Table of Contents - Volume 14 Number 2

ZnO nanostructures containing doped with different atom % of Nb are fabricated through ultrasound assisted hydrolysis in water. Effects of Nd incorporation on the structure, morphology, defect structure, optical, and magnetic behaviors of the nanostructures have been studied utilizing X-ray diffraction, scanning electron microscopy, photoluminescence spectroscopy and magnetometry. We demonstrate that while Nb incorporation in ZnO nanostructures drastically modify their morphology and crystallinity, it does not affect the band gap energy of of ZnO significantly. While Nb incorporation in small concentration creates higher oxygen vacancy related defects in ZnO nanostructures, which are responsible for their visible emissions, incorporation of Nb in higher concentration reduces those defect structures from the band gap of the nanostructures. While oxygen vacancies have been frequently associated to the ferromagnetic behavior of ZnO nanostructures, our results indicate that a mere presence of oxygen vacancy in Nb-doped ZnO nanostructure does not guaranty their ferromagnetic behavior.

Hide Abstract

Chitosan is a biodegradable, biocompatible and extracellular matrix mimicking polymer. These tunable biological properties make chitosan highly useful in a wide range of applications like tissue-engineering, wound dressing material, controlled drug delivery system, biosensors and membrane separators, and as antibacterial coatings etc. Moreover, its similarity with glycosaminoglycans makes its suitable candidate for tissue-engineering. Electrospinning is a novel technique to manufacture nanofibers of chitosan and these nanofibers possess high porosity and surface area, making them excellent candidates for biomedical applications. However, lack of mechanical strength and water insolubility make it difficult to fabricate chitosan nanofibers scaffolds. This often requires blending with other polymers and use of harsh solvents. Also, the functionalization of chitosan with different chemical moieties provides a solution to these limitations. This article reviews the recent trends and sphere of application of chitosan nanofibers produced by electrospinning process. Further, we present the latest developments in the functionalization of this polymer to produce materials of biological and environmental importance.

Hide Abstract

 To investigate radiation damage in bulk II-VI oxides with electronic and optical applications, 50 to 55 MeV Li ion beam from the Pelletron at IUAC, New Delhi, is suitable, and has been available. Maximum sample thickness that prevents undesirable ion implantation turns out, from TRIM calculation, to be ~ 200 µm for CdO & ZnO, and 400 to 450 µm for MgO. The need and difficulty of making such ultrathin ceramic samples (as desirable for radiation damage without implantation) are addressed first. Films, easily fulfilling the low thickness requirement, have properties different from the bulk, and are usually on a substrate to complicate the matter. Ultrathin un-fired pellets, in contrast to thick and sturdy pellets, become curved on conventional sintering. Curved pellets are useless for ion irradiation and most other experiments. Qualitative understanding of the curving, its prevention and test of these newly made ultrathin but flat ceramics for swift ion irradiation have been undertaken in this work.

Hide Abstract

This paper deals with the investigation of the reactions of aqueous molybdates in the presence of copper ions under varying pH to obtain new copper molybdates and rationalize the structures formed in terms of the self-assembling nano-building blocks of polyoxomolybdates (POMs). The reactions led to the precipitation of porous copper molybdates: 1D polymeric anions in (NH₄)₆[{Cu(H₂O)₄}{Mo₃₆O₁₁₂(H₂O)₁₆}].21H₂O, 1, a 3D framework bimetallic oxide in Cu₃Mo₂O₉, 2. Our results reported here clearly suggest that copper complexes formed during the initial stages of the reaction probably dictate the architecture of the final solids. Interestingly the magnetic properties studied on these compounds showed that 1 shows paramagnetic ordering since magnetically active centres i.e. Cu(II) are separated by large diamagnetic centres of {Mo₃₆} cluster anions where as 2 shows the dominance of antiferromagnetic near-neighbor interaction.

Hide Abstract

Nanocrystalline ZnGa₂O₄ spinel powders were prepared through a simple and facile microwave-irradiation assisted solution-based route, using ethylene glycol as the reaction medium and, without using any structure-directing agents. The as-prepared product consists of ZnGa₂O₄ nanoparticles, which are crystalline as revealed by X-ray diffraction studies and TEM analysis. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) studies also show that, the size of these as-prepared nanoparticles is less than 10 nm. The annealed nanopowders show intense blue luminescence, under UV excitation, which makes these nanopowders important in the field of phosphor applications.

