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Dmitri Golberg

Publications and source records attributed to Dmitri Golberg.

At least 19 recordsLinked to original sources
PubMed2006

Size-tunable synthesis of SiO(2) nanotubes via a simple in situ templatelike process.

SiO(2) nanotubes with tunable diameters and lengths have been successfully synthesized via a simple in situ templatelike process by thermal evaporation of SiO, ZnS, and GaN in a vertical induction furnace. The structure and morphologies were systematically investigated using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectrometry. Studies found that both the diameters and lengths of the SiO(2) nanotubes can be effectively tuned by simply changing the reaction temperatures. The range of changes was from 30 nm (diameter) and several hundred micrometers (length) at 1450 degrees C to 100 nm (diameter) and 2-10 micrometers (length) at 1300 degrees C. Varying some other experimental parameters results in the formation of additional SiO(2)-based nanostructures, such as core-shell ZnS-SiO(2) nanocables, ZnS nanoparticle filled SiO(2) nanotubes, and fluffy SiO(2) spheres. Based on the observations, an in situ templatelike process was proposed to explain the possible growth mechanism.

Journal Article↗
PubMed2006

Carbon-coated single-crystalline zinc sulfide nanowires.

Single-crystalline ZnS nanowires coated with graphitic carbon shells were synthesized by thermal evaporation of a mixture of ZnS and SnS powders in a graphite crucible. As-synthesized ZnS/C nanostructures were characterized using X-ray diffraction, scanning electron microscope, and transmission electron microscopy equipped with an energy-dispersive X-ray spectrometer. The ZnS core nanowires were formed by a Sn-catalytic vapor-liquid-solid process and grew along the [210] directions. Photoluminescence spectrum reveals that the carbon-coated ZnS nanowires have a strong emission band centered at 586 nm and a shoulder band at 645 nm.

Journal Article↗
PubMed2006

Unconventional zigzag indium phosphide single-crystalline and twinned nanowires.

Unconventional zigzag indium phosphide (InP) single-crystalline and twinned nanowires were produced via thermal evaporation of indium phosphide in the presence of zinc selenide. The structure and morphology of the as-synthesized products were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Studies found that two type of nanowires exist in the products, namely, the periodic-rhombus-decorated single-crystalline InP (type I) nanowires and jagged twinned InP (type II) nanowires. Both of them have preferential 111 growth directions. The optical properties were also investigated at room temperature, and they show that the nanowires display a strong emission at approximately 750 nm, which is quite different from that observed in all previous reports related to the InP nanostructures.

Journal Article↗
PubMed2006

Thickness-dependent photocatalytic performance of ZnO nanoplatelets.

In this paper, we report the large-scale synthesis of ZnO nanoplatelets as thin as 10 nm. The nanoplatelets show higher efficiency in photodegrading organic dyes than ZnO nanorods do, and for the nanoplatelets, the thinner they are, the higher the performance. The photocatalytic decomposition of organic dyes (eosin B) by ZnO nanoplatelets compares favorably to the performances of ZnS porous nanoparticles and commercial Degussa P25 titania particles. This finding may have significant implications in the environment remediation and the fabrication of functional nanodevices.

Journal Article↗
PubMed2006

Synthesis and interface structures of zinc sulfide sheathed zinc-cadmium nanowire heterojunctions.

Zinc sulfide (ZnS) sheathed zinc (Zn)-cadmium (Cd) nanowire heterojunctions have been prepared by thermal evaporating of ZnS and CdS powders in a vertical induction furnace at 1200 degrees C. Studies found that both the Zn and Cd subnanowires, within a single nanoheterojunction, are single-crystallines with the growth directions perpendicular to the [210] plane, whereas the sheathed ZnS is polycrystalline with a thickness of ca. 5 nm. The Zn/Cd interface structure in the ZnS sheathed Zn-Cd nanowire heterojunctions was thoroughly experimentally studied by high-resolution transmission electron microscopy and theoretically studied using a near-coincidence site lattice (NCSL) concept. The results show that the Cd and Zn have a crystalline orientation relationship as [0001]Zn//[0001]Cd, (10(-)10)Zn//(10(-)10)Cd, (01(-)10)Zn//(01(-)10)Cd, and ((-)1100)Zn//((-)1100)Cd.

Journal Article↗
PubMed2006

Tubular carbon nano-/microstructures synthesized from graphite powders by an in situ template process.

Through the use of commercial graphite powders as the carbon sources, a variety of interesting tubular carbon nano- and microstructures, such as networked carbon nanotubes, aligned carbon microtubes with hexagonal cross-sections, aligned tapered carbon tubes, and hollow carbon microhorns, have been successfully synthesized. As-grown tubular carbon structures were characterized using scanning electron microscopy, transmission electron microscopy, and X-ray energy-dispersive spectroscopy. An in situ template mechanism was proposed to explain the possible growth process. The vibrational properties of the synthesized tubular carbon structures were also studied by Raman spectroscopy.

Journal Article↗
PubMed2006

Thermal conductivity of nanostructured boron nitride materials.

We have measured the thermal conductivity of bulky pellets made of various boron nitride (BN)-based nanomaterials, including spherical nanoparticles, perfectly structured, bamboo-like nanotubes, and collapsed nanotubes. The thermal conductivity strongly depends on the morphology of the BN nanomaterials, especially on the surface structure. Spherical BN particles have the lowest thermal conductivity while the collapsed BN nanotubes possess the best thermoconductive properties. A model was proposed to explain the experimental observations based on the heat percolation passage considerations.

