Volume 5, Issue 3, March 2014


Editorial

International Conference On Smart Materials And Surfaces (SMS), Bangkok

Ashutosh Tiwari

Advanced Materials Letters, 2014, Volume 5, Issue 3, Pages 111-112
DOI: 10.5185/amlett.2014.3001

We are pleased to announce International Conference on Smart Materials and Surfaces (SMS). It will be organised jointly by SETCOR, IAAM and VBRI Press during 26-28 August 2014 at Sheraton Grande Sukhumvit Hotel, Bangkok, Thailand. Smart Materials and Surfaces (SMS), Bangkok is a three-day event targeting researchers interested in the design, modification, characterisation and applications of Novel Smart & Active Surfaces and Materials. The goal of conference is to provide a global platform for researchers and engineers coming from academia and industry to present their research results and activities in the field of Intelligent Materials science and engineering. The conference will provide opportunities for the delegates to exchange face-to-face their novel ideas and experiences with the international experts during plenary & invited talks, oral presentations and poster sessions. We will set up sessions with keynote forum, panel discussion, project negotiation along with welcome cocktail and gala dinner.

Preparation of ZnS-graphene Nanocomposite and its Photocatalytic Behavior for Dye Degradation

B. N. Patil; S. A. Acharya

Advanced Materials Letters, 2014, Volume 5, Issue 3, Pages 113-116
DOI: 10.5185/amlett.2013.fdm.16

In the present work, ZnS-Gaphene (ZnS-GNS) composite was prepared by microwave irradiation method. The prepared samples were characterized by X-ray diffraction (XRD), to confirm the formation of GNS by reducing Graphite as well as ZnS-GNS nanocomposite. Raman spectroscopy identified D and G photon vibration mode of GNS in the ZnS-GNS composite. X-ray photoelectrons spectra are also detected presence of graphene in ZnS. UV/VIS Spectra are studied for evaluation of photocatalytic activity. The composite is explored as photocatalysts to study dye degradation using methylene blue dye in aqueous slurry under irradiation of 663 nm wavelength. Under the same conditions the photocatalytic activity of the pure ZnS is also examined. The ZnS-GNS composite is found in enhancing the rate of photodegradation of toxic dyes as compared to pure ZnS. This Graphene based metal sulphide/oxide semiconductor nanocomposites are high potential material for Photo-degradation of toxic dyes, and act as good photocatalyst.

The Structural, Electrical And Magnetic Properties Of Perovskite (1-x)Ba(Fe1/2Nb1/2)O3–xBaTiO3 Ceramics

S. Bhagat; K. Amar Nath; K.P. Chandra; R.K. Singh; A.R. Kulkarni; K. Prasad

Advanced Materials Letters, 2014, Volume 5, Issue 3, Pages 117-121
DOI: 10.5185/amlett.2013.fdm.28

Lead-free pseudo-binary compounds (1-x)Ba(Fe1/2Nb1/2)O3–xBaTiO3; (0 ≤ x ≤ 1) have been synthesized at 1200°C using conventional ceramic technique and characterized by X-ray diffraction, scanning electron microscopy, dielectric and vibration sample magnetometer studies. The crystal structure of the compounds is found to be monoclinic with the space group P2/m except for BaTiO3 for which it is tetragonal (P4/mmm). The incorporation of BaTiO3 significantly reduces the dielectric loss and improve the frequency and temperature stability of the dielectric properties of Ba(Fe1/2Nb1/2)O3. Compound 0.25Ba(Fe1/2Nb1/2)O3-0.75BaTiO3 exhibited a low value of temperature coefficient of capacitance (< ±3%) in the working temperature range (up to +85°C), room temperature dielectric constant equal to 282 and low loss tangent (~10-2) which meets the specifications for “Z5D” of Class II dielectrics of Electronic Industries Association. Hence, this composition might be a suitable candidate for capacitor applications. Besides, magnetic studies indicated the possibility of magneto-electric coupling in the system.

Synthesis, Electrical And Thermal Properties Of  Bi4V2-xCuxO11 (x=0.0 And 0.02) Ceramics 

M. Roy; S. Sahu; S. K. Barbar; S. Jangid

Advanced Materials Letters, 2014, Volume 5, Issue 3, Pages 122-126
DOI: 10.5185/amlett.2013.fdm.30

Polycrystalline ceramic samples of pure and Cu +2 doped Bi4V2-xCuxO11(x=0.0 and 0.02) have been synthesized by standard solid state reaction method using high purity oxides. The dielectric constant and dielectric loss and hence ac conductivity as a function of frequency and temperature have been measured. The dielectric studies indicate that the material is highly lossy and hence its ac conductivity increases with the increase of temperature. The dc conductivity of material has been measured as a function of temperature from room temperature to 653 K and its activation energy was calculated using the relation σ = σo exp (- Ea/kT). The dc conductivity increases with the substitution of Cu on the vanadium site. The Modulated Differential Scanning Calorimetry (MDSC) has been used to investigate the effect of substitution on the phase transition of the compounds. The results are discussed in detail.

