ZIRCONIUM AND HAFNIUM DIOXIDES DOPED BY OXIDES OF YTTRIUM, SCANDIUM AND ERBIUM: NEW METHODS OF SYNTHESIS AND PROPERTIES

The results of elaborating a method for the synthesis of zirconia and hafnia doped by rare earths (yttrium, erbium and scandium) by using low-hydrated hydroxides of zirconium and hafnium as precursors are reported. The low-hydrated zirconium and hafnium hydroxides were prepared using the heterophase reaction. The physicochemical properties (including sorption properties) of low-hydrated zirconium and hafnium hydroxides ZrxHf1-x(OH)3÷1O0.5÷1.5·0.9÷2.9H2Owere studied. The scheme of thermal decomposition of low-hydrated hydroxides in air was determined. The sorption properties of the low-hydrated hafnium hydroxide are less pronounced owing to the lower amount of sorption centers, in this case, hydroxo and aqua groups. The sequence of stages of thermal decomposition of rare earth acetates was elucidated. Single-phase zirconia and hafnia doped by rare earths (yttrium, erbium and scandium) were obtained. The parameters of the elementary lattice were calculated for each phase. It was established that the stabilization of zirconium dioxide with yttria leads to the formation of interstitial solid solutions based on tetragonal zirconia (in the case of the composition Y2O3×4ZrO2 - cubic modification), with erbium oxide - interstitial solid solutions based on cubic zirconia; with scandium oxide - solid solutions based on tetragonal zirconia. The article presents the results of measuring electrical conductivity.

zirconium, hafnium, rare-earths, low-hydrated hydroxide, sorption, doping, thermal decomposition

1. Simoncic P., Navrotsky A. Systematics of phase transition and mixing energetics in rare earth, yttrium, and scandium stabilized zirconia and hafnia. J. Amer. Cer. Soc. 2007; 90(7): 2143-2150.

2. Milyavskii V.V., Akopov F.A., Borovkova L.B., Borodina T.I., Val'yano G.E., Ziborov V.S., Savinykh A.S., Lukin E.S., Popova N.E. A ceramic based on partially stabilized zirconia: Synthesis, structure, and properties under dynamic load. High Temperature. 2011; 49(5): 685-689.

3. Konakov V.G., Ovid'ko I.A., Kurapova O.Yu., Novik N.N., Archakov I.Yu. Usage of nanoceramic based on ZrO2 in fabrication of sources for magnetron sputtering. Materials Physics and Mechanics. 2014; 21(3): 305-310. (in Russ.)

4. Borik M.A., Bublik V.T., Kulebyakin A.V., Lomonova E.E., Milovich F.O., Myzina V.A., Osico V.V., Tabachkova N.Y. Phase composition, structure and mechanical properties of PSZ (partially stabilized zirconia) crystals as a function of stabilizing impurity content. J. Alloys and Comp. 2013; 586(1): 231-235.

5. Steele B.C.H., Heinzel A. Materials for fuel-cell technologies. Nature. 2001; 414(6861): 345-352.

6. Clarke D.R., Oechsner M., Padture N.P. Thermal-barrier coatings for more efficient gas-turbine engines. MRS Bull. 2012; 37(10): 891-898.

7. Jeon S., Im K., Yang H., Lee H., Sim H., Choi S., Jang T., Hwang H. Excellent electrical characteristics of lanthanide (Pr, Nd, Sm, Gd, and Dy) oxide and lanthanidedoped oxide for MOS gate dielectric applications. IEEE Electron Devices Meeting. 2001; 20.6.1-20.6.4.

8. Ewing R.C., Weber W.J., Lian J. Nuclear waste disposal–pyrochlore (A2B2O7): Nuclear waste form for the immobilization of plutonium and «minor» actinides. J. Appl. Phys. 2004. V. 95. № 11. P. 5949–5971.

9. Nikishina E.E., Lebedeva E.N., Drobot D.V. Individual and bimetallic low-hydrated zirconium and hafnium hydroxides: synthesis and properties. Rus. J. Inorg. Chem. 2015; 60(8): 921-929.

10. Nikishina E.E., Lebedeva E.N., Prokudina N.A., Drobot D.V. Physicochemical properties of low-hydrated zirconium and hafnium hydroxides and their thermolysis products. Inorg. Mater. 2015; 51(12): 1190-1198.

11. Encyclopedia of Physical Science and Technology, Ed. by R.A. Meyers. 3rd edition. Analytical Chemistry. N.-Y.: Academic Press, 2001. P. 543-938.

12. Krishnamurthy N., Gupta C.K. Extractive Metallurgy of Rare Earths. Boca Raton: CRC Press, 2005. 504 p.