Structural Transformations in Ferroelectrics Discovered by Raman Spectroscopy

Ferroelectrics systems are of great interest from the fundamental as well as applications points, such as ferroelectric random access memories, electro-optic switches and a number of electro-optic devices. Curie temperature (TC) is one of the important parameters of ferroelectrics for high-temperature applications. Particularly, the optical modes, which are associated with the ferroelectric to paraelectric phase transition, are of great interest. Structural transformations that alter the crystal symmetry often have a significant effect on the Raman spectroscopy. This chapter systematically studies the type ferroelectric oxides and rare earth element doped ferroelectric materials such as PbTiO3-Bi(Mg0.5Ti0.5)O3 (PT-BMT), Sr x Ba1−x Nb2O6 (SBN), Pb1−1.5x La x Zr0.42Sn0.4Ti0.18O3 (PLZST), Bi1−xLaxFe1−yTiyO3 (BLFT) and (K0.5Na0.5)NbO3-0.05LiNbO3 (KNN-LN) and so on synthesis of single crystal/ceramic and optical phonon vibration modes and the improvement of the Curie temperature characteristic using spectrometry measurements. The TC, distortion degree, and phase structure of the ferroelectric materials have been investigated by temperature-dependent Raman spectroscopy. Meanwhile, the important physical parameters exhibited a strong dependence on dopants resulting in structural modifications and performance promotion

SDT: A Low-cost and Topology-reconfigurable Testbed for Network Research

Network experiments are essential to network-related scientific research (e.g., congestion control, QoS, network topology design, and traffic engineering). However, (re)configuring various topologies on a real testbed is expensive, time-consuming, and error-prone. In this paper, we propose \emph{Software Defined Topology Testbed (SDT)}, a method for constructing a user-defined network topology using a few commodity switches. SDT is low-cost, deployment-friendly, and reconfigurable, which can run multiple sets of experiments under different topologies by simply using different topology configuration files at the controller we designed. We implement a prototype of SDT and conduct numerous experiments. Evaluations show that SDT only introduces at most 2\% extra overhead than full testbeds on multi-hop latency and is far more efficient than software simulators (reducing the evaluation time by up to 2899x). SDT is more cost-effective and scalable than existing Topology Projection (TP) solutions. Further experiments show that SDT can support various network research experiments at a low cost on topics including but not limited to topology design, congestion control, and traffic engineering.Comment: This paper will be published in IEEE CLUSTER 2023. Preview version onl

A Dynamical Innovation Diffusion Model with Fuzzy Coefficient and Its Application to Local Telephone Diffusion in China

This paper studies the innovation diffusion problem with the affection of urbanization, proposing a dynamical innovation diffusion model with fuzzy coefficient, and uses the shifting rate of people from rural areas stepping into urban areas to show the process of urbanization. The numerical simulation shows the diffusion process for telephones in China with Genetic Algorithms and this model is effective to show the process of innovation diffusion with the condition of urbanization process

Photon upconversion through triplet exciton-mediated energy relay.

Exploration of upconversion luminescence from lanthanide emitters through energy migration has profound implications for fundamental research and technology development. However, energy migration-mediated upconversion requires stringent experimental conditions, such as high power excitation and special migratory ions in the host lattice, imposing selection constraints on lanthanide emitters. Here we demonstrate photon upconversion of diverse lanthanide emitters by harnessing triplet exciton-mediated energy relay. Compared with gadolinium-based systems, this energy relay is less dependent on excitation power and enhances the emission intensity of Tb3+ by 158-fold. Mechanistic investigations reveal that emission enhancement is attributable to strong coupling between lanthanides and surface molecules, which enables fast triplet generation (<100 ps) and subsequent near-unity triplet transfer efficiency from surface ligands to lanthanides. Moreover, the energy relay approach supports long-distance energy transfer and allows upconversion modulation in microstructures. These findings enhance fundamental understanding of energy transfer at molecule-nanoparticle interfaces and open exciting avenues for developing hybrid, high-performance optical materials

Gas sensing performance of In2O3 nanostructures: A mini review

Effective detection of toxic and hazardous gases is crucial for ensuring human safety, and high-performance metal oxide-based gas sensors play an important role in achieving this goal. In2O3 is a widely used n-type metal oxide in gas sensors, and various In2O3 nanostructures have been synthesized for detecting small gas molecules. In this review, we provide a brief summary of current research on In2O3-based gas sensors. We discuss methods for synthesizing In2O3 nanostructures with various morphologies, and mainly review the sensing behaviors of these structures in order to better understand their potential in gas sensors. Additionally, the sensing mechanism of In2O3 nanostructures is discussed. Our review further indicates that In2O3-based nanomaterials hold great promise for assembling high-performance gas sensors

Photon upconversion through triplet exciton-mediated energy relay

Funder: Innovation programme under the Marie Skłodowska-Curie grant agreement No 797619Funder: China Scholarship Council (CSC); doi: https://doi.org/10.13039/501100004543Funder: RCUK | Engineering and Physical Sciences Research Council (EPSRC); doi: https://doi.org/10.13039/501100000266Abstract: Exploration of upconversion luminescence from lanthanide emitters through energy migration has profound implications for fundamental research and technology development. However, energy migration-mediated upconversion requires stringent experimental conditions, such as high power excitation and special migratory ions in the host lattice, imposing selection constraints on lanthanide emitters. Here we demonstrate photon upconversion of diverse lanthanide emitters by harnessing triplet exciton-mediated energy relay. Compared with gadolinium-based systems, this energy relay is less dependent on excitation power and enhances the emission intensity of Tb3+ by 158-fold. Mechanistic investigations reveal that emission enhancement is attributable to strong coupling between lanthanides and surface molecules, which enables fast triplet generation (<100 ps) and subsequent near-unity triplet transfer efficiency from surface ligands to lanthanides. Moreover, the energy relay approach supports long-distance energy transfer and allows upconversion modulation in microstructures. These findings enhance fundamental understanding of energy transfer at molecule-nanoparticle interfaces and open exciting avenues for developing hybrid, high-performance optical materials

Enhanced photocatalysis by coupling of anatase TiO2 film to triangular Ag nanoparticle island

In order to overcome the low utilization ratio of solar light and high electron-hole pair recombination rate of TiO(2), the triangular Ag nanoparticle island is covered on the surface of the TiO(2) thin film. Enhancement of the photocatalytic activity of the Ag/TiO(2) nanocomposite system is observed. The increase of electron-hole pair generation is caused by the enhanced near-field amplitudes of localized surface plasmon of the Ag nanoparticles. The efficiently suppressed recombination of electron-hole pair caused by the metal-semiconductor contact can also enhance the photocatalytic activity of the TiO(2) film