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 ≈ 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.