Article
Chemistry, Multidisciplinary
Pritha Biswas, Tamara D. Koledin, Skylar N. Farmer, Melissa K. Santala, Janet Tate
Summary: The transformation from amorphous to crystalline in TiO2 films in air leads to different polymorphs, which can be manipulated by introducing Sn into the system. Sn stabilizes the rutile structure at the Sn/TiO2 interfaces by scavenging oxygen, resulting in rutile formation.
CRYSTAL GROWTH & DESIGN
(2023)
Article
Materials Science, Multidisciplinary
Mojtaba Mansoorianfar, Reza Rahighi, Akbar Hojjati-Najafabadi, Changtong Mei, Dagang Li
Summary: A novel pressure-engineered electrochemical process (PEEP) method was introduced in this study to fabricate high-quality TiO2 nanotubes by controlling the pressure of the electrolyte. It was found that under negative pressure condition, the TiO2 nanotubes produced were of better quality and larger in diameter compared to ambient and positive pressure conditions.
MATERIALS & DESIGN
(2021)
Article
Nanoscience & Nanotechnology
Jodie A. Yuwono, Patrick Burr, Conor Galvin, Alison Lennon
Summary: Density functional theory calculations were used to study phase transformations, Li+ diffusion, and charge-transfer reactions in LixTiO2. It was found that in amorphous TiO2, the energy barrier for Li+ diffusion decreases with increasing Li+ fraction, with longer Li-Ti and Li-O interactions having lower insertion energies and higher migration barriers. Amorphous TiO2 exhibits both surface and bulk storage mechanisms due to its disordered atomic arrangement and increased Li+ diffusivity at higher fractions.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Chemistry, Inorganic & Nuclear
Xue Chen, Biyi Chen, Dan Li, Longhua Li, Dongbo Xu, Weidong Shi
Summary: In this study, Indium (In) ions were successfully diffused into a TiO2 photoelectrode via a flame doping method, resulting in improved photo-induced carrier separation and enhanced photoelectrochemical performance. The relationship between dopant concentration and PEC performance showed a volcano-type pattern.
DALTON TRANSACTIONS
(2023)
Article
Materials Science, Multidisciplinary
Takaya Kawagishi, Yusuke Adachi, Taizo Kobayashi
Summary: This study investigates the impact of different crystallographic structures of sputter-deposited TiO2 n-type window layers on the power conversion of TiO2/Se photovoltaic devices. The efficient photovoltaic conversion of TiO2/Se devices requires improving carrier collection in the Se layer and reducing recombination at the TiO2/Se interface. TiO2 window layers with varying anatase and rutile crystallographic structures were applied to TiO2/Se heterojunction devices. The power conversion efficiency of TiO2/Se photovoltaic devices was increased from 3.04% to 4.48% in devices with anatase/rutile mixture window layer.
MATERIALS CHEMISTRY AND PHYSICS
(2023)
Article
Chemistry, Physical
Jesse Saari, Harri Ali-Loytty, Minttu Maria Kauppinen, Markku Hannula, Ramsha Khan, Kimmo Lahtonen, Lauri Palmolahti, Antti Tukiainen, Henrik Gronbeck, Nikolai Tkachenko, Mika Valden
Summary: This study investigates the effects of intrinsic Ti3+ and nitrogen defects on the optical and electrical properties of amorphous titania thin films. It is found that the formation of Ti3+ defects is related to the presence of structural disorder-induced penta- and heptacoordinated Ti4+ ions. The Ti3+-rich amorphous titania exhibits stoichiometric composition and increased visible-light absorption and electrical conductivity through the occupation of Ti3+ 3d in-gap states. Nitrogen defects have minimal effects on optical and charge transfer properties.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Chemistry, Physical
Cheol Hyoun Ahn, Won Seok Yang, Jeong Jae Kim, Jae Hyun Kim, Hyung Koun Cho
Summary: A bronze-rich dual-phasic TiO2-embedded amorphous carbon nanoarchitecture, DP-TiO2@C, was synthesized for the first time using sacrificial Ti-metal-organic frameworks. This material exhibits high specific capacities and high-rate capability, as well as long-term stability and even distribution of nanoparticles.
