Microstructural dependence of the thermal and mechanical properties of monazite LnPO4 (Ln = La to Gd)

In this work are given some thermal and mechanical properties of monazite, related to the microstructure. This compound is a poor thermal conductive (λ ≤ 5 W m-1 K-1, with a thermal expansion in between 9 and 10 * 10-6 K-1 according to the considered crystallographic direction, and a relatively high specific heat (Cp approximate to 110 J mol-1 K-1. Mechanical properties of monazite are characteristic of a brittle behavior: bending strength is of about 100 MPa and fracture toughness is close to 1 MPa m1/2. Porosity plays a large role on both thermal and mechanical properties pointing out the importance of controlling the whole elaboration process. (authors)