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Influence of orientation and ferroelectric domains on the photochemical reactivity of La2Ti2O7

In the article “Influence of orientation and ferroelectric domains on the photochemical reactivity of La₂Ti₂O₇” Mingyi Zhang, Paul A. Salvador and Gregory S. Rohrer describe how they measured the effects of crystal orientation and ferroelectric domain structure on the photochemical reactivity of La₂Ti₂O_7.*

The reactivity is greatest on (001) surfaces (this is the orientation of the layers in this (110)p layered perovskite structure) while surfaces perpendicular to this orientation have the least reactivity. Complex domain structures were observed within the grains, but they appeared to have no effect on the photocathodic reduction of silver, in contrast to previous observations on other ferroelectrics. La₂Ti₂O₇ is an example of a ferroelectric oxide in which the crystal orientation has a greater influence on the photochemical reactivity than polarization from the internal domain structure. *

NanoWorld™ conductive Platinum Iridium coated Arrow-EFM AFM probes were used for the Piezo-force microscopy (PFM) that was used to determine the ferroelectric domain structure on the surface. *

The ferroelectric domains on the surface were found to have irregular shapes and there was no correlation between the pattern of silver reduction and the domain shape. The results indicate that the ferroelectric polarization of La2Ti2O7 does not alter the reactivity enough to overcome the influence of the anisotropic crystal structure. *

Fig. 6 a and b from “Influence of orientation and ferroelectric domains on the photochemical reactivity of La2Ti2O7” by Mingyi Zhang et al.
A La2Ti2O7 grain imaged with different modalities. (a) a PFM out-of-plane amplitude image. (b) a PFM out-of-plane phase image. A meandering black line in (a), marked by the arrow, corresponds to a change from light to dark contrast in the phase image. The dark (light) contrast corresponds to regions with -180° (0°) phase shift. NanoWorld conductive Arrow-EFM AFM probes were used for the piezo-force microscopy.

Please have a look at the full article cited below for the full figure — Fig. 6 a and b from “Influence of orientation and ferroelectric domains on the photochemical reactivity of La2Ti2O7” by Mingyi Zhang et al.
A La2Ti2O7 grain imaged with different modalities. (a) a PFM out-of-plane amplitude image. (b) a PFM out-of-plane phase image. A meandering black line in (a), marked by the arrow, corresponds to a change from light to dark contrast in the phase image. The dark (light) contrast corresponds to regions with -180° (0°) phase shift. Please have a look at the full article cited below for the full figure

*Mingyi Zhang, Paul A. Salvador and Gregory S.Rohrer
Influence of orientation and ferroelectric domains on the photochemical reactivity of La₂Ti₂O₇
Journal of the European Ceramic Society (2020)
DOI: https://doi.org/10.1016/j.jeurceramsoc.2020.09.020

Please follow this external link to read the full article https://www.sciencedirect.com/science/article/pii/S0955221920307445

Open Access : The article “Influence of orientation and ferroelectric domains on the photochemical reactivity of La₂Ti₂O₇” by Mingyi Zhang, Paul A. Salvador, Gregory S. Rohrer is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit https://creativecommons.org/licenses/by/4.0/.

Chemical switching of low-loss phonon polaritons in α-MoO3 by hydrogen intercalation

Phonon polaritons (PhPs) have attracted significant interest in the nano-optics communities because of their nanoscale confinement and long lifetimes. Although PhP modification by changing the local dielectric environment has been reported, controlled manipulation of PhPs by direct modification of the polaritonic material itself has remained elusive.*

In the article “Chemical switching of low-loss phonon polaritons in α-MoO3 by hydrogen intercalation” Yingjie Wu, Qingdong Ou, Yuefeng Yin, Yun Li, Weiliang Ma, Wenzhi Yu, Guanyu Liu, Xiaoqiang Cui, Xiaozhi Bao, Jiahua Duan, Gonzalo Álvarez-Pérez, Zhigao Dai, Babar Shabbir, Nikhil Medhekar, Xiangping Li, Chang-Ming Li, Pablo Alonso-González and Qiaoliang Bao demonstrate an effective chemical approach to manipulate PhPs in α-MoO3 by the hydrogen intercalation-induced perturbation of lattice vibrations.*

Their methodology establishes a proof of concept for chemically manipulating polaritons, offering opportunities for the growing nanophotonics community.*

The surface topography and near-field images presented in this article were captured using a commercial s-SNOM setup with a platinum iridium coated NanoWorld Arrow-NCPt AFM probe in tapping mode.*

