Synthesis and Characterization of BZO doped YBCO Superconducting Films With Different Types of Precursors

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Synthesis and Characterization of BZO doped YBCO
Superconducting Films With Different Types of
Precursors
DOKUZ EYLUL UNIVERSITY DEPARTMANT OF
METALLURGICAL MATERIALS ENGINEERING

• Murat BEKTAS
• Dr. Isil BIRLIK
• Dr. Osman ÇULHA
• Doç. Dr. Mustafa TOPARLI
• Supervisor Prof. Dr. Erdal ÇELIK

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Content

• AIM Of THE STUDY
• INTRODUCTION
• Superconductivity
• TFA-MOD Technique
• EXPERIMENTAL STUDIES
• Characterization of
• YBCO Thin Film Production from Oxide Powder
• YBCO Thin Film Production from Acetate-based
  Presursor
• CONCLUSION

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AIM OF THE STUDY

• TFA-MOD process using highly purified metal
  acetates as starting materials are rather
  expensive and thus it is desirable to find more
  economic route.
• Recently, several attempts to use oxide powders
  such as commercially available REBCO powder as
  starting materials have been reported which
  showed comparable Jc (critical current density)
  for the YBCO films.
• In this study, two different types of BaZrO3
  doped YBa2Cu3O7-d (YBCO) superconducting thin
  films were prepared using commercially available
  YBCO powder and yttrium, barium and copper
  acetate on SrTiO3 (STO) substrates by TFA-MOD
  method.
• The effect of precursor type on the film
  structure and superconducting properties were
  studied.

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SUPERCONDUCTIVITY
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Superconductivity was first discovered in 1911
by the Dutch physicist, Heike Kammerlingh Onnes.
He discovered that the electical resistance goes
to zero when mercury is cooled at about 4.2K.
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Vortex and Flux Pinning
Importance of Flux Pinning for HTS

• Power applications and high field applications
• Nuclear magnetic resonance (NMR)
• Superconducting magnetic energy storage (SMES)
• HTS conductors need to possess a high critical
  current density under high magnetic fields.
• Improving the in-field Jc has been a topic of
  enormous technological importance!!!

• Crystal defects act as natural pinning centers
• Fine precipitates of non-superconducting phases
• Dislocations
• Oxygen vacancies
• Small-angle grain boundaries
• Twin boundaries

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Artificial Pinning Centers

• Types of defects such as Y2BaCuO5 inclusions or
  the introduction of random BaMeO3 (Me Mn, Zr,
  Ir, Hf, ...) nanoparticles.
• By building up a layered distribution of a
  second phase such as Y2BaCuO5 or Y2O3 using a
  multilayer deposition.
• Process induced modifications with excess
  yttrium, and decoration of substrate surfaces by
  nanoscaled particles.

Types of Defects

• Defects need to be of similar size as the
  coherence length
• Coherence length in HTS are on the order of
  nanometers. So, nanoparticles are necessary.
• Compatibility of the nano-structure with
  superconductor is required.

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YBCO (YBa2Cu307-x)

• The compound YBa2Cu307-x, sometimes called YBCO
  or Y-123 compound, in its orthorhombic form is a
  superconductor below the transition temperature
  Tc 92 K.
• YBCO has perovskite structure.

The structure of YBa2Cu3O7-x.
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TFA-MOD
Schematic illustration of metal organic
deposition using trifluoroacetates (TFA-MOD) for
fabricating YBCO superconductors.
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EXPERIMENTAL STUDIES
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YBCO Thin Film Preparation
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Solution Preparation
YBCO oxide powder propionic acid Sol A
Y, Ba and Cu acetates methanol Sol B
Repeat  
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Solution Preparation
Adding Zr-penthanedionate results
in YBa2-xCu3O7-d x(BaZrO3) X 0.006, 0.012,
0.018 (corresponds 6, 12 and 18 mol BaZrO3 )
Precursors Name of Solution Doped-BZO concentration (mol) Name of Films
YBCO powder SolA0 0 F-A0
YBCO powder SolA1 6 F-A1
YBCO powder SolA2 12 F-A2
YBCO powder SolA3 18 F-A3
Yttrium, Barium and Copper acetates SolB0 0 F-B0
Yttrium, Barium and Copper acetates SolB1 6 F-B1
Yttrium, Barium and Copper acetates SolB2 12 F-B2
Yttrium, Barium and Copper acetates SolB3 18 F-B3
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• Heat Treatment Process