Hide Abstract

This paper is a report of a study conducted on Structural, thermal and optical Properties of pure PMMA, pure PEO and PMMA-PEO-LiClO₄ polymer blend electrolyte thin films. These films were prepared using solution casting technique and characterized by X-ray Diffractometer (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC). XRD analysis Observations confirmed that amorphous, crystalline and semi crystalline nature of pure PMMA, pure PEO and PMMA-PEO-LiClO₄ polymer blend electrolyte thin films the SEM micrographs suggest that the surface morphology of pure PEO changes from smooth to rough when PMMA and LiClO₄ added to PEO polymer, which shows the interaction/ interface between the two polymers and polymer blend electrolyte due to cross – linking. Glass transition (T_g) and melting temperatures (T_m) of pure PMMA, pure PEO and PMMA-PEO-LiClO₄ polymer blend electrolyte thin films were confirmed by DSC analysis. FTIR spectra confirmed that complex formation and interaction among PMMA, PEO polymers and LiClO₄ salt.

Hide Abstract

Double Exposure Holographic Interferometry (DEHI) technique has wide applications in the field of science and engineering. DEHI can be used to determine very small surface changes in an object at very small interval of time.

In present case, DEHI technique is used to record the hologram of the same object at different times subjected to different loads. This method has been advantageously used to determine Young’s Modulus (Y) of Aluminium, Copper, iron, brass and some steel alloys. It is found that the values of Y obtained by using DEHI technique are in close agreement with standard values of Y available for respective metals and their alloys. The method is also used to make standard relation between effect of carbon composition and Y of steel alloys.

Hide Abstract

Ce³⁺ doped Nickel Zinc ferrites have been synthesised by sol-gel method followed by sintering at 400⁰C for 4 hours. Powder X-ray diffraction patterns of the prepared samples confirm the formation of single phase cubic spinel structure. Crystallite size of samples doped with Ce are smaller than that of undoped ferrite. The lattice parameters decrease with increase in doping concentration of Ce³⁺ ion. W-H plots are drawn to study  the strain effect in crystal structure.SEM micrographs show formation of spherical shaped nanoparticles. The vibration bands corresponding to metal oxygen vibrations at tetrahedral and octahedral sites in the FTIR spectra are in the reported range suggesting Ce³⁺occupation on octahedral sites predominantly. The doped samples exhibited lower saturation magnetization. The relative permittivity is found to show a decreasing trend with increase in frequency for all the samples which is characteristic of normal ferrimagnetism. The AC conductivity initially increases with frequency then remains constant over a wide range of frequencies. The UV analyses give the band gap which is less than 2 eV for all the samples which show that these are semiconducting materials.

Hide Abstract

To develop efficient upconversion laser materials in the visible region an active lead borate glasses doped with Er³⁺/Yb³⁺  rare earth ions (GEY) has been studied extensively. In this investigation characterization techniques like Optical absorption, FTIR and photoluminescence were recorded and the data was analyzed. To evaluate the values of Ω₂, Ω₄ and Ω₆ Judd-Ofelt theory has been applied to the f ↔ f transitions. Based on Judd–Ofelt theory branching ratio (β_r) oscillator strength and the radiative life time (τ_R) values were determined. The upconversion spectra exhibited three emission bands at around 525 nm (²H_11/2 ® ⁴I_15/2), 545 nm (⁴S_3/2 ® ⁴I_15/2) and 660 nm (⁴F_9/2 ® ⁴I_15/2). The energy transfer mechanism between Yb³⁺ and Er³⁺ was discussed very clearly. Comparing the data obtained in other Er³⁺/Yb³⁺ doped materials, the lead bismuth gallium borate glasses doped with 0.6 mol% of Er₂O_3­/0.2 mol% of Yb₂O₃ ions are suitable materials for developing red upconversion lasers in the visible region.

Hide Abstract

In present study, undoped ZnO, Zn_0.8Ag_0.2O, Zn_0.8Al_0.2O and Zn_0.6Al_0.2Ag_0.2O samples are synthesized by simple solution method. X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray spectroscopy (EDX) and UV-visible (UV-Vis) spectroscopy are used to perform the characterization of undoped, doped and codoped samples. XRD analysis is exposed that hexagonal wurtzite crystalline structure obtained for undoped, doped and codoped samples without any extra representation of impurity phases. The crystalline size is when evaluated by using Scherrer, It has 44, 49, 41and 37nm for undoped ZnO, Zn_0.8Ag_0.2O, Zn_0.8Al_0.2O and Zn_0.6Al_0.2Ag_0.2O samples. Similarly, the crystalline size and strain are also evaluated by Williamson hall (W-H) and size strain plot (SSP) for the undoped, doped and codoped nanoparticles. The evaluated crystalline size by SSP is three times greater than the result of the scherrer method. The SEM exposes that surface morphology of nanoparticle samples, in this case is the formation of large agglomeration in spherical shape with nanocrystallites of undoped and doped ZnO with apparent and definite boundaries. EDX points out the replacement of Al²⁺ and Ag⁺ with Zn²⁺ in ZnO matrix and consequences in the development of single-phase Zn_1−x−yAg_xAl_yO. The blueshift is shown in UV-Vis absorption spectra because the band gap value increases with the increase in doping, except Ag⁺ doped ZnO nanoparticles.

