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RUSSIAN CONTRIBUTION FOR THE JOINT PAPER OF THE U.S. NATIONAL ACADEMY OF SCIENCES - RUSSIAN ACADEMY OF SCIENCES WORKING GROUP ON STRUCTURAL (FUNCTIONAL) MATERIALS*

Prof. Alexander A. Ovchinnikov

Corresponding Member

Russian Academy of Sciences

(Head of the Case Study for RAS)

INTRODUCTION

The following RAS prepared program recommendation is specific to organic materials. It should be noted that while focus was placed upon this domain, parallel Russian R&D capability encompasses the entire field of dual purpose HPSM listed in the American paper.

Materials science is a rapidly developing field of modern knowledge. The interest to fundamental studies in the field is mainly caused by immediate practical considerations. Both the development of high-tech branches of industry and the economic side of mass production depend basically on an accelerated introduction of new materials, optimized to the designed purpose. A new drive has arisen with an introduction of organic materials on a wider scale, and we are facing now an "era of polymers." Polymers and other organic materials have already made a noticeable impact on civilization, as they are used in many industrial fields as binders, glues, lacquers, insulators, synthetic fabrics, etc. A much stronger impact should be expected from the development and introduction of organic materials with designer properties—the so called "functional" or "structural'' materials which are the subject of new branches of science, i.e., electronics of organic materials and molecular electronics. These branches of science have been brought to life by the demands of the defense industry and by the developments of high technologies. Research in these fields has consequently allowed the preparation of organic semiconductors, synthetic metals including superconductors, organic photo conductors, and organic and inorganic dielectrics including ferroelectrics. Organic materials with ferromagnetic properties have eluded materials science for a long

*  

Topic selected and approved at the 2nd U.S. National Academy of Sciences-Russian Academy of Sciences Joint Meeting on Dual-Use Technologies (Washington, May 1992) and presented at the 3rd U.S. National Academy of Sciences-Russian Academy of Sciences Joint Meeting on Dual-Use Technologies (Moscow, December 1992).



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Dual-Use Technologies and Export Administration in the Post-Cold War Era: Documents from a Joint Program of the National Academy of Sciences and the Russian Academy of Sciences RUSSIAN CONTRIBUTION FOR THE JOINT PAPER OF THE U.S. NATIONAL ACADEMY OF SCIENCES - RUSSIAN ACADEMY OF SCIENCES WORKING GROUP ON STRUCTURAL (FUNCTIONAL) MATERIALS* Prof. Alexander A. Ovchinnikov Corresponding Member Russian Academy of Sciences (Head of the Case Study for RAS) INTRODUCTION The following RAS prepared program recommendation is specific to organic materials. It should be noted that while focus was placed upon this domain, parallel Russian R&D capability encompasses the entire field of dual purpose HPSM listed in the American paper. Materials science is a rapidly developing field of modern knowledge. The interest to fundamental studies in the field is mainly caused by immediate practical considerations. Both the development of high-tech branches of industry and the economic side of mass production depend basically on an accelerated introduction of new materials, optimized to the designed purpose. A new drive has arisen with an introduction of organic materials on a wider scale, and we are facing now an "era of polymers." Polymers and other organic materials have already made a noticeable impact on civilization, as they are used in many industrial fields as binders, glues, lacquers, insulators, synthetic fabrics, etc. A much stronger impact should be expected from the development and introduction of organic materials with designer properties—the so called "functional" or "structural'' materials which are the subject of new branches of science, i.e., electronics of organic materials and molecular electronics. These branches of science have been brought to life by the demands of the defense industry and by the developments of high technologies. Research in these fields has consequently allowed the preparation of organic semiconductors, synthetic metals including superconductors, organic photo conductors, and organic and inorganic dielectrics including ferroelectrics. Organic materials with ferromagnetic properties have eluded materials science for a long *   Topic selected and approved at the 2nd U.S. National Academy of Sciences-Russian Academy of Sciences Joint Meeting on Dual-Use Technologies (Washington, May 1992) and presented at the 3rd U.S. National Academy of Sciences-Russian Academy of Sciences Joint Meeting on Dual-Use Technologies (Moscow, December 1992).

