Materials Letters (MATER LETT)

Publications in this journal

• Article: A facile method to tune electronic properties of carbon nanotube films

  Dawid Janas, Slawomir Boncel, Adam A. Marek, Krzysztof K. Koziol
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  ABSTRACT: We report a simple approach of tailoring electronic properties of carbon nanotube (CNT) films. The process was carried out in the gas phase using fuming nitric acid vapors, gases generated from piranha solution or ozone in high and low concentration in O2 as reactants. The results showed a significant alteration in terms of electrical resistance, wherein it was changed by -50% up to +1,300% depending on the employed conditions. Furthermore, as a result of chemical functionalization of the CNT backbone, we witnessed changes to the sample morphology both on the micro- and nanoscale, what could be an asset. Most interestingly, fuming HNO3 treatment introduced carboxylic and phenolic groups to the structure and as a result of hydrogen bonding, we observed bundling up of the material. This strategy could be a tool to yield CNT macroassemblies of predetermined electronic and structural properties without the need of problematic multi-step solution processing.
  Materials Letters 04/2013;
• Article: Study on local zones constituting to band growth associated with inhomogeneous plastic deformation

  Srinivasan Nagarajan, Raghu Narayanaswamy, Venkatraman Balasubramaniam
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  ABSTRACT: Plastic instability associated with Lüders band deformation affects the surface quality of structural steel products during metal forming operations such as drawing. In this work band growth mechanism involved in Lüders deformation is studied in mild steel by analyzing deformation in two local zones within the Lüders band width namely effective width and active zone using digital image correlation, an imaging, noninvasive technique for strain mapping. Change in magnitude of these local zones in the load plateau and associated strain rate variations within these zones clearly revealed the irregular growth of these zones reflecting the irregularity involved in two stage Lüders band growth mechanism.
  Materials Letters 04/2013; In Press.
• Article: Production of N-doped carbon nanotubes using α- and β-cyclodextrins: The effect of solubility

  EN Nxumalo, PF Msomi, SD Mhlanga, BB Mamba
  Materials Letters 03/2013; 100:66-69.
• Article: Synthesis of TiO2−xNy/Ag-PbMoO4 nanocomposites: An effective approach for photoinactivation of green tide under simulated solar light

  Tae-Ho Kim, Yong-Hyun Jo, Gobinda Gyawali, Rajesh Adhikari, Soo-Wohn Lee
  Materials Letters 03/2013;
• Article: Optimization of UV emission intensit y of ZnO nanoparticles by changing the excitation wavelength

  K.Sowri Babu, A.Ramachandra Reddy, Ch.Sujatha, K.Venugopal Reddy
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  ABSTRACT: Zinc oxide (ZnO) nanoparticles were prepared by using the sol–gel method with polyvinyl alcohol as surfactant. These ZnO nanoparticles exhibited excitation wavelength dependent photoluminescence (PL). PL spectra of ZnO were composed of different emission peaks at 384, 398, 418, 434, 467 and 492 nm depending on excitation wavelengths used. The maximum UV emission intensity was obtained when the excitation wavelength was chosen from the photoluminescence excitation (PLE) spectrum. The excitation wavelength selected from PLE is 353 nm; at this, there is more than 23 times enhancement in the UV emission intensity compared to 340 nm. At 370 nm excitation wavelength, UV emission at 398 nm was quenched completely
  Materials Letters 02/2013;
• Article: Phase transformation in semi-transparent TiO< sub> 2</sub> films irradiated with CO< sub> 2</sub> laser

  Jorge Medina-Valtierra, Claudio Frausto-Reyes, Martín Ortiz-Morales
  Materials Letters 02/2013; 66(1):172-175.
• Article: Growth and Electron Field-Emission of singlecrystalline ZnO Nanowires

  Edgar Mosqueraa, Jimmy Bernala, Ramón A. Zarateb, Frank Mendozac, Ram S. Katiyarc, Gerardo Morellc
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  ABSTRACT: ZnO nanowires with high density are grown over zinc foil by thermal evaporation process at relatively low temperature. Electron microscopy studies confirmed that the as-grown nanowires are of single crystal hexagonal wurtzite structure, growing preferentially in the c-axis direction. The Raman spectrum of the ZnO nanowires shows an optical-phonon E2 mode at 440 cm−1 confirming good crystallinity for the grown nanowires. The field emission measurement indicated that ZnO nanowires have a turn-on field of 9.1 V/μm at current density of 0.001 μA/cm2.
  Materials Letters 02/2013; 93:326–329.
• Article: Modified Pechini synthesis of hexaferrite Co2Z with high permeability

  Lang Qin, Henk Verweij
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  ABSTRACT: Magnetic ceramic hexagonal ferrites with strong magnetocrystalline anisotropy are considered for application in high frequency antennas. In particular, Ba3Co2Fe24O41 (Co2Z) is expected to exhibit a high permeability and low loss at frequencies > 1 GHz. In this paper, we report the fabrication of Co2Z material starting from precursor powders made by a modified-Pechini route. The precursor powders are compacted by dry pressing, followed by sintering to achieve a relative density of 90.3%. The morphology, crystal structure and high frequency magnetic permeability of thus formed materials are presented. The highest initial permeability, μ′ = 11.9, was achieved for the samples calcined/sintered at 1300/1330 °C. It is expected that further improvement can be achieved by optimization of the sintered micro-structures.
  Materials Letters 02/2013; 68:143.