A Comprative Study Of Sol-gel And Solid-state Prepared La3+ Doped Multiferroic BiFeO3

Pittala Suresh; S. Srinath

Advanced Materials Letters, 2014, Volume 5, Issue 3, Pages 127-130
DOI: 10.5185/amlett.2013.fdm.34

LaxBi1-xFeO3 (LBFO) samples were prepared by sol-gel route using citric acid as chelating agent for x = 0.0 - 0.4. The structure, dielectric and magnetic properties of the LBFO compounds were studied and compared with the corresponding properties of the materials prepared by a conventional solid state reaction. The use of the sol–gel method in preparation lowered the reaction threshold temperature by 200 °C. Effects of the preparation routes and conditions on the phase and microstructures of the materials were investigated in this study using XRD and SEM. The pure BFO without bismuth loss, which cannot be prepared by the solid state reaction, was obtained by the sol–gel method. Sol-gel synthesis could yield a pure phase material at relatively lower temperatures while the solid state method yielded powder with a small amount of the secondary Bi25FeO40 phase. Single phase LBFO prepared by sol-gel method (SG) revealed huge value of dielectric constant than same obtained by the solid state reaction method (SS). Maxwell-Wagner type dielectric dispersion is observed in sol-gel method. Dielectric constant and loss tangent are found to be higher for SG as compared to SS. Huge coercivity (HC) of the order of ~ 15 kOe is observed in both SG and SS samples due to the high anisotropy in these samples. The increase in the magnetization is observed due to the destruction of spin cycloid structure. The enhanced properties made LBFO a promising candidate for the applications in novel memory devices and spintronics.

Synthesis And Electrical Properties Of Sr(Bi0.5V0.5)O3 Electroceramic 

B. C. Sutar; Piyush R. Das; R. N. P. Choudhary

Advanced Materials Letters, 2014, Volume 5, Issue 3, Pages 131-137
DOI: 10.5185/amlett.2013.fdm.51

Lead-free polycrystalline material Sr(Bi0.5V0.5)O3 was prepared using a high- temperature solid state reaction technique (calcinations and sintering temperature =850 and 950 o C, respectively) using high-purity ingredients. The formation of the material in the monoclinic crystal structure was confirmed by preliminary X-ray structural analysis with room temperature data.The nature of microstructure obtained by scanning electron microscopy (SEM) shows that the compound has well defined grains which are uniformly distributed throughout the surface of the sample. Detailed studies of dielectric and impedance properties of the material carried out in the frequency range of 1 kHz –1MHz at different temperatures (30 0 C to 455 0 C) have provided many interesting properties. Detailed studies of dielectric properties of the compound showed an existence of diffus e phase transition around 258 0 C. The temperature dependence of electrical parameters (impedance, modulus etc.) of the material exhibits a strong correlation of its microstructure with the electrical parameters. The negative temperature coefficient of resistance (NTCR) behavior also was observed in the material. The complex electric modulus analysis indicates the presence of hopping conduction mechanism in the system with non-exponential type of conductivity relaxation. The nature of variation of dc conductivity with temperature confirms the Arrhenius behavior of the material. The ac conductivity spectra show a typical signature of an ionic conducting system, and are found to obey Jonscher’s universal power law.

Investigations Of Impedance And Electric Modulus Properties Of Pb1-xSmx(Zr0.45 Ti0.55)1-x/4O3 Ceramics

Rajiv Ranjan; Nawnit Kumar; Banarji Behera; R. N. P.Choudhary

Advanced Materials Letters, 2014, Volume 5, Issue 3, Pages 138-142
DOI: 10.5185/amlett.2013.fdm.52

Pb1-xSmx(Zr0.45Ti0.55)1-x/4O3 (PSZT; x = 0.00, 0.03 and 0.06) ceramic samples were prepared by high temperature mixed oxide method. Using complex impedance spectroscopy (CIS) technique, the complex impedance (Z*) and modulus (M*) properties of the materials were analyzed within a wide range of temperature and frequency. Impedance analysis indicates the presence of mostly bulk resistive (grain) contributions which is found to decrease with the increase in temperature. It suggests about the negative temperature coefficient of resistance (NTCR) type behaviour of the materials. Complex modulus plots exhibit the presence of grain (bulk) as well as grain boundary contributions in the materials and also support their NTCR type behaviour. Both the complex impedance and complex modulus plots confirm the presence of non-Debye type of relaxation in the materials. At higher temperatures, bulk resistance is found to increase with the increase in Sm 3+ concentration in PSZT along with the increase in relaxation phenomenon.

