5. SYNTHESIS, STRUCTURE AND PROPERTIES OF NANOSTRUCTURED MATERIALS (THEORETICAL MODELING)

I.A. Ovid'ko
Institute of Machine Science Problems
Russian Academy of Sciences
Bolshoi 61, Vas. Ostrov
St. Petersburg, 199178, Russia
fax: (812) 217 8614
e-mail: ovidko@pgpt.ioffe.rssi.ru or ovidko@def.ipme.ru

Introduction

First, this presentation will discuss the general peculiarities of theoretical studies in Russia. It is no secret that, due to financial hardships, support of scientific research in Russia is rather low. This fact causes problems, first of all, in the development of experimental investigations that usually need high investment. Theorists, in contrast, need only a salary and information in the form of access to the latest journals. Under these circumstances, theoretical investigations, at least in solid state physics and materials science in Russia, continue to be rather effective. In particular, Russian theoretical examinations in the area of nanostructured materials continue to be competitive.

As to the general situation in the world of nanoscience, development in the theory of nanostructures is of high interest. Many technological methods and a huge set of experimental data in the field of nanostructured materials exist. However, present-day theoretical representations of the structural and unique behavioral features of nanoparticles and nanostructured materials usually are not effective in modifying the technologies involving the synthesis and processing of nanoparticles and nanostructured materials.

To summarize: on the one hand, there is a community of Russian theorists capable of producing theoretical models of nanostructured materials, and on the other hand, there is a high general need to develop theories of nanostructured materials. This situation seems to be worth the attention of experts dealing with grant programs on nanoscience. (Research projects involving cooperation between Western scientists and Russian theorists do not need much money, but, at the same time, financial support of these projects can effectively contribute to progress in both nanoscience and nanotechnologies.)

Theoretical Modeling of Nanostructured Materials in Russia

I now wish to give a brief overview of Russian theoretical work in the area of nanostructured materials. In doing so, the author, of course, does not pretend to review all Russian works in this field. However, he hopes that the theoretical research dealing with the synthesis, structure, and mechanical properties of nanostructured materials, for the most part, will be discussed here.

V. Gryaznov (Institute of High Pressure Physics, Russian Academy of Sciences, RAS, Moscow Region) and A. Romanov (Ioffe Physico-Technical Institute, RAS, St. Petersburg) with co-workers developed theoretical models that describe (1) the disclinations and relaxation of elastic stresses in nanoparticles (Gryaznov et al. 1991b, Gryaznov et al. 1991c, Polonskii 1991, Trusov 1991, Romanov et al 1993, Gryaznov et al.1993); (2) the size effects of dislocation stability in nanoparticles and their aggregates (Gryaznov et al 1993, Gryaznov et al. 1989, Gryaznov et al. 1991a); (3) mass-transfer and plasticity in contacting nanoparticles (Gryaznov et al. 1993, Gryaznov et al. 1992); and (4) the yield stress of compacted aggregates of nanoparticles (Gryaznov et al. 1994). G. Malygin (Ioffe Physico-Technical Institute, RAS, St. Petersburg) has examined theoretically the microscopic aspects of the deviation of "yield stress-grain size" dependence from the Hall-Petch relationship in microcrystalline and nanocrystalline materials (Malygin 1995). A. Nazarov (Institute of Superplasticity of Metals, RAS, Ufa) and A. Romanov with co-workers have constructed theoretical models that effectively describe ensembles of grain boundary dislocations and disclinations in nanocrystalline materials (Nazarov et al. 1993a, Nazarov et al. 1993b, Nazarov et al. 1993c, Nazarov et al. 1996). In these models, special attention is paid to the description of so-called inequilibrium grain boundaries that are characterized by disorder in their arrangement of boundary defects and to the calculation of the energetic and stress-field characteristics of highly defected boundaries in nanocrystalline materials.

Some models dealing with polycrystalline materials were developed, and their results can be related to the description of nanocrystalline materials as well. Examples of such models are those that describe stress fields of grain boundaries and intergrain sliding in plastically deformed materials (Perevezentsev et al. 1992, Rybin et al. 1993, Perevezentsev et al. 1996).

