Issue 3

The industrial and commercial perspective of peer-reviewed research

Raeann Gifford

Advanced Materials Letters, 2011, Volume 2, Issue 3, Pages 170-171
DOI: 10.5185/amlett.2011.9001

Peer reviewed publications are essential in demonstrating valuable research to fellow academics, funding agencies, as well as moving important scientific concepts into areas that ultimately benefit our global society. Both theoretical and applied research are vital scientific pursuits, therefore, both must be pursued with equal vigor. In pursuing a research path researchers should consider the entire scope of their audience. Granted, most frequently, the readers are other academics, students, and government research and funding agencies; generally people whose source of income is not tied to producing a commercial product. On the other hand, there is a significant audience that reviews the scientific literature scouting for product ideas and solutions to problems they may encounter in producing a product or service.

Preparation and characterization of novel spin labeled magnetic nanoparticles

Hongli Zhao; Zhigang Zhang; Zijun Zhao; Ronghua Yu; Yuanyuan Wan; Minbo Lan

Advanced Materials Letters, 2011, Volume 2, Issue 3, Pages 172-175
DOI: 10.5185/amlett.2011.1210

Novel spin-labeled magnetic nanoparticles (MNPs) were prepared through the reaction between carboxylic acids modified Fe3O4 particles and 4-amino-2,2,6,6-tetramethylpiperidin-1-oxyl (4-NH2-TEMPO). And X-ray diffractometer (XRD), FT-IR spectra, thermogravimetric analysis (TGA), transmission electronic microscopy (TEM) and room temperature electron paramagnetic resonance (EPR) were employed to characterize the prepared materials. The results of EPR measurements indicated that the spin-labeled MNPs exhibited both the paramagnetism of nitroxide free radicals and superparamagnetism of ferrimagnetic nanoparticles could act as a bio-probe or potential drug delivery vehicles tracking by EPR technique.

Structural and hardness of nonlinear optical L-alanine single crystals

S. Gokul Raj; G. Ramesh Kumar

Advanced Materials Letters, 2011, Volume 2, Issue 3, Pages 176-182
DOI: 10.5185/amlett.2011.1219

Single crystals of pure and Deuterated L-alanine have been grown by both slow cooling and seed rotation techniques. The grown nonlinear optical crystals were subjected to single crystal X-ray diffraction for determining its lattice parameters and morphology. Thermal expansion measurements were carried for the Deuterated crystals of L-alanine using thermomechanical analyzer in order to ascertain the strain tensors along the three mutually perpendicular crystallographic directions. Microhardness study was also undergone on deuterated L-alanine single crystals on a prominent plane for determining the mechanical strength of the grown crystals. The results have been discussed in detail.

Growth and characterization of ZnO nanorods by microwave-assisted route: green chemistry approach

Faheem Ahmed; Shalendra Kumar; Nishat Arshi; Ram Prakash

Advanced Materials Letters, 2011, Volume 2, Issue 3, Pages 183-187
DOI: 10.5185/amlett.2011.1213

ZnO nanorods with diameter 90-100 nm range (tip diameter~15 nm) and length of about 2 μm have been prepared using microwave irradiation technique. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results indicate that the nanorods have single phase nature with wurtzite structure and preferentially grow along [0001] direction. Raman spectrum shows the mode E2 high at 439 cm −1 that is related to the vibration of oxygen atoms in wurtzite ZnO. Room-temperature ultraviolet-visible (UV-vis) absorption spectrum shows the absorption band at around 399 nm (red-shifted as compared to bulk). This novel nanostructure would be a promising candidate for a variety of future applications.

