Theoretical investigation of anisotropic mechanical and thermal properties of ABO₃ (A=Sr, Ba; B=Ti, Zr, Hf) perovskites

Abstract

As promising TBC (thermal barrier coating) candidates, perovskite oxides own designable properties for their various options of cations and structural diversity, but limited comprehensions of structure-property relationship delay their engineering applications. In this work, mechanical/thermal properties of ABO 3 (A=Sr, Ba;B=Ti, Zr, Hf) perovskites and their anisotropic nature are predicted employing density functional theory. Their theoretical minimum thermal conductivities range from 1.09 to 1.74 WÁm À1 ÁK À1 , being lower than Y 2 O 3 partially stabilized ZrO 2 . Reduced thermal conductivities up to 16% along particular directions are reached after considering thermal conductivity anisotropy. All compounds own high hardness while SrZrO 3 , SrHfO 3 , and BaHfO 3 possess well damage tolerance. We found that small electronegativity discrepancy leads to big anisotropy of chemical bond, Young's/shear moduli and thermal conductivities, together with good damage tolerance. These results suggest that the next generation TBCs with extra low thermal conductivity should be achieved through combining material design and orientation-growth tailoring. K E Y W O R D S density functional theory, mechanical properties, perovskites, thermal conductivity

High‐temperature mechanical and thermal properties of Ca1−xSrxZrO3solid solutions

“…The experimental bulk, shear, and Young's moduli of Ca 1− x Sr x ZrO 3 are 134.50‐159.18 GPa, 83.27‐88.37 GPa, and 207.08‐223.71 GPa, respectively, decreasing with increasing Sr content. These results are consistent with the generally accepted rule that polycrystalline moduli enhance with increment of the average bonding strength (or decrease of bond lengths) . Compared with other zirconium‐containing materials, Young's moduli of Ca 1− x Sr x ZrO 3 are quite similar to those of BaZrO 3 and tetragonal ZrO 2 , with a deviation less than 4.4% and 5.3%, respectively.…”

“…These results are consistent with the generally accepted rule that polycrystalline moduli enhance with increment of the average bonding strength (or decrease of bond lengths). 16,43 Compared with other zirconium-containing materials, Young's moduli of Ca 1−x Sr x ZrO 3 are quite similar to those of BaZrO 3 2 and tetragonal ZrO 2 , 36 with a deviation less than 4.4% and 5.3%, respectively. In general, the experimental mechanical properties are comparable to BaZrO 3 , ZrO 2 , and YSZ.…”

“…15 Liu et al identified ternary ABO 3 -type perovskites as low thermal conductivity oxides with tailorable mechanical/thermal properties, which are underpinned by the various options for A and/or B cations as well as the structural diversity. 16 Recently, CaZrO 3 and SrZrO 3 are thought to be promising TBCs materials as they have high melting points (2690°C and 2800°C), 17 low thermal conductivities (2.0 and 2.3 W·(m·K) −1 ), 1,18 high thermal expansion coefficients (9.2-9.7 × 10 −6 /K, 780-1180 K and 10.0-10.9 × 10 −6 /K, 600-1200 K), 19,20 thermal and chemical stability, and high heat resistance. 21 In addition, their properties can be further optimized through doping rare earth elements.…”

Theoretical and experimental investigations of mechanical properties for polymorphous YTaO4ceramics

“…Compared with other promising thermal barrier coatings materials such as YSZ, rare earth zirconia, rare earth stannates, rare earth aluminum oxides, and cubic perovskite oxides, the polymorphous YTaO 4 ceramics possess much lower Young's modulus and hardness. It should be noticed that the low Young's modulus can be conducive to high strain tolerance especially for the coatings fabricated by electron beam physical vapor deposition (EB‐PVD) technology .…”

The thermo‐mechanical properties and ferroelastic phase transition of RENbO4(RE = Y, La, Nd, Sm, Gd, Dy, Yb) ceramics

“…The martensite transformation of the tetragonal phase to the monoclinic phase (m) phase occurs during cooling and produces a volume expansion of about 3% to 5%, which leads to a large number of cracks under long‐term thermal cycling conditions and accelerating the premature failure of the coating . Therefore, the operate temperature of YSZ is limited to 1200°C . As aero‐engines and gas turbines are moving toward higher thrust‐to‐weight ratios and higher efficiency, the traditional YSZ ceramics have been unable to meet the ever‐increasing operating temperatures of engines, so looking for novel insulation materials to replace YSZ has become the research focus in the field of TBCs.…”