Functional materials are of critical importance to electronic and smart devices. A deep understanding of the structure–property relationship is essential for designing new materials. In this work, instead of utilizing conventional atomic coordinates, a symmetry-mode approach is successfully used to conduct structure refinement of the neutron powder diffraction data of (1−x)AgNbO3–xLiTaO3 (0 ≤ x ≤ 0.09) ceramics. This provides rich structural information that not only clarifies the controversial symmetry assigned to pure AgNbO3 but also explains well the detailed structural evolution of (1−x)AgNbO3–xLiTaO3 (0 ≤ x ≤ 0.09) ceramics, and builds a comprehensive and straightforward relationship between structural distortion and electrical properties. It is concluded that there are four relatively large-amplitude major modes that dominate the distorted Pmc21 structure of pure AgNbO3, namely a Λ3 antiferroelectric mode, a T4+ a
−
a
−
c
0 octahedral tilting mode, an H2 a
0
a
0
c
+/a
0
a
0
c
− octahedral tilting mode and a Γ4− ferroelectric mode. The H2 and Λ3 modes become progressively inactive with increasing x and their destabilization is the driving force behind the composition-driven phase transition between the Pmc21 and R3c phases. This structural variation is consistent with the trend observed in the measured temperature-dependent dielectric properties and polarization–electric field (P-E) hysteresis loops. The mode crystallography applied in this study provides a strategy for optimizing related properties by tuning the amplitudes of the corresponding modes in these novel AgNbO3-based (anti)ferroelectric materials.
A Raman spectroscopy study has been performed, at room temperature, on the (Bi 0.5 Na 0.5 ) 0.92 Ba 0.08-3x/2 La x TiO 3 lead-free ceramic system (with x = 0, 1, 2, and 3 at.% La). The signature of the Raman spectra showed that the structural properties were noticeably affected by the La 3+ -ions concentration, revealing the
A series of lanthanide, Ln, ion doped lead titanate ceramics, at 2 and 8 at.%, have been prepared with starting compositions Pb 1-3x/2 Ln x TiO 3 , Ln = La, Nd, Sm, Eu, Gd, Dy, using a standard ceramic method. Structural, and differential scanning calorimetry, measurements are reported. Doping with La 3+ results in a reduction in tetragonality and cell volume; a partial recovery was then observed for the smaller Ln 3+ ions and suggests the onset of partial substitution of the rare earth on the B-site. The ferroelectricparaelectric transition temperature results also consistent with an increased probability the B-site occupation with decreasing ion size.
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
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.