NANO AND MICROPARTICLES of HfB₂: THERMAL-EXPANSION COEFFICIENT AND ITS ANISOTROPY

The paper deals with the influence of a dimension factor on the thermal-expansion coefficient (TEC) of hafnium diboride. Nano-sized and microcrystalline hafnium diboride is investigated by method of X-ray diffraction in the temperature range of 300–1500 K. The size of nanocrystal HfB₂ with coherent scattering is 15 nanometers and remained constant during heating. The analysis of temperature dependence of the nano and microcrystalline HfB₂ parameters shows the non-linear growth of the cell metrics with increase in temperature. For the first time, the TEC of nano and microcrystalline HfB2 in the directions of crystallographic axes a and c are defined. The analytical expressions of temperature dependences of nano and microcrystalline HfB₂ of the cell parameters are received in the form of 2 degree polynomials. At the linear approximation of temperature dependence of the lattice parameters (i.e. at lack of temperature dependence of TEC), the TEC of microcrystalline HfB₂ in the studied temperature range are αa = 7.37 · 10^–6 and αс = 7.48 · 10^–6 K ^–1 for axes 0a and 0c respectively. The TEC of microcrystalline HfB₂ calculated according to X-ray diffraction data corresponds to TEC calculated by a dilatometric technique α = 7.49 · 10^–6 K ^–1 . At linear approximation of temperature dependence of the lattice parameters, the TEC of the nanocrystal HfB₂ are αa = 7.40 · 10^–6 and αс = 9.88 · 10^–6 K ^–1 for axes 0a and 0c respectively. The paper shows that the TEC of HfB₂ in nanocrystalline state is greater than the TEC of microcrystalline one. The difference between the TEC of nano and microcrystalline HfB2 are bound with increase in the surface energy of material with increase in dispersion. The paper finds the anisotropy of thermal expansion both micro and nanocrystal HfB₂. The TEC on the axis 0c is higher than the TEC on the axis 0a. The anisotropy of TEC is explained taking into account the lengths and the nature of interconnections in crystalline structure of HfB₂. The essential anisotropy of TEC in nanodimensional HfB₂ indicates the domination of the atomic fluctuations anharmonicity growth in nanocrystals in the direction of the axis 0c. The results obtained can be employed to create new environmentally friendly materials for the needs of alternative power engineering.

1. Simonenko E.P. Sevast'yanov D.V., Simonenko N.P., Sevast'yanov V.G., Kuznetsov N.T. Promising Ultra High Temperature Ceramic Materials for Aerospace. Applications Russ. J. Inorg. Chem., 2013;58(14):1669–1693 (in Eng.).

2. Upadhya K., Yang J.M., Hoffman W.P. Materials for ultra-high temperature structural applications. Am. Ceram. Soc. Bull., 1997;76:51–56 (in Eng.).

3. Fahrenholtz W.G., Hilmas G.E., Talmy I.G., Zaykoski J.A. Refractory diborides of zirconium and hafnium. J. Am. Ceram. Soc., 2007;90:1347–1364 (in Eng.).

4. Opeka M.M., Talmy. I.G. and Zaykoski J.A. Oxidation-Based Materials Selection for 2000ºC + Hypersonic Aero surfaces: Theoretical Considerations and Historical Experience. J. Mater. Sci., 2004;39(19):5887– 5904 (in Eng.).

5. Monteverde F., Bellos A., Scatteia L. Processing and properties of ultra-high temperature ceramics for space applications. Mater. Sci. Eng., A 2008;485:415–421 (in Eng.).

6. Savinoa R., Stefano Fumo M.De, Silvestron L., Sciti D. Arc-jet testing on HfB2 and HfC-based ultrahigh temperature ceramic materials. J. Eur. Ceram. Soc., 2008;28:1899–1907 (in Eng.).

7. Andrievski R.A. Nanostructured titanium, zirconium and hafnium diborides: the synthesis, properties, size effects and stability (Nanostrukturnye diboridy titana, cirkoniya i gafniya: sintez, svojstva, razmernie jeffekty i stabil'nost'). Russ Chem Rev., 2015:84;540–554 (in Russ.)

8. Andrievski R.A., Khatchoyan A.V. Nanomaterials in Extreme Environments. Fundamentals and Applications, Heidelberg: Springer, 2016 (in Eng.).

9. Carenco S., Portehault D., Boissiere C., Mezailles N., Sanchez C. Nanoscaled metal borides and phosphides: recent developments and perspectives. Chem. Rev., 2013;113(10):7981–8065 (in Eng.).

