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Crystal growth of oxide crystals by the image furnace
floating zone technique: an adventure of several decades
A. REVCOLEVSCHI
Synthèse Propriétés et Modélisation des Matériaux (SP2M)
Université Paris Sud - Orsay
OUTLINE
1°) A brief personal history of image furnace crystal
growth
2°) Crystals grown and studied in recent years
3°) Assessment of cristalline perfection
4°) Influence of purity. Cation segregation during
growth
5°) Oxygen partial pressure during growth and oxygen
stoichiometry control
6°) A recent development: crystal growth under
electric field
« Image furnace » floating zone (1965-)
Carbon arc
Xenon lamp
Movie projector equipped with a 6.5 kw quartz lamp with
tungsten electrodes
Ga2O3 6N
(1970)
Zone refining of 99.5% Al2O3 (1970)
99.5% Al2O3 thermocouple
cylindrical rods as feeds
CRYSTALS GROWN
- La1-xSrxMnO3 , Pr1-xCaxMnO3 - La2-xSrxCuO4
- La2-2xSr1+2xMn2O7 , La2MnO4 (La0.5Sr1.5MnO4) - CuFeO2 , Li2CuO2
- CuGeO3 (Si, Zn, Ni, Mn, Mg) - Bi2CuO4
- SrCuO2 , Sr2CuO3 - Yb2Ti2O7
- BaCu2Si2O7 - (R.E.)2NiO4 , La2CoO4
- Sr14-x CaxCu24O41 - LaCoO3
- Cu2O - Sr2RuO4
faisceau de neutrons
monocristal
film Polaroïd
plan (h k l)
I
II
I
(200) plane of a single
crystal of La0.85Sr0.15MnO3
image
Sr2CuO3 and SrCuO2 Purity influence on thermal conductivity
κm
ag (
WK
-1m
-1)
κb
~ 1/T ² +
cste
Chains
4N Purity
2N Sologubenko (2001)
3N Kawamata (2008)
Sr2CuO3 SrCuO2
Chains
99.9995% CuO – 4N SrO
2N Ribeiro (2005)
4N CuO – 4N SrO
Purity of samples plays an important role on thermal
conductivity along the spin chains at low temperature
R. Saint-Martin Ph.D Dissertation (2012)
La1-xSr1+xMnO4 : oxygen pressure during
growth
x atmosphere
0 CO2
0,125 CO2
0,25 O2 (1 bar)
0,40 O2 (1 bar)
0,50 O2 (2.5 bar)
0,60 O2 (3.5 bar)
from P. Reutler et al. J.Cryst. Growth(2003)
(2003)(2003)
Going from Mn3+ to Mn4+ requires
« oxidation » : pO2 has to be increased
Magnetoresistance of La0.85Sr0.15MnO3 :
Influence of oxygen non-stoichiometry on TCurie
[holes] = [Mn 4+] = 0.15 – 2δ
if δ , [Mn4+] and double exchange is less active,
and T Curie
Besides, oxygen vacancies break the path of the
electron jumps and act as electron scattering
centers. This additional resistivity reduces
magnetoresistance
(a)
B = 0
Song JY et al. J Mater Sci 2008
B ≠ 0
Pearlite Nucleation Magnetic texturing: Co particles alignment from a Co - B melt
Gaucherand F et al. Physica B 2004
B
31
Crystal growth under magnetic field
Piezoelectric Langasite La3Ga5SiO14
used in 3G communication systems
Uda et al. Journal of Crystal Growth 2005
Ice crystallization (simulation)
J. L. Aragones et al. Phys. Rev. Letters 2011
Influence of E on phase boundaries
Transformation of an incongruent-melting state to a
congruent-melting one under electric field:
the phase from which a crystal is solidified
congruently from a liquid is shifted
under electric field
10 kV
de-e = 2,5 cm
Anisotropic field strength in the melt
volume and at the interface
E max ~ 70 kV/m
E min ~ 35 kV/m
E(V/m)
DC
COMSOL modeling (LGEP, Supelec)
Feed rod
Melt
Crystal
34
Floating zone crystal growth under electric field
(b)(d)
BaCo2V2O8
Constant Lamp power
35
P. Hicher, R. Haumont et al. Journal of Crystal Growth (2015)
COWORKERS
- Guy Dhalenne
- Udo Ammerahl
- Mircea Apostu
- C. Hess, B. Büchner
- Surjeet Singh
- Neela Sekhar Beesetty
- Romuald Saint-Martin
- Patrick Hicher
- Raphaël Haumont
…./….
A POSSIBLE CANDIDATE
Additional peak due to magnonsSr14Cu24O41
The compound is: (1) Electrical insulator (2) Anisotropic thermal
conductor (3) Thermal conductivity along the chains is high, but low at RT.
How to improve this conductivity ?
Thermal conduction takes place mainly along the c axis
CuGeO3
SPIN PEIERLS TRANSITION
- magnetic analog of the Peierls instability
Heisenberg AF chains S = 1/2 (1D)
- coupling
3D phonon field
at T > TSP , uniform chains
at T < TSP , magnetic energy reduced by dimerisation
alternating exchanges
non magnetic fundamental state (S = 0) separated
from the continuum of first excited states by an
energy gap
CuGeO 3
Chains
J
a
bc
a
b
c
Chains
J
J’
Sr2CuO3 and SrCuO2
Structures Sr2CuO3 SrCuO2
J ~ 2000 K
J’ / J < 0.2J ~ 2000 K
Cmcm
a = 3.5711 Å
b = 16.3264 Å
c = 3.9121 Å
Immm
a = 12.7161 Å
b = 3.9153 Å
c = 3.5038 Å
Spinons are responsible of κmag
a) SrCuO2 single crystal. Inset: (0k0) cleavage plane. The crystallographic c-
axis corresponds to the growth axis.
b) Single crystal of SrCu0.99Ni0.01O2
(b)(d)
BaCo2V2O8
Constant Lamp power
47
Applied tension (kV)
Image AnalysisQuenched
P. Hicher, R. Haumont et al. Journal of Crystal Growth (2015)
(a) (b) (c) (d)
BaCo2V2
O8
Applied tension (kV)
Image Analysis
Quenching measurement
P. Hicher, R. Haumont et al. Journal of Crystal Growth
(2015)
48
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