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The four effects of Nano material
(scientific knowledge)
纳米材料的四大效应（科普知识）
First, surface effect
T
he direct ratio exists
between the surface area and diameter’s square of
spherical
particles, also exsits
between its volume and cubic, so
its
specific
surface
area
(surface
area/volume)
and
is
in
inversely
proportion
to
the
diameter.
With the diameter of particle becoming smaller,
surface area will increases
gradually,
indicates
the
percentage
of
the
surface
atomic
accounts
for
will
dramatically increases. The surface
effect of particle what the diameter is bigger
than
0.1 microns could be ignored, when
the size is less than 0.1 microns, the percentage
of
its
surface
atom
will
dramatically
grows,
even
the
sum
of
surface
area
of
1
g
ultramicroparticles is 100 square
meters, the surface effect will not be ignored at
this
time.
The surface of
ultramicroparticles is
very different
with
the surface of the
large
object, if we take the television
camera to the metal ultramicroparticles (diameter
of
10 ^ 2 * 3 microns) by using the
high-rate electron microscope, and you will found
that the particles has no fixed form
through the real-time observation ,
with the time’s
changing,it
will
automatically
forms
into
various
shapes
(such
as
cubic
octahedron,
ten surface
body, with 20 ulrich, etc.),
the body which is different from the
general
solid and liquid, is a quasi
solid. under the radiation of electron beam of the
electron
microscope,the surface atomic
looks like entering into the condition of
the
unstability
of
particle
structure
could
be
seen
when
the
size
is
bigger
than
10
nanometer,
then
microparticle
has
the
stable
structure
surface
of
ultramicroparticles has high activity,
the metal particles will be quickly oxidated and
burnt in the air. We can use the
surface coating or deliberately control the
oxidation
rate to prevent spontaneous
combustion, make its slowly oxidated to generated
a very
thin and dens oxide layer to
ensure the stabilizationof surface., because of
the surface
activity,the metal
ultramicroparticles will become a new efficient
catalyst ,gas storage
materials and low
melting point material
Second, small size effect
As
the quantitative chang of particles size, in
certain conditions , the properties of
particle
would
change
in
quality.
particle
size
becomes
smaller
will
be
in
order
to
macro
physical
characters
changes
,we
called
this
phenominon
as
small
size
effect.
For
Ultramicroparticles,
Its
size
becomes
smaller,and
the
surface
area
will
dramatically increases at the same
time,then produces the following a series of novel
properties
(1)
The special properties of the optical: when gold
was subdivided into the size
that
smaller
than
the
wavelength
of
light
wave,
which
means
the
gold
loses
their
lusters of rich and honour and to be
black. In fact, all of the metals are black in the
state
of
ultramicroparticles.
Size
becomes
smaller,
the
color
is
much
more
black,
silver
platinum
(platinum)
into
platinum
black,
metallic
chromium
into
chromium
shows
the
reflectivity
of
metal
ultramicroparticles
to
the
light
is
very
low,
usually less than l %, thickness of a
few microns could completely extincts the
light
.
Because
of
the
property,
it
could
be
as
converted
materials
with
the
high
efficient
sunlight
and
optoelectronics
and
other
materials,
could
also
change
efficiently
the
solar energy into heat energy, electric
power. In addition, it also may be applied in the
infrared sensitive components, infrared
stealth technology, etc.
(2)
when
the
size
of
solid
matter
what
has
special
thermal
properties
becomes
bigger, its melting point is
fixed,
we will find its
melting point significantly
reduce
after being super
fined, the phenominon is very remarkable
especially when particles
are less than
10 nanometer magnitude. For example, the
conventional melting point of
gold is
1064 C
℃
, when the size of
particle reduces to 10 nanometer, the temperature
would
lower
27
℃
,
the
melting
point
is
327
℃
when
the
size
is
2
nanometer;
the
conventional
melting
point
of
Silve
is
670
℃
,
and
the
melting
point
of
superfine
silver particles could be lower than
100
℃
. Therefore, the
Conductive slurry what is
made of
ultrafine silver could sinter at the low-
temperature, at this time ,the substrate
of components could only use plastic
not the high-temperature ceramic materials, the