Structural evolution and thermophysical properties of (SmxGd1−x)2Zr2O7 (0≤x≤1.0) ceramics

Liu, Zhan‐Guo; Ouyang, Jia‐Hu; Zhou, Yu

doi:10.1016/j.jallcom.2008.04.042

Cited by 103 publications

(46 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In comparison, Gd2Zr2O7 and Gd2Hf2O7 exhibit much less variation in γ for the TA/TA' branches. This is because that the lowest optical branches of Gd2Pb2O7 and Gd2Sn2O7 are located at ~2 THz, higher than those of Gd2Zr2O7 and Gd2Hf2O7 (located at ~1 THz), 17 so that their TA/TA' branches are able to better retain acoustic feature even near the boundary of Brillouin zone, showing smaller γ values. Fundamentally the difference between the (Gd2Zr2O7, Gd2Hf2O7) and (Gd2Pb2O7, Gd2Sn2O7) pairs can be attributed to the fact that Gd2Zr2O7 and Gd2Hf2O7 exhibit strong ionic characters while Gd2Pb2O7 and Gd2Sn2O7 are of more covalent bonding features.…”

Section: Grüneisen Parametersmentioning

confidence: 99%

“…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].…”

Section: Introductionmentioning

confidence: 99%

“…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.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

2015

View full text Add to dashboard Cite

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.

show abstract

Section: Grüneisen Parametersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

2015

View full text Add to dashboard Cite

show abstract

“…After the FCTF test, the DLC TBC with the buffer layer of regular purity and the Co-Ni-based bond coat showed a better thermal durability. However, all of the TBC samples were delaminated at the interface between the YGYZ top coat and the bond coat or within the YGYZ top coat 17 near the interface. The DLC TBC with the buffer layer of high purity and the Ni-based bond coat was in a sound condition after 2000 cycles in the JETS tests, whereas the other TBCs were delaminated before 1130 cycles.…”

Section: Discussionmentioning

confidence: 99%

“…One of the promising leading candidates for advanced TBC materials is the Yb-Gd-Y-stabilized zirconia (hereinafter YGYZ). The YGYZ coating has better oxidation resistance, improved sintering resistance, higher calcium-magnesium-alumino-silicate (CMAS) resistance, excellent phase stability, and lower thermal conductivity than YSZ coating; it has thermal conductivity of 0.80-1.24 W•(m•K) -1 for bulk YGYZ and of 2.1 W•(m•K) -1 for bulk 8YSZ [16][17][18][19]. The principal drawback of YGYZ coating is its low coefficient of thermal expansion (CTE), which does 4 not match the bond coat with a relatively large CTE; CTE is 9-1010 -6 •K -1 for bulk YGYZ, 10.5-11.510 -6 •K -1 for bulk 8YSZ, and 15.010 -6 •K -1 at 1000 o C for Ni-based bond coat [20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Thermal durability and fracture behavior of layered Yb-Gd-Y-based thermal barrier coatings in thermal cyclic exposure

Jung

et al. 2017

Surface and Coatings Technology

View full text Add to dashboard Cite

The effects of structural design on the thermal durability of Yb-Gd-Y-based thermal barrier coatings (TBCs) were investigated through thermal cyclic exposure tests, such as furnace cyclic thermal fatigue (FCTF) and jet engine thermal shock (JETS) tests. The effects of composition in the bond coat and feedstock purity for the buffer layer on its lifetime performance were also examined. To overcome the drawbacks of Yb-Gd-Y material with poor thermal durability due to poor mechanical properties and low coefficient of thermal expansion, a buffer layer was introduced in the Yb-Gd-Y-based TBC systems. In the FCTF tests, the TBC with the CoNi-based bond coat and the buffer layer of regular purity showed a longer lifetime performance than other TBCs, especially the TBCs without the buffer layer.In the JETS tests, the TBC with the Ni-based bond coat and the buffer layer of high purity showed a sound condition after 2000 cycles, showing better interfacial stability for TBC with the Ni-based bond coat rather than that with the CoNi-based bond coat in the single layer coatings without the buffer layer. The buffer layer effectively enhanced the thermal durability in slow temperature change, while the bond-coat composition and the feedstock purity for the buffer layer were found to be important factor to improve the thermal durability of the TBC in fast temperature change. Finally, these research findings allow us to control the structure, composition, and feedstock purity in TBC system for improving the thermal durability in cyclic thermal environments.

show abstract

Advanced Materials for High‐Temperature Thermal Transport

Shin

Wang

Luo

et al. 2019

Adv Funct Materials

View full text Add to dashboard Cite

High temperature processes are widely used in a variety of existing and emerging industrial and aerospace applications. The thermal properties of high‐temperature materials thus play an important role in controlling the thermal energy, as highlighted by successful applications of thermal barrier coating and aerogels. While thermal transport processes at room and low temperature have witnessed tremendous progress in the past two decades, particularly on the fronts of understanding basic heat transfer properties at the micro‐ and nanoscale, the understanding at high temperature is still at the nascent stage, owing to several unique features at high temperature, such as the dominant Umklapp scattering effect that can render a crystalline material amorphous‐like thermal properties, and the important radiation contribution at high temperature. This lack of systematic understanding, coupled with the challenges in maintaining high‐temperature stability in a large number of materials, has limited the development of materials to meet the thermal transport properties pertaining to several current and emerging high‐temperature applications. This Review is aimed at providing an overview of the basic mechanisms governing thermal transport processes at high temperature, to identify their unique features and challenges, and to explore opportunities in material research for high‐temperature thermal materials.

show abstract

Structural evolution and thermophysical properties of (SmxGd1−x)2Zr2O7 (0≤x≤1.0) ceramics

Cited by 103 publications

References 23 publications

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

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

Thermal durability and fracture behavior of layered Yb-Gd-Y-based thermal barrier coatings in thermal cyclic exposure

Advanced Materials for High‐Temperature Thermal Transport

Contact Info

Product

Resources

About