Anisotropy of Indentation Cracks Propagation of PZT-5H Ferroelectric Ceramics in Air and Water under Sustained Load

Abstract

The propagation process and the anisotropy of the indentation cracks of poled

Ferroelastic domain switching and R‐curve behavior in lead zirconate titanate (Zr/Ti = 52/48)‐based ferroelectric ceramics

“…According to fracture mechanics, the efficient stress intensity factor ( K Ieff ) can be expressed as the sum of the applied stress intensity factor ( K Ia ) and the additive stress intensity factor decided by the 90° domain switching (Δ K I ), which is written as…”

“…According to fracture mechanics, the efficient stress intensity factor (K Ieff ) can be expressed as the sum of the applied stress intensity factor (K Ia ) and the additive stress intensity factor decided by the 90° domain switching (ΔK I ), which is written as 40 Based on a mode of small scale domain switching, the shielding effect by domain switch is scaled by a key dimensionless group of material parameters 41 where Ω is the dimensionless function depended on the domain orientation, V f the volume fraction of switched domains, Y the Young's modulus, ε sp (also written as γ s ) the spontaneous switching strain (in a tetragonal material with domains randomly distributed, the maximum possible value of ε sp , is given by ε sp = (2/3)(c/a-1), ν the Poisson's ratio, P s the saturated polarization, E c the coercive field. If assumed that K Ia is equal to the apparent fracture toughness (K IC ) while K Ieff approximates to the intrinsic fracture toughness (K I0 ), and then we have For PZT-NC ceramics, ν = ~0.3, the ferroelectric loops measurement has given the values of P s = 28.02 μC/cm 2 and E c = 10.03 kV/cm.…”