Iron
manganese
trioxide
(FexMn1-x)2O3
nanocrystals
were
synthesized
by
the
sol-gel
method.
The
80
K
Mössbauer
spectrum
was
well-fitted
using
two
doublets
representing
8b
and
24d
crystallographic
sites
of
phase
weak
extra
sextets
which
attributed
to
crystalline
amorphous
hematite.
area
ratio
between
percentage
areas
used
as
constraints
in
Rietveld
analysis
x-ray
diffraction
(XRD)
data.
Our
findings
showed
formation
a
bixbyite
primary
with
stoichiometry
(Fe0.248Mn0.717)2O3,
mean
size
~48
±
1
nm
plus
secondary
hematite
~8
nm.
Raman
exhibits
six
active
modes,
typical
(Fe,Mn)2O3,
modes
associated
phase.
photoelectron
spectroscopy
(XPS)
confirmed
presence
oxygen
vacancy
onto
particle
surface,
varying
oxidation
states
(Fe3+,
Fe2+,
Mn3+,
Mn4+).
strong
predominance
Fe2+
over
Fe3+
vacancies
at
leading
reduction
order
keep
charge
balance.
X-band
magnetic
resonance
(MR)
data
revealed
single
broad
line
whole
temperature
range
(3.8
≤
T
300
K),
g-value
decreasing
monotonically
from
3.93
0.01
50
down
2.18
K.
dependence
both
field
linewidth
shows
remarkable
change
40-50
K,
herein
credited
surface
spin
glass
behavior.
model
picture
explain
MR
lower
(below
about
K)
assumes
nanoparticles
core-shell
structure.
Results
indicate
that
below
shell’s
system
reveals
paramagnetic
glass-like
transition
upon
cooling,
critical
estimated
43
In
higher
range,
superparamagnetic
(secondary)
contributes
remarkably
linewidth.
Zero-field-cooled
(ZFC)
field-cooled
(FC)
show
irreversibility
peak
ZFC
curve
~33
paramagnetic-ferrimagnetic
main
Hysteresis
5
low
coercive
4
kOe,
magnetization
not
reaching
saturation
70
suggesting
ocurrence
ferrimagnetic
core
disorder
characteristic
spin-glass-like
Acta Physica Sinica,
Год журнала:
2023,
Номер
72(18), С. 186101 - 186101
Опубликована: Янв. 1, 2023
Corner-shared
coordination
polyhedral
crystals
(CSCPCs)
represented
by
perovskites
have
unique
and
various
properties
in
optics,
electrics,
magnetism,
leading
to
their
broad
applications
such
as
serving
ferroelectric
material,
fast
ionic
conductors,
electro/photo-catalysts.
However,
the
excellent
are
owned
only
a
very
small
fraction
of
CSCPS
phases.
How
obtain
phases
through
structural
operation
has
always
been
research
hotspot
bottleneck
related
fields.
Herein,
we
review
recent
progress
synthesis
high-performance
CSCPC
materials
from
perspective
phase
structure,
order
clarify
intrinsic
rules
evolution
reveal
mechanism
behind
manipulation.
We
first
systematically
summarize
types
polyhedra
crystal
frameworks
CSCPCs
classify
distortions
three
main
types,
i.e.
cation
displacements,
rotations,
deformations.
Based
on
that,
further
analyze
conclude
different
material
methods.
find
that
most
traditional
methods
rely
transitions
induced
change
external
physical
conditions
at
macroscopic
level,
composition,
temperature,
pressure.
Recently,
there
was
an
emerging
method
focusing
microscopic
manipulation
geometry
topology,
constructions
according
tolerance-factor
substrate-proximity
effects.
The
share
same
mechanism:
making
transit
into
structure-specified
inducing
distortions.
difference
is
latter
more
target-oriented,
but
its
currently
limited
octahedral
tilt/rotation
systems.
Expanding
application
scope
still
challenge.
In
addition,
propose
two
aspects
may
be
useful
optimizing
method:
one
origin
interaction
between
distortions,
other
customize
guidelines
based
computer
science.
hope
reviewed
this
article
can
provide
some
valuable
references
inspirations
for
designing
synthesizing
materials.
Iron
manganese
trioxide
(FexMn1-x)2O3
nanocrystals
were
synthesized
by
the
sol-gel
method.
The
80
K
Mössbauer
spectrum
was
well-fitted
using
two
doublets
representing
8b
and
24d
crystallographic
sites
of
phase
weak
extra
sextets
which
attributed
to
crystalline
amorphous
hematite.
area
ratio
between
percentage
areas
used
as
constraints
in
Rietveld
analysis
x-ray
diffraction
(XRD)
data.
Our
findings
showed
formation
a
bixbyite
primary
with
stoichiometry
(Fe0.248Mn0.717)2O3,
mean
size
~48
±
1
nm
plus
secondary
hematite
~8
nm.
Raman
exhibits
six
active
modes,
typical
(Fe,Mn)2O3,
modes
associated
phase.
photoelectron
spectroscopy
(XPS)
confirmed
presence
oxygen
vacancy
onto
particle
surface,
varying
oxidation
states
(Fe3+,
Fe2+,
Mn3+,
Mn4+).
strong
predominance
Fe2+
over
Fe3+
vacancies
at
leading
reduction
order
keep
charge
balance.
X-band
magnetic
resonance
(MR)
data
revealed
single
broad
line
whole
temperature
range
(3.8
≤
T
300
K),
g-value
decreasing
monotonically
from
3.93
0.01
50
down
2.18
K.
dependence
both
field
linewidth
shows
remarkable
change
40-50
K,
herein
credited
surface
spin
glass
behavior.
model
picture
explain
MR
lower
(below
about
K)
assumes
nanoparticles
core-shell
structure.
Results
indicate
that
below
shell’s
system
reveals
paramagnetic
glass-like
transition
upon
cooling,
critical
estimated
43
In
higher
range,
superparamagnetic
(secondary)
contributes
remarkably
linewidth.
Zero-field-cooled
(ZFC)
field-cooled
(FC)
show
irreversibility
peak
ZFC
curve
~33
paramagnetic-ferrimagnetic
main
Hysteresis
5
low
coercive
4
kOe,
magnetization
not
reaching
saturation
70
suggesting
ocurrence
ferrimagnetic
core
disorder
characteristic
spin-glass-like