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Dual-Use Technologies and Export Administration in the Post-Cold War Era: Documents from a Joint Program of the National Academy of Sciences and the Russian Academy of Sciences time. Nevertheless, this problem has now been solved both theoretically and experimentally. The Russian school of materials science has played a recognized role in the development of this field, and the process of conversion now allows it to use its achievements for peaceful purposes and for universal development. The structure of the Program is shown in the flow chart below: PROGRAM STRUCTURE Electronics of Organic Materials Program Subgroups Organic and Inorganic Ferromagnets Polyfunctional polymers, conducting ploymers, carbon containing materials Second order nonlinear optical materials Gas transducers based on organic semiconductors Organosiloxanes binders and file forming materials Theoretical investigations Organosiloxanes binders and file forming materials Theoretical investigations The Program includes several subprograms from different branches of science, but all of them are aimed to solve most important problems in the field of electronics of organic materials. Organic and Inorganic Ferromagnets The design and synthesis of molecular magnetoresponsive materials (ferro-, ferri-, meta-, high spin para- and/or super-para-magnetics and spin glasses) is an area of steadily increasing interest among organic, inorganic, polymer, and physical chemists. Molecular magnets are desirable as they may have magnetic properties associated with light weight, solubility in organic solvents, and processability analogous to that of plastics and optical transparency, which could make them useful in the development of new electronic devices. They also provide an intellectual challenge to synthesize new classes of compounds that do not yet exist. Moreover, beyond the basic problem of establishing structure-property correlations, molecular-based magnetic materials appear promising for the development of totally new properties or associations of properties (in magnetooptics,

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Dual-Use Technologies and Export Administration in the Post-Cold War Era: Documents from a Joint Program of the National Academy of Sciences and the Russian Academy of Sciences as organic materials with nonlinear optical and magnetic response, or in studying organic conductors and superconductors). Development of Highly Sensitive Photoresists Based On Polyfunctional Polymers A possible line of development of the next generation integrated circuits leads to design and construction of molecular electronic devices. As device elements dimensions approach the submicron range, the introduction of new lithographic technologies are required. Resist layers with improved resolution and sensitivity are needed. In a new lithographic process, irradiation (visible light, ultraviolet, electron beam, X-rays, etc.) might not be used to obtain a pattern on a photoresist (with subsequent treatment of a plate through "windows" in a pattern) but rather for direct production of a working molecular device from polyfunctional polymers. The use of the photolithographic technique will allow one to obtain active organic elements having linear dimension smaller then l µ. The purpose is to create new highly sensitive resists based on polyfunctional polymers using both chemical and optical amplification. Development of Polymer Compositions for Photochemical Etching of Metallic Films The fabrication of metallic images finds a wide application in modem science and high technologies, particularly in manufacturing printed circuit boards, integrated circuits, optical disks and so on. For the fabrication of metallic images either many-stage lithographic processes or powerful pulses of excimer lasers (ablative optical recording) are needed. To achieve higher patterning speeds, an excimer laser irradiation of a copper foil, for example, is performed in Cl2, Br2 and halogenated methane atmospheres. Under irradiation gas-phase molecules or surface-bound adsorbates dissociate, giving halogen containing free radicals which rapidly react with metallic atoms in the film to produce the CuCl and CuBr surface layers. The principal object is to develop a dry resistless process for the photochemical and electron-beam etching of thin metallic films by reactive fragments produced in a course of irradiation of the polymer layer cast on top of this metallic film. Conjugated Polymers As Electroconducting and Electrochromic Materials Conducting polymers are of great interest because of their unusual electronic properties as well as high conductivity and other features acquired with doping. The most important applications of the conducting polymers are connected with the modulation of their electronic and optical properties, ion diffusion rates, redox potentials, spatial dimensions, and so on. One of the most promising tasks is the investigation of composite materials based on conducting polymers and their applications in practice. The production of conducting polymer films of large area holds special interest for certain

