An environmentally-benign NaNbO3 based perovskite antiferroelectric alternative to traditional lead-based counterparts

2019 ◽  
Vol 7 (48) ◽  
pp. 15153-15161 ◽  
Author(s):  
Aiwen Xie ◽  
He Qi ◽  
Ruzhong Zuo ◽  
Ao Tian ◽  
Jun Chen ◽  
...  
Keyword(s):  
Phase Transition ◽  
Environmentally Benign ◽  
Lead Free ◽  
Stripe Domain ◽  
Space Group

NaNbO3-based lead-free AFE R-phase ceramics with Pnma space group and nanoscale stripe domain exhibit completely reversible field induced AFE–FE phase transition, featuring a relatively low EA–F of ∼8 kV mm−1 and a large repeatable strain of ∼0.29%.

scholarly journals Crystal and electronic structure engineering of tin monoxide by external pressure

2021 ◽  
Author(s):  
Kun Li ◽  
Junjie Wang ◽  
Vladislav A. Blatov ◽  
Yutong Gong ◽  
Naoto Umezawa ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Band Gap ◽  
High Pressures ◽  
Low Pressure ◽  
Widespread Application ◽  
Space Group ◽  
Tin Monoxide ◽  
High Possibility ◽  
Pressure Phase

AbstractAlthough tin monoxide (SnO) is an interesting compound due to its p-type conductivity, a widespread application of SnO has been limited by its narrow band gap of 0.7 eV. In this work, we theoretically investigate the structural and electronic properties of several SnO phases under high pressures through employing van der Waals (vdW) functionals. Our calculations reveal that a metastable SnO (β-SnO), which possesses space group P21/c and a wide band gap of 1.9 eV, is more stable than α-SnO at pressures higher than 80 GPa. Moreover, a stable (space group P2/c) and a metastable (space group Pnma) phases of SnO appear at pressures higher than 120 GPa. Energy and topological analyses show that P2/c-SnO has a high possibility to directly transform to β-SnO at around 120 GPa. Our work also reveals that β-SnO is a necessary intermediate state between high-pressure phase Pnma-SnO and low-pressure phase α-SnO for the phase transition path Pnma-SnO →β-SnO → α-SnO. Two phase transition analyses indicate that there is a high possibility to synthesize β-SnO under high-pressure conditions and have it remain stable under normal pressure. Finally, our study reveals that the conductive property of β-SnO can be engineered in a low-pressure range (0–9 GPa) through a semiconductor-to-metal transition, while maintaining transparency in the visible light range.

Phase transition and temperature stability of KNN-based lead-free piezoceramics

2021 ◽  
Vol 570 (1) ◽  
pp. 31-36
Author(s):  
Yang Zhang ◽  
Honglin Li ◽  
Mingling Li ◽  
Xiaoyong Xu
Keyword(s):  
Phase Transition ◽  
Temperature Stability ◽  
Lead Free

Temperature-induced phase transition of -oriented 0.92Na0.5Bi0.5TiO3-0.08Bi(Zn0.5Ti0.5)O3 lead-free single crystals

2021 ◽  
Author(s):  
Junjie Xiao ◽  
Sixing Liu ◽  
Jushan Wang ◽  
Jialin Xu ◽  
Zhang Zhang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Single Crystals ◽  
Lead Free

Niobate-based lead-free piezoceramics: a diffused phase transition boundary leading to temperature-insensitive high piezoelectric voltage coefficients

2018 ◽  
Vol 6 (5) ◽  
pp. 1116-1125 ◽  
Author(s):  
Qing Liu ◽  
Jing-Feng Li ◽  
Lei Zhao ◽  
Yichi Zhang ◽  
Jing Gao ◽  
...  
Keyword(s):  
Phase Transition ◽  
Thermal Stability ◽  
Lead Free ◽  
Thermally Stable ◽  
Transition Boundary ◽  
Diffused Phase Transition ◽  
Piezoelectric Voltage ◽  
Phase Transition Boundary

A large and thermally stable d33 was observed in dense and translucent KNN-based ceramics. Forming the R–O–T diffused phase transition is validated as a feasible way to realize the simultaneous enhancement of piezoelectricity and thermal stability.

NQR and Crystal Structure of 4,5-Dichloroimidazole, C3H2N2Cl2

1992 ◽  
Vol 47 (1-2) ◽  
pp. 177-181 ◽  
Author(s):  
Shi-Qi Dou ◽  
Alarich Weiss
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Unit Cell ◽  
Space Group ◽  
Temperature Range ◽  
Temperature Coefficients ◽  
Group D

AbstractThe two line 35Cl NQR spectrum of 4,5-dichloroimidazole was measured in the temperature range 77≦ T/K ≦ 389. The temperature dependence of the NQR frequencies conforms with the Bayer model and no phase transition is indicated in the curves v ( 35Cl)= f(T). Also the temperature coefficients of the 35Cl NQR frequencies are "normal". At 77 K the 35Cl NQR frequencies are 37.409 MHz and 36.172 MHz and at 389 K 35.758 MHz and 34.565 MHz. The compound crystallizes at room temperature with the tetragonal space group D44-P41212, Z = 8 molecules per unit cell; at 295 K : a = 684.2(5) pm, c = 2414.0(20) pm. The relations between the crystal structure and the NQR spectrum are discussed.

Structures and Phase Transitions of the A 7PSe6 (A = Ag, Cu) Argyrodite-Type Ionic Conductors. I. Ag7PSe6

1998 ◽  
Vol 54 (4) ◽  
pp. 376-383 ◽  
Author(s):  
M. Evain ◽  
E. Gaudin ◽  
F. Boucher ◽  
V. Petricek ◽  
F. Taulelle
Keyword(s):  
Phase Transition ◽  
Atomic Displacement ◽  
Ionic Conductors ◽  
Reliability Factor ◽  
Conducting Phase ◽  
Cubic Symmetry ◽  
Space Group ◽  
Ionic Conducting ◽  
Jahn Teller ◽  
Diffusion Paths

The crystal structures of the two polymorphic forms of the argyrodite Ag7PSe6 compound are analysed by means of single-crystal X-ray diffraction. Above the phase transition at 453 K leading to the ionic conducting phase, γ-Ag7PSe6 crystallizes in cubic symmetry, space group F4¯3m, with a = 10.838 (3) Å, V = 1273.1 (12) Å3 and Z = 4 at 473 K. The refinement of the 473 K structure leads to a reliability factor of R = 0.0326 for 192 independent reflections and 33 variables. Diffusion paths for silver d 10 ions are evidenced by means of a combination of a Gram–Charlier development of the atomic displacement factors and a split model. Below the phase transition β-Ag7PSe6 crystallizes again in cubic symmetry, but with the space group P213 and a = 10.772 (2) Å, V = 1250.1 (6) Å3 and Z = 4 at room temperature. The refinement of the 293 K structure leads to a reliability factor of R = 0.0267 for 1125 independent reflections and 68 variables. In the β-Ag7PSe6 ordered phase the silver cations are found in various sites corresponding to the most pronounced probability density locations of the high-temperature diffusion paths. Those positions correspond to low coordination (2, 3 and 4) sites, in agreement with the silver preference for such environments. In addition, the Ag atoms are found slightly displaced from the true linear, triangular or tetrahedral coordination, as expected from second-order Jahn–Teller effects.

Sign in / Sign up

Export Citation Format

Share Document