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.

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