Modulation of Morphology and Optical Property of Multi-Metallic PdAuAg and PdAg Alloy Nanostructures

Pandey, Puran,Kunwar, Sundar,Sui, Mao,Bastola, Sushil,Lee, Jihoon Springer US 2018 NANOSCALE RESEARCH LETTERS Vol.13 No.1

<P>In this work, the evolution of PdAg and PdAuAg alloy nanostructures is demonstrated on sapphire (0001) via the solid-state dewetting of multi-metallic thin films. Various surface configurations, size, and arrangements of bi- and tri-metallic alloy nanostructures are fabricated as a function of annealing temperature, annealing duration, film thickness, and deposition arrangements such as bi-layers (Pd/Ag), tri-layers (Pd/Au/Ag), and multi-layers (Pd/Au/Ag × 5). Specifically, the tri-layers film shows the gradual evolution of over-grown NPs, voids, wiggly nanostructures, and isolated PdAuAg alloy nanoparticles (NPs) along with the increased annealing temperature. In contrast, the multi-layers film with same thickness show the enhanced dewetting rate, which results in the formation of voids at relatively lower temperature, wider spacing, and structural regularity of alloy NPs at higher temperature. The dewetting enhancement is attributed to the increased number of interfaces and reduced individual layer thickness, which aid the inter-diffusion process at the initial stage. In addition, the time evolution of the Pd<SUB>150 nm</SUB>/Ag<SUB>80 nm</SUB> bi-layer films at constant temperature show the wiggly-connected and isolated PdAg alloy NPs. The overall evolution of alloy NPs is discussed based on the solid-state dewetting mechanism in conjunction with the diffusion, inter-diffusion, alloying, sublimation, Rayleigh instability, and surface energy minimization. Depending upon their surface morphologies, the bi- and tri-metallic alloy nanostructures exhibit the dynamic reflectance spectra, which show the formation of dipolar (above 700 nm) and quadrupolar resonance peaks (~ 380 nm) and wide dips in the visible region as correlated to the localized surface plasmon resonance (LSPR) effect. An absorption dip is readily shifted from ~ 510 to ~ 475 nm along with the decreased average size of alloy nanostructures.</P><P><B>Electronic supplementary material</B></P><P>The online version of this article (10.1186/s11671-018-2551-0) contains supplementary material, which is available to authorized users.</P>

Morphologically Controlled Growth of Aluminum Nitride Nanostructures by the Carbothermal Reduction and Nitridation Method

Jung, Woo-Sik Korean Chemical Society 2009 Bulletin of the Korean Chemical Society Vol.30 No.7

One-dimensional aluminum nitride (AlN) nanostructures were synthesized by calcining an Al(OH)(succinate) complex, which contained a very small amount of iron as a catalyst, under a mixed gas flow of nitrogen and CO (1 vol%). The complex decomposed into a homogeneous mixture of alumina and carbon at the molecular level, resulting in the lowering of the formation temperature of the AlN nanostructures. The morphology of the nanostructures such as nanocone, nanoneedle, nanowire, and nanobamboo was controlled by varying the reaction conditions, including the reaction atmosphere, reaction temperature, duration time, and ramping rate. Iron droplets were observed on the tips of the AlN nanostructures, strongly supporting that the nanostructures grow through the vapor-liquid-solid mechanism. The variation in the morphology of the nanostructures was well explained in terms of the relationship between the diffusion rate of AlN vapor into the iron droplets and the growth rate of the nanostructures.

Shape-controlled synthesis of zinc nanostructures mediating macromolecules for biomedical applications

Seyyed Mojtaba Mousavi,Gity Behbudi,Ahmad Gholami,Seyyed Alireza Hashemi,Zohre Mousavi Nejad,Sonia Bahrani,Wei-Hung Chiang,Lai Chin Wei,Navid Omidifar 한국생체재료학회 2022 생체재료학회지 Vol.26 No.1

Zinc nanostructures (ZnONSs) have attracted much attention due to their morphological, physicochemical, and electrical properties, which were entailed for various biomedical applications such as cancer and diabetes treatment, anti-inflammatory activity, drug delivery. ZnONS play an important role in inducing cellular apoptosis, triggering excess reactive oxygen species (ROS) production, and releasing zinc ions due to their inherent nature and specific shape. Therefore, several new synthetic organometallic method has been developed to prepare ZnO crystalline nanostructures with controlled size and shape. Zinc oxide nanostructures’ crystal size and shape can be controlled by simply changing the physical synthesis condition such as microwave irradiation time, reaction temperature, and TEA concentration at reflux. Physicochemical properties which are determined by the shape and size of ZnO nanostructures, directly affect their biological applications. These nanostructures can decompose the cell membrane and accumulate in the cytoplasm, which leads to apoptosis or cell death. In this study, we reviewed the various synthesis methods which affect the nano shapes of zinc particles, and physicochemical properties of zinc nanostructures that determined the shape of zinc nanomaterials. Also, we mentioned some macromolecules that controlled their physicochemical properties in a green and biological approaches. In addition, we present the recent progress of ZnONSs in the biomedical fields, which will help centralize biomedical fields and assist their future research development.

