Investigation of the thermal conductivity of selected compounds of lanthanum, samarium and europium

Zirconia and Pyrochlore Oxides for Thermal Barrier Coatings in Gas Turbine Engines

“…9-Thermal conductivity of Ln 2 Zr 2 O 7 (Ln = Nd, Dy, Er, Eu, Y, Yb). [16,52,53,56,58,[66][67][68][69] doping of La 2 Zr 2 O 7 and ytterbium doping of Gd 2 Zr 2 O 7 , are shown in Figure 10. [53,60] Because of the structural similarities among the lanthanide zirconates, solid solutions between lanthanide zirconates can be formed and provide lower thermal conductivities.…”

“…[20,25] Although the thermal conductivity dependence on the size of the B-site (i.e., Zr in Ln 2 Zr 2 O 7 ) is stronger, the size of the A-site also has an effect, and simulations predict the lowest thermal conductivities for samarium, europium, and gadolinium on the A-site. [57] [16,18,55,56,[58][59][60][61] and 8, [16,56,[61][62][63][64][65][66][67] [67] are similarly in the lower range of the YSZ materials, as shown in Figure 9. Gd 2 Zr 2 O 7 and Sm 2 Zr 2 O 7 have received the most attention as candidate thermal barrier coating materials due to their good combination of thermal and mechanical properties.…”

“…Similarly, the thermal conductivity of Gd 2 Zr 2 O 7 has been reduced with additions of yttrium, [70] ytterbium, [60] and neodymium. [71] Two examples of the beneficial effect of doping, yttrium [ 16,56,[61][62][63][64][65][66][67] Fig. 9-Thermal conductivity of Ln 2 Zr 2 O 7 (Ln = Nd, Dy, Er, Eu, Y, Yb).…”

Effect of Thermal Aging on Microstructure and Mechanical Properties of Plasma-Sprayed Samarium Zirconate Coatings

“…Among the numerous oxides that have been explored as TBCs candidate, the pyrochlore-structured rare-earth zirconates-Ln 2 Zr 2 O 7 (Ln-La, Nd, Sm, and Gd)-have attracted particular interest (Ref 6-10). Suresh et al (Ref 11,12) have reported that the thermal conductivities of (87-91% dense) pyrochlore-structured Ln 2 Zr 2 O 7 ceramics vary from 1.5 to 1.6 W m À1 K À1 (at 700°C). However, the 7 wt.% Y 2 O 3 -ZrO 2 (7YSZ) ceramics exhibit a thermal conductivity of 3.0 W m À1 K À1 at room temperature and 2.3 W m À1 K À1 at 700°C ( Ref 8).…”

Heat capacities and derived thermodynamic functions of neodymium–gadolinium zirconates from 298.15 to 1050K

“…The rare-earth zirconates with the general formula Ln 2 Zr 2 O 7 (Ln = lanthanide) have a wide variety of interesting physical and chemical properties, such as high melting point, high thermal stability, high thermal expansion, low thermal conductivity, unique luminescence and high radiation stability, which make them suitable for applications as catalysts, solid electrolytes, nuclear waste forms and thermal barrier coating materials [1][2][3][4][5]. These compounds exhibit a pyrochlore-type structure or a defective fluorite-type structure, which is mostly governed by the ionic radius difference between Ln 3+ and Zr 4+ [1].…”