Investigation of the thermal conductivity of selected compounds of gadolinium and lanthanum

The role of low-lying optical phonons in lattice thermal conductance of rare-earth pyrochlores: A first-principle study

“…The phonon velocity is taken as the slope of each acoustic branch close to the Г point while the reduced Debye temperature is computed using Eqs 5-6. [17] Lehmann [19] Suresh [15] Pan [67] La2Zr2O7 [14] (hexagon), Lehmann et al [19] (down triangle), Suresh et al [15] (up triangle), Liu et al [17] (star), Pan et al [67] (square), Wu et al [16] (circle) and Qu et al [70] (diamond), respectively. The experimental data for Gd2Hf2O7 and Gd2Pb2O7 are missing.…”

“…Wm -1 K -1 ) [14][15][16][17][18][19]. The RE pyrochlore also exhibits high temperature stability [4], similar thermal expansion coefficient as its beneath substrate [20,21], and can react with the CMAS melt to seal the surface against further infiltration [22].…”

“…In addition, RE pyrochlores can well preserve the pore content and architecture owing to their sluggish 3 sintering kinetics [23]. The thermal properties of various RE pyrochlores were well characterized in many experimental studies [14][15][16][17][18][19]. It was postulated in some studies [24,25] that the abnormally low thermal conductivities of these pyrochlores may be attributed to the abundance of intrinsic oxygen vacancies and low-lying optical phonons due to RE elements rattling.…”

Synthesis, characterization and lattice thermal expansion of some compounds in the system Gd2CexZr2−xO7

“…good neutron economy, superior thermophysical properties such as high thermal conductivity, low thermal expansion, absence of phase changes and decomposition at higher temperatures, etc. In addition, the high temperature structure ceramics with low thermal conductivity and thermal expansion are very much in demand for a variety of thermal insulation applications and also as nuclear reactor components [7]. For fixation of transuranic elements, the ceramic matrix seems to be a better choice as it has high thermodynamic stability for a longer time.…”

Crystal structures, phase stability, and dielectric properties of (1− x ) Bi 3/2 MgNb 3/2 O 7 − x Bi 2 Zn 2/3 Nb 4/3 O 7 ceramics

“…The pyrochlores family with the general formula, A 2 B 2 O 7 , is fascinating for the A-and B-sites can be occupied by a broad range of elements that can give rise to a great variety of physical properties, [1] which allow a diverse useful technological applications, such as high frequency dielectric microwave materials for LTCC technique, the electrolyte in solid-oxide fuel cells, host materials for the immobilization of fission products, catalysis, piezoelectricity, ferro-and ferri-magnetism, luminescence, giant magneto resistance, and thermal barrier coatings [2][3][4][5][6][7][8][9].…”