Influence of the Conditions for Preparing LaPO4-Based Materials with Inclusions of the LaP3O9 Phase on Their Thermal and Mechanical Properties


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Abstract

A material based on lanthanum orthophosphate LaPO4 with inclusion of particles of lanthanum metaphosphate LaP3O9 was synthesized. The influence of the process parameters of the synthesis on the structure and properties of the material was determined. Heat treatment of the coprecipitated lanthanum phosphates at 700°C leads to the formation of a nanopowder with the LaPO4crystallite size of approximately 17 nm. Heat treatment of the nanopowder at temperatures from 1100 to 1500°C yields compact materials based on the LaPO4–LaP3O9 system. The heat treatment of the nanopowder at 1100°C leads to a sharp decrease in the porosity of the material (to ~5%) at insignificant grain growth (200–400 nm); under these conditions, the thermal conductivity [λ(25°C) = 3.2 W m–1 K–1], microhardness [Hv(25°C) = 4.6 ± 0.4 GPa], Young’s modulus [E(25°C) = 132 ± 9 GPa], and cracking resistance [K1c(25°C) = 1.6 ± 0.1 MPa m1/2] pass through maxima. The thermal expansion coefficient of the material depends on the heat treatment conditions only slightly and amounts to (8.2 ± 0.2) × 10–6 K–1.

About the authors

K. M. Kenges

Al-Farabi Kazakh National University

Email: proskurinaov@mail.ru
Kazakhstan, Al’ Farabi ave. 71, Almaty, 050040

O. V. Proskurina

Ioffe Institute; St. Petersburg State Institute of Technology (Technical University)

Author for correspondence.
Email: proskurinaov@mail.ru
Russian Federation, St. Petersburg, 194021; St. Petersburg, 190013

D. P. Danilovich

St. Petersburg State Institute of Technology (Technical University)

Email: proskurinaov@mail.ru
Russian Federation, St. Petersburg, 190013

M. K. Aldabergenov

Al-Farabi Kazakh National University

Email: proskurinaov@mail.ru
Kazakhstan, Al’ Farabi ave. 71, Almaty, 050040

V. V. Gusarov

Ioffe Institute

Email: proskurinaov@mail.ru
Russian Federation, St. Petersburg, 194021

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