Review
Chemistry, Multidisciplinary
Diana Rakhmawaty Eddy, Muhamad Diki Permana, Lintang Kumoro Sakti, Geometry Amal Nur Sheha, Solihudin, Sahrul Hidayat, Takahiro Takei, Nobuhiro Kumada, Iman Rahayu
Summary: This study aims to clarify the differences between titanium dioxide polymorphs and their properties in different photocatalytic applications. Homophase titanium dioxide has disadvantages such as high recombination rates and low adsorption capacity. On the other hand, heterophase titanium dioxide can effectively stimulate electron transfer and exhibit superior photocatalytic performance. Various biphase and triphase polymorphs of titanium dioxide are discussed, and the focus is on the synthesis and application of heterophase titanium dioxide as a photocatalyst.
Article
Materials Science, Multidisciplinary
Chao Yang, Tristan Olsen, Miu Lun Lau, Kassiopeia A. Smith, Khalid Hattar, Amrita Sen, Yaqiao Wu, Dewen Hou, Badri Narayanan, Min Long, Janelle P. Wharry, Hui Xiong
Summary: Understanding the evolution of structure and morphology in nanomaterials is crucial for controlling their functionality. In this study, the effects of irradiation on the morphology and structure of amorphous and anatase TiO2 nanotubes were investigated. The anatase TiO2 nanotubes showed stability under irradiation due to their grain boundaries and surfaces, while the amorphous TiO2 nanotubes underwent irradiation-induced crystallization, with partially crystallized tubes bending due to internal stresses. These findings provide a new pathway for controlling the structure and morphology of energy storage materials.
JOURNAL OF MATERIALS RESEARCH
(2022)
Article
Chemistry, Physical
K. Santhi, S. Harish, M. Navaneethan, S. Ponnusamy
Summary: We synthesized ZnS/TiO2 nanocomposite through a one-step hydrothermal method and studied the effect of ZnS concentration on the phase and morphology of the materials. XRD confirmed the formation of tetragonal structure of anatase phase TiO2. UV-Visible spectra showed increased absorption towards higher wavelength with higher ZnS concentration. TEM revealed the formation of mesoporous structure of TiO2 and EDX analysis confirmed the presence of ZnS on the surface. The addition of ZnS prevented TiO2 aggregation and enhanced photocatalytic activity, achieving a highest degradation efficiency of 93% for methylene blue solution under visible light irradiation after 60 minutes.
SURFACES AND INTERFACES
(2023)
Article
Nanoscience & Nanotechnology
Mehrdad Abbasi, Yutao Dong, Jun Meng, Dane Morgan, Xudong Wang, Jinwoo Hwang
Summary: The evolution of medium range ordering (MRO) and crystallization behavior of amorphous TiO2 films grown by atomic layer deposition were investigated using in situ four-dimensional scanning transmission electron microscopy. The degree of MRO increases with temperature and reaches the maximum when crystallization starts to occur. In addition, post-annealing only develops a small portion of MRO into crystal nuclei, while the remaining MRO regions undergo structural relaxation. Crystallographic defects within crystal phases were observed, which may affect the corrosion resistance of the film. Understanding and controlling MRO is important for optimizing ALD-grown amorphous films for future functional devices and renewable energy applications.
Article
Multidisciplinary Sciences
Ashraf K. K. Eessaa, Omayma A. A. Elkady, A. M. El-Shamy
Summary: Powder metallurgy (PM) is a technique for manufacturing solid, dense materials by mixing metal powders with other materials and applying heat and pressure. The use of PM has advantages in creating complex shapes and improving material properties. Cu-TiO2 composites synthesized using the PM technique can be finely tuned in terms of microstructure and optical properties, making them useful for applications such as photocatalysis and solar energy conversion.
