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

Abstract : In this work are given some thermal and mechanical properties of monazite, related to the microstructure. This compound is a poor thermal conductive (lambda < 5 W m(-1) K-1), with a thermal expansion in between 9 and 10 x 10(-6) K-1 according to the considered crystallographic direction, and a relatively high specific heat (C-p 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 m(1/2). Porosity plays a large role on both thermal and mechanical properties pointing out the importance of controlling the whole elaboration process.