•Good lattice match with perovskite structure superconductors •Stable structure with much less defects than SrTiO3 •Low dielectric constant suitable for microwave or high frequency application
Comparison of SrTiO3 - LaAlO3 - SrAlO4 Crystal
Properties/Crystal
SrTiO3
LaAlO3
SrLaAlO4
Structure
Cubic
Rhombohedral at 25 oC : Cubic at > 435 oC :
Tetragonal
Lattice Constant
a = 3.905
a = 3.821 A
a = b = 3.756 A c = 12.636
mismatch to YBCO (a = 3.9)
+0.12 %
-2.0 %
-3.7 %
Dielectric Constant
~ 300
~ 25
~ 17
Grown Method
Vernuil
CZ
CZ
Thermal expansion
10.4 (x10-6 / oC)
10 (x10-6 / oC)
12 (x10-6 / oC)
Melting point
2100 oC
2080 oC
1650 oC
Density
5.175 g/cm3
6.52 g/cm3
5.92 g/cc
Max. Crystal size
30 mm dia.
75 mm dia
35 mm dia
Crystal quality
Wide rocking curve due to dislocation density
Visible twin due to phase transition around 400 oC