Hide Abstract

Nano ZnO was synthesised by green approach employing aqueous extract of Adulsa and Lemongrass leaves. XRD suggested hexagonal wutzite structure for these prepared ZnO. Synthesised nanoparticles efficiently catalysed Biginelli reaction.

Hide Abstract

An optimized platinum (Pt) doped tin oxide (SnO₂) ink was prepared by chemical route and was deposited on low temperature co-fired ceramics (LTCC) micro-hotplate by screen printing. An alkoxide ink was prepared by mixing tin(II) 2-ethylexanoate (17 wt%) with isopropanol (27 wt%) and SnO₂ powder (55 wt%). Doping of the ink was done using Pt (1 wt%) which increased the resistance of SnO₂ film at room temperature and also reduced the operating temperature. The temperature of ensor was obtained and stabilised using MOSFET based temperature stability circuit. Film characterization was performed using Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) technique. Small grain size and high porosity is the requirement for good sensing. The grain size was found to be in the range of 150-180 nm and the film was sufficiently porous. Resistance change of the film was also investigated in the presence of carbon  monoxide (CO) to assure gas sensing.

Hide Abstract

The CdO and ZnO are n- type semiconductors are transparent conducting in nature, inexpensive, mechanically stable and highly resistance to oxidation. In the present work these films have been obtained from thermal annealing of chemically deposited CdS and ZnS thin films. The structural properties of chemically deposited CdS and ZnS thin films and thermally annealed CdO and ZnO thin films have been studied. From x-ray diffraction data it is observed that annealing of the thin films at a particular temperature enhance the structural properties.

Hide Abstract

Ferrite samples of Zn_0.5Me_0.5Fe₂O₄ (Me = Co, Ni, and Cu) nanoparticles were synthesized by the sol-gel auto-combustion technique. Structural and magnetic properties of the samples carried out by using x-ray diffraction (XRD), vibrating sample magnetometer (VSM) respectively. On applying curve fitting of Rietveld method, unit cell dimensions, ion occupancy and exact coordinates of atoms have been determined. The cation distribution was estimated with the help of magnetization measurements and accessible occupancy of substituted ions in the crystal system. Cationic distribution was also confirmed theoretically from lattice constants calculation. The theoretically lattice constant was found to be 8.5110 Å, 8.3911 Å and 8.5229 Å for the Ni, Co, and Cu doped cations respectively. The saturation magnetization was found to be 110-148 emu/g which is good agreement with their corresponding magnetic moment and distribution of cations of their respective site preference.

Hide Abstract

Cast irons are basically binary alloys of iron and carbon having carbon exceeding its maximum solid solubility in austenite but less than the carbon content of iron carbide. However, like steels, cast irons have varying quantities of silicon, manganese, phosphorus and sulphur. Silicon plays an important role in controlling the properties of cast irons and for this reason, the term cast iron is usually applied to a series of iron, carbon and silicon alloys. Special purpose cast irons include white and alloy cast irons which are mainly used for applications demanding enhanced abrasion, corrosion or heat resistance. In present study, corrosion resistant cast irons are of our interest.

A detailed review of literature disclosed that corrosion resistant alloy cast irons currently in use is a compound of high percentage of silicon, nickel and chromium. Hence is called as chromium-molybdenum irons. It is widely used for oxidizing purpose. However, it shows low mechanical strength and shock resistance. Hence it is less useful for applications related with high mechanical strength and shocks. Ni-resist irons are useful in various types of ambient. It has low strength and become unsuitable at temperature higher than 780°C. High Ni- austenitic gray irons also suffer from corrosion due to graphite. High chromium irons is useful in all types of mold depending on chromium content. It demonstrates good resistance against attrition, abrasion and oxidation. The jostle resistivity of high chromium irons can be improved by reducing carbon content.   

Low cost substitutes for these cast irons may be aimed at substituting the scarce elements namely nickel and/or molybdenum partly or fully. Nickel can be replaced partially by manganese and copper. Manganese also controls austenite like nickel completely. Hence it can be used to refine pearlite and promote the formation of any desired matrix (bainite or martensite or austenite) in the as-cast condition. It has a mild carbide-forming tendency. The carbide morphology of manganese bearing chromium irons was found to be similar to that observed in high chromium irons because both manganese and chromium have a similar carbide-forming tendency. Copper cannot fully stabilize austenite and is effective only in the presence of another austenite stabilizer.

