Failure mode, ferroelastic behavior and toughening effect of bismuth titanate ferroelectric ceramics under uniaxial compression load

A typic BLSF ceramics: bismuth titanate (BL4Ti3O12), whose failure mode, ferroelastic behavior and toughening effect under uniaxial compression load were comprehensively assessed. Firstly, a series of crystallographic parameters including lattice constants (a, h, c and v), orthorhombicity (g) and single-crystal distortion (S degrees lattice) were calculated from XRD patterns. The ferroelastic behavior referred to the 90 degrees switching of domains with compression stress was identified by the nonlinear stress-strain curve, and the underlying micromechanism was more accurately described by the non-180 degrees domain wall motion. SEM observation on the fracture surface of the broken sample reveals its failure mode in terms of microcrack initiation and propagation behaviors. Further, a simplified domain distribution model was constructed for unpolecl fel-Fueled:6c ceramics based on a constitutive framework, which deduced their constitutive relation subjected to uniaxial compression load. The ferroelasticily induced toughening was verified by indentation test, and further analyzed by a micromechanics model of crack propagation. The expression of roughening effect (Delta Gamma/ Gamma) was also deduced from the indentation fracture mechanics. Finally, the evolution in mechanical properties (including coercive stress (sigma(c)), switching strain (epsilon(zz)), apparent elastic modulus (E) and compression strength (sigma(cf)) of Bl(4)Ti(3)O(12) ceramics with the doping content of W was also quantified by the compression test. (C) 2018 Elsevier Ltd. All rights reserved.