Theoretical and experimental investigations of mechanical properties for polymorphous YTaO₄ceramics

Abstract

In this work, the dense bulk polymorphous YTaO4 ceramics with M or M' phase are synthesized by spark plasma sintering method accompanying with different tempering procedures. Combined with the nano‐indentation and theoretical calculation, their mechanical properties are systematically investigated. The identification of crystal structure reveals that the YTaO4 crystallizes into M phase (space group: I2/a) with higher tempering temperature, otherwise it crystallizes into M' phase (space group: P2/a). The results of mechanical properties indicate M‐phase YTaO4 possesses larger Young's modulus and hardness than that of M' phase. It is stemmed from the chemical bonding strength of M phase is stronger than that of M' phase, and the stronger bonding strength of M phase also results in its elastic resilience is superior to M' phase. Besides, on account of the low symmetry of monoclinic crystal system, the Young's modulus of polymorphous YTaO4 ceramics exhibit strong anisotropy.

High‐entropy ferroelastic rare‐earth tantalite ceramic: (Y0.2Ce0.2Sm0.2Gd0.2Dy0.2)TaO4

“…is independent of the work-hardening behavior 38 ; the lower the ratio, the better the elastic resilience of (5RE 0.2 )TaO 4 ceramics. In this study, the ratio (W r /W t =0.29) was lower than that of YTaO 4 (W r /W t = 0.45), as reported by Wu, 15 indicating that the (5RE 0.2 )TaO 4 ceramics have better ferroelasticity than YTaO 4 . The Young's modulus (E) and hardness (H) are 141-162 GPa and 4.4-7.7 GPa respectively, and they were calculated using nanoindentation method with continuous stiffness model, as shown in Figure 3G 1 -G 3 .…”

“…The novel ferroelastic material rare-earth tantalate (RETaO 4 ) ceramic, with excellent comprehensive performance, has attracted significant research attention in the field of TBCs, and it is considered as one of the most promising new generation TBC material. [12][13][14][15] Chen et al 13 studied the thermal and mechanical properties of rare-earth tantalate RETaO 4 (RE = Nd, Sm, Eu, Gd, Dy, Ho, Y, or Er) and found that the thermal conductivity and thermal expansion coefficients of RETaO 4 ceramics are 1.40-3.94 W m -1 K -1 and 4.7-10.7 × 10 −6 K −1 , respectively. To optimize the properties of RETaO 4 by doping, Wu et al 16 studied the thermal conductivities (1.7-2.0 W m -1 K -1 at 900°C) and thermal expansion coefficients (TECs) (10-11 × 10 -6 K -1 ) of (Y 1-x Dy x )TaO 4 ceramics.…”

Phase Formation and Thermal Stability of Reactively Sputtered YTaO4–ZrO2 Coatings

“…While Wu et al [ 44 ] obtained a value of 147 GPa, Zhang et al [ 14 ] calculated the elastic modulus to be 170.2 GPa. Hence, the measured elastic modulus of the as-deposited coatings is significantly higher than the calculated value by Wu et al but agrees within the error of the measurement with ab initio results by Zhang et al Wu et al also reported an experimentally derived elastic modulus of 100 GPa determined by nanoindentation for spark plasma sintered M’ [ 44 ]. The higher elastic moduli in this work may be rationalized by a higher density of the samples and by compressive stresses common for PVD-deposited coatings [ 45 ].…”

“… Elastic modulus measured by nanoindentation as a function of ZrO 2 content for as-deposited coatings (blue). Black symbols indicate ab initio calculated elastic moduli by Wu et al (filled symbol) [ 44 ] and Zhang et al (open symbol) [ 14 ] for M’. Experimental results by Wu et al [ 44 ] are shown in orange.…”

The toughening of pyrochlore La2Zr2O7 by a ferroelastic NdAlO3 second phase for potential thermal barrier coating applications

“…3,[5][6][7][8][9][10][11][12][13] The essence of ceramic toughening is either to open up energy dissipation channels or to retard crack propagation. A variety of strategies [5][6][7][8][9][10][11][12][13] have been proposed to toughen ceramics, among which the introduction of a second phase is the most well-known. In particular for those ferroelastic second phases, which have a toughening mechanism by the switching of ferroelastic domains, they are very ideal for the toughening of high temperature TBC topcoat materials, as this mechanism is still valid at high temperatures given the Curie temperature of the introduced second phase sufficiently high.…”