Silver nanoparticles: preparation, characterization, and kinetics

Javed Ijaz Hussain; Sunil Kumar; Athar Adil Hashmi; Zaheer Khan

Advanced Materials Letters, 2011, Volume 2, Issue 3, Pages 188-194
DOI: 10.5185/amlett.2011.1206

In this paper we report the effect of aniline concentrations on the growth and size of silver nanocrystals using aniline and silver nitrate as reductant and oxidant, respectively. UV-Vis spectroscopy, transmission electron microscopy (TEM) and selected areas electron diffraction (SAED) have been employed to characterize silver nanoparticles. The TEM images show that silver nanocrystals are roughly spherical and of uniform particle size, and the average particle size is ca. 25 nm. A broad surface plasmon resonance band appears at 400 nm. The rings patterns are in good agreement with the standard values of the face-centered-cubic form of silver nanocrystals. This is attributed to the adsorption of aniline and /or interparticle interaction onto the surface of Ag-nanocrystals through electrostatic interactions between the lone-pairs electrons of –NH2 and positive surface of Ag- nanoparticles.

Magnetic and luminescent dual-functional SiO2 beads created through controlled sol-gel process

Zhongsen Yang

Advanced Materials Letters, 2011, Volume 2, Issue 3, Pages 195-199
DOI: 10.5185/amlett.2011.1212

A controlled sol-gel approach was developed to encapsulate luminescent CdTe and magnetic Fe3O4 nanocrystals (NCs) into SiO2 beads. The preparation procedure included the preparation of SiO2-coated Fe3O4 NCs, the attachment of the CdTe NCs on the SiO2-coated Fe3O4 NCs, the assembly of the CdTe NCs-attached Fe3O4 NCs, and the growth of a SiO2 shell. To prevent the photoluminescence (PL) quenching, Fe3O4 NCs were coated with a thin SiO2 layer before encapsulating into SiO2 beads together with CdTe NCs. The CdTe NCs retained high PL efficiency (30 %) in dual functional SiO2 beads. These SiO2 beads also revealed superparamagnetic behavior. The result would be utilizable for further application because of their high PL efficiency and magnetic property. The strategy described here should give a useful enlightenment for the design and fabrication of multiple functional SiO2 beads.

Comparative study of structure, dielectric and electrical behavior of Ba(Fe0.5Nb0.5)O3 ceramics and their solid solutions with BaTiO3

N.K. Singh; Pritam Kumar; Radheshyam Rai

Advanced Materials Letters, 2011, Volume 2, Issue 3, Pages 200-205
DOI: 10.5185/amlett.2010.11178

Dielectric properties of (1-x)Ba(Fe0.5Nb0.5)O3-xBaTiO3 (where x = 0.00, 0.05 and 0.10) solid solution ceramics at high temperature range of RT ~ 270 o C have been characterized in this paper. The above said polycrystalline ceramics with (x = 0.0, 0.05 and 0.10) have been produced via a mixed oxide route. The effects of BaTiO3 substitution on the structure and on the electrical and ferroelectric properties of Ba(Fe0.5Nb0.5)O3 samples have been studied by performing x-ray diffraction and dielectric measurements. The dielectric properties (e¢ and tan d) were investigated in the temperature range of 30-270 °C and in the frequency range of 100 Hz-5 MHz. The variation of relative dielectric permittivity (tan d) and tangent loss (tan d) has suggested a significant role of hopping of trapped charge carriers, which is resulted in an extra dielectric response in addition to the dipole response. It is observed that: (i) the relative dielectric permittivity and tangent loss (tan d) are dependent on frequency, (ii) the temperature of dielectric permittivity maximum shifts toward lower temperature side and (iii) dielectric permittivity and tangent loss rapidly increase by making solid solution of BFN with BaTiO3. X-ray diffraction analysis of the compound suggests the formation of single-phase compound with monoclinic structure. SEM photographs exhibit the uniform distribution of grains. The maximum ferroelectric transition temperature (Tc) of this system was 250-270 °C with the dielectric constant peak of 72500 at 1.09 kHz for x = 0.05.