S. Aizikovich (Rostov State University, Rostov) has constructed analytic methods for calculating elastic stress fields in spatially inhomogeneous films and multilayered systems under nanoindentor action, this being an effective non-destructive technique for characterizing films and multilayered systems (Aizikovich 1993, Aizikovich, 1995). R. Suris (Ioffe Physico-Technical Institute, RAS, St. Petersburg) and co-workers have proposed models of the electronic properties of nanostructured films (Ryvkin et al. 1995, Andreev et al. 1996). E.L. Nagaev (Institute of High Pressure Physics, RAS and Moscow Region) has constructed models describing electron emission, catalytic processes, and partial melting on the surfaces of nanoparticles as well as size-dependent electronic effects in magnetic and non-magnetic nanoparticles (Nagaev 1995).

Computer modeling of nanomaterials is being developed by the group headed by E. Sheka (Russian Peoples' Friendship University, Moscow) (Sheka et al. 1995, Sheka n.d.). The atomic dynamics of metal clusters is the subject of computer models by A. Galashev (Institute of Heat Physics, RAS, Ekaterinburg) (Galashev 1994, Galashev 1997). Yu.E. Lozovik and A.M. Popov (Institute of Spectroscopy, RAS, Moscow Region) work on theoretical models of carbon nanostructures: fullerenes, nanoparticles, etc. (Lozovik 1997). A theoretical group from the Institute of Crystallography (RAS, Moscow) has analyzed orientational ordering in cubic C 60 (Dilanyan et al. 1995). Prof. Kukushkin and his co-workers (Institute of Machine Science Problems, RAS, St. Petersburg) have developed a theoretical scheme effectively describing the kinetics of first-order transitions in multicomponent cases at the initial stage and at the later Oswald-ripening stage. They have also developed a technique for controlling the size-distribution function of thin-film nuclei using certain variations of external parameters (substrate temperature, deposition power) with time (Kukushkin 1994, Kukushkin et al. 1995, Osipov 1995a, Osipov 1995b, Kukushkin et al. 1996a, Kukushkin et al. 1996b, Kukushkin et al. 1996c).

The Laboratory for the Theory of Defects in Materials (Institute of Machine Science Problems, RAS, St. Petersburg), headed by I. Ovid'ko, has developed models describing (1) the role of dislocations and disclinations in the plastic deformation of metallic glass-nanocrystal composites (Gutkin et al. 1993, Ovid'ko 1995b, Ovid'ko 1995a); (2) the splitting of triple-junction disclinations in nanostructured and polycrystalline materials (Gutkin et al. 1994a, Gutkin et al. 1995a, Gutkin et al. 1995b, Gutkin et al. 1996a); (3) the special strengthening effect due to quasiperiodic boundaries in polycrystalline and nanostructured materials (Ovid'ko 1994c, Ovid'ko 1995b, Gutkin et al. 1996b); (4) dislocations in ultrathin heterogeneous plates, heteroepitaxial structures, and superlattices (Gutkin et al. 1991a, Gutkin et al. 1991b, Gutkin et al. 1992b, Gutkin 1992c, Gutkin 1993a); (5) quasiperiodic interfaces and their role in plastic deformation processes in nanostructured materials (Ovid'ko 1997a, Ovid'ko 1997b, Ovid'ko n.d.); and (6) quasinanocrystalline materials as a new class of nanostructured materials (Ovid'ko 1997a, Ovid'ko 1997b, Ovid'ko n.d.). Special attention in recent studies has been paid to quasiperiodic interfaces in thin films and nanostructured polycrystals as well as to quasinanocrystalline materials (consisting of nanocrystallites and quasiperiodic grain boundaries). These topics will be covered in the next section in more detail.

Quasiperiodic Interfaces in Nanostructured Materials and Quasinanocrystalline Materials

The notion that quasiperiodic interfaces are interfaces of a special type is rather new in both materials science and solid state physics (Sutton 1988, Rivier et al. 1988, Gratias et al. 1988, Ovid'ko 1994c, Ovid'ko 1995b, Gutkin et al. 1996b, Ovid'ko 1997a, Ovid'ko 1997b, Ovid'ko n.d.). In particular, the idea is not widespread among experts in the area of nanostructured materials. In contrast to periodic interfaces, each having one characteristic spatial scale (period), any quasiperiodic interface has at least two characteristic spatial scales. So, a quasiperiodic interface in a film-substrate system is an interface with the smoothest (but non-periodic) alteration of misfit dislocations separated by either characteristic distance 11 or characteristic distance 12 (Fig. 5.1).