10. Vajeeston P., Ravindran P., Ravi C., Asokamani R. Electronic Structure, Bonding, and Ground State Properties of AlB2-Type Transition Metal Diborides. Phys. Rev. B, 2001;63(4):04115(1)–04115(12) (in Eng.).

11. Cutle R.A. Engineering Properties of Borides in Ceramics and Glasses: Engineered Materials Handbook, edited by S. J. Schneider Jr., Ohio: ASM International, 1991;(4):787–803 (in Eng.).

12. NIST-JANAF Thermochemical Tables, edited by M. W. Chase Jr., NY: American Chemical Society and the Woodbury, American Institute of Physics, 1998 (in Eng.).

13. Wuchina. E., Opeka M., Causey S., Buesking S., Spain J., Cull A, Routbort J., Guitierrez-Mora F. Designing for Ultrahigh-Temperature Applications: The Mechanical and Thermal Properties of HfB2, HfCx, and aHf(N). J. Mater. Sci., 2004;39:5939–5949 (in Eng.).

14. Andrievski R.A., Spivak I.I. Durability of refractory compounds and materials on it's basis (Prochnost' tugoplavkih soedineniy i materialov na ih osnove) R.A. Andrievski and I.I. Spivak Reference book, Chelyabinsk: Mettalurgiya Publ., 1989 (in Russ.)

15. Serebryakova T.I., Neronov V.A., Peshev P.D. High-temperature borides (Vysokotemperaturnye boridy). Moscow: Metallurgiya Publ., 1991 (in Russ.).

16. Basu B., Balani K. Advanced Structural Ceramics NJ: Wiley, 2011 (in Eng.).

17. Nakamory F., Ohishi Y., Muta H., Kurosaki K., Fukumoto K.-I., Yamanaka Sh. Mechanical and thermal properties of bulk ZrB2. J. Nucl. Mater., 2015;467:612– 617 (in Eng.).

18. Loehman R, Corral E, Dumm H-P, Kotula P, Tandon R. Ultra-high temperature ceramics for hypersonic vehicle applications, Sandia Report SAND2006- 2925, NM: Albuquerque, 2006. (in Eng.).

19. Pilladi T.R., Panneerselvam G., Anthonysamy S., Ganesam V. Thermal expansion of nanocrystalline boron carbide. Ceramic Intern., 2012;38:3723–3728 (in Eng.).

20. Kuru Y., Wohlschlögel M., Welzel., U., and Mittemeijer E. J. Crystallite size dependence of the coefficient of thermal expansion of metals. Appl. Phys. Lett., 2007;90: 243113(1)–243113(3) (in Eng.).

21. Sadovnikov V.I., Gusev A.I. Thermal expansion of the nanostructured PbSi films and anharmonicity of atomic fluctuations (Teplovoe rasshirenie nanostrukturirovannih plenok PbS i angarmonizm atomnih kolebaniy). Phys. Solid State, 2014;56:2274– 2278 (in Russ.).

22. Gusev A.I., Sadovnikov V.I., Chukin A.V., Rempel' A.A. Thermal expansion of nanocrystal and macrocrystalline Ag2S (Teplovoe rasshirenie nanokristallicheskogo i krupnokristallicheskogo Ag2S). Phys. Solid State, 2016;58:246–251 (in Russ.).

23. Kravchenko S.E., Burlakova A.G., Shul'ga Yu.M., Korobov I.I., Domashnev I.A., Dremova N.N., Kalinnikov G.V., Shilkin S.P., Andrievski R.A. et al. Special features of preparation of nanosized hafnium diboride of different dispersity (Osobennosti polucheniya nanorazmernogo diborida gafniya razlichnoi disperstnosti). Russ. J. Gen. Chem. 2015;85:720–725 (in Russ.).

24. Pease, R.S. An X-ray study of boron nitride. Acta Crystallogr., 1952;5:356–361 (in Eng.).

25. Langreiter T., Kahlenberg V. TEV–A Program for the Determination of the Thermal Expansion Tensor from Diffraction Data. Crystals, 2015;5:143–153 (in Eng.).

26. Bacanov S.S. Structural chemistry (Strukturnaya himiya). Moscow: Dialog MGU, 2000 (in Russ).

27. Konovalikhin S.V., Ponomarev V.I. Crystal structure features in a new compound C4B25Mg1.42 (Osobennosti kristallicheskoj strukturi novogo soedineniya C4B25Mg1,42). Crystallogr. Rep., 2015;60:700–703 Rep. (in Russ.)