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

1°) A brief personal history of image

furnace crystal growth

« 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

Four-mirror image furnace (Crystal Systems)

2°) Crystals grown and studied in

recent years

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

SrO-CuO phase diagram

A-type atom

Pyrochlore

B-type atom

Yb2Ti2O7CuGeO3

Congruent melting

La5Ca9Cu24O41

SrCuO2

Sr2CuO3

Non-congruent melting

3°) Assessment of

crystalline perfection

faisceau de neutrons

monocristal

film Polaroïd

plan (h k l)

I

II

I

(200) plane of a single

crystal of La0.85Sr0.15MnO3

image

4°) Influence of purity. Cation

segregation during growth

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)

Chain doping of spin-Peierls CuGeO3

Zn segregation in CuGeO3

5°)Oxygen partial pressure during growth

and oxygen stoichiometry control

pO2 control necessary during

growth of cuprite Cu2O and

subsequent annealing

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

PRB 56,10 (1997)

Magnetoresistance

decreases when 𝛿

5°) Other « objects » made by vertical

float-zone growth

Bicrystal growth

NiO - ZrO2 aligned eutectic

(longitudinal section)CuGeO3-SiO2

5 µm

6°) A recent development: crystal

growth under electric field

(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

33

DC

Floating zone crystal growth 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

Sr2CuO3SrCuO2

κmag = κb - κa

Influence of purity on thermal conductivity

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

Zn segregation in CuGeO3

xl

k

ekCCs

)1(10

x

l

k

ekC

C

110

Heater

Solid (C) Unmelted solid (C0)

0 L

x

Molten zone

l

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

Temperature (K)

k of

iron

European union contracts NOVMAG and LOTHERM

SrCuO2 Sr2CuO3

Chaque ion Cu 2+ de la chaine porte un spin ½