Journal Article↗
PubMed2006

SnO2 nanoparticle-functionalized boron nitride nanotubes.

Boron nitride nanotubes (BNNTs) were synthesized by a carbon-free chemical vapor deposition method using boron and metal oxide as reactants. Then SnO(2) nanoparticles were functionalized on them via a simple wet chemistry method. Detailed transmission electron microscopy (TEM) observations reveal that SnO(2) nanoparticles may cover the tube surface or be encapsulated in tube channels. The lattice distances of both BNNT and SnO(2) have been changed due to the strong interactions between them. The band gap energy of SnO(2) particles is found enlarged due to the size effect and interaction with BNNTs.

Boron Compounds↗
PubMed2006

Self-organized hierarchical ZnS/SiO(2) nanowire heterostructures.

Novel hierarchical heterostructures formed by wrapping ZnS nanowires with highly dense SiO(2) nanowires were successfully synthesized by a vapor-liquid-solid process. The as-synthesized products were characterized using X-ray diffraction, scanning electron microscopy and transmission electron microscopy equipped with an energy-dispersive X-ray spectrometer. Studies indicate that a typical hierarchical ZnS/SiO(2) heterostructure consists of a single-crystalline ZnS nanowire (core) with diameter gradually decreasing from several hundred nanometers to 20 nm and adjacent amorphous SiO(2) nanowires (branches) with diameters of about 20 nm. A possible growth mechanism was also proposed for the growth of the hierarchical heterostructures.

Journal Article↗
PubMed2006

Systematic investigation of the formation of 1D alpha-Si(3)N(4) nanostructures by using a thermal-decomposition/nitridation process.

This article describes a simple thermal-decomposition/nitridation method for the large-scale synthesis of 1D alpha-Si(3)N(4) nanostructures, such as millimeter-scale microribbons, nanosaws, nanoribbons, and nanowires. These nanostructures are systematically investigated by checking the product deposited at different areas by using powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and electron energy loss spectroscopy. Studies show that all these nanostructures have a single-crystalline nature and predominantely grow along the [011] direction. These 1D nanostructures are formed by thermal decomposition, followed by the nitridation of SiO.

Journal Article↗
PubMed2006

Synthesis and microstructure of Cd4SiS6/Si composite nanowires.

Cd4SiS6/Si composite nanowires are produced through co-thermal evaporation of CdS and Si powders with a small amount of tin sulfide as an additive. A vapor-liquid-solid growth mechanism is proposed for the anisotropic growth of the composite nanowires based on the presence of metallic tin particles at their tip-ends. Both side-by-side and core-shell composite nanowires are obtained. The product is characterized using X-ray powder diffraction and scanning electron microscopy. Detailed structural and chemical analyses of individual composite nanowires are carried out using transmission electron microscopy (TEM), high-resolution TEM (HRTEM), electron diffraction (ED) and energy-dispersive X-ray spectroscopy. Planar defects, including microtwins and stacking faults, are abundant in a Si core, as revealed by HRTEM and selected-area ED. The formation of composite nanowires is discussed in the light of thermodynamic and kinetic aspects.

Journal Article↗
PubMed2006

Morphology-controlled synthesis of ZnO nanostructures by a simple round-to-round metal vapor deposition route.

One-dimensional ZnO nanostructures with different morphologies have been successfully synthesized through a simple round-to-round metal vapor deposition route at 550 degrees C with a zinc powder covered indium film as the source material. The structures and morphologies of the products were characterized in detail by using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Studies found that the morphology of the products can be easily tuned from one experimental round to another. Possible growth mechanisms for the formation of one-dimensional ZnO nanostructures with different morphologies are discussed. Photoluminescence studies show that there are sharp UV emission and broad defect-related green emissions for the products obtained in all experimental rounds. Relative intensity of the UV emission to defect-related emissions gradually increased from one experimental round to another.

Journal Article↗
PubMed2006

Purification of boron nitride nanotubes through polymer wrapping.

An effective method was proposed to remove obstinate boron nitride phase impurities in boron nitride nanotubes (BNNTs). The method is based on strong interactions between BNNTs and a conjugated polymer wrapping them and significant weight and size difference between BNNTs and impurities. The as-grown samples and purified samples were compared through detailed characterization, using scanning electron microscopy, transmission electron microscopy, and Raman and Fourier transformed infrared spectroscopy. The results reveal that impurities are effectively removed and resultant BNNTs possess perfect crystallization.

Journal Article↗
PubMed2006

Carbon nanotubes as nanoreactors for fabrication of single-crystalline Mg3N2 nanowires.

Due to fast decomposition of Mg3N2 in the presence of water in the atmosphere (Mg3N2+6H2O-->3Mg(OH)2+2NH3), the synthesis of single-crystalline Mg3N2 nanowires has been a challenge. Here, we demonstrate that carbon nanotubes may serve as nanoreactors for a simple thermal reaction process resulting in the first fabrication of high-quality, large-yield, single-crystalline Mg3N2 nanowires. The Mg3N2 nanowires are homogeneously sheathed over their entire lengths with very thin graphitic carbon tubular layers, which effectively prevent their decomposition (even when the samples are put into water or exposed to atmosphere for several months). We have systematically analyzed for the first time the Mg3N2 nanomaterial by means of transmission electron microscopy (TEM), high-resolution TEM, and electron diffraction. Successful fabrication of carbon sheath protected Mg3N2 nanowires may promote further experimental studies on their crystal structures and properties.

Adsorption↗