Fig. 5.1. Quasiperiodic interface with misfit dislocations in the film-substrate system.

Since misfit dislocations repel each other, the quasiperiodic (smoothest) ordering of misfit dislocations provides a minimum of the elastic energy of the system (Ovid'ko n.d.). A quasiperiodic tilt (small- or high-angle) boundary is represented as a boundary with the smoothest (but non-periodic) alteration of the secondary boundary dislocations separated by either characteristic distance g 1 or characteristic distance g 2 (Fig. 5.2).


Fig. 5.2. Quasiperiodic tilt boundary consisting of structural units of type A (associated with secondary boundary dislocations) and structural (non-dislocated) units of type B.

The quasiperiodic ordering provides a minimum of the elastic energy of the tilt boundary (Sutton 1988, Ovid'ko n.d.). Quasiperiodic interfaces exhibit properties that, generally speaking, are different from those of periodic and disordered interfaces (Sutton 1988, Rivier et al. 1988, Gratias et al. 1988, Ovid'ko 1994c, Ovid'ko 1995b, Gutkin et al. 1996b, Ovid'ko 1997a, Ovid'ko 1997b, Ovid'ko n.d.). In particular, quasiperiodic tilt boundaries serve as plastifying elements in nanostructured polycrystals, where their effect is capable of contributing to experimentally observed deviations of "yield stress-grain size" dependence from the standard Hall-Petch relationship (Ovid'ko 1997a, Ovid'ko 1997b, Ovid'ko n.d.).

Quasiperiodic interfaces are inherent structural elements in nanostructured materials. So, according to estimates (Ovid'ko n.d.), the ratio of Q/P is close to 5, where Q and P are the densities of respectively quasiperiodic and periodic tilt boundaries in nanostructured polycrystals. Thus, one can suppose the limiting situation to occur in which all grain boundaries in a nanostructured polycrystal are quasiperiodic. This limiting situation is a radical change from the usually modeled situation with nanocrystalline solids containing only disordered and/or periodic grain boundaries. Actually, the structure and properties of quasiperiodic grain boundaries are different from those of "normal," disordered, and/or periodic boundaries; the quasiperiodic boundary phase differs (in both thermodynamic and crystallographic senses) from both the disordered and periodic boundary phases in crystals (Sutton 1988, Rivier et al. 1988, Gratias et al. 1988). At the same time, an influence of the grain boundary phase (whose volume fraction in nanostructured polycrystals is very high, ranging from 10 to 50%) on properties of nanostructured polycrystals is determinative. It suggests that nanostructured polycrystals with quasiperiodic grain boundaries represent a new type of nanostructured materials whose structure and properties are different from those of conventional nanocrystalline materials with disordered and/or periodic boundaries (and of other nanostructured solids).

In order to emphasize the fact that the nanoscale structure and quasiperiodic elements are the definitive structural features of nanostructured polycrystals with quasiperiodic grain boundaries, researchers call such polycrystals quasinanocrystalline materials (Ovid'ko 1997a, Ovid'ko 1997b).

The synthesis of quasinanocrystalline materials is an open technological problem. In any event, however, nanostructured polycrystals synthesized by presently available methods can be effectively treated as composites consisting of the quasinanocrystalline phase and the conventional nanocrystalline phase. Therefore, the concept of quasinanocrystalline materials is important to the analysis and characterization of both the structure and the macroscopic properties of real nanostructured polycrystals (Ovid'ko n.d.).

