New finding of coherent hybrid structure of BaTiO3 single crystal in the room temperature phase

Domain Wall Displacement is the Origin of Superior Permittivity and Piezoelectricity in BaTiO3 at Intermediate Grain Sizes

“…Field-induced phase transitions in BaTiO 3 have been reported previously [46][47][48][49][50], and some of these studies [46][47][48] showed that the Curie temperature is shifted to higher values in the presence of an electric field, suggesting the proximity to a cubic phase decreases, or equally that the proximity to the orthorhombic phase increases. It is therefore possible that the field-induced phase is of orthorhombic symmetry.…”

“…It is therefore possible that the field-induced phase is of orthorhombic symmetry. Further, other studies on BaTiO 3 single crystals [49,50] have reported an electric field-induced monoclinic phase close to the tetragonal-orthorhombic phase transition temperature. Once formed, this monoclinic phase is observed to be stable even upon removal of the field, a characteristic that is not observed in the present field-induced transition, though does not eliminate this phase from being the phase observed in the present work.…”

Thermotropic phase boundaries in classic ferroelectrics

“…In classic lead-free materials such as BaTiO 3 and KNbO 3 for example, creating frustrated ferroelectric domains by external fields has been shown to substantially enhance piezoelectric response 16,17 . However, the exact mechanism of this phenomenon has been the subject of extensive debate in recent years [19][20][21][22][23][24][25][26][27] ; the possible existence of a monoclinic phase in BaTiO 3 single crystals has been reported 25,28,29 , but it has never been directly imaged on a microscopic level. As a result, the important question of whether the observed phase is of intrinsic monoclinic symmetry, or in fact corresponds to a symmetry-adaptive superlattice of nanodomains 21,[30][31][32][33][34][35][36][37] (such as those observed in MPBs) remains open.…”

Raman Spectroscopic Evidence of a Coherent Room Temperature Hybrid Structure of BaTiO3Single Crystal

“…Motivated by the stimulating results of the phase transition on cooling, X-ray diffraction studies have been performed in the ferroelectric room temperature phase [11], using BaTiO 3 single crystals. The result is notable: the ferroelectric phase has the coherent hybrid structure (CHS) composed of tetragonal and monoclinic forms [11,12], opposite to the common today knowledge. However there comes about a question concerning its materialization in the bulk single crystal.…”

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Recently, a precession X-ray study has discovered that ferroelectric BaTiO3 single crystals have a coherent hybrid structure that consists of tetragonal and monoclinic lattices that share the (101) face of the tetragonal [11,12]. Microscopic observations attest that the single crystal has two kinds of stripes (dark and white regions).

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