Site: Moscow Institute of Chemical Technology
(formerly Mendeleyev University of
Chemical Technology of Russia)
Miusskaya Sq., 9
Moscow, A-190 125190
Russia

Date Visited: October 26, 1993

Report Author: J. Talbot

ATTENDEES

WTEC:

D. Slobodin
J. Talbot

HOSTS:

Edward G. Rakov, DSc

Chaired Professor of Less-Common Metal Chemistry

Stanislav Haustov

Professor

BACKGROUND

The Moscow Institute has seven main groups of faculty in the areas of: (1) technology of inorganic substances, (2) chemical technology of silicates, (3) chemical technology of polymers, (4) technology of organic substances, (5) cybernetics of chemical processes, (6) ecology for engineers, and (7) physical chemistry. The Institute was originally established in 1949 to explore nuclear technology. There are four chaired professors in physical chemistry: high-energy processes and radioecology, technology of isotope and pure substances, chemical technology of materials for quantum generators and electronic devices, and less-common metals. The WTEC team's host, Professor Edward Rakov, is a chaired professor of less-common metal technology and the head of the Fluorine Chemistry Laboratory. Dr. Stanislav Haustov is a senior research scientist of the Fluorine Chemistry Laboratory. Professor Rakov's division is concerned with research of U, Zr, Ta, Nb, Re, Ru, rare earth chemistry, chemistry and production of metal halogenides, methods of liquid- liquid extraction, ion-exchange sorption, plasma chemistry, and production of zirconia ceramics. The Fluorine Chemistry Laboratory is concerned with research of volatile metal fluorides (e.g., UF6), rare earth metal and zirconium fluorides, solid sources of pure fluorine gas, purification processes, and chemical etching of crystals and glasses.

RESEARCH AND DEVELOPMENT ACTIVITIES

The primary objectives of the scientists' work include the processing of inorganic and piezoelectric materials by chemical methods, enhancement of production (i.e., "labor technology"l), environmental issues of production, and miniaturization of electronic structures and devices. Their work is not directly related to display technology. The applications for the work were for the materials in the manufacture of resonators (from different cuts of -quartz), coarsening of the backside of surface acoustic wave filters (for black-and-white televisions made in Ukraine). The tests using their process were completed in 1990 at the Impulse Plant in Ukraine, but the work was stopped. There is no interest at this time in continuing this technology in Russia.

Professors Rakov and Haustov have been successful in obtaining a high reaction rate process for the etching of quartz and glasses in aqueous HF solutions and gas reagents to reduce thicknesses to 10 m dimensions and to reduce roughness. The reagents used include F2, HF, NH4NF2, KHF2, and B2F3 for all the glasses studied. The reaction rates were increased by 10 to 50 times. The dissolution was dependent on the exposed surface plane, with very low rates in some directions. These chemical methods did not produce the surface damage layers observed with mechanical polishing. (Two papers published in the Russian journal Inorganic Materials were on these methods of etching.) There are environmental problems with the volumes of aqueous HF wastes from the aqueous etching process. There is no similar Russian technology for recovery and regeneration of these wastes. The U.S. company Aquatech has a possible recovery technique for membrane technology, and a German company, Rorchtmain, uses HSO3F additives, which decrease the volume of waste by a factor of two.

A molten-salt method for etching was pursued in order to avoid large waste generation. The vapors from this process could be condensed and the dissolved material could be solidified. Also, the aqueous process could only operate in a narrow concentration range of HF-H2O; therefore, the molten salt process avoided this problem. Melts (fluxes) of the same type of reagents were also used as etchants, which have typical melting points of 126 degrees centigrade. For example, at 170 degrees centigrade, the z-cut of -quartz cuts was etched at a rate of 18 microns/min. The melts etched all the glasses studied. The flux process results are not published. The main problems with the flux process are corrosion of equipment, quality of processing (i.e., it is not as precise in etching), and automation. For corrosion, Teflon, and glossy carbon, W and Mo were the best containment materials; however, Ni was found to be adequate and was used. This process does not produce the high precision required, but could be used for lower-quality etching. The panel saw a design for etching 100 disks (approx. 2,000 elements) and a prototype of pilot scale equipment. Professor Rakov has six inventor's certificates on the process. Professor Rakov organized two conferences in Russia where his work was presented, the last of which was in 1991. He hopes to organize another conference in one to two years.

Other work done in Professor Rakov's laboratory was discussed. The rare earth-related research did not apply to phosphors, but to separation and purification of fluorides and rare earth elements. The Rakov group has worked with quartz fibers and ZBLAN (Zr, Ba, La, Al, Na fluorides) glass for applications in reduction of optical losses for high-purity components and for the chemical protection of preforms.

There is no work presently underway on diamond films, although Professor Haustov had studied the etching of polycrystalline diamond films. The graphite inclusions were dissolved, but a high-polishing level was not attainable. There was work on the processing of disks for laser information in order to replace the many-staged mechanical process with a chemical method. However, a high-quality surface could not be achieved. The surface roughness was the same as with mechanical polishing, although the final composition differed. The process was used by a plant producing art glass. Photolithography was used in conjunction with etching for attaining small details. The problems of the protection layer were resolved for the flux process. The process was also used in the sharpening of 200 micron lenses (used in Omsk, a Siberian plant for optics). There is no work on ion- exchange glass in his group. They used deep-chemical exchange for the formation of new crystal phase. The task was to develop a protection layer, but not a gradient index material. The funding situation was discussed. Most previous projects were defense-oriented. Funds are available for teaching staff for education. The research staff apply for state grants with a success rate of two out of four to five applications being funded with grant lengths of one to three years. The grants and contracts with industry cover the research and part of the teaching staff salaries. The head of the Physical Chemistry Group was in China. There seems to be much interest in collaboration with the Chinese. Professor Rakov was unsure about commercial contacts with the United States, mainly due to inexperience with commercial enterprises abroad in general. He looks forward to changes in the psychology in both the United States and Russia about collaborative efforts. He can provide names of other researchers in his field available for collaboration, but meetings must be officially arranged.


Published: December 1994; WTEC Hyper-Librarian