Ferromagnetism in undoped ZnO nanostructures synthesized by solution plasma process

Kim, Soo-Whan,Lee, Sunghun,Saqib, Ahmad Nauman Shah,Lee, Young Haeng,Jung, Myung-Hwa Elsevier 2017 CURRENT APPLIED PHYSICS Vol.17 No.2

<P>Ferromagnetism in undoped metal oxide nanostructures provides a precious platform for realizing advanced nanoelectronic and spintronic applications. Such ferromagnetism is dependent on various factors. In this work, we report the ferromagnetism of undoped ZnO nanostructures for different discharge times from 10 to 40 min by employing solution plasma process, which has a great benefit for the synthesis of nanostructures due to relatively facile and cost-effective method. Through crystallographic and morphological characterization, we reveal how crystallite size and morphological change affect the magnetic properties of ZnO nanostructures. Moreover, ZnO nanostructures discharged for 30 min show the strongest ferromagnetic behavior, which could be explained by the combined effect of more oxygen vacancies and larger surface to volume ratio. Our work paves the way for attempts to develop the ferromagnetism of metal oxide nanostructures for applications in nanoelectronics and spintronics. (C) 2016 Elsevier B.V. All rights reserved.</P>

Controlled Synthesis and Properties of ZnO Nanostructures Grown by Metalorganic Chemical Vapor Deposition: A Review

( Won Il Park ) 대한금속재료학회 ( 구 대한금속학회 ) 2008 METALS AND MATERIALS International Vol.14 No.6

The unique and fascinating properties of one-dimensional (1D) ZnO nanostructures have triggered tremendous interest in exploring their possibilities for future electronic and photonic device applications. This paper provides current information on the progress of ZnO nanostructures grown by metalorganic chemical vapor deposition (MOCVD); it covers issues ranging from controlled synthesis of various ZnO nanostructures to their properties and potential applications. The unique features of MOCVD have been exploited to grow high-quality 1D ZnO nanostructures with tunable sizes, enabling the study of excitonic dynamics in low-dimensional nanostructures and size-dependent quantum confinement. A better understanding of the growth behaviors of ZnO nanostructures-particularly the anisotropic surface energy and adsorbate-surface interaction with regard to the crystal planes-allows control over the positions, morphologies, and surface polarities of the ZnO nanostructures as appropriate for device integration.

Morphologically Controlled Growth of Aluminum Nitride Nanostructures by the Carbothermal Reduction and Nitridation Method

Woo-Sik Jung 대한화학회 2009 Bulletin of the Korean Chemical Society Vol.30 No.7

One-dimensional aluminum nitride (AlN) nanostructures were synthesized by calcining an Al(OH)(succinate) complex, which contained a very small amount of iron as a catalyst, under a mixed gas flow of nitrogen and CO (1 vol%). The complex decomposed into a homogeneous mixture of alumina and carbon at the molecular level, resulting in the lowering of the formation temperature of the AlN nanostructures. The morphology of the nanostructures such as nanocone, nanoneedle, nanowire, and nanobamboo was controlled by varying the reaction conditions, including the reaction atmosphere, reaction temperature, duration time, and ramping rate. Iron droplets were observed on the tips of the AlN nanostructures, strongly supporting that the nanostructures grow through the vapor-liquid-solid mechanism. The variation in the morphology of the nanostructures was well explained in terms of the relationship between the diffusion rate of AlN vapor into the iron droplets and the growth rate of the nanostructures.

Ferromagnetism in undoped ZnO nanostructures synthesized by solution plasma process

김수환,이성훈,Ahmad Nauman Shah Saqib,이영행,정명화 한국물리학회 2017 Current Applied Physics Vol.17 No.2

Ferromagnetism in undoped metal oxide nanostructures provides a precious platform for realizing advanced nanoelectronic and spintronic applications. Such ferromagnetism is dependent on various factors. In this work, we report the ferromagnetism of undoped ZnO nanostructures for different discharge times from 10 to 40 min by employing solution plasma process, which has a great benefit for the synthesis of nanostructures due to relatively facile and cost-effective method. Through crystallographic and morphological characterization, we reveal how crystallite size and morphological change affect the magnetic properties of ZnO nanostructures. Moreover, ZnO nanostructures discharged for 30 min show the strongest ferromagnetic behavior, which could be explained by the combined effect of more oxygen vacancies and larger surface to volume ratio. Our work paves the way for attempts to develop the ferromagnetism of metal oxide nanostructures for applications in nanoelectronics and spintronics.

