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Dielectric, magnetic and magnetoelectric properties of ferrite-ferroelectric based particulate composites
No full textParticulate composites based on ferrite and ferroelectric phase viz. cobalt zinc ferrite (Co0.8Zn 0.2Fe2O4 ) and bismuth sodium titanate (Bi0.5Na0.5TiO3) were synthesized using solid state reaction method. The formation of diphase composite was established using x-ray diffraction. Field emission scanning electron microscopy was used to study the microstructure of the composites, exhibiting fine blending of constituent phases in the composites. Dielectric behaviour of the composites was studied as a function of temperature and frequency. Variation of dielectric constant with temperature exhibits a shift in Curie temperature with increase in ferrite content. Usual dielectric dispersion is observed for the composites with increase in frequency. The consequence of addition of ferrite phase on ferroelectric and magnetic properties of composites was studied. All composites exhibit typical ferromagnetic hysteresis loops. Magnetoelctric coupling in the composites was confirmed by measuring magnetoelctric voltage coefficient (alpha(ME)). The maximum a ME of 7.11 mV cm(-1) -Oe was obtained for 10% Co0.8Zn0.2Fe2O4-90% Bi0.5Na0.5TiO3 composite
70 years of Elastohydrodynamic Lubrication (EHL): A Review on Experimental Techniques for Film Thickness and Pressure Measurement
No full textElastic deformation of surfaces and piezo-viscous effect of lubricant make EHL a very complex lubrication regime. Elastohydrodynamic Lubrication becomes much more complex when conditions like rough surfaces, non-newtonian behavior of lubricant and temperature dependent flow are considered. The present paper takes the task of reviewing experimental methods applied till date for measuring film thickness and pressure. The paper has been divided into many sections and sub-sections to deal with these techniques in a lucid manner. Experimental methods have been categorized into Electrical, Optical and Acoustic methods. The difference of 8-10% between theoretical and experimental results are witnessed using Electrical methods. Whereas, this difference is less than 1% using Optical methods. Among all optical methods, Relative Optical Interference Intensity Technique is the most effective technique with an ability to measure the film thickness as small as 1 nm or less. The last section of the paper deals with the scope of improvement in measurement techniques in future to understand EHL in more detail
Design of MWCNT bucky paper reinforced PANI-DBSA-DVB composites with superior electrical and mechanical properties
No full textHigh-strength conducting polymer composites are in high demand in modern aerospace and automobile industries. Therefore, a thermosetting conducting polymer system, polyaniline (PANI) doped with dodecylbenzenesulfonic acid (DBSA) interconnected with divinylbenzene (DVB), has been used to design high-loading multiwalled carbon nanotube (MWCNT)-reinforced composites. Herein, MWCNTs were used on a macroscale in the form of bucky paper (BP) and as secondary reinforcement in the matrix system. The mechanical and electrical properties of the resultant BP reinforced PANI-DBSA-DVB (PDD) composites were investigated. The maximum flexural strength and storage modulus were 45.8 MPa and 18.5 GPa, obtained in 16ply MWCNT BP composite with 0.05 wt% dispersed MWCNT (16ply0.05), representing overall improvements of approximate to 48.2% and approximate to 55.4%, respectively, compared with the neat PDD matrix system. The maximum in-plane and through-plane electrical conductivities of the 16ply0.05 composite were 39.5 and 1.4 S cm(-1), which were three and two orders of magnitude higher, respectively, compared with those of neat PDD matrix. This high electrical conductivity resulted in a maximum electromagnetic power loss of -37.5 dBm for the 16Ply0.05 composite, which represented an overall improvement of approximate to 231% over the neat PDD system. Furthermore, the effect of secondary phase of MWCNTs was investigated using FT-IR, UV-Vis, and DSC analyses
Seasonal and annual trends of carbonaceous species of PM10 over a megacity Delhi, India during 2010-2017