Effect of temperature on the present forms of MgO in the reconstruction of steel slags

Zhaofeng Li; Zonghui Zhou; Xin Cheng

Advanced Materials Letters, 2011, Volume 2, Issue 3, Pages 206-209
DOI: 10.5185/amlett.2010.11175

By varying reconstructed temperature of steel slag, present form, crystallizing conditions and lithofacies characteristics of MgO and RO were tested by XRD, SEM and lithofacies analyses. Contents of MgO and RO phase in other phases of steel slag were analyzed by phase separation. The results show that when the reconstructed temperature of steel slag increases, the content of gel minerals also increases, and the degree of crystallization comes nearer to completion. The existing state of MgO changed to solid solution state from the free state. When the reconstructed temperature of steel slag was at 1300 ºC, the contents of MgO solid dissolved in gel minerals (e.g., silicate and mesophase). However, at very high temperature, recrystallization occurred in the steel slag, and larger amounts of free MgO were generated, which could affect the strength of steel slag.

Effect of KBF4 and K2TiF6 on precipitation kinetics of TiB2 in aluminium matrix composite

N.B. Dhokey; S. Ghule; K. Rane; R.S. Ranade

Advanced Materials Letters, 2011, Volume 2, Issue 3, Pages 210-216
DOI: 10.5185/amlett.2010.12192

Aluminium reinforced with TiB2 is an emerging class of metal matrix composites for many engineering applications such as automobiles, aerospace and naval vessels. The initial part of the present work study involves melting of individual fluxes of KBF4 and KTiF6 in premelted aluminium in an induction furnace. In the later part of the work covers the combined effect of these fluxes to produce aluminium metal matrix composites containing 2.5% TiB2. The effect of the varying amount of KBF4 on kinetics of TiB2 formation and elimination other unstable phases was studied. The material was examined for hardness, microstructures and wear rates using Pin-on-Disc test machine, XRD and SEM-EDX analysis. The effect of TiB2 on properties was analysed. It was concluded that an optimum level of KBF4 is needed to get critical population of TiB2 particles in the matrix.

Effects of chloride ions and poly (vinyl- pyrrolidone) on morphology of silver particles in solvothermal process

Yulan Zhang; Yingzi Wang; Ping Yang

Advanced Materials Letters, 2011, Volume 2, Issue 3, Pages 217-221
DOI: 10.5185/amlett.2011.2223

Silver particles with various morphologies including cubic, spherical, and rod-shaped have been synthesized by a facile solvothermal procedure using poly (vinyl pyrrolidone) (PVP) as an adsorption agent and architecture soft template. Preparation conditions such as the molar ratio and concentration of starting materials were optimized for studying the growth kinetics of silver particles. The amount of chloride ions and PVP plays an important role for the morphology of silver particles during synthesis. Chloride ions as a stabilizer against the aggregation of particles could sufficiently retard particle growth. The selected bounding of PVP molecules on the silver particle is a key for morphological controlling. The morphological evolution of the silver particle was investigated by adjusting systematically preparation parameters. Because of PVP molecules are easily bounded to the (100) facet of silver crystals, the growth of the silver particle occurred around (111) plane. Silver particles with a series of morphologies were created via such anisotropic growth.

Machining characteristics of nanocomposites

K.S. Umashankar; K.V. Gangadharan; Vijay Desai; B. Shivamurthy

Advanced Materials Letters, 2011, Volume 2, Issue 3, Pages 222-226
DOI: 10.5185/amlett.2011.1209

Nanocomposites were prepared with Al/Al-Si alloys (LM 6 and LM 25) as matrix and multi-wall carbon nanotube (MWNT) of 0.25, 0.5, 0.75, 1.0 and 1.5 wt. % as reinforcement through powder metallurgy (PM) followed by sintering and hot extrusion techniques. Fabricated nanocomposites were machined on a Panther 1530/1650 lathe by using tungsten carbide tool. Recurrence quantification analysis (RQA) was used to study the machining characteristics by using cutting force signal stability. Highest value of determinism (DET-one of the RQA parameter) was observed for 0.5 wt.% MWNT reinforced Al and Al-Si nanocomposites. This attributes better machining characteristic due uniformity of the signals. Also it is observed better mechanical properties at 0.5 wt.% reinforced nanocomposite and further reinforcement deteriorate the machinability and mechanical properties.

