prepared with BZO mean grain size of about 1 m. Structural and morphological character- izations of the films obtained by PLD from these targets have been carried out through X-ray diffractometry and Scanning Electron Microscopy (SEM) analysis. Dc electrical transport measurements at 77 K have revealed a better magnetic field retention of the critical current density, , being at 3 T the 14.6% and the 16.4% of the zero field values for YBCO-BZO 5% and 7%, respectively. The complex surface impedance has been measured by means of a dielectric resonator at a high microwave frequency (50 GHz). In order to identify the potentially strong pinning induced by the inclusions, the field-dependent complex resistivity has been determined as a function of temperature in a moderate magnetic field ( 1 T). Very high depinning frequency are estimated in YBCO films with BZO inclusions indicating extremely high vortex pinning and steep potential wells.

The paper presents the growth and characterization of highly textured La 2 Zr 2 O 7 (LZO) multilayer coatings on Ni–5 at.%W (NiW) biaxially textured substrates by chemical solution deposition (CSD) under highly reducing conditions (Ar + 12%H 2 ) in order to protect the metallic substrate from oxidation. The coating solution consists in a stoichiometric mixture of lanthanum and zirconium acetylacetonates dissolved in an excess of propionic acid. The precursor chemistry was studied by means of infrared spectroscopy, thermogravimetric–differential thermal analyses, Raman spectroscopy and X-ray diffraction carried out on the precursor powder. The as-grown multilayer LZO coating exhibits a sharp in-plane and out-of-plane texture, with the full-width-at-half-maximum of the ω -scans and φ -scans of about 7.2° and 8.0°, respectively, close to that of the NiW substrate. The volume fraction of the c -axis oriented grains from the top layer of the coating increases with the number of layers. The LZO coating exhibits a smooth and crack-free surface, appropriate for the further epitaxial growth of a seed layer for the YBa 2 Cu 3 O 7 − x (YBCO) deposition. Transmission Electron Microscopy was used to investigate the microstructure of the CSD LZO thin films deposited on flexible NiW substrates. A high density of nanovoids, with a size ranging between 10 and 30 nm, was observed in the LZO layers. YBCO films epitaxially grown by pulsed laser deposition on the CSD LZO buffer layer exhibit critical current densities, J c , close to 1.6 MA/cm 2 at 77 K and self-field and zero resistance critical temperature ( T c (R = 0)) of 90.3 K.

International audience; This paper presents our results regarding oxygen incorporation effects in epitaxial La(1-x)SrxMnO3 thin films, deposited on SrTiO3 (001) single crystal substrates, by annealing in different gas mixtures of argon and oxygen. A particular emphasis is placed on the correlation of structural properties with the magnetic properties of the films, Curie temperature, and coercive field. In this sense, we demonstrate that the evolution of the diffuse part of the ω-scans performed on the films are due to oxygen excess in the film lattice, which creates cationic vacancies within the films. Also, we show that two regimes of oxygen incorporation in the films exist, one in which the films evolve toward a single phase and oxygen stoichiometry is recovered, and a second one dominated by oxygen over-doping effects. In order to support our study, XPS measurements were performed, from which we have evaluated the Mn3+/Mn4+ ionic ratio

Barium zirconate is the most attractive material used to induce artificial pinning centers both in melt textured and YBa2Cu3Ox (YBCO) thin films, in order to increase the critical current density. In the present work a systematic investigation of the crystallization kinetics of nanocrystalline BaZrO2 (BZO) obtained by the thermal decomposition of an oxalate precursor has been made. The crystallization process was analyzed by thermal analyses, infrared spectroscopy and X‐ ray diffraction and have shown that between 700 – 900°C the barium zirconate phase is partially formed, while between 1000 – 1200°C a pure barium zirconate phase appears. The as‐obtained nanocrystalline BZO powders have been successfully used in YBCO‐BZO composite targets manufacturing for pulsed laser deposition of superconducting YBCO thin films.

IEEE Transaction on Applied Superconductivity 15, 2 pp. 2691-2694 (2005)

The controlling factor in determining Tc in Y1-xBa2Cu3Oy (0

The present paper presents the effects of a nanostructured, ferromagnetic La1−xSrxMnO3(LSMO) thin film on the pinning characteristics of an epitaxial YBa2Cu3O7(YBCO) thin film deposited on top. Ordered arrays of LSMO grains were obtained upon growing the film on a terraced (001) SrTiO3 substrate. The analyses of magnetic measurements revealed the presence of a complex vortex pinning mechanism within the YBCO film. With respect to a reference single YBCO layer, an additional pinning potential was observed. Its temperature evolution suggests that a magnetic pinning mechanism is responsible for improved pinning characteristics in the high temperature and field region. Based on the morphology of the underlying LSMO buffer, a strong pinning force is expected to arise due to the anti-dot formations, where a high magnetization gradient exists.

