Ceramics International xxx (xxxx) xxx Please cite this article as: D.R. Belichko, Ceramics International, https://doi.org/10.1016/j.ceramint.2020.09.151 Available online 17 September 2020 0272-8842/© 2020 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Infuence of hafnium oxide on the structure and properties of powders and ceramics of the YSZ–HfO 2 composition D.R. Belichko a, * , T.E. Konstantinova a , A.V. Maletsky a , G.K. Volkova a , A.S. Doroshkevich a, b , M. V. Lakusta a , M. Kulik c , A.A. Tatarinova b , D. Mardare d , C. Mita e , N. Cornei e a Donetsk Institute for Physics and Engineering Named After O.O. Galkin, Donetsk, Ukraine b Joint Institute for Nuclear Research, str. Joliot-Curie, 6, Dubna, 141980, Russia c Institute of Physics, Maria Curie-Sklodowska University, Pl. Marii Curie-Sklodowskiej 1, 20-031, Lublin, Poland d Alexandru Ioan Cuza University of Iasi, Faculty of Physics, Romania e Alexandru Ioan Cuza University of Iasi, Faculty of Chemistry, Romania A R T I C L E INFO Keywords: Zirconium dioxide Hafnium oxide Nanopowders Ceramics Mechanical properties Structure ABSTRACT Using the X-ray diffraction, internal friction, 4-point bending, and electron microscopy methods we have studied the structural compatibility and infuence of Y 2 O 3 and HfO 2 dopants addition on the structure and phase composition of ZrO 2 powders and ceramics based on them. The mechanical properties of ZrO 2 –Y 2 O 3 -HfO 2 (YSZ) system have been investigated. It was determined that the similarity of the structure and properties of yttrium and hafnium oxides is not complete. The individual structural features of ZrO 2 , Y 2 O 3 , and HfO 2 oxides reviled themselves during the for- mation of ternary systems of the YSZ-Hf type. Studies of the nY 2 O 3 –ZrO 2 - mHf 2 O 3 system in the range of hafnium amount from 1 to 15 wt% and yttrium oxide concentration from 0 to 12 mol% showed the possibility of increase in the values of physical and mechanical properties of common two-component zirconium ceramics by the forming ternary systems of the YSZ-Hf type. 1. Introduction Nowadays ceramic materials are widely used in the engineering, industry and medicine [1,2] due to the high level of their mechanical properties, in particular, wear resistance and hardness. In the series of oxide ceramics, a special place is occupied by materials based on zir- conium dioxide (ZrO 2 ). ZrO 2 -based ceramics are distinguished by the presence of ionic conductivity at temperatures above 600 ◦ C [3,4], biocompatibility, high wear resistance [5,6], chemical, thermal [7] and radiation resistance [8]. Zirconia ceramics are also indispensable in mechanical engineering for the manufacturing of parts of mechanisms operating under high mechanical loads, in chemically aggressive envi- ronments; it is used in medicine, as transplants [9] and for energy pro- ducing (structural elements of SOFC, nuclear reactors [10]), etc. The development of the novel technologies requires continuous improvement of the technical and functional characteristics of ceramics. The main part of zirconia based ceramics of industrial importance is binary solid solutions of ZrO 2 –Y 2 O 3 or ZrO 2 –MgO type. Doping with the third component is a promising way to obtain new properties of ceramics based on zirconium dioxide along with the physical modif- cation of the microstructure during technological processes. To date, the issues about obtaining metal oxide ceramics based on ZrO 2 have been rather widely studied in the papers [11,12]. Nevertheless, ternary oxide systems, in particular, having hafnium in their composition, have not been suffciently studied. Thus, they undoubtedly arouse a scientifc interest. The aim of this work is to study of the effect of hafnium oxide addition on the structure and properties of yttrium-stabilized zirconia nanopowders and to investigate hafnium oxide powders and ceramics based on them. 2. Materials and methods In the present study, we have used hafnium oxide powders stabilized by the different amounts of yttrium oxide: nY 2 O 3 + HfO 2 , where n = 0, 3, 6, 8, 12% mol. (system: nY 2 O 3 –HfO 2 ), as well as zirconium oxide powders stabilized with yttrium oxide and additionally doped with hafnium oxide 3% mol. Y 2 O 3 + ZrO 2 + mHfO 2 , where m = 1, 5, 10, 15% wt (system: 3YSZ - mHfO 2 ). Powder materials were prepared by co- * Corresponding author. Donetsk Institute for Physics and Engineering Named After O.O.Galkin, Kiev, Ukraine E-mail addresses: danil.belichko@yandex.ru (D.R. Belichko), doroh@jinr.ru (A.S. Doroshkevich), mkulik@hektor.umcs.lublin.pl (M. Kulik). Contents lists available at ScienceDirect Ceramics International journal homepage: www.elsevier.com/locate/ceramint https://doi.org/10.1016/j.ceramint.2020.09.151 Received 12 August 2020; Received in revised form 14 September 2020; Accepted 15 September 2020