The possibility of evolving low cost corrosion resistant white irons is based on the fact that the difference of electrochemical potential between austenite and graphite is higher than that between austenite and carbide and it is a reason of reduction in graphitic corrosion which is a typical problem in high alloyed corrosion resistance gray irons. The mixture of materials is preferred due to the fact that the elements are locally available and effective in production of corrosion resistant white irons. It is assumed that iron-manganese-chromium-copper white irons are capable to resist corrosion, wear and corrosive-wear.

The present study essentially comprised a detailed investigation of certain newly designed Fe-Mn-Cr-Mo white irons, containing 10% Mn-6% Cr-3.0% C,0.3%Mo, The investigation was aimed at developing cheaper corrosion resistant white cast irons having corrosion resistance similar to expensive highly alloyed Ni-Resist irons. The study comprised assessing the heat treatment response of the experimental alloy with a view to establish interrelation between structure and properties. Hardness measurements, optical and scanning metallography, quantitative metallography, electron probe micro analysis and differential thermal analysis were carried out to correlate structure, properties and corrosion rate. However corrosion rates in 6% NaCl solution were found comparable to that of Ni-Resist irons.

Hide Abstract

Magnetoplumite type of lithium ferrites substituted by aluminium ions  having general chemical formula Li_0.5Fe_0.5+xAl_12-X O₁₉  (where x = 1 to 6) were prepared by standard solid state reaction method The compounds are in single hexagonal phase without traces of uncertainly ambiguous reflection. From XRD pattern lattice parameters has recorded with increasing doped aluminium element in the range from  a = 5.807 Å to 5.906 Å and c = 22.507 Å to 22.585 Å pertaining the space group P6₃/mmc (No.194). The mass density of the ferrites were found linearly varies and depends upon the mass and volume of sample. The X-Ray density has depends upon the lattice constant and molecular weight of the compounds. The average particle size was also estimated. Electrical properties such as dc conductivity, activation energy were studied. Also, the type of carriers responsible in each was determined from thermoelectric studies. The higher resistivity of the compounds Li_0.5Fe_0.5+xAl_12-X O₁₉ suggests less presence of mixed valency cations on equivalent lattice. While Fe show low value due to the ferrous ions present on the octahedral sites along with ferric ions.

Hide Abstract

Hydrazide-hydrazone   derivatives   play  vital  role  in  development  of  various pharmacological activities such as anti-tubercular, antiproliferative  and antitumor activities. Some novel biologically active   Hydrazide   derivatives substituted   with  heterocyclic   moiety have  been synthesized.  All the synthesized  compounds  structures   were   confirmed  by   IR,  NMR  and  Mass  spectra. Synthesized  compounds  were  subjected  to  antibacterial  screening in  vitro  and  biological  activity in vivo.

Hide Abstract

Metal matrix composites have exhibited better mechanical properties in comparison withconventional metals over an extensive range of working conditions. This makes them an appealing alternative in substituting metals for different applications. This paper gives a survey report, on machining of Aluminium metal Matrix composites (AMMC), particularly the molecule strengthened Aluminium metal matrix composites. It is an endeavour to give brief record of latest work to anticipate cutting parameters and surface structures in AMMC. The machinability can be enhanced by the utilization of Minimum Quantity Lubrication (MQL) during the machining of AMMC.

Hide Abstract

In this work we report a simple way for the conducting polymer nanocomposites synthesis using on algerian hydrophilic natural Montmorillonite (MMT) nanoclay named Maghnite (Mag) as dopant. The electrochemical properties study of the following conducting polymers: poly(4-aminobenzylamine) (P4ABA) and polyaniline (PANI) nanocomposites with copper maghnite (Mag-Cu) were successfully prepared by In-Situ polymerization, in presence of inorganic nanolayers of clay, and oxidizing agent ammonium persulfate. The synthesis of copolymers was developed at different feed mole fractions of monomer. The products were characterized by the Fourier transform Infrared (FT-IR), the ultraviolet-visible (UV–vis) spectroscopies and X-ray diffraction (XRD). The results showed that the in-situ polymerization produced real nanocomposites containing aniline and 4-aminobenzylamine units.

Hide Abstract

Intermolecular interaction among methyl formate with selected primary alcohols studied using Time Domain reflectometry at 303K. Dielectric constants, dielectric loss, were determined. The parameters changed with concentration and chain length of alcohols in methylformate system. Strength of intermolecular interaction of alcohols with methyl formate determined as 1-butanol<1-pentanol<1-hexanol

Hide Abstract