SCIENTIFIC REPORTS
(2023)
Article
Chemistry, Multidisciplinary
Xiaojia Ma, Xuejing Tang, Zhenzhong Hu, Mengmeng Zhen, Boxiong Shen, Sheng-Qi Guo, Fan Dong
Summary: Defect engineering is an effective method to improve the photocatalytic performance of TiO2. This study investigates the synergy between oxygen vacancy (V-O) defects and crystal facets in TiO2 nanostructures and their impact on photocatalytic O-2 activation. The results show that a high concentration of V-O combined with the {101} facet significantly enhances the photocatalytic performance compared to other combinations. This study provides valuable insights into the role and interaction of defects and facets in photocatalysts.
Article
Materials Science, Multidisciplinary
Kadhim Al-Attafi, Majed H. Dwech, Hamza A. Mezher, Andrew Nattestad, Jung Ho Kim
Summary: This study investigates the performance of metal-free organic dye (D149)-based dye-sensitized solar cells (DSCs) with different titanium(IV) oxide (TiO2) films. The post-processing of Degussa P25 (TiO2-HP25) improves the performance of DSCs compared to TiO2-DSL and as-received P25 nanoparticles. The enhancement is attributed to the removal of amorphous barriers and associated defect states.
Article
Materials Science, Multidisciplinary
Junichi Shiogai, Junya Ikeda, Kohei Fujiwara, Takeshi Seki, Koki Takanashi, Atsushi Tsukazaki
Summary: By measuring Hall resistance, we found that the Co3Sn2S2 thin films have a large coercivity, which is attributed to the uniform crystallinity within grains and strong domain-wall pinning at grain boundaries. This is important for controlling the nucleation, manipulation, and detection of single domain walls in thin-film devices.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Nanoscience & Nanotechnology
Sisira Suresh, Orad Reshef, M. Zahirul Alam, Jeremy Upham, Mohammad Karimi, Robert W. Boyd
Summary: This study demonstrates the strong nonlinear optical properties of an optical ENZ metamaterial, showing that the nonlinear enhancement is proportional to the linear effective refractive index. In contrast to homogeneous ENZ materials, these metamaterials offer greater tunability and can be designed with large nonlinearities at any specified optical wavelength within the visible spectrum.
Article
Nanoscience & Nanotechnology
Raymond A. Wambold, Zhaoning Yu, Yuzhe Xiao, Benjamin Bachman, Gabriel Jaffe, Shimon Kolkowitz, Jennifer T. Choy, Mark A. Eriksson, Robert J. Hamers, Mikhail A. Kats
Summary: Researchers have developed a nanoscale light extractor (NLE) for efficient outcoupling and beaming of broadband light emitted by shallow, negatively charged nitrogenvacancy (NV) centers in bulk diamond. The NLE, consisting of a patterned silicon layer on diamond, can enhance the optical power extracted from an NV center positioned 10 nm below the diamond surface and beam the light into a +/- 30 degrees cone in the far field. The design process, based on adjoint optimization using broadband time-domain simulations, yields robust structures adaptable to other solid-state color centers.
Article
Multidisciplinary Sciences
M. Saad Bin-Alam, Orad Reshef, Yaryna Mamchur, M. Zahirul Alam, Graham Carlow, Jeremy Upham, Brian T. Sullivan, Jean-Michel Menard, Mikko J. Huttunen, Robert W. Boyd, Ksenia Dolgaleva
Summary: Plasmonic nanostructures show great potential in ultra-thin sub-wavelength devices, but are often limited by resistive losses. By utilizing surface lattice resonances (SLRs), researchers have achieved a high quality-factor metasurface in the telecommunication band, offering exciting possibilities for manipulating incident light fields and creating flexible wavelength-scale devices.
