Thermal diffusivity of samarium–gadolinium zirconate solid solutions

Pan, Wei; Wan, Chunlei; Xu, Qian; Wang, J.D.; Zhi, Qu

doi:10.1016/j.tca.2006.12.001

Cited by 57 publications

(38 citation statements)

References 27 publications

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“…4 (99,99%, Onyx-Met). The substrates were weighed to obtain the molar ratio RE 3+ /Zr 4+ = 1 and dissolved in distilled water.…”

Section: Materials and Experimental Proceduresmentioning

confidence: 99%

“…The former, often called Solid-State-Reaction (SSR) the input materials are oxide powders, which are weighed in order to obtain certain stoichiometry, then mixed and homogenized and finally sintered. This method is relatively easy, hence it is commonly used [4], however its disadvantage is inhomogeneity of the final product in terms of chemical and phase composition. It is caused by the fact that the interaction between the different powder grains takes place on their interface so the efficiency of synthesis process is governed by the diffusion.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis, Characterization and Thermal Diffusivity of Holmium and Praseodymium Zirconates

Stopyra¹,

Niemiec²,

Moskal³

2016

Archives of Metallurgy and Materials

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A 2 B 2 O 7 oxides with pyrochlore or defected fluorite structure are among the most promising candidates for insulation layer material in thermal barrier coatings. The present paper presents the procedure of synthesis of holmium zirconate Ho 2 Zr 2 O 7 and praseodymium zirconate Pr 2 Zr 2 O 7 via Polymerized-Complex Method (PCM). Thermal analysis of precursor revealed that after calcination at relatively low temperature (700°C) fine-crystalline, single-phase material is obtained. Thermal diffusivity was measured in temperature range 25-200°C, Ho 2 Zr 2 O 7 exhibits lower thermal diffusivity than Pr 2 Zr 2 O 7 . Additionally, PrHoZr 2 O 7 was synthesized. The powder in as-calcined condition is single-phase, but during the sintering decomposition of solid solution took place and Ho-rich phase precipitated. This material exhibited the best insulating properties among the tested ones.

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“…4 (99,99%, Onyx-Met). The substrates were weighed to obtain the molar ratio RE 3+ /Zr 4+ = 1 and dissolved in distilled water.…”

Section: Materials and Experimental Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthesis, Characterization and Thermal Diffusivity of Holmium and Praseodymium Zirconates

Stopyra¹,

Niemiec²,

Moskal³

2016

Archives of Metallurgy and Materials

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“…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.…”

Section: Prediction Of Thermal Conductivitiesmentioning

confidence: 99%

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

2015

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Rare-earth pyrochlores, commonly exhibiting anomalously low lattice thermal conductivities, are considered as promising topcoat materials for thermal barrier coatings. However the structural origin underlying their low thermal conductivities remain unclear. In the present study, we investigated the phonon properties of two groups of RE pyrochlores, Ln2Zr2O7 (Ln = La, Nd, Sm, Gd) and Gd2T2O7 (T = Zr, Hf, Sn, Pb) employing density functional theory and quasi harmonic approximation.Through the relaxation time approximation (RTA) with Debye model, the thermal conductivities of those RE pyrochlores were predicted, showing good agreement with experimental measurements. The low thermal conductivities of RE pyrochlores were shown to largely come from the interference between the low-lying optical branches and acoustic branches. The structural origin underlying the low-lying optical branches was then clarified and the competition between scattering processes in transverse and longitude acoustic branches was discussed.

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“…[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.…”

Section: Thermal Conductivitymentioning

confidence: 99%

“…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).…”

Section: Thermal Conductivitymentioning

confidence: 99%

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

Fergus

2014

Metallurgical and Materials Transactions E

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One of the important applications of yttria-stabilized zirconia (YSZ) is as a thermal barrier coating for gas turbine engines. While YSZ performs well in this function, the need for increased operating temperatures to achieve higher energy conversion efficiencies, requires the development of improved materials. To meet this challenge, some rare-earth zirconates that form the cubic fluorite-derived pyrochlore structure are being developed for use in thermal barrier coatings due to their low thermal conductivity, excellent chemical stability, and other suitable properties. In this paper, the thermal conductivities of current and prospective oxides for use in thermal barrier coatings are reviewed. The factors affecting the variations and differences in the thermal conductivities and the degradation behaviors of these materials are discussed.

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Thermal diffusivity of samarium–gadolinium zirconate solid solutions

Cited by 57 publications

References 27 publications

Synthesis, Characterization and Thermal Diffusivity of Holmium and Praseodymium Zirconates

Synthesis, Characterization and Thermal Diffusivity of Holmium and Praseodymium Zirconates

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

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

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