Mechanical and thermal properties of hot pressed neodymium-substituted britholite Ca9Nd(PO4)5(SiO4)F2

Neodymium-substituted britholite, a phosphate-silicate apatite Ca9Nd(PO4)(5)(SiO4)F-2, is considered as a potential host matrix for specific immobilization of radionuclides. Complementary investigations have been carried out to complete the database concerning this compound. The aim was to establish mechanical and thermal properties of dense britholite. Hot pressing was used to nearly fully densify the material. Low values of mechanical properties were found: 0.75 MPa m(1/2) for the fracture toughness and 95 MPa for the flexural strength. The Young's modulus and the Poisson's ratio were 108 GPa and 0.30, respectively. The specific and the thermal conductivity at 298 K were Cp = 0.75 J g(-1) K-1 and lambda = 1.15 W m(-1) K-1. The average coefficient of thermal expansion in the 20-1000 degreesC temperature range was alpha = 21 X 10(-6) K-1. (C) 2003 Elsevier Science B.V. All rights reserved.