Microstructure at morphotropic phase boundary in Pb(Mg1/3Nb2/3)O3-PbTiO3 ceramic: Coexistence of nano-scaled {110}-type rhombohedral twin and {110}-type tetragonal twin

Abstract

For more than half a century, the morphotropic phase boundary (MPB) has drawn constant interest in developing piezoelectric materials, as the phase instability at the region significantly enhances piezoelectricity. However, the local structure/symmetry at the MPB region is still under controversy. The investigation on morphology and origin of the local structure at MPB is of considerable importance to provide a microstructure basis for high piezoelectricity. In the present study, we thus use high resolution transmission electron microscopy to investigate the microstructure feature of MPB at PMN-PT ceramics. The local structure is shown to be the coexistence of nano-scaled {110}-type rhombohedral (R) twin and {110}-type tetragonal (T) twin. Such nano-scaled coexistence can be due to a nearly vanishing polarization anisotropy and low domain wall energy at MPB, which thus facilitates polarization rotation between 〈001〉T and 〈111〉R states and leads to high properties of MPB compositions.

Electrocaloric properties in relaxor ferroelectric (1−x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 system

“…In fact, the PMN-25PT composition lies close to a possible tricritical point where a second order phase transition arises in the x-T phase diagram. 36 The critical point in polycrystalline PMN-xPT system is also likely to be diffuse in nature due to the observed orientational heterogeneity or even absence of critical point depending on the electric field direction. 35,[37][38][39][40] The temperature of the maximum ECE responsivity was observed to lie just above T d (¼ T C ) (extrapolated from Figure 4) which is reflected in their similar concentration dependence ( Figure 5).…”

Effect of Reoriented Nanodomains on Crystal Structure and Piezoelectric Properties of Polycrystalline Ferroelectric Ceramics

“…Monoclinic (M) or orthorhombic (O) adaptive phases with nanoscale textures and low-symmetry phases with nanotwin diffraction in the MPB region have been proposed based on x-ray diffraction (XRD), neutron diffraction, and transmission electron microscopy (TEM) analyses. [7][8][9][10][11][12][13] So far, the microstructure of lead zirconate titanate Pb(Ti 1Àx Zr x ) O 3 (PZT) and (1Àx)Bi 0.5 Na 0.5 TiO 3 -xBaTiO 3 (BNT-BT) close to the morphotropic phase boundary (MPB) remains unclear, and is even controversially reported by different groups. [12][13][14][15][16] On the other hand, polycrystalline materials must be poled by electric fields in order to exhibit piezoelectricity.…”

A new insight into structural complexity in ferroelectric ceramics

“…It is noted that the existence of nanodomains is a common feature of the MPB region [18,19,[25][26][27][28][29][30][31]. It has been reported that the nanodomains, whose size is much smaller than the coherence length of diffraction radiations, scatter waves from individual nanodomains coherently superimposed in diffraction profiles, and cause anisotropic broadening, asymmetries, intensity distribution variation between the peaks, and even new peaks appearance in diffraction patterns [31,32].…”