Structural and microstructural features of lead‐free BNT–BT thin films: Nanoscale electromechanical response analysis

Abstract

It is known that lead-based ferroelectric compounds, such as Pb(Zr,Ti)O 3 and PbTiO 3 , and others based on them, have attracted most of the attention of the scientific community for several decades due to their excellent piezo-, pyro-, and ferroelectric properties. [1][2][3][4] However, the lead toxicity and the negative implications to the environment and human health have conducted to the researchers to reevaluate their efforts in order to develop environmentally friendly lead-free materials

Evidences of the ferroelectric and antiferroelectric phases coexistence in the (Pb0.96La0.04)(Zr0.95Ti0.05)0.99O3 ceramic system by probing nanoscale analyses via piezoresponse force microscopy

“…These regions could be ascribed to the antiferroelectric phase existing in the studied sample, 50 which confirms the coexistence of the rhombohedral ferroelectric (R3 c ) and orthorhombic antiferroelectric (P bam ) phases, as was previously demonstrated through the structural analyses. Such zones with no piezoresponse, attributed to AFE phase, were previously reported at room temperature for BNT–BT thin films 50 or GeSe nanoflakes, 51 and at high temperature (200°C) for Sm‐doped BiFeO 3 thin films 52 . In the latter two cases and at room temperature, the application of an external electric field for GeSe nanoflakes, or the applied driving voltage (3 V) during PFM scanning for Sm‐doped BiFeO 3 films, enabled the transition from the (metastable) AFE phase to the FE phase at room temperature.…”

“…In addition, areas with almost zero deformation amplitude are also observed, as evidenced by black contrast in Figure 5B. These regions could be ascribed to the antiferroelectric phase existing in the studied sample, 50 which confirms the coexistence of the rhombohedral ferroelectric (R3 c ) and orthorhombic antiferroelectric (P bam ) phases, as was previously demonstrated through the structural analyses. Such zones with no piezoresponse, attributed to AFE phase, were previously reported at room temperature for BNT–BT thin films 50 or GeSe nanoflakes, 51 and at high temperature (200°C) for Sm‐doped BiFeO 3 thin films 52 .…”

High‐Polarizability Organic Ferroelectric Materials Doping for Enhancing the Built‐In Electric Field of Perovskite Solar Cells Realizing Efficiency over 24%

“…Notably, the composite metal (Pt/Ir)-coated tip, which was used as the probe for the PFM measurements, could establish a local BEF with the bottom ITO driven by the electrode work function difference. [42,43] Interestingly, the integrated phase angles related to area C are evenly localized between the peaks corresponding to www.advmat.de www.advancedsciencenews.com of a material, was calculated according to the equation: A = d 33 V ac Q, [44,45] where A is the amplitude in the loop, V ac is the loaded high-frequency voltage (1 V), and Q is a gain factor (Q = 10). Evidently, the d 33 values dramatically increase from 19.3 pm V −1 for the PVK film and 33.6 pm V −1 for the PVK-PVDF film to 58.1 pm V −1 for the PVK-PVDF:DH film (Figure 3d; Figure S11b and Table S1, Supporting Information).…”

“…Compared to the PVK and PVK–PVDF films, the PVK–PVDF:DH film shows an increased amplitude contrast (Figure 3e; Figure S11a, Supporting Information), confirming the strong ferroelectric response of PVDF:DH under the BEF. The piezoelectric constant d 33 , which represents the ÷ strength of a material, was calculated according to the equation: A = d 33 V ac Q , [ 44,45 ] where A is the amplitude in the loop, V ac is the loaded high‐frequency voltage (1 V), and Q is a gain factor ( Q = 10). Evidently, the d 33 values dramatically increase from 19.3 pm V −1 for the PVK film and 33.6 pm V −1 for the PVK–PVDF film to 58.1 pm V −1 for the PVK–PVDF:DH film (Figure 3d; Figure S11b and Table S1, Supporting Information).…”

Polarization Rotation Control Domain Dynamic Response Modulates Piezoelectric Properties of Lead‐Free Thin Films

“…[ 34,35 ] The A 1 mode attributed to the vibrations of the A‐site ion (100–200 cm −1 ) of the perovskite structure; the B 1 and B 2 modes correlated with the vibrations of BO bond (200–450 cm −1 ); the C 1 –C 5 modes linked to the vibrations of BO 6 octahedron (>450 cm −1 ). [ 36 ] According to our previous research results, this feature belongs to the local coexistence of rhombohedral (R) and tetragonal (T) phases. [ 32 ] It is evident that the vibrational models of the BO bond and BO 6 octahedron (B 1 –B 2 and C 1 –C 5 ) fuse after the thin films are meritocratically oriented, as marked by the dashed arrows in the figure, but the vibrational modes are not reduced.…”