Energy Materials Testing Laboratory EVALUATION FROM

Preparing the Target
With K(OC 2 H 5 ) 5 (95%), Nb(OC 2 H 5 ) 5
(99.8%) and Ta(OC 2 H 5 ) 5 (99.8%) as the
starting materials, we prepared
KTa 0.65 NB 0.35 O 3 powder that included
the excessive K(OC 2 H 5 ) 5 , ≈1%, by the
sol-gel method.
We then pressed the powder into a
30-mm diameter disk. When the temperature
reached 1100°C, we sintered
it for 45 h in the Kali atmosphere.
Details are given in the literature. 8
Preparing the Films
We used Lamda EMG201MSC quasimolecular
laser equipment in the
experiment. The output wavelength
was 308 nm. The repeat frequency
rate was 20 Hz. The single pulsed
laser energy density was 1.6 J/cm 2 ,
2.0 J/cm 2 and 2.4 J/cm 2 , respectively.
The system's automatic scanning of
the beam focuses the laser beam into
a 3 mm 2 flare, after it passes through
a lens. The scanning speed is 20 rpm,
which generates the best proportional
films.
KTN, or K(Ta 1-x Nb x )O 3 , has many
good properties, including electrooptic
characteristics, nonlinear optic
characteristics and pyroelectricity. It
also has a high K. When x = 0.35, it
can be applied in a wide variety of
fields with the highest electro-optic
coefficient.
During deposition and the addition
of oxygen atmosphere, the pressure
was kept between 10 and 15 pa. The
substrate was the simple quartz crystal
(100). The target was the potassium-rich
ceramics. The distance from
the substrate to the target was about
5 cm.
From the experiment, we found
that when the temperature of the
substrate exceeds 350°C, the simple
quartz crystal breaks. The reason was
that the thermal-dilatation coefficient
of quartz differs greatly from
that of the substrate.
The substrate’s temperature must
be controlled at ≈300°C, and the
depositing time at 30 min. At the end
of the experiments, the temperature
of the films must be cooled slowly to
room temperature under a certain
pressure of oxygen.
After analyzing the prepared films
by XRD, we found that the films were
I/I °
100
80
60
40
20
0
(3.993)
20 40 60 80 100
The X-ray diffraction diagram of the polycrystal KTa 1-x Nb x O 3 powder.
in an amorphous state. According to
the theory of the growth of films,
amorphous films belong to the structure
of the metastable state, which
has high internal energy. Under the
action of neighbor energy, e.g., illumination,
heating, etc., the amorphous
state can conquer the
potential energy hill and transform
into a homeostatic state, namely
crystal.
The literature has reported that the
best substrate temperature (TS) for
preparing the LiTaO 3 electrical waveguide
by PLD is 650°C. 10 Amorphous
films prepared at