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NANOSYSTEMS: PHYSICS, CHEMISTRY, MATHEMATICS, 2021, 12 (6), P. 799–807

The influence of condition of the monazite structured La0.9Y0.1PO4 nanocrystals sintering on thermal and mechanical properties of the material

M. O. Enikeeva – Ioffe Institute, 26, Politekhnicheskaya St., 194021, St. Petersburg; Saint Petersburg State Institute of Technology, 26, Moskovsky Ave., 190013, St. Petersburg, Russia; enikeevamo@gmail.com
O.V. Proskurina – Ioffe Institute, 26, Politekhnicheskaya St., 194021, St. Petersburg; Saint Petersburg State Institute of Technology, 26, Moskovsky Ave., 190013, St. Petersburg, Russia
E. S. Motaylo – Saint Petersburg State Institute of Technology, 26, Moskovsky Ave., 190013, St. Petersburg, Russia
D. P. Danilovich – Saint Petersburg State Institute of Technology, 26, Moskovsky Ave., 190013, St. Petersburg, Russia
V.V. Gusarov – Ioffe Institute, 26, Politekhnicheskaya St., 194021, St. Petersburg, Russia

A lanthanum orthophosphate- and yttrium-based monazite structured La0.9Y0.1PO4 nanocrystalline material was synthesized. The influence of the thermal treatment temperature on its thermal and mechanical properties has been determined. It was shown that the hydrothermal treatment of coprecipitated phosphates at 230 °C for 110 minutes yielded monazite structured nanoparticles with the crystallite size of about 16 nm. Nanopowder thermal treatment for 20 min in the annealing-quenching mode at 1000–1400 °C resulted in obtaining compact materials, the porosity of which varied from 52 to 27% with the grain growth from ~20 to ~100 nm. Active sintering occurred at temperatures above 1300 °C. Nanocrystalline materials obtained by heat treatment at 1200 °C with a grain size of ~40 nm have a porosity of 42%, microhardness of Hv(25 °C) = 40.5 GPa, thermal conductivity λ(25 °C) = 0.4 ·m-1·K-1, and can be used as thermal insulation material.

Keywords: hydrothermal treatment, lanthanum and yttrium orthophosphates, thermal diffusivity, specific heat capacity, thermal conductivity.

DOI 10.17586/2220-8054-2021-12-6-799-807

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