Geoscience Reference
In-Depth Information
to understand the natural processes of mineral formation changed dramatically into
an important method characteristic for inorganic chemistry. During the early 1980s,
a new sealing for the autoclave was designed, that is, Grey-Loc sealing, which
facilitates the construction of the very large-size autoclaves with a volume of
5000 l
[60]
. The world's largest autoclave is located in Japan and works with such
a Grey-Loc sealing mechanism. The details of the sealing mechanism are discussed
in Chapter 3.
Toward the end of the 1970s, on the whole, the hydrothermal field experienced
a declining trend for two reasons: There was no scope for further work on the
growth of large-size single crystals of quartz on the one hand, and on the other
hand, large-scale attempts to grow bigger crystals of other compounds investigated
during the 1960s and 1970s failed. It was unanimously decided that the hydrother-
mal technique is not suitable for the growth of large crystals other than quartz. The
focus at this time was on Czechrolskii, metal-organic chemical vapor deposition
(MOCVD), and molecular beam epitaxy (MBE). This is largely connected to the
general approach of the hydrothermal researchers to grow large single crystals
without looking into the hydrothermal solvent chemistry and kinetics of the crystal-
lization process. Although Franck started working on the study of the behavior of
electrolytic solutions with temperature and pressure conditions way back in the
1950s
[61,62]
,
it did not attract the hydrothermal researchers' attention immedi-
ately. They thought that the conditions under which Franck worked were confined
to the lower pressure and lower temperature conditions, whereas the hydrothermal
technique actually belonged to the higher pressure and higher temperature condi-
tions at least until recently. In fact, Ballman and Laudise
[63]
, in their famous
article published in the topic, Art and Science of Growing Crystals edited by
Gilman, write that “crystal growth is more an art than science.” However, the
Nobel Symposium organized by the Swedish Academy of Sciences, during
September 17
21, 1979, on “The Chemistry and Geochemistry of Solutions at
High Temperatures and Pressures” is remembered as an eye opener. The presence
of pioneers in the field of hydrothermal physical chemistry like Franck, Seward,
Helgeson, and Pitzer drew the attention of hydrothermal crystal growers and a new
trend was set to look into the hydrothermal solvent chemistry and the physical
chemistry of the hydrothermal systems
[64
2
67]
. Following this, Japan organized
the first ever International Hydrothermal Symposium during April 1982
[68]
, which
was attended largely by specialists from different branches of science like physical
chemistry, inorganic chemistry, solid-state physics, materials scientists, organic
chemists, hydrometallurgists, and hydrothermal engineers. This is the dawn of
modern hydrothermal research. Since then, new avenues in the field of hydrother-
mal research are being explored. The modeling of the hydrothermal systems, study
of the hydrothermal crystallization mechanism, thermodynamics, and kinetics of
the reactions began. New designs of the reactors to suit the specific requirements
of research into areas like crystal growth and materials processing were developed.
Unfortunately, this period also marks the fall of the Russian domination in the field
of hydrothermal research. Japan emerged as a leader in hydrothermal research on
par with the United States. The decade-wise evolution of the hydrothermal research
2
