at the First Symposium on Crystal Growth in 1958.
Next to him is M.P. Shaskolskaya.
A.V. Stepanov
Here, on our site, we suggest to read an article of prof. P.I.Antonov about Alexandr Vasil'evitch Stepanov - the inventor of the Shaped Crystals Growth Method.
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A.V.
Stepanov
at the First Symposium on Crystal Growth in 1958. Next to him is M.P. Shaskolskaya. |
"In 2003 it will be 95 years since the birthday of A.V. Stepanov
(1908-1972). It is not easy to speak or write about this talented scientist
because of his very broad interests. His approach
to problems was always original and uncommon. At the age of 15, he wrote in his
diary about his doubts concerning what his future profession would be;
mathematics, physics, biology, and music were all of equal interest to him.
Indeed, although his abilities could manifest themselves in many areas,
physics was his choice, and he devoted his life to this science.
A.V. Stepanov's scientific activity
was connected with Leningrad Physical-Technical Institute
through A.F. Ioffe; he worked there as a lab
assistant, an engineer, a junior and later senior research
associate, and eventually became laboratory head. At that time he had a
professorship and was chairman of theoretical physics at the Leningrad
Pedagogical Institute; he was a full professor, Doctor of Science (physics and
mathematics), and a corresponding member of the Academy of Sciences of the USSR.
He always remained a very hardworking scientist
and his daily schedule was very demanding. He
usually left the Institute not earlier then ten
o'clock in the evening. Stepanov's
ideas were always on a grand scale and he tried to make them tangible as soon
as possible. Many of his ideas were ahead of his time. Now and then he had
something in common with a certain physicist from a science fiction novel.
A.V. Stepanov was not a narrow specialist in some
particular area of physics, and it is not possible to enumerate all his discoveries
in one short article. While studying the plastic flow of ionic
crystals he discovered the effect of slip band electrization, which since
then has been referred to as "the Stepanov
effect."
A small bell is kept at the Institute that was originally used by
Stepanov's colleague Dr. Ioffe, to call members of the Institute Scientific
Council for a session. Stepanov made this bell in
1934 of silver chloride, a unique transparent metal he discovered while studying
the mechanical properties of different crystals. Later, silver chloride single
crystals were important in the development of new optical polarization methods
for studying stressed crystalline, semicrystalline, and anisotropic
media.
Stepanov's interest in biology was not in vain. He put forth a theory about the
fracture of composites, which he considered to be periodically inhomogeneous. A
lot of hard work was done investigating the mechanical behavior of wood and
bones, which have great strength despite their cellular structure. Stepanov
explained this fact with regard to the especially fine structure of wood and
bones resulting in the anisotropy of elasticity
and strength. The anisotropy of mechanical properties can prevent
the growth of damage in certain directions, thus providing a greater strength.
Today these ideas have become incorporated in the making of new composite
materials.
A theoretical work by Stepanov
on the properties of crystals with hypothetical close-packed structures is not
widely known. Since the atoms of most structures have crystalline lattices that
are not close-packed, to obtain close-packed atomic structures of different
materials would be of great significance both in theory and practice. Stepanov
was the first to suggest manufacturing super-hard materials on the basis of
hydrogen, carbon, and other chemical elements, of which the mechanical and
thermal properties exceed the characteristics of diamond and have nearly the
same mechanical properties of rock salt. Even today this goal seems unattainable,
but even many of Jules Verne's ideas seemed
improbable in his time.
Today the pioneering works of Stepanov
have developed into broad scientific areas including elasticity and
nonelasticity and the mechanical behavior of solids at liquid helium
temperatures, an area of great significance in space research. Stepanov
also contributed considerably to the understanding of dislocations in solids.
Stepanov's most well known work was his method of
obtaining shaped crystals directly from the melt. Today this method is known
in scientific literature as Stepanov's method. The essence of this method lays
in the fact that the required shape of a crystal is determined primarily with
the help of a new element-the shaper-in the liquid
state. The shaped liquid-melt column is then converted into a solid by means of
proper control of temperature and growth rate. An old film on Stepanov's method
that won a prize at the 1960 cinematographic festival in Bulgaria contains an
interesting scene where Stepanov is observing a
daddy long-legs spider traveling along a wafer surface. The spider is able to
move on the water surface due to the forces of surface tension. It is this force
that forms the basis of the capillary shaping method. At the present time, there
are many versions of Stepanov's method that have been proposed by scientists of
different countries.
Shaped crystals and articles have been grown from
semiconductors, metals, and dielectrics. In particular, sapphire ribbons serve
as substrates for integrated circuits, silicon ribbons are used in solar energy
converters, germanium rods are used in semiconductor devices, and sapphire
tubes are used for illuminating high-pressure sodium lamps and laser devices.
Stepanov was the first to understand the importance of the future of
shaped products with respect to the conservation pf material, process
automation, and new engineering materials. The title of his book. The Future
of Metal Treatment, published in the USSR in 1963, illustrates his insight
into the future. At the present time the variety of shaped materials and the
scope of their application can be attributed to Stepanov's methods.
Stepanov constantly promoted his method. In 1967 he oiganized the First
All-Union Conference on the growth of shaped crystals and their application to
industry. The propagation of Stepanov's method, however, was not easy,
and many rejected its novelty and importance. Stepanov applied for a patent
prior to World War II, but only in 1956 did he receive the first of the patents
for the growth of shaped semiconductors; in 1974 the patent for the growth of
shaped metals, with the request dated 1941, was issued.
Stepanov's talent as a scientist and his characteristic outstanding
personality was in accord. He was kind and clever, a very quiet gentleman. He
never raised his voice when speaking to people, regardless of how heated a
discussion might become. He used to say that a person's primary advantage is the
ability to listen to his opponent. He was known for his humor and his love of
young people, and was an active participant in many amusing parties held at the
laboratory. He was a strong man and a sportsman who played tennis and was a
good alpine skier and water skier. Professor Stepanov was often invited as a
referee at football and other competitions between the Institute laboratories.
He was a great lover of the Black Sea; nearly all his holidays were spent at the
seashore, and it was the embankment in the Jalta resort where his life ended.
There is a saying that an estimation is given "at distant run," which can be fully related to Professor A.V. Stepanov. At present, many of his ideas have been realized while others are yet to be solved."
P.I. Antonov,
Ioffe Physico-Technical Inst., Shaped Crystals Growth Group