This work reports on the structural and morphological characterization of ceria thin films grown by chemical solution deposition (CSD) techniques. The coating solution was prepared starting from cerium 2,4-pentadionate, Ce(CH3COCHCOCH3)3, and propionic acid, C2H5COOH, further concentrated by distillation. The as-prepared solution was spin coated on single crystalline (100) SrTiO3 (STO) substrates. The precursor films were heat treated in air at 900°C both by a rapid heating and quenching to room temperature (A) and annealing (B). The X-ray structural analysis and the SEM and AFM morphological analysis for the CeO2/STO thin film have revealed the influence of the thermal treatment on the growth mechanism. The as-obtained polycrystalline nanostructured ceria thin films present an average grain size of 40–50 nm and a roughness of 1.5–5.4 nm, depending on the thermal treatment. The annealing renders the ceria thin film a smoother surface with respect to the rapid heat treatment followed by quenching, performed both at the same temperature.

A modified TFA-MOD method, using only barium trifluoroacetate, is presented. The yttrium and copper triflouroacetates were replaced by the alcoholic solutions of Cu and Y acetates dispersed in propionic acid. Fourier transformed infrared spectroscopy (FT-IR), thermal analyses (DTA/TG) coupled with mass spectrometry (MS) and X-ray diffraction analyses were used to study the decomposition of the precursor. The method permits the shortening of the pyrolysis time by a factor 4, with respect to conventional TFA-MOD method, due to the smaller amount of evolved hydrofluoric acid. Using this method 600 nm thick YBCO films were grown both on (100)SrTiO3 and on CeO2/YSZ/CeO2/Pd buffered Ni-5at.%W substrates. The as obtained films exhibit good morphological, structural and superconducting properties with Tc (R=0) greater than 91K and with an out-of-plain texture of 0.240 and 1.90, respectively.

A detailed study on YBa(2)Cu(3)O(7-delta) (YBCO) films with BaZrO(3) (BZO) inclusions (YBCO-BZO) deposited on SrTiO(3) substrate with different BZO contents is presented. X ray diffraction, SEM imaging and superconductive critical temperature (T(c)) measurements were performed to evaluate film growth quality. Independently from the BZO content, all YBCO-BZO films showed T(c) values close to that of pure YBCO indicating that the T(c) reduction which is usually observed on YBCO-BZO films can be successfully recovered by changing the deposition conditions. All YBCO-BZO films showed an improved critical current density (J(c)) dependence on magnetic field if compared to the typical J(c)(H) of YBCO, resulting in higher irreversibility fields up to 9 T at 77 K. SEM observation on etched samples suggests a direct link between the defect density measured in YBCO-BZO samples and that calculated from the observed in field performances. The analysis of J(c)(B) as a function of applied magnetic field direction revealed that the pinning due to isotropic pinning centers typical for YBCO is coupled with a c-axis correlated pinning in YBCO-BZO which can be ascribed to BZO induced columnar defects. J(c)(B) recorded at several temperatures down to 10 K revealed matching effect features.

We perform measurements of high-frequency (similar to 48 GHz) microwave surface impedance with an applied magnetic field in YBa(2)Cu(3)O(7-delta) ( YBCO) laser-ablated films with various amounts of BaZrO(3) ( BZO) sub-micrometric inclusions, up to 7 mol % concentration. BZO inclusions are very effective in the reduction of the field-induced surface resistance in our experimentally accessible field range [ 0, 0.8] T. At temperatures low enough, the application of a moderate (similar to 0.2 T) field makes the YBCO/BZO films markedly less dissipative than pure YBCO. This result, examined in the light of the very high measuring frequency ( very small vortex oscillation amplitude) shows that BZO inclusions are even more effective pinning centers than columnar defects. We study the dependence of the vortex parameters ( vortex viscosity, pinning constant) on the BZO concentration. We examine the correlation between the reduction of the microwave dissipation and the areal density of BZO-induced defects. We argue that the very improved performances in a magnetic field are due to individual pinning of vortices on BZO inclusions.

We present measurements of the magnetic field dependent microwave surface resistance in laser-ablated YBa$_2$Cu$_3$O$_{7-\delta}$ films on SrTiO$_3$ substrates. BaZrO$_3$ crystallites were included in the films using composite targets containing BaZrO$_3$ inclusions with mean grain size smaller than 1 $\mu$m. X-ray diffraction showed single epitaxial relationship between BaZrO$_3$ and YBa$_2$Cu$_3$O$_{7-\delta}$. The effective surface resistance was measured at 47.7 GHz for 60$< T, Comment: LaTeX, 6 pages, 4 figures, uses jpconf.cls and jpconf11.clo class files, talk given at EUCAS 2007, submitted to J. Phys.: Conf. Series