Effects of Texture on the Thermal Conductivity of the LaPO₄ Monazite

Abstract

LaPO4 monazite, as an excellent structural ceramic, is expected to have thermal conductivity anisotropy because of its asymmetric crystal structure (monoclinic). For this motivation, the LaPO4 samples with different degrees of texture are fabricated via varying the powder synthesis processes and using hot‐pressing sintering and spark plasma sintering technique. The effect of the texture on the thermal conductivity of the LaPO4 samples is subsequently explored in this study. The results reveal that the thermal conductivities of the LaPO4 samples decrease firstly with the increasing degree of preferred orientation of the (200) planes along the direction perpendicular to the pressing direction, and approach a particular value, which is possibly the conductivity of the LaPO4 single crystal along the direction perpendicular to the (200) planes (a‐axis direction), when the orientation achieves a certain degree. The longitudinal or transverse speeds of all the textured LaPO4 samples are also measured and used to clarify the thermal conductivity anisotropy.

New insights into phosphate based materials for the immobilisation of actinides

“…Hot-pressing methods allow for lowering the sintering temperature by about 250-300°C at 30 MPa, yielding pellets with 98 % relative density [143,[148][149][150][151][152]. Du et al [153][154][155] achieved the same density (98 %) of La-monazite after 3 min of sintering at 1350°C (heating rate 100°C · min −1 ) at a pressure of 40 MPa using Spark Plasma Sintering (SPS).…”

Lattice thermal expansion of the solid solutions (La1−xSmx)2Ce2O7

“…[3,7], pyrochlore structure A 2 3+ B 2 4+ O 7 [8][9][10][11], monazite structure (LaPO 4 ) [12][13][14], and the magnetoplumbite lanthanum hexaaluminate structure (LaMgAl 11 O 19 ) [15,16]. La 2 Ce 2 O 7 with fluorite structure was a potential material for TBC, due to its high thermal expansion coefficient and low thermal conductivity [17,18].…”

Formation of nanocrystals based on equimolar mixture of lanthanum and yttrium orthophosphates under microwave-assisted hydrothermal synthesis

“…Much attention to the study of formation processes, structure and properties of materials, including nanocrystalline materials, based on orthophosphates of rare earth elements is associated with set of practically important properties that they possess. Ceramic materials based on rare earth element (REE) orthophosphates due to their high strength, thermal stability and resistance to aggressive media are used as high-temperature insulation [1][2][3]. They have a high isomorphic capacity for large number of lanthanides and actinides [4][5][6][7], are resistant to radiation damage [8], which makes them promising as ceramic matrices for radioactive waste immobilization.…”