No full textPM10 samples were collected to characterize the seasonal and annual trends of carbonaceous content inPM(10) at an urban site of megacity Delhi, India from January 2010 to December 2017. Organic carbon (OC) and elemental carbon (EC) concentrations were quantified by thermal-optical transmission (TOT) method of PM10 samples collected at Delhi. The average concentrations of PM10, OC, EC and TCA (total carbonaceous aerosol) were 222 +/- 87 (range: 48.2-583.8gm(-3)), 25.6 +/- 14.0 (range: 4.2-82.5gm(-3)), 8.7 +/- 5.8 (range: 0.8-35.6gm(-3)) and 54.7 +/- 30.6gm(-3) (range: 8.4-175.2gm(-3)), respectively during entire sampling period. The average secondary organic carbon (SOC) concentration ranged from 2.5-9.1 gm(-3) in PM10, accounting from 14 to 28% of total OC mass concentration of PM10. Significant seasonal variations were recorded in concentrations of PM10, OC, EC and TCA with maxima during winter and minima during monsoon seasons. In the present study, the positive linear trend between OC and EC were recorded during winter (R-2=0.53), summer (R-2=0.59) and monsoon (R-2=0.78) seasons. This behaviour suggests the contribution of similar sources and common atmospheric processes in both the fractions. OC/EC weightratio suggested that vehicular emissions, fossil fuel combustion and biomass burning could be the major sources of carbonaceous aerosols of PM10 at the megacity Delhi, India. Trajectory analysis indicates that the air mass approches to the sampling site is mainly from Indo Gangetic plain (IGP) region (Uttar Pradesh, Haryana and Punjab etc.), Thar desert, Afghanistan, Pakistan and surrounding areas
Sintering dependent Ca2+ solubility in barium titanate synthesized by sol-gel auto combustion method
No full textWe report the preparation of ferroelectric Ba0.7Ca0.3TiO3 (BCT) ceramics by sol-gel auto combustion technique and its specific functional properties. The structural, dielectric and ferroelectric properties of BCT are strongly depending on the sintering temperature which also improves the phase purity and crystalline quality of the system. The formation of single-phase BCT is realized by sintering at 1450 degrees C for 4h. suggesting the solubility limit of Ca2+ cation. Grain size and relative density are increased as the sintering temperature increased. The Rietveld refinement technique is employed for the detailed crystal structural analysis. The temperature and frequency dependent dielectric properties are investigated; the measured dielectric constant is epsilon(r)=2680at the transition temperature T-c=120 degrees C for the single phase ferroelectric BCT. Sintering and electrical poling improved the shape of the hysteresis curve and reduced the leakage current. Electrical conduction mechanism is also discussed
Trimetallic Au/Pt/Ag based nanofluid for enhanced antibacterial response
No full textThe antimicrobial activity of trimetallic Au/Pt/Ag nanoparticle based nanofluids were studied and compared with that of monometallic Au and bimetallic Au/Pt nanofluid. The trimetallic nanofluid was prepared by green microwave assisted successive chemical reduction method and characterized by UV-Vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The metallic nanofluids were tested for antibacterial properties using agar disc diffusion test method against various micro-organisms and their minimum inhibitory concentration (MIC) values were calculated. The trimetallic nanofluid exhibited efficient antibacterial activity and were found to be better agent than bimetallic and single metallic nanofluid at a very low metal concentration. These results of trimetallic nanofluids may be utilized in the field of many applications such as medical research, pharmaceutical industries and environmental sciences
Realization of Highly Efficient Polymer Solar Cell Based on PBDTTT-EFT and [71]PCBM
No full textIn this work, we have fabricated highly efficient polymer solar cells based on the blend of PBDTTT-EFT:PC71BM in the inverted device configuration. By using low temperature processed zinc oxide (ZnO) nanoparticles as an electron-transport layer (ETL) and 1,8-diiodooctane (DIO) as additive in chlorobenzene (CB) solvent we have achieved PCE of 9.43% with an excellent short-circuit current density (J(sc)) of 17.6 mAcm(-2), open circuit voltage (V-oc) of 0.80 V and fill factor (FF) of 0.67. These results reveals that addition of 3% DIO additive in CB solvent improve the morphology (lower charge carrier recombination and better metal/organic semiconductor interface) and provide uniform interpenetrating networks in PBDTTT-EFT:PC71BM blend active layer
Sol-gel synthesis of Cu-doped p-CdS nanoparticles and their analysis as p-CdS/n-ZnO thin film photodiode