Proposals for Cooperation

The Laboratory for the Theory of Defects in Materials (Institute of Machine Science Problems, Russian Academy of Sciences), headed by I. Ovid'ko, is interested in the development of collaboration with foreign scientific groups. This group can propose objectives for forthcoming investigations with foreign scientific groups because of its previous experience in elaborating theoretical models of defects and plastic deformation processes in condensed media (in particular, nanostructured, crystalline, and noncrystalline solids) and in analyzing present-day state-of-the-art theory in the area of nanostructured materials (for instance, Barakhtin et al. 1986, Barakhtin et al. 1987a, Barakhtin et al. 1987b, Barakhtin et al. 1989a, Barakhtin et al. 1989b, Gutkin et al. 1991a, Gutkin et al. 1991b, Gutkin et al. 1992a, Gutkin et al. 1992b, Gutkin et al. 1992c, Gutkin et al. 1993a, Gutkin et al. 1993b, Gutkin et al 1993c, Gutkin et al. 1994a, Gutkin et al. 1994b, Gutkin et al. 1995a, Gutkin et al 1995b, Gutkin et al. 1996a, Gutkin et al. 1996b, Kolesnikova et al. 1997, Melker et al. 1985, Osipov et al. 1992, Ovid'ko 1985a, Ovid'ko 1985b, Ovid'ko et al. 1986a, Ovid'ko 1986b, Ovid'ko 1986c, Ovid'ko 1987a, Ovid'ko 1987b, Ovid'ko 1987c, Ovid'ko et al. 1987d, Ovid'ko 1987e, Ovid'ko 1988a, Ovid'ko 1988b, Ovid'ko 1989a, Ovid'ko 1989b, Ovid'ko 1989c, Ovid'ko 1989d, Ovid'ko 1989e, Ovid'ko 1989f, Ovid'ko 1989g, Ovid'ko 1990a, Ovid'ko 1990b, Ovid'ko 1990c, Ovid'ko 1990d, Ovid'ko 1990e, Ovid'ko 1990f, Ovid'ko 1991a, Ovid'ko 1991b, Ovid'ko 1991c, Ovid'ko 1992a, Ovid'ko 1992b, Ovid'ko 1993a, Ovid'ko 1993b, Ovid'ko 1993c, Ovid'ko 1994a, Ovid'ko 1994b, Ovid'ko 1994c, Ovid'ko 1994d, Ovid'ko 1995a, Ovid'ko 1995b, Ovid'ko 1995c, Ovid'ko 1997a, Ovid'ko 1997b, Ovid'ko n.d., Vladimirov et al. 1989).

The following are some possible projects:

References

Aizikovich, S.M. 1993. Doklady RAN 332:702.

____. 1995. Prikladnaya Matematika i Mekhanika 59:688.

Andreev, A.D., and R.A. Suris. 1996. Fizika i Technika Poluprovodnikov 30:520 (transl. in Phys. Tech. Semicond.).

Barakhtin, B.K., V.I. Vladimirov, S.A. Ivanov, I.A. Ovid'ko, and A.E. Romanov. 1986. Fiz. Tverd. Tela 28: 2250.

____. 1987a. Fiz. Metal. Metalloved. 63:1185.

Barakhtin, B.K., S.A. Ivanov, I.A. Ovid'ko, A.E. Romanov, and V.I. Vladimirov. 1987b. Nucl. Instr. Meth. Phys. Res. A 261:223.

____. 1989a. J. Phys. D 22:519.

Barakhtin, B.K., I.A. Ovid'ko, and E.P. Savicheva. 1989b. Nucl. Instr. Meth. Phys. Res. A 282:651.

Dilanyan, R.A., O.B. Rybchenko, and V.Sh. Shehtman. 1995. i 40:604.

Galashev, A.E. 1994. Vysokochistye Veshchestva 5-6:71.

____. 1997. Poverkhnost 2:5.

Gratias, D., and A. Thalal. 1988. Phil. Mag. Lett. 57:63.

Gryaznov, V.G., A.M. Kaprelov, and A.E. Romanov. 1989. Scr. Metall. 23:1443.

Gryaznov, V.G., I.A. Polonskii, A.E. Romanov, and L.I. Trusov. 1991a. Phys. Rev. B 44:42. .

Gryaznov, V.G., A.M. Kaprelov, I.A. Polonskii, and A.E. Romanov. 1991b. Phys. Stat. Sol. 167:20.

Gryaznov, V.G., A.M. Kaprelov, A.E. Romanov, and I.A. Polonskii. 1991c. Phys. Stat. Sol. 167:441.

Gryaznov, V.G., M.Yu. Tanakov, and L.I. Trusov. 1992. J. Mater. Sci. 27:4829.

Gryaznov, V.G., and L.I. Trusov. 1993. Progr. Mater. Sci. 37:289.

Gryaznov, V.G., M.Yu. Gutkin, A.E. Romanov, and L.I. Trusov. 1994. J. Mater. Sci. 28:4359.