Effect of H3PO4 reactant and NaF additive on the crystallization and properties of brushite

C. Sekar; K. Suguna

Advanced Materials Letters, 2011, Volume 2, Issue 3, Pages 227-232
DOI: 10.5185/amlett.2011.1217

Calcium hydrogen phosphate dihydrate (CaHPO4.2H2O, CHPD) or brushite crystal is a well known urinary substance found frequently in urinary stones. The CHPD crystals have been crystallized in sodium metasilicate gel (SMS) at room temperature under pH 6 in the presence of sodium fluoride. Here, H3PO4 and CaCl2 were used as reactants which resulted in simultaneous crystallization of mostly dentritic brushite crystals and a small quantity of hydroxyapatite (HA). On the other hand, use of Na2HPO4 and CaCl2 as reactants yielded the large quantity of HA along with platelet brushite crystals. In both the cases, addition of sodium fluoride is found to inhibit the nucleation and subsequent growth of brushite crystals. The crystal morphology, structure and elemental composition of the grown crystals have been analyzed using SEM-EDX and powder XRD studies. Functional groups present in the grown crystals have been confirmed from the vibrational frequencies of the recorded FTIR spectrum.

Strength and microstructure of semi-solid stirring brazing of SiCp/A356 composites and aluminum alloy in air

Huibin Xu; Hui Yang; Quanxiang Luo; Youliang Zeng; Bofang Zhou; Changhua Du

Advanced Materials Letters, 2011, Volume 2, Issue 3, Pages 233-238
DOI: 10.5185/amlett.2011.1216

The semi-solid stirring brazing process of SiCp < /sub>/A356 composites and 2024 aluminum alloy was investigated. The two substrates were heated up to the semisolid temperature range of Zn27Al filler metal in the joint region by a resistance heating plate in air. At this point a stirrer was penetrated into the semi-solid weld seam in order to mix filler metal and the two sides of substrates into a single uniform joint. After stirring, specimens were sectioned for analysis of macro- and micro-structures along the weld region. The research shows that SiCp < /sub>/A356 composites and aluminum alloy can be successfully joined with semi-solid filler metal by optimizing stirring temperature. It can be found that most of the oxide film on the surface of the base metal was disrupted and removed through the observation by SEM. The metallurgical bonds formed between the filler metal and the base materials. Since the semisolid temperature range of filler metal is narrow, the accurate controlling of weld pool temperature must be considered.

Structural And Dielectric Properties Of Y2(Ba0.5R0.5)2O7 (R = W, Mo) Ceramics

N.K. Singh; Pritam Kumar

Advanced Materials Letters, 2011, Volume 2, Issue 3, Pages 239-244
DOI: 10.5185/amlett.2011.1215

Defect pyrochlore-type Y2(Ba0.5R0.5)2O7 (R = W, Mo) oxides ceramics were prepared by using high-temperature solid-state reaction technique. Preliminary studies of X-ray diffraction (XRD) patterns and scanning electron micrographs (SEM) of the compounds at room temperature suggested that compounds have single phase orthorhombic structures and uniform grain distribution throughout the surface of the samples. Detailed studies of dielectric and electrical properties of the materials in a wide range of frequency (1 kHz–1MHz) and temperatures (23–344°C) showed that these properties are strongly temperature and frequency dependent. Variation of dielectric constant (ε') and tangent loss (tanδ) as a function temperatures showed the abnormal behavior around 132°C at 10 kHz and 141°C at 30 kHz of Y2(Ba0.5W0.5)2O7 and around 293°C at 10 kHz and 305°C at 30 kHz of Y2(Ba0.5Mo0.5)2O7 ceramics respectively.