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Dual-Use Technologies and Export Administration in the Post-Cold War Era: Documents from a Joint Program of the National Academy of Sciences and the Russian Academy of Sciences practical applications, such as smart windows, light filters, and heating panels. Thin conducting polymer layers will also be used as semitransparent electrodes in organic electroluminescent devices and photocells for the conversion of solar radiation. Transport Properties of Conducting Polymers and Carbon-Containing Materials Conducting polymers (i.e., polymers with conjugation in the main chain), and high temperature treated carbon containing materials are among the most promising classes of conducting materials. Extensive research in the domain of conducting polymers began in the early 1970s, after the synthesis of polyacetylene of a principally new structure and the discovery that its conductivity can be increased by over 10 orders of magnitude upon doping. Polyacetylene, possessing the simplest chemical structure (CH)x, was studied using practically all physical and chemical techniques. The highest conductivity obtained on polyacetylene is as high as 106 Ohm-lcm-1. In contrast to conducting polymers, carbon containing materials have been used for a long time. They are widely used in the aircraft and space industries for various purposes due to their superior mechanical and thermal properties. However, electrical properties of these materials are not yet effectively used, though they have conductivities as high as 104 Ohm-1 cm-1. To this end, one should pursue primarily studies of transport properties together with structural investigations, and improve technology. Carbon-containing materials are normally heat-treated in carbonization ovens for 15-20 hours or more. Recently, a new method of heat treatment (HT), just several seconds long, was proposed. Maximum conductivity obtained is_ 104 Ohm-lcm-1 for HT temperature of 1100˚C. Electrophysical properties of these new films are practically unknown as yet. Carbon fibers possess unique physical-chemical and mechanical properties that determine different fields of their practical application. Fibers of high modulus and strength attract particular attention. We propose to study fibers heat-treated in the laboratory and otherwise modified. Carbon and Metallocarbon Clusters (Fullerenes) The discovery of polyhedral carbon clusters is one of the most important events in chemistry of the last several years. It is the fourth allotropic modification of carbon (after diamond, graphite, and carbide) known to humans. The existence of Polyhedral carbon clusters was discovered experimentally in 1985 by observation of 720 (C60) and 840 (C70) masses in mass spectra of carbon vapors, evaporated by laser beam. The structure of both compounds was studied by different physico-chemical methods, including X-ray structure analysis. Now there are arguments of existence of a large family of such carbon clusters Cn, called fullerenes. Fullerenes provoke great interest due to their unique

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Dual-Use Technologies and Export Administration in the Post-Cold War Era: Documents from a Joint Program of the National Academy of Sciences and the Russian Academy of Sciences chemical and physical properties and to the prospect for creating new conductive, superconductive, magnetic, composite, and antifrictional materials, as well as biologically active and medical preparations. An arc evaporation of carbon is the main method of fullerenes production now. It involves forming soot, containing less than 15% of fullerenes (C60 (~80-85%), C70 (~15%-20%) mixture and higher fullerenes n>70(~1-2%)). However, the influence of synthesis parameters (current shape and form of graphite electrodes, gas medium, vacuum) on yield and structure of fullerenes is still not known in details. Fullerene complexes are reported to show ferromagnetic properties, and Fluorinated fullerenes may exhibit lubricating properties. Thus, the first investigations of synthesis and properties of fullerenes show that these compounds are interesting both from a scientific point of view and as prospective sources of new types of useful materials. In particular, it can be predicted that fullerenes can be the basis of new, conductive, superconductive, and magnetic materials; materials and coatings, and thermostable and oxidation resistant materials materials for electronic applications. Very recently, carbon nanotubes excited great interest. It seems that this new facet of carbon materials will be greatly stimulated by the discovery that pure nanotubes and nanoscale particles can be obtained with high yield.* These materials could find potential applications in areas such as catalysis, composite materials, nanowires and nanoelectronics. New experiments, which have shown that extraction yield of fullerenes can be increased considerably, are worth mentioning. Photorefractive Crystals for Highly Sensitive High-Speed Optical Processing Optical processing of information is now considered as very promising. New principles of computing architecture are based on parallel flow and processing. Photorefractive crystals may be used in such an architecture as interconnectors, integrated neural network processors, and memory elements. To perform these functions, high resolution dynamic holograms should be recorded in the media. The necessary sensitivity, processing speed, and resolution may be achieved only as a result of joint work on crystal growth technology and determination of nonlinear optical properties. Special demands for the crystal arise in applications to phase-conjugate lithography and tracking systems for optical communication. It is planned to investigate the crystals barium, barium titanate, strontium barium niobate, lithium niobate, barium titanate, potassium niobate, GaAs, InP, and some other new materials, with the aim of control of the growth conditions. The methods of investigation are two- and four-wave mixing in the presence of DC and AC externally *   Ebbesen, T.W., and P.M. Ajayan, Nature, vol. 358, July 16, 1992, pp. 220-222.

