LuFe O F. Damay from magnetism to oxygen storage E. Elkaim · J. Rouquette, J. Haines om e 2 O 4.5...
Transcript of LuFe O F. Damay from magnetism to oxygen storage E. Elkaim · J. Rouquette, J. Haines om e 2 O 4.5...
J. Rouquette, J. Haines
from LuFe2O4.5
= CYCLES
Effect of oxygen stoichiometry on magnetic properties
E. Elkaim
k1 = (0 2/3 0)m and k2 = (0 2/3 1/2)m
hkl broadening : disordered stacking of magnetic
platelets
AFM at RT
Loss of the triangular character
of the Fe lattice
50 nm
Nanostructures in LuFe2O4+δ M. Hervieu et al. Solid State Science 23, 26 (2013)
ADAPTABILITY and FLEXIBILITY : towards new coupling types for applications ?
M -LuFe2O4
C2/m subcell
+ O
2
- O2
[001] [100] [010]
M’ -LuFe2O4.5
C2/m subcell
O supercell
+ Reversibility Without altering the quality of the material
(by Ar/H2 annealing )
Sensitivity of the oxygen uptake phenomena:
Low temperature (200°C) And low pressure
(primary vacuum)
aM
bM
cM
cR
aR
Lu
Fe
LuO6 octahedra = CdI2 type layer
FeO
5
= t
rian
gula
r b
i-p
yram
ids
Fe
Lu
[LuFe2] [LuFe2] [Fe2]
[Lu]
M - LuFe2O4 M’ - LuFe2O4.5 hp - LuFe2O4
Similarity between oxygen non stoichiometry and pressure effects
LuFe2O4+d:
from magnetism to oxygen storage
C. Martin, M. Hervieu, A. Guesdon, A. Maignan
LuFe2O4
T >
T CO
= 3
30
K :
R-3
m
Oxygen insertion
from LuFe2O4 … to LuFe2O4.5
[= 1Fe+2: 1 Fe+3]
[= 2 Fe+3]
OSC = 1 426 mmol O g-1
DV/V = +2.2%
….to LuFe2O4
Ordering inside layers
and inter-layers
M -LuFe2O4
modulated M -LuFe2O4.25
and M -LuFe2O4.286
‘’LuFe2O5’’
‘’LuFe2O4’’
M supercell R13 -LuFe2O4.318
M’ supercell
O -LuFe2O4.5
aM
bM
aM bM
aR
aR13
bM’ aM’
bO
aO
3 3 4 4 4 4 4
Rev
ersi
ble
ph
eno
men
a st
ud
ied
by
XR
, e-
and
neu
tro
n d
iffr
acti
on
, TG
A a
nd
Mo
ssb
auer
Oxygen insertion - by a progressive transition characterized by (at least)
3 metastable structures (M, R13, M’) - involving short range ordering phenomena in more or less extended domains
and shearing mechanisms. For all, the stacking of 1 Lu for 2 Fe layers is preserved.
Complex magnetism linked to the 2D triangular iron lattice: two TN (250 and 200K) and two magnetic propagation vectors → magnetic phase separation at low temperature
Lay
ered
str
uct
ure
Complex microstructure in connection with Fe2+ : Fe3+ charge ordering at ≈ 330K (modulations q = βb *+ γc *)
New modulations in the h0l plane q = αa* + γc*
Evidence of oxygen-dependent modulation in LuFe2O4. J. Bourgeois et al. Phys. Rev. B85, 064102 (2012)
Evidence of magnetic phase separation in LuFe2O4.
J. Bourgeois et al. Phys. Rev. B86, 024413 (2012)
Oxygen storage capacity and structural flexibility of LuFe2O4+x (0 ≤ x ≤ 0.5)
M. Hervieu et al. Nature Materials (2013) doi:10.1038/nmat3809
Rare earth ferrites LuFe2O4±δ: polymorphism,
polytypism and metastable phases M. Hervieu et al.
Solid State Sciences 48, A1-A16 (2015)
From LuFe2O4 to hp-Fe2O4: High pressure effect
F. Damay
Stacking of 1 Lu for 2 Fe layers and intercrossing of diagonal atomic layers preserved.
Pressure-Induced Structural Transition in LuFe2O4: Towards a New Charge Ordered State. J. Rouquette et al. Phys. Rev. Lett 105, 237203 (2010) Pressure effect on the magnetic order of LuFe2O4. O. L. Makarova et al Appl. Phys. Lett. 103, 082907 (2013) A high-pressure polymorph of LuFe2O4 with room temperature antiferromagnetic order F. Damay et al. Phys. Rev. B 91, 214111 (2015)
LuFe2O4
hp-LuFe2O4