NATURE COMMUNICATIONS
(2021)
Article
Nanoscience & Nanotechnology
Cong Liu, M. Zahirul Alam, Kai Pang, Karapet Manukyan, Orad Reshef, Yiyu Zhou, Saumya Choudhary, Joel Patrow, Anuj Pennathurs, Hao Song, Zhe Zhao, Runzhou Zhang, Fatemeh Alishahi, Ahmad Fallahpour, Yinwen Cao, Ahmed Almaiman, Jahan M. Dawlaty, Moshe Tur, Robert W. Boyd, Alan E. Willner
Summary: The study found that using a metasurface made of a plasmonic antenna array on a thin indium tin oxide (ITO) can change the frequency of a light beam through self-action effect. Experimentally, it was observed that optical excitation of a 92 nm thick metasurface led to an intensity-dependent blueshift of the excitation pulse, with an energy requirement up to 200 times lower than using ITO alone.
Article
Chemistry, Multidisciplinary
Benjamin F. Bachman, Zachary R. Jones, Gabriel R. Jaffe, Jad Salman, Raymond Wambold, Zhaoning Yu, Jennifer T. Choy, Shimon J. Kolkowitz, Mark A. Eriksson, Mikhail A. Kats, Robert J. Hamers
Summary: This study demonstrates a highly controlled approach to functionalizing diamond surfaces with carboxylic acid groups through all-carbon tethers of different lengths, followed by covalent chemistry to yield high-quality TEMPO-modified surfaces. The estimated surface densities of 4-amino-TEMPO on nanodiamond and planar diamond are higher than those reported previously using other functionalization methods. The zeta-potential of nanodiamonds was used to track reaction progress and elucidate the regioselectivity of the reaction.
Article
Chemistry, Multidisciplinary
Kai Pang, M. Zahirul Alam, Yiyu Zhou, Cong Liu, Orad Reshef, Karapet Manukyan, Matt Voegtle, Anuj Pennathur, Cindy Tseng, Xinzhou Su, Hao Song, Zhe Zhao, Runzhou Zhang, Haoqian Song, Nanzhe Hu, Ahmed Almaiman, Jahan M. Dawlaty, Robert W. Boyd, Moshe Tur, Alan E. Willner
Summary: In this study, it was demonstrated that the adiabatic frequency conversion effect can be significantly enhanced by using a nonlinear epsilon-near-zero-based plasmonic metasurface. The experimental results showed a large, tunable, and broadband frequency shift with a thinner metasurface, reducing device thickness and pump peak intensity compared to traditional materials. This finding could potentially lead to new insights for designing efficient time-varying metasurfaces for manipulating ultrafast pulses.
Article
Optics
Cong Liu, M. Zahirul Alam, Kai Pang, Karapet Manukyan, Joshua R. Hendrickson, Evan M. Smith, Yiyu Zhou, Orad Reshef, Hao Song, Runzhou Zhang, Haoqian Song, Fatemeh Alishahi, Ahmad Fallahpour, Ahmed Almaiman, Robert W. Boyd, Moshe Tur, Alan E. Willner
Summary: In this study, the tunable Doppler shift in ITO film at its ENZ region was experimentally investigated, demonstrating a maximum frequency redshift of 1.8 THz. The frequency redshift increases with pump intensity and decreases with pump duration. The pump energy required to saturate the frequency shift decreases for durations less than or approximately 1 ps.
Article
Multidisciplinary Sciences
Orad Reshef, Michael P. DelMastro, Katherine K. M. Bearne, Ali H. Alhulaymi, Lambert Giner, Robert W. Boyd, Jeff S. Lundeen
Summary: This study introduces the concept of an optical 'spaceplate' and demonstrates experimentally that it can effectively propagate light for a distance considerably longer than its thickness. This innovation has the potential to shrink future imaging systems, allowing for the development of ultra-thin monolithic cameras.