• Spin Coating

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Characterization of Solutions YBCO Films

• Solution characterization
• Viscosity and contact angle,
• DTA-TG (Differential Thermal Analysis-Thermal
  Gravimetric Analysis),
• YBCO film characterization
• XRD (X-Ray Diffractometer),
• SEM (Scanning Electron Microscopy)
• Physical properties
• Inductive Tc measurement
• Inductive Jc measurement

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Solution Characterization

• Viscosity and Contact Angle

Solution Name Viscosity m(Pa.s) Contact Angle (o)
Sol A0 7.80 22.26
Sol A1 6.99 22.26
Sol A2 24.72 22.26
Sol A3 87.49 22.26
Sol B0 4.12 21.28
Sol B1 4.76 21.28
Sol B2 4.64 21.28
Sol B3 4.30 21.28
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Solution Characterization

• DTA-TG

Sol B
Sol A

• Below 200 oC Evaporation and release of acetic
  acid and gel network water.
• 233 oC Large loss in mass, combustion reaction
  due to the presence of acetate groups and loss of
  TFA, initial formation of BaF2 and CuO phases.
• 275 C Formation of a yttrium intermediate as
  Y2O3 .
• Final combustion Release of relatively large
  quantity of CO and CO2 .

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Characterization of YBCO Films

• XRD

F-A series
F-B series
F-B3
F-B2
F-B1
F-B0

• Major peaks (00l) YBCO and (h00) substrate.
• BZO (200) peak intensities increases slightly
  with increasing BZO concentration.
• (103) orientation of YBCO is observable, peak
  intensity decreases as the BZO concentration
  increases.

• (00l) reflections of the YBCO phase and (100)
  STO substrate indicate that the YBCO film has a
  strong c-axis texture.
• (004) and (007) orientations of YBCO are lower
  than expected for a textured structure.

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Characterization of YBCO Films

• SEM

F-A series
F-B series
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Characterization of YBCO Films

• Tc (Critical Temperature)

Resistivity vs. temperature and Dependence of
critical temperature Tc and transition width ?Tc
on the amount of BZO concentration graphs doped
and undoped YBCO films prepared from Sol A and
Sol B.
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Characterization of YBCO Films

• Jc (Critical Current Density)

Dependence of inductively measured critical
current density Jc on the amount of BZO
concentration graph for YBCO films prepared from
Sol A Sol B
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Conclusion

• YBCO superconducting thin films were successfully
  prepared from YBCO powder and yttrium, barium,
  copper acetate precursors via TFA-MOD method on
  STO single crystal substrates and BZO was
  incorporated into the structures of them as
  artificial pinning centers.
• According to SEM images, YBCO films prepared from
  SolA exhibit better surface morphology and all of
  them are generally formed by c-axis oriented
  grains. BZO doped YBCO films present a denser
  surface structure with decreasing porosity
  compared with the undoped YBCO films. On the
  other hand, 18 mol BZO doped sample surface
  possesses bigger sized grains in comparison to
  the fine grains of 6 and 12 mol BZO doped sample
  surfaces.
• As a result of Jc measurements, 6 mol BZO doped
  YBCO sample prepared from SolA (YBCO powder) has
  the highest Jc value.

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Thanks for your attention
ACKNOWLEDGEMENT TO
TUBITAK-109M054 Leibniz Enstitute For
Solid State and Materials Research
Dresden