| 1. |
- Ahmed, Shafique, et al.
(author)
-
Terahertz probing of low-temperature degradation in zirconia bioceramics
- 2022
-
In: Journal of The American Ceramic Society. - : Wiley. - 0002-7820 .- 1551-2916. ; 105:2, s. 1106-1115
-
Journal article (peer-reviewed)abstract
- ZrO2-based ceramics are widely used in biomedical applications due to its color, biocompatibility, and excellent mechanical properties. However, low-temperature degradation (LTD) introduces a potential risk for long-term reliability of these materials. The development of innovative nondestructive techniques, which can explore LTD in zirconia-derived compounds, is strongly required. Yttria stabilized zirconia, 3Y-TZP, is one of the well-developed ZrO2-based ceramics with improved resistance to LTD for dental crown and implant applications. Here, 3Y-TZP ceramic powders were pressed and sintered to study the LTD phenomenon by phase transition behavior. The LTD-driven tetragonal-to-monoclinic phase transition was confirmed by XRD. XPS analysis demonstrated that induced LTD reduced the oxygen vacancies which supports these findings. It is proved that after the degradation, the 3Y-TZP ceramics show the decreased dielectric permittivity at terahertz frequencies due to the crystallographic phase transformation. Terahertz nondestructive probe is a promising method to investigate LTD in zirconia ceramics.
|
|
| 2. |
- Jacobs, Thorsten, et al.
(author)
-
Sequence of Quantum Phase Transitions in Bi2Sr2CaCu2O8+δ Cuprates Revealed by In Situ Electrical Doping of One and the Same Sample
- 2016
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 116:6
-
Journal article (peer-reviewed)abstract
- Our recently discovered electrical doping technique allows a broad-range variation of carrier concentration without changing the chemical composition. We show that it is possible to induce superconductivity in a nondoped insulating sample and to tune it reversibly all the way to an overdoped metallic state. This way, we can investigate the whole doping diagram of one and the same sample. Our study reveals two distinct critical points. The one at the overdoped side is associated with the onset of the pseudogap and with the metal-to-insulator transition in the c-axis transport. The other at optimal doping is associated with the appearance of a dressed electron energy. Our study confirms the existence of multiple phase transitions under the superconducting dome in cuprates.
|
|
| 3. |
- Wu, Jiyue, et al.
(author)
-
Ultrahigh field-induced strain in lead-free ceramics
- 2020
-
In: Nano Energy. - : Elsevier BV. - 2211-2855 .- 2211-3282. ; 76
-
Journal article (peer-reviewed)abstract
- Due to the worldwide concerns of environmental protection and sustainable development, lead-free piezoelectric materials are greatly desired for bridging the electrical energy to the mechanical energy. However, their lower energy conversion coefficient compared to the conventional lead-containing piezoelectric materials significantly limits their device applications. Herein, we introduce a novel strategy to increase the strain of lead-free ferroelectric system via material structure design to create polar nano regions (PNRs) and point defects in the material while retaining the global ferroelectric phase. This added short-range structural heterogeneity in the material will facilitate the field-induced phase transition and reversible domain wall switching to enhance the strain. Following this strategy, we demonstrate an ultrahigh strain induced by an electric field in non-textured lead-free Bi0.5Na0.5TiO3 (BNT)-based ceramics. The strain in unipolar mode (Suni) can reach up to 0.74% at 70 kV/cm, making it the highest value in reported lead-free ceramics so far. This puts forward a good route to design high-performance piezoelectric materials by material structure engineering. It also reveals the promising potential of lead-free piezoelectric materials in practical electromechanical device applications.
|
|