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Dual-Use Technologies and Export Administration in the Post-Cold War Era: Documents from a Joint Program of the National Academy of Sciences and the Russian Academy of Sciences applied fields, including phase-locked detection of a running interference pattern and self-organization processes in the light/nonlinear crystal system. The result of the optical part of those studies will consist of the recommendations for types and concentrations of necessary dopants as well as aftergrowth handling technology. Nonlinear Optical Materials for Second Harmonic Generation (SHG) Semiconductor lasers and diode-pumped solid-state lasers presently demonstrate high efficiency, compact size, and moderate cost. However, they radiate in the near infrared (IR) region of spectrum, whereas many commercial applications use visible light. A solution of the problem is the frequency doubling of light. However, for most strongly needed low power quasi-CW devices, the doubling efficiency via known materials and schemes proves to be low. The objective of this part of the subproject is to develop the growth technology for the known KTP and KDP crystals with much better quality and to study the new alternative methods of SHG. The latter include the integrated optical approach and the record of second order nonlinearity gratings in amorphous materials. Gas Transducers Based on Organic Semiconductors The demand for sensors for determining the composition of gaseous and liquid mixtures is constantly increasing and stimulates the search for new, particularly organic materials for the transducing sensitive elements (TSE). Environmental protection requires a determination of pollution sources, mechanisms of action, gradient, and temporal changes profile as the major problems of local monitoring. From the ecological point of view, the most dangerous pollutants are gaseous oxides and volatile hydrides that are formed as a result of human activity, as well as gases, having limited occurrence but higher toxicity that are used in a number of technologies. These include AsH3, PH3, and some volatile inorganic compounds containing Bi, Tl, Pb, Hg, and others used in special processes. For the solution of the above problems, one needs inexpensive, low energy sensors of sufficient sensitivity and selectivity, with preference given to the ones of the directed appointment rather than gas analyzers. It is necessary to state from the very beginning that there is no civilian mass production of instruments for gas analysis based on organic materials, either in Russia or overseas, though the studies and design project in this direction are being intensively carded out. Virtually all classes of organic substances are present among the materials, which are used in TSE polymers and low molecular organic and inorganicorganic compounds, dyes, charge transfer complexes and ion-radical salts, biological substances and free-radicals, and also their various compositions and modified materials.

