Geoscience Reference
In-Depth Information
Table 5.1 Applications for
α
-Quartz
Industrial equipment
Precision oscillators, optical fibers, dielectric materials,
radiocommunications, cable communications, electronic
applications, measurement equipment, pagers, security
systems (alarms)
...
Consumer equipment
Electronic hand calculators, watches, clocks, timers, cable TVs,
color TVs, video recorders, RF converters, transceivers, radio
equipment, microphones, electronic appliances, microphones,
microcomputer and computer terminals, TV-game machines,
telephones, copy machines
...
production of quartz ahead of Japan and the United States. More recently, several
other Japanese companies such as Kyocera, Shin-Etsu, and Asahi Glass Co. have
started producing quartz for highly specialized applications. Figure 2.11 shows a
photograph of synthetic quartz crystals pulled out from the world's largest autoclave
located at the Toyo Electric Co., Japan
[12]
. The inner diameter of the autoclave is
65 cm. To quote an example, the combined production quantity of quartz crystal
units, filters, and oscillators in 1980 was 390 million pieces in Japan and it was
remarkably increased to 2.13 billion pieces in 1990. About 50% of the quartz
produced goes into devices in the automotive industries, 30% of production goes
into frequency control devices, and the remaining 20% goes into optical devices.
The total cost involved in the production of quartz is:
End users
:
US$1,000,000,000,000
Equipment
:
US$5,000,000,000
US$100,000,000
Components
:
Thus, quartz takes the first place in value and quantity of single-crystal piezo-
electric materials produced. Much of the interest related to quartz today is confined
to industry, while only scant publications emerge from research laboratories on
new applications of quartz and the preparation of nanoscale silica particles.
Otherwise, it is mainly research and development (R&D) based industries that carry
out research on the production of high-quality quartz and its applications, and these
results are not published
[13,14]
.
The hydrothermal growth of quartz has been described and reviewed in several
earlier works
[15
19]
. Hence, we will only consider the conventional method of
the growth of
-quartz and its kinetics data in brief. Instead, we discuss the more
recent developments in the growth of high-purity and low dislocation quartz.
The
α
transition in quartz takes place at about 573
C, and the crystal growth
of quartz insists upon a growth technique suitable to the low-temperature crystal
growth process. This led to the development of hydrothermal process. In fact, much
of our knowledge of the hydrothermal technique has resulted from the success in the
growth of quartz crystals. The first publication in hydrothermal research is again
αβ