No full textCopper (Cu) doped p-CdS nanoparticles have been synthesized via sol-gel method. The as-synthesized nano particles were successfully characterized and implemented for fabrication of Glass/ITO/n-ZnO/p-CdS/Al thin film photodiode. The fabricated device is tested for small (-1 V to + 1 V) bias voltage. Results verified that the junction leakage current within the dark is very small. During reverse bias condition, the maximum amount of photocurrent is obtained under illumination of 100 mu W/cm(2). Electrical characterizations confirmed that the external quantum efficiency (EQE), gain and responsivity of n-ZnO/p-CdS photodiode show improved photo response than conventional p-type materials for such a small bias voltage. It is therefore revealed that the Cu doped CdS nanoparticles is an efficient p-type material for fabrication of thin film photo-devices
Long-term fertilization effects on soil organic carbon sequestration in an Inceptisol
No full textLimited information is available on long-term fertilization impacts on soil organic carbon (SOC) sequestration in deep soils and C pools within bulk soils and aggregates. Hence, the major objectives of this study were to evaluate long-term (44 years) fertilization impacts on: (i) soil aggregation, labile and recalcitrant C pools within bulk soils and aggregates and (ii) deep soil C accumulation versus sequestration. Treatments were: no mineral fertilizer or manure (control), 100% recommended dose of nitrogen (N), N and phosphorus (NP), N, P and potassium (NPK), 150% recommended NPK (150% NPK), and NPK + farmyard manure (FYM) (NPK + FYM). Labile C, recalcitrant C, total SOC and glomalin in bulk soils and their aggregates were determined in the 0-15 and 15-30 cm soil layers. In addition, total SOC, labile and recalcitrant C contents were measured in the 30-60 and 60-90 cm soil layers. Results revealed that C accumulation and sequestration in NPK + FYM over control plots were 0.74 and 0.22 Mg C ha(-1) yr(-1), respectively, in 0-90 cm soil layer with > 50% of the accumulated C in deep soil layers (30-90 cm). In 0-15 cm layer, despite NPK + FYM and NPK plots had similar amounts of soil macroaggregates, microaggregates were 27% higher with NPK + FYM than NPK, causing higher aggregate stability. Plots with NPK and NPK + FYM had more labile: recalcitrant C ratios in bulk soils than control, NP and N plots. The NPK + FYM plots also had highest recalcitrant C pools within macro- and microaggregates. Glomalin was generally positively correlated with all labile C pools in both soil layers. Additionally, mean weight diameter (MWD) was positively correlated with aggregate-associated C and glomalin within bulk soils. Overall, NPK + FYM management practice not only had higher C accumulation and sequestration in surface and deep soils, but also had better aggregation and similar to 26% greater carbon management index than NPK in soil surface and hence should be adopted
Dielectric and impedance properties of three dimension graphene oxide carbon nanotube acrylonitrile butadiene styrene hybrid composites
No full textIn this work, comparison of dielectric and impedance studies of multi-walled carbon nanotube (MWCNTs), graphene oxide-carbon nanotube (GCNTs) reinforced acrylonitrile-butadiene-styrene (ABS) composites prepared by twin-screw extruder with back flow channel have been carried out. The dielectric relaxation and impedance behavior of these polymer composites have been studied with varying wt. % of MWCNTs and GCNTs reinforced ABS matrix in the frequency range of 10(2)-10(6) Hz. The results showed that the real part of the impedance of the composites with MWCNTs content of 7 wt % or higher exhibits frequency independent behavior at the low-frequency region, and GCNTs-ABS demonstrates frequency dependent. Also, the relaxation time decreases with increase in wt. % of carbon nanofillers due to the formation of an interconnecting path within the polymer matrix. The Nyquist plots for MWCNTs-ABS composites showed the appearance of a single semicircular arc, whose radius of curvature decreases with increase in MWCNTs loading, suggest the decrease in overall impedance of the composite with high amount of filler loading. The radius of arc in impedance spectra decreases with increasing the percentage of fillers indicating the occurence of conducting behavior. In GCNTs-ABS composites Nyquist plots showed the appearance of a single straight line. The dielectric responses of MWCNTs, GCNTs reinforced ABS composites were investigated. The dielectric constant of MWCNTs-ABS composites gets enhanced significantly with addition 0 to 3 wt MWCNTs. Room temperature AC conductivity increased with increase in the wt. % of MWCNTs and GCNTs from 10(-12)S/cm for the unfilled polymer to 10(-5)S/cm for 10 wt % of MWCNTs-ABS and 10(-7)S/cm for 10 wt % of GCNTs-ABS composites. The decrease in impedance and enhancement of dielectric properties were due to the interfacial polarization between MWCNTs and ABS. Improved conductivity of MWCNTs-ABS and GCNTs-ABS composites may be useful in electromagnetic interference (EMI) shielding and antistatic materials