Structural And Electrical Properties Of Li2Pb2Sm2W2Ti4Ta4O30 Ceramics 

S. Behera; Piyush R. Das; B. N. Parida; P. Nayak; R. N. P Choudhary

Advanced Materials Letters, 2014, Volume 5, Issue 3, Pages 143-147
DOI: 10.5185/amlett.2013.fdm.60

The polycrystalline sample of complex tungsten-bronze compound Li2Pb2Sm2W2Ti4Ta4O30 was prepared by a high-temperature solid-state reaction technique. Room temperature X-ray diffraction (XRD) study suggests the formation of a single-phase compound. Microstructure of the pellet sample was studied by scanning electron microscope. The temperature variation of dielectric constant shows dielectric anomaly in the sample. Study of electrical properties (impedance, conductivity, etc.,) of the material exhibits a strong correlation between its micro-structure (i.e., bulk, grain boundary, etc) and electrical parameters. A typical Arrhenius behavior was observed in the temperature dependence of dc conductivity.

Elastic Moduli Of Perovskite-type Rare Earth Rhodium Borides And Carbides 

A. S. Verma; R. Bhandari;A. Kumar

Advanced Materials Letters, 2014, Volume 5, Issue 3, Pages 148-151
DOI: 0.5185/amlett.2013.fdm.02

In this paper, semi-empirical formula for the bulk modulus (B in GPa) and shear modulus (G in GPa) of perovskite structured solids are elaborated in terms of lattice constant (a in Å) and product of ionic charges (Za Zx) of the bonding. Values of bulk modulus, of the group ARh3X, (X = B and C) perovskite-type materials exhibit a linear relationship when plotted against the lattice constant (a) normalization, but fall on different straight lines according to the product of ionic charges of the compounds. The resulting expressions can be applied to a broad selection of perovskite (ARh3X = A: large cation with different valence and X: borides and carbides) materials and their modulus predictions are in good agreement with the experimental data and those from ab initio calculations.

Dielectric And Electrical Properties Of ZnSb2O4 Ceramics 

Anita Mekap; Piyush R. Das; R. N. P. Choudhary

Advanced Materials Letters, 2014, Volume 5, Issue 3, Pages 152-156
DOI: 10.5185/amlett.2013.fdm.65

The polycrystalline sample of ZnSb2O4 was prepared by a high-temperature solid-state reaction technique. Preliminary X-ray diffraction (XRD) studies of powder sample of ZnSb2O4 showed the formation of single-phase compound at room temperature. The surface morphology of the pellet sample of ZnSb2O4 was recorded at room temperature using a scanning electron microscope (SEM). Detailed studies of dielectric properties (εr, tan δ) and impedance parameters of the material provide an insight into the electrical properties and understanding of types of relaxation process occurred in the material. Temperature variation of dc conductivity shows that this compound exhibits negative temperature coefficient of resistance (NTCR) and frequency dependence of ac conductivity suggests that the material obeys Jonscher’s universal power law.

Investigation On Magnetic Behaviour Of BiFeO3: SPIN Glass View Point 

V. M. Gaikwad; S. A. Acharya

Advanced Materials Letters, 2014, Volume 5, Issue 3, Pages 157-160
DOI: 10.5185/amlett.2013.fdm.82

Field cooled (FC) and zero field cooled (ZFC) magnetization measurements of Bismuth Ferrite (BiFeO3) multiferroic obtained by microwave-assisted gel combustion method are reported. The structural investigation of sythesized and calcined sample is done by XRD and the obtained data is well fitted with Rietveld refinement using full-pro software suite. M-H hysterisis shows that BFO nanoparticles exhibit ferromagnetic properties at room temperature, which is unusally observed in BFO. The M -T plot at H = 1 and 2 kOe shows that the FC and ZFC magnetization curve start to differ at below 331K and 236 K respectively with sharp cusp around 124 K revealing spin glass behaviour of BiFeO3. Both ferromagnetic properties and spin-glass-like behavior are observed in BFO nanoparticles. Ferromagnetic behavior is attributed to a partial destruction in nanoparticles of the long-wavelength cycloid spin structure expected in bulk BFO. Spin-glass-like behavior is assigned to diffusion of domain walls, with possible contributions from pinning of the cycloid spin structure at the nanoparticle surface.