NATURE COMMUNICATIONS
(2021)
Article
Optics
Jordan T. R. Page, Orad Reshef, Robert W. Boyd, Jeff S. Lundeen
Summary: The development of metasurfaces has enabled portable and functional flat optical devices. Spaceplates, as a complementary element, reduce the space between metalenses and further miniaturize imaging devices. This study employs inverse-design techniques to explore the behavior of thin-film-based spaceplates and discovers a tradeoff between the compression factor and the numerical aperture. Even simple designs with realistic materials can achieve capable spaceplates for monochromatic applications.
Article
Optics
N. Apurv Chaitanya, M. A. T. Butt, O. Reshef, Robert W. Boyd, P. Banzer, Israel De Leon
Summary: Asymmetric transmission in chiral plasmonic metasurfaces can be achieved by controlling the scattering of plasmonic nanoparticles. This effect is caused by an unbalanced excitation of lattice modes by circularly polarized light of opposite handedness. Only nonzero diffraction orders contribute to this effect.
Article
Green & Sustainable Science & Technology
Matthew Skiles, Euijin Yang, Orad Reshef, Diego Robalino Munoz, Diana Cintron, Mary Laura Lind, Alexander Rush, Patricia Perez Calleja, Robert Nerenberg, Andrea Armani, Kasey M. Faust, Manish Kumar
Summary: Converting traditional in-person conferences to virtual conferences can significantly improve diversity, equity, and inclusion, mainly due to reduced financial and personal-life burdens. However, further development of virtual networking features and poster sessions is needed to achieve widespread adoption and acceptance of this new format.
NATURE SUSTAINABILITY
(2022)
Article
Nanoscience & Nanotechnology
Aedan Gardill, Ishita Kemeny, Yanfei Li, Maryam Zahedian, Matthew C. Cambria, Xiyu Xu, Vincenzo Lordi, Adam Gali, Jeronimo R. . Maze, Jennifer T. Choy, Shimon Kolkowitz
Summary: Super-resolution Airy disk microscopy, a novel technique presented in this study, allows nanoscale microscopy in a standard confocal microscope without specialized optics. The technique, combined with ground state depletion, successfully images and controls NV centers in diamond below the diffraction limit, achieving more than 14-fold improvement in resolution compared to the conventional limit.
Article
Optics
Maryam Zahedian, Jietian T. Liu, Ricardo Vidrio, Shimon Kolkowitz, Jennifer T. T. Choy
Summary: Optically active defects in diamond are commonly used as bright single-photon sources for various quantum applications. Placing these emitters near the diamond surface alters their radiative properties due to the surrounding dielectric environment. The relationship between the emitter's orientation, surface cut direction, and emission characteristics in crystalline solids is crucial to model and understand the effect of dielectric interfaces. This paper presents a framework for analyzing the emission rates and depth-dependent radiative lifetimes of shallow (<100 nm) defects in diamond, which can be extended to other vacancy defects.
LASER & PHOTONICS REVIEWS
(2023)
Article
Optics
Xuting Yang, Meryem Benelajla, Steven Carpenter, Jennifer T. Choy
Summary: Atomic magnetometry is a highly sensitive field-measurement technique with diverse applications. This work focuses on the design and analysis of a silicon-metasurface-based polarization beam splitter for a rubidium magnetometer. The polarization beam splitter operates at a wavelength of 795 nm with high transmission efficiency and polarization extinction ratio. This study discusses the potential of realizing compact, high-sensitivity atomic magnetometers with nanophotonic component integration.
Article
Optics
Paul M. Pellegrino, Gilberto Brambilla, Frank Vollmer, Jennifer T. Choy
Summary: This journal issue showcases the latest research findings from authors who presented at the OPTICA Optical Sensors and Sensing Congress held in Vancouver, British Columbia, Canada from July 11 to 15, 2022. The issue features 9 contributed papers that further delve into their respective conference proceedings. The published papers cover a range of timely research topics in optics and photonics for chip-based sensing, open-path and remote sensing, and fiber devices.