Method of manufacture of single phase ceramic superconductors

Patent · Sun Jan 01 00:00:00 EST 1995

OSTI ID:869804

Singh, Jitrenda P ^[1]; Poeppel, Roger B ^[2]; Goretta, Kenneth C ^[3]; Chen, Nan ^[3]

---

1. Naperville, IL
2. Glen Ellyn, IL
3. Downers Grove, IL

A ceramic superconductor is produced by close control of oxygen partial pressure during sintering of the material. The resulting microstructure of YBa.sub.2 Cu.sub.3 O.sub.x indicates that sintering kinetics are enhanced at reduced p(O.sub.2) and that because of second phase precipitates, grain growth is prevented. The density of specimens sintered at 910.degree. C. increased from 79 to 94% theoretical when p(O.sub.2) was decreased from 0.1 to 0.0001 MPa. The increase in density with decrease in p(O.sub.2) derives from enhanced sintering kinetics, due to increased defect concentration and decreased activation energy of the rate-controlling species undergoing diffusion. Sintering at 910.degree. C resulted in a fine-grain microstructure, with an average grain size of about 4 .mu.m. Post sintering annealing in a region of stability for the desired phase converts the second phases and limits grain growth. The method of pinning grain boundaries by small scale decompositive products and then annealing to convert its product to the desired phase can be used for other complex asides. Such a microstructure results in reduced microcracking, strengths as high as 230 MPa and high critical current density capacity.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States)
• DOE Contract Number: W-31109-ENG-38
• Assignee: University of Chicago (Chicago, IL)
• Patent Number(s): US 5401712
• OSTI ID: 869804
• Country of Publication: United States
• Language: English

Related Subjects

method
manufacture
single
phase
ceramic
superconductors
superconductor
produced
close
control
oxygen
partial
pressure
sintering
material
resulting
microstructure
yba
cu
indicates
kinetics
enhanced
reduced
precipitates
grain
growth
prevented
density
specimens
sintered
910
degree
increased
79
94
theoretical
decreased
0001
mpa
increase
decrease
derives
due
defect
concentration
activation
energy
rate-controlling
species
undergoing
diffusion
resulted
fine-grain
average
size
post
annealing
region
stability
desired
converts
phases
limits
pinning
boundaries
scale
decompositive
products
convert
product
complex
asides
results
microcracking
strengths
230
critical
current
capacity
ceramic superconductor
average grain
desired phase
oxygen partial
current density
grain boundaries
grain size
partial pressure
critical current
single phase
activation energy
grain growth
close control
ceramic superconductors
resulting microstructure
phase ceramic
phase precipitate
ceramic superco
/505/252/