Fig. 2 a) from “Chemical switching of low-loss phonon polaritons in α-MoO3 by hydrogen intercalation” by Yingjie Wu et al. :
Reversible switching of PhPs in the L-RB of α-MoO3 a Schematic of the s-SNOM measurement and PhP propagation in a typical H-MoO3/α-MoO3 in-plane heterostructure.
2 a Schematic of the s-SNOM measurement and PhP propagation in a typical H-MoO3/α-MoO3 in-plane heterostructure. P — Fig. 2 a) from “*Chemical switching of low-loss phonon polaritons in α-MoO3 by hydrogen intercalation*” by Yingjie Wu et al. :
Reversible switching of PhPs in the L-RB of α-MoO3 a Schematic of the s-SNOM measurement and PhP propagation in a typical H-MoO3/α-MoO3 in-plane heterostructure.
2 a Schematic of the s-SNOM measurement and PhP propagation in a typical H-MoO3/α-MoO3 in-plane heterostructure. Please follow this external link for the full figure: https://www.nature.com/articles/s41467-020-16459-3/figures/2

*Yingjie Wu, Qingdong Ou, Yuefeng Yin, Yun Li, Weiliang Ma, Wenzhi Yu, Guanyu Liu, Xiaoqiang Cui, Xiaozhi Bao, Jiahua Duan, Gonzalo Álvarez-Pérez, Zhigao Dai, Babar Shabbir, Nikhil Medhekar, Xiangping Li, Chang-Ming Li, Pablo Alonso-González & Qiaoliang Bao
Chemical switching of low-loss phonon polaritons in α-MoO3 by hydrogen intercalation
Nature Communications volume 11, Article number: 2646 (2020)
DOI: https://doi.org/10.1038/s41467-020-16459-3

Please follow this external link to read the full article https://rdcu.be/b46eT

Open Access The article “ Chemical switching of low-loss phonon polaritons in α-MoO3 by hydrogen intercalation “ by Yingjie Wu, Qingdong Ou, Yuefeng Yin, Yun Li, Weiliang Ma, Wenzhi Yu, Guanyu Liu, Xiaoqiang Cui, Xiaozhi Bao, Jiahua Duan, Gonzalo Álvarez-Pérez, Zhigao Dai, Babar Shabbir, Nikhil Medhekar, Xiangping Li, Chang-Ming Li, Pablo Alonso-González and Qiaoliang Bao is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

Flexible Robust and High‐Density FeRAM from Array of Organic Ferroelectric Nano‐Lamellae by Self‐Assembly

Ferroelectric memories are endowed with high data storage density by nanostructure designing, while the robustness is also impaired. For organic ferroelectrics favored by flexible memories, low Curie transition temperature limits their thermal stability.*

In their article “Flexible Robust and High‐Density FeRAM from Array of Organic Ferroelectric Nano‐Lamellae by Self‐Assembly “ Mengfan Guo, Jianyong Jiang, Jianfeng Qian, Chen Liu, Jing Ma, Ce‐Wen Nan and Yang Shen demonstrate that a ferroelectric random access memory ( FeRAM ) with high thermal stability and data storage density of ≈60 GB inch−2 could be achieved from an array of edge‐on nano‐lamellae by low‐temperature self‐assembly of P(VDF‐TrFE).*

The self‐assembled P(VDF‐TrFE) described in the article exhibits high storage density of 60 GB inch−2 as a prototype of flexible FeRAM. The authors experimentally determine the self‐assembled FeRAM stored data more robustly, with temperature endurance enhanced over 10 °C and reliable thermal cycling ability. The article shows a novel path to address the thermal stability issues in organic FeRAMs and presents a detailed analysis about the origin of enhanced performance in aligned P(VDF‐TrFE). *

NanoWorld Arrow-CONTPt AFM probes with a conducting Pt/Ir coating were used for the Piezoresponse Force Microscopy ( PFM ) measurements described in this article.

Figure 4 from “*Flexible Robust and High‐Density FeRAM from Array of Organic Ferroelectric Nano‐Lamellae by Self‐Assembly*” by Mengfan Guo et al.:
Enhanced thermal stability in SA P(VDF‐TrFE). a–c) PFM images of data stored in self‐assembled film at a) 25 °C and b) 90 °C, as well as c) numeric figure of residual area of reversal domains as a function of elevated temperature in a SA film (blue) and a NSA film (red). d) Numeric figure of residual area of reversal domains as a function of thermal cycles in a SA film (blue) and a NSA film (red). Scale bars: 200 nm.

*Mengfan Guo, Jianyong Jiang, Jianfeng Qian, Chen Liu, Jing Ma, Ce‐Wen Nan, Yang Shen
Flexible Robust and High‐Density FeRAM from Array of Organic Ferroelectric Nano‐Lamellae by Self‐Assembly
Advanced Science, Volume6, Issue6, March 20, 2019, 1801931
DOI: https://doi.org/10.1002/advs.201801931

Please follow this external link to read the full article: https://onlinelibrary.wiley.com/doi/full/10.1002/advs.201801931

Open Access: The article « Flexible Robust and High‐Density FeRAM from Array of Organic Ferroelectric Nano‐Lamellae by Self‐Assembly » by Mengfan Guo, Jianyong Jiang, Jianfeng Qian, Chen Liu, Jing Ma, Ce‐Wen Nan and Yang Shen is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.