YTTRIUM BARIUM COPPER

OXIDEand its use as a superconductor:

production and application

 

YBA2CU3O7

•YBCO is a 2G high-temperature superconductor•It is characterized as a ceramic oxide and crystallizes in the perovskite structure

SUPER CONDUCTIVITY “Superconductivity is a

phenomenon of exactly zero electrical resistance and expulsion of magnetic fields occurring in certain materials when cooled below a characteristic critical temperature.”

High-temperature (93K) Type 2

HOW DOES IT WORK? The BCS theory

electrons move as pairs through the lattice

due to a combination of the excited state pairing and low thermal energy of the crystal lattice, the electrons contain sufficient energy to “gap” the energy barrier of the lattice and experience no resistance

PRODUCTION Bulk YBCO cannot be made into

wires the way that copper is

Instead, superconducting wires are made by depositing thin films of YBCO onto textured substrates

YBCO-COATED WIRES YBCO wires contain

only a thin layer (300-800nm) of YBCO

The other components are a textured metal substrate, an oxide buffer layer, and another metal seal

CURRENT DENSITY The amount of current a wire of

given size can carry J = I/A; where J is current

density, I is current, A is area Conventional units for current

density of wires is A/cm-width

RABITS VS. IBADLength RABiTS IBADShorter than 20cm (short)

270 423

Longer than 20cm (long)

270 233

*All units are in A/cm-width*

DEPOSITION TECHNIQUES After the preparation of the

textured substrate, the YBCO must be deposited

The two most common techniques are:

1. metalorganic deposition (MOD) 2. high-rate pulse laser deposition

(HR-PLD)

METALORGANIC DEPOSITION Solution-based deposition, employing

chemical reactions to bind the film to the surface

HIGH-RATE PULSE LASER DEPOSITION High-powered laser ablates

source material Plume of atoms are deposited

onto target Issue with small deposition area

MOD VS. HR-PLD

MOD HR-PLD

Large scale deposition

Very uniform quality over long wires

Complex deposition process

Acceptable but not incredible current densities

Very high current density over both long and short wires

Simplified process

High energy required

Not as efficient at large-scale deposition

APPLICATIONS Underground transmission cables Oil-free transformers Magnetic energy storage units High-efficiency motors Compact generators

MAGNETIC APPLICATIONS Meissner Effect Magnetic Resonance Imaging

(MRI) and Nuclear Magnetic Resonance (NMI)

Future use: levitating force in maglev trains

DOWN TO BUSINESS Goal: replace copper wire as the

industry standard for high current transfer

Price performance: balances cost against current density

Currently, copper wire has a price performance ranging from $30-60kA/m

For YBCO to economically replace copper, it would require a price performance of $10kA/m

Currently, YBCO wire ranges from $15-30kA/m but because of the cooling and containment requirements, it is still more expensive than copper

As deposition efficiency increases, cost decreases

Price trends indicate a steady drop over time

STARTING YOUR VERY OWN YBCO STAND

Large overhead costs Production speed vs.

performance? Testing & research

Metal fluoroacetate

Yttrium oxide

Copper oxide

Liquid nitrogen

~$4000/kg $60-90/kg

$12-15/kg $0.06/L

BUYING YBCO MAGNETS As a consumer, bulk YBCO is available

for purchase as part of magnetic levitation kits

A 22mm diameter YBCO disc costs around $70

A 100nm thin film deposited onto LaAlO3 costs $300

Price depends heavily on how much the material was processed

CONCLUSION YBCO is a material that has yet

to completely reach its potential as the conducting wire of tomorrow

As deposition techniques improve, and it becomes continually less expensive to produce, YBCO will be used more and more in applications around the world