Synthesis and Optical Properties of ZnS Nanostructures

H. V. Chung,P. T. Huy,T. T. An,N. T. M. Thuy,N. D. Chien 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5

Pure and transition-metal (Cu, Mn, Ag)-doped ZnS nanostructures were synthesized by using a thermal evaporation technique. By monitoring the experimental parameters such as deposition temperature, carrier-gas ux density and deposition time, we showed that ZnS nanostructures with different morphologies could be achieved, namely, nanobelts, nanowires and nanorods. A eld emission scanning electron microscopy (FE-SEM) study of the obtained ZnS nanowires reveals that their diameters ranged from 30 to hundreds of nanometers while their lengths ranged up to hundreds of micron. Room-temperature photoluminescence (PL) measurements showed a common peak around 517nm for all ZnS nanowires samples, while impurity-related emission bands were observed in doped ZnS nanowires. This result indicates the important role of dopants in controlling the emission color from ZnS nanostructures. Pure and transition-metal (Cu, Mn, Ag)-doped ZnS nanostructures were synthesized by using a thermal evaporation technique. By monitoring the experimental parameters such as deposition temperature, carrier-gas ux density and deposition time, we showed that ZnS nanostructures with different morphologies could be achieved, namely, nanobelts, nanowires and nanorods. A eld emission scanning electron microscopy (FE-SEM) study of the obtained ZnS nanowires reveals that their diameters ranged from 30 to hundreds of nanometers while their lengths ranged up to hundreds of micron. Room-temperature photoluminescence (PL) measurements showed a common peak around 517nm for all ZnS nanowires samples, while impurity-related emission bands were observed in doped ZnS nanowires. This result indicates the important role of dopants in controlling the emission color from ZnS nanostructures.

대기 분위기에서 열증발법에 의해 성장된 여러 가지 형상의 일차원 MgO 나노구조

김남우,김진수,이근형 한국재료학회 2023 한국재료학회지 Vol.33 No.7

One-dimensional MgO nanostructures with various morphologies were synthesized by a thermal evaporation method. The synthesis process was carried out in air at atmospheric pressure, which made the process very simple. A mixed powder of magnesium and active carbon was used as the source powder. The morphologies of the MgO nanostructures were changed by varying the growth temperature. When the growth temperature was 700 °C, untapered nanowires with smooth surfaces were grown. As the temperature increased to 850 °C, 1,000 °C and 1,100 °C, tapered nanobelts, tapered nanowires and then knotted nanowires were sequentially observed. X-ray diffraction analysis revealed that the MgO nanostructures had a cubic crystallographic structure. Energy dispersive X-ray analysis showed that the nanostructures were composed of Mg and O elements, indicating high purity MgO nanostructures. Fourier transform infrared spectra peaks showed the characteristic absorption of MgO. No catalyst particles were observed at the tips of the one-dimensional nanostructures, which suggested that the one-dimensional nanostructures were grown in a vapor-solid growth mechanism.

Various Quantum- and Nano-Structures by III–V Droplet Epitaxy on GaAs Substrates

Lee, JH,Wang, Zh M,Kim, ES,Kim, NY,Park, SH,Salamo, GJ Springer 2010 NANOSCALE RESEARCH LETTERS Vol.5 No.2

<P>We report on various self-assembled In(Ga)As nanostructures by droplet epitaxy on GaAs substrates using molecular beam epitaxy. Depending on the growth condition and index of surfaces, various nanostructures can be fabricated: quantum dots (QDs), ring-like and holed-triangular nanostructures. At near room temperatures, by limiting surface diffusion of adatoms, the size of In droplets suitable for quantum confinement can be fabricated and thus InAs QDs are demonstrated on GaAs (100) surface. On the other hand, at relatively higher substrate temperatures, by enhancing the surface migrations of In adatoms, super lower density of InGaAs ring-shaped nanostructures can be fabricated on GaAs (100). Under an identical growth condition, holed-triangular InGaAs nanostructures can be fabricated on GaAs type-A surfaces, while ring-shaped nanostructures are formed on GaAs (100). The formation mechanism of various nanostructures can be understood in terms of intermixing, surface diffusion, and surface reconstruction.</P>