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Dual-Use Technologies and Export Administration in the Post-Cold War Era: Documents from a Joint Program of the National Academy of Sciences and the Russian Academy of Sciences The use of a simple resistive variance of a gas sensor may not fully satisfy the sensitivity of the requirements. These parameters may be reached by the conjugation of the properties of an organic material with traditional n-p-junction in Ge, Si, or GaAs. The various modes are possible with the use of high level fundamental studies in organic materials science and the studied properties of organic substances variable with a gas impact. There is unique information on NH3 detection with a piezocrystal, an L2-glutaminic acid at a thousand-time excess of CO NO2, HCl, H2S, SO2, CO2. Sensors of NH3, AsH3, NOx based on Pb-substituted phthalocyanines derivatives of quinoline and acridine, a number of donor and acceptor polymers (polyvinyl and siloxane based) should be noted among the works of Russian authors. The reason for the limited application by industry of sensors based on organic materials is insufficient insight into their fundamental electrophysical, structural and technological properties, into mechanisms of gas interaction with their surfaces, and interface phenomena in MDS-structures. If one considers the total expenditures for the design of such sensors, it turns out that they are incomparably less than the ones which have been allotted for a design of sensors based on inorganic compounds, particularly, transition metal oxides. Accumulated scientific experience allows one to assume very good perspectives for advancing gas sensors based on organic materials, which should be economical and energy conserving. Organosiloxanes Binders and Film-Forming Materials Organic binders and film-forming materials have been known for centuries and have been exhaustively studied during the last 30 years. The volume of their use nowadays has probably reached its limit. An obstacle for further expansion of their use is inherent in their chemical nature. Virtually all of them are flammable, water-sorbing, weather-sensitive, dangerous (poisonous fumes) on oxidative decomposition, and/or unstable at elevated and/or low temperatures, under UV-irradiation, etc. New opportunities may arise as a result of R&D studies and application of inorganic, especially siloxiorganic polymers. Theoretical Investigation of the Characteristics of a Charge: Carrier Transport in Polymer Matrices In recent years a significant effort has been expended to understand the main features of the charge carrier transport in the disordered organic matrices, such as various

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Dual-Use Technologies and Export Administration in the Post-Cold War Era: Documents from a Joint Program of the National Academy of Sciences and the Russian Academy of Sciences polymers or the low-molecular-weight organic glasses. This effort was stimulated both by the pure scientific interest in the characteristics of the highly disordered materials and by the commercial uses of such transport processes in copiers and laser printers, for instance. A Study on Multicomponent Functional Optical Ceramics Based on Metal Fluorides The study goal lies in vastly increasing the assortment and application of inorganic fluoride materials in modem fields of science and technology, improving exploitation performances, and lowering production costs. Objectives can be achieved by substituting the traditionally used single-crystalline materials for their polycrystalline form (optical, ceramic-OC), simultaneously using multicomponent compositions instead of a single component. Multicomponent functional optical ceramics (MFOC) are prepared by a hot pressing technique. Up to the present, articles produced by this technology have found application primarily in military fields. The study provides improvements in hot pressing technique to prepare new fluoride MFOC with a specific (partially disordered) structure and properties available in wide limits for civilian purposes. The study provides new information on the chemistry and physics of solids with high concentrations of structural defects (with strongly distorted stoichiometry). Behavior of MFOC as polycrystalline material is complicated by high concentration of one-and two-dimensional defects in a real structure (dislocations, grain boundaries), the contribution of which in exploitation performances will be the object of the investigation. The practical importance of the study is the preparation of fluoride MFOC surpassing single-crystalline analogs by technico-economical characteristics. The largest-scale peaceful applications of the fluoride MFOC, which have been established for the single-crystal analogs are: new generation of scintillators for application in high energy physics, nuclear physics, astrophysics, nuclear medicine, and related fields, which have high time resolution, high density, radiation hardness, low cost, and other improved characteristics; optical construction materials (lenses, prisms, etc.) for scientific instruments, air-space technology, and other uses; and

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Dual-Use Technologies and Export Administration in the Post-Cold War Era: Documents from a Joint Program of the National Academy of Sciences and the Russian Academy of Sciences chemical sensors for fluorine in gaseous atmospheres for automated and controlled metallurgical and chemical production processes, as well as for monitoring the environment.

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Dual-Use Technologies and Export Administration in the Post-Cold War Era: Documents from a Joint Program of the National Academy of Sciences and the Russian Academy of Sciences This page in the original is blank.