Gutkin, M.Yu., and A.E. Romanov. 1991a. Fiz. Tverd. Tela 33:1553 (transl. in Sov. Phys. Sol. State).

____. 1991b. Phys. Stat. Sol. 125:107.

Gutkin, M.Yu., and I.A. Ovid'ko. 1992a. Mater. Sci. Eng. A 154:L9.

Gutkin, M.Yu. and A.E. Romanov. 1992b. Phys. Stat. Sol. 129:117.

____. 1992c. Phys. Stat. Sol. 129:363.

Gutkin, M.Yu., A.L. Kolesnikova, and A.E. Romanov. 1993a. Mater. Sci. Eng. A 164:433.

Gutkin, M.Yu. and I.A. Ovid'ko. 1993b. Nanostructur. Mater. 2:631.

Gutkin, M.Yu., I.A. Ovid'ko, and Yu.I. Meshcheryakov. 1993c. J. Physique III 3:1563

Gutkin, M.Yu. and I.A. Ovid'ko. 1994a. Phil. Mag. A 70:561

Gutkin, M.Yu., I.A. Ovid'ko, and A.E. Romanov. 1994b. Rad. Eff. Def. Solids 129:239.

Gutkin, M.Yu., K.N. Mikaelyan, and I.A. Ovid'ko. 1995a. Nanostruct. Mater. 6:779.

____. 1995b. Phys. Sol. State 37:300.

____. 1996a. Phys. Stat. Sol. 153:337.

Gutkin, M.Yu. and I.A. Ovid'ko. 1996b. Mater. Sci. Forum 207-209:321.

Kolesnikova, A.L., I.A. Ovid'ko, and A.E. Romanov. 1997. Phys. Sol. State 39:432.

Kukushkin, S.A. 1994. Acta Metall. Mater. 43:715.

Kukushkin, S.A., and A.V. Osipov. 1995. J. Phys. Chem. Solids 56:831.

Kukushkin, S.A., and V.V. Slezov. 1996a. Dispersed Systems on Solid Surfaces. St.Petersburg: Nauka. (in Russian).

Kukushkin, S.A., and A.V. Osipov. 1996b. Phys. Rev. E 53:4964.

____. 1996c. Progr. Surf. Sci. 51:1.

Lozovik, Yu.E., and A.M. Popov. 1997. Uspekhi Fiz. Nauk 167:751 (transl. in Uspekhi).

Malygin, G.A. 1995. Fiz. Tverd. Tela 37:2281 (transl. in Phys. Sol. State).

Melker, A.I., and I.A. Ovid'ko. 1985. Fiz. Tverd. Tela 27:594.

Nagaev, E.L. 1995. Reports at Symposium on the Science and Technology of Atomically Engineered Materials. Richmond.

Nazarov, A.A., and A.E. Romanov. 1993a. Phil. Mag. Lett. 68:297.

Nazarov, A.A., A.E. Romanov, and B. Baudelet. 1993b. Phil. Mag. Lett. 68:303

Nazarov, A.A., A.E. Romanov, and R.Z. Valiev. 1993c. Acta Metall. Mater. 41:1033.

____. 1996.Scr. Mater. 34:729.

Osipov, A.V., and I.A. Ovid'ko. 1992. Appl. Phys. A 54:517.

Osipov, A.V. 1995a. J. Phys. D 28:1670.

____. 1995b. Thin Solid Films 231:173.

Ovid'ko, I.A. 1985a. Phys. Lett. A 110:408.

____. 1985b. Zh. Exp. Teor. Fiz. (Sov. Phys. JETP) 89:1301.

Ovid'ko, I.A., and A.E. Romanov. 1986a. Comm. Math. Phys. 105:443.

Ovid'ko, I.A. 1986b. Fiz. Nizk. Temp. (Sov. Low Temp. Phys.) 12:1275.

____. 1986c. Zh. Exp. Teor. Fiz. (Sov. Phys. JETP) 91:1427.

____. 1987a. Fiz. Tverd. Tela 29:2137.

Ovid'ko, I.A., and A.E. Romanov. 1987b. Izvest. VU Zov-Fizika 12:84.

____. 1987c. Phys. Stat. Sol. 104:13.

Ovid'ko, I.A. 1987d. Pisma Zh. Exp. Teor. Fiz. (JETP Lett.) 45:3.

____. 1987e. Pisma Zh. Tech. Phys. 13 7:443.

____. 1988a. Fiz. Khim. Stekla 14:305.

____. 1988b. Izvest. VUZov-Fizika 4:91.

____. 1989a. Fiz. Khim. Stekla 15:636.

____. 1989b. Fiz. Met. Metall. (Phys. Met. Metallogr.) 67:649.

____. 1989c. Metallofizika 11 2:35.

____. 1989d. Phil. Mag. B 59:523.

____. 1989e. Phys. Stat. Sol. 151:K7.

____. 1989f. Ukrain. Fiz. Zh. 34:1343.

____. 1989g. Zeit. Phys. B 77:409.

____. 1990a. J. Phys. A 23:31.

____. 1990b. J. Phys. D 23:365.

____. 1990c. Mater. Sci. Eng. A 128:L5.

____. 1990d. Mater. Sci. Forum 62-64:717.

____. 1990e. Metallofizika 12 1:81.

____. 1990f. Pisma Zh. Tech. Phys. 16 13:1.

____. 1991a. Defects in Condensed Media: Glasses, Crystals, Quasicrystals, Liquid Crystals, Magnetics, Superfluids. St. Petersburg:Znanie. (in Russian).

____. 1991b. J. Phys. D 24:2190

____. 1991c. In Shock Compression of Condensed Matter. Amsterdam: Elsevier Sci. Publ. p.563.

Ovid'ko, I.A., and A.V. Osipov. 1992a. Fiz. Tverd. Tela 34:288.

Ovid'ko, I.A. 1992b. Mater. Sci. Eng. A 154:29.

____. 1993a. Mater. Sci. Eng. A 160:L1.

____. 1993b. Mater. Sci. Eng. A 163:68.

____. 1993c. Metallofizika 15 3:39.

____. 1994a. J. Phys. D 27:999.

____. 1994b. Fiz. Tverd. Tela 36:3632.

____. 1994c. Mater. Sci. Eng. A 168:37.

____. 1994d. Zeit. Phys. B 95:321.

____. 1995a. Key Eng. Mater. 104-107:633.

____. 1995b. Nanostructur. Mater. 6:743.

____. 1995c. Phys. Stat. Sol. 149:389.

____. 1997a. Nanostruct. Mater. 8:149.

____. 1997b. Phys. Sol. State 39:268.

____. 1998. Quasiperiodic and disordered interfaces in nanostructured materials. In Nanostructured Materials: Science and Technology. Ed. G.M. Chow. NATO ASI Series Volume. Amsterdam: Kluwer Academic Publ.

Perevezentsev, V.N., V.V. Rybin, and V.N. Chuvil'deev. 1992. Acta Metall. Mater. 40:895.

Perevezentsev, V.N. 1996. Mater. Sci. Forum 207-209:541.

Polonskii, I.A., A.E. Romanov, V.G. Gryaznov, and A.M. Kaprelov. 1991. Phil. Mag. A 64:281.

Rivier, N., and A.J.A. Lawrence. 1988. Physica B 150:190.

Romanov, A.E., I.A. Polonskii, V.G. Gryaznov, S.A. Nepijko, T. Junghaus, and N.I. Vitrikovskii. 1993. J. Cryst. Growth 129:289.

Rybin, V.V., A.A. Zisman, and N.Yu. Zolotarevskii. 1993. Acta Metall. Mater. 41:2211.

Ryvkin, B.S., and R.A. Suris. 1995. Fizika i Technika Poluprovodnikov 29:757 (transl. in Phys. Tech. Semicond.).

Sheka, E.F. n.d.. Proceedings of workshop on Russian Research and Development Activities on Nanoparticles and Nanostructured Materials. Baltimore: WTEC (in press).

Sheka, E.F., and V.D. Khavryutchenko. 1995. Nanostruct. Mater. 6:803.

Sutton, A.P. 1988. Acta Metall. 36:1291.

Trusov, L.I., M.Yu. Tanakov, V.G. Gryaznov, A.M. Kaprelov, and A.E. Romanov. 1991. J. Cryst. Growth 114:133.

Vladimirov, V.I., and I.A. Ovid'ko. 1989. Fiz. Tverd. Tela 31:259.


Published: August 1997; WTEC Hyper-Librarian