S. S. Bhoga

Influence of aliovalent cation on the conductivity of monoclinic Li2SO4 and the sulphate-carbonate eutectic

Abstract The extension of the solid solubility of MSO 4 (M = Mg, Ca, Sr and Ba) in β-Li 2 SO 4 has been observed due to quenching the melt at room temperature. The substitution of Li + by aliovalent cations gave an enhancement in the conductivity by about an order of magnitude for Li 1.87 Ca 0.0638 2+ □ 0.0638 SO 4 . A similar study has been carried out for Li 2 SO 4 : Li 2 CO 3 (60: 40) eutectic, where the conductivity decreases.

Fabrication of 1D Microtubes of ZnS by Microwave Irradiation Method

1D tubes of ZnS were prepared by microwave irradiation process. The X-RD pattern indicated that as-prepared sample was hexagonal ZnS structure with cell constant a = 3.5277 A° and c = 5.79 A°. SEM observed the tubes-like structure having the length ranging from 10–20 μm with the average diameter of 5 μm and wall thickness of 1–2 μm. The EDAX pattern exhibited the atomic percentage ratio of Zn : S = 59 : 41, indicating that it was rich in zinc. Effect of microwave power and exposure time on the growth process was investigated. It was revealed that the microwave power plays a vital role in determining the diameter of the tubes. This simple technique using a multimode microwave source may prove to be a potential tool for growing similar 1D structure of other -oxide, -sulphide, -selenide based compounds.

Preparation and Characterization of Proton Conducting Polymer Electrolyte

Ammonium acetate complexed polyvinyl alchohol (PVA) samples are prepared following the solution cast technique. Pure PVA shows semicrystalline nature. The amorphous nature of the PVA increases with the increase in ammonium acetate salt concentration in it. The bands due to pure PVA in FTIR spectra shift towards higher frequency region with increase in concentration indicate salt dissolution. The 20 mole% ammonium acetate complexed PVA exhibits highest conductivity at 25°C amongst all samples under study.

Galvanic CO2 sensor with Li2O: B2O3 glass ceramics based composite

In order to develop an electrolyte with better thermal-stability, a new composite is prepared by partially crystallizing the lithium borate glass along the grain boundaries of Li2CO3: BaCO3 binary system. Highly dense material is obtained on controlled partial crystallization. The structural and electrical characterization proved its composite nature with enhancement in conductivity. A few potentiometric CO2 gas sensors prepared by using optimized composite electrolyte with lithium titanate as the reference electrode. This configuration resulted in a device of high mechanical strength with ease of fabrication and free from interfacial failures. Reproducible and reversible response is obtained for these sensors over a long-term operation at lower temperatures (275 – 450 °C). The sensor response found to obey Nernst relation with sensitivity and emf approaching the theoretical value.

Influence of LiX (X=F, Cl and Br) addition on the ionic conductivity of 6Li2SO4:4Li2CO3 eutectic system

Abstract The ionic conductivity of 6Li 2 SO 4 :4Li 2 CO 3 eutectic system with the addition of LiX (X=F, Cl and Br) has been systematically investigated as a function of impurity concentration, temperature and frequency. The observed enhancement in ionic conductivity has been explained in the light of dispersed phase theory.

Kaluza–Klein Cosmological Model, Strange Quark Matter, and Time-Varying Lambda

In this paper, exact solutions of the Einstein field equations of the Kaluza-Klein cosmological model have been obtained in the presence of strange quark matter. We have considered the timevarying cosmological constant Λ as Λ = αH2 + βR-2, where α and β are free parameters. The solutions are obtained with the help of the equation of state for strange quark matter as per the Bag model, i.e. quark pressure p = 1/3(ρ - 4BC), where BC is Bag’s constant. We also discussed the physical implications of the solutions obtained for the model for different types of universes.

Structural and Electrical Characterization of Ce1-x Cu x O2-δ (x = 0.05–0.5) Prepared by Combustion Technique

The XRD confirms the formation of Ce1-x Cu x O2-δ (x = 0.05, 0.1 and 0.3). The solid solubility limit for Ce1-x Cu x O2-δ is up to x = 0.3. The crystallite size of material decreases with an increase in content of Cu. The Cu addition increases the porosity. The highest conductivity 1.83 × 10−3 Scm−1 is achieved for x = 0.5. The combustion synthesis method gives nanostructured materials leading to good electrically conductivity.

Study of Mechanochemically Prepared Nanostructured Nd1.8Ce0.2CuO4 Cathode

The Nd1.8Ce0.2CuO4, a mixed ionic-electronic conductor (MIEC), forms on ball milling reagents with stearic acid as process control agent (PCA) at 600 revolutions per minute for 4 h and subsequently sintering at 900°C for 9 h. Nd1.8Ce0.2CuO4 without PCA does not form in spite of ball milling for 12 h and subsequently sintered at 900°C for 9 h. The mechanochemical alloying with PCA not only lowers sintering temperature considerably but also shortens sintering time. It also provide nano-structured (∼130 nm) compound. The Nd1.8Ce0.2CuO4 with ethanol as PCA gives conductivity, 0.822 S cm−1 at 600°C, which is highest amongst all.

Synthesis and Characterization of Nanosized Dy-Doped of Ceria Developed by Microwave Assisted Combustion Route

Nanosized Ce1-xDyxO2-x/2 (DDC, x = 0.05—0.25 mol%) were synthesized by combustion routes induced by microwaves (MS) and compared with the same composition prepared by conventional (CS) method. The conventional and microwave sintering routes were also used to consolidate the pellets. The samples were characterized by X-ray diffractometry (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and AC impedance spectroscopy. The as-combusted powders prepared by microwaves were found to be pure oxides with low crystallinity, and exhibited excellent sintering behavior. Highly dense DDC pellets with fine and homogeneously grown grains (400 nm) were achieved by microwave, while conventionally densified pellets had average grain size of 1100 −1400 nm. The ionic conductivity measured for pellet sintered by MS at 1050°C for 1 h is, σ550°C = 7.42 × 10−2 S/cm, Ea = 0.86 eV, and for CS at 1300°C for 5 h, is σ550°C = 9.79 × 10−3 S/cm, Ea = 1.05 eV.

Performance of solid state protonic battery with different cathodes

To establish the fact that the performance of a solid state battery is predominantly governed by the cathode, primary electrochemical cells were fabricated using FeH(SO4)2-xH2O solid electrolyte having proton transport number close to unity (prepared by chemical route) taken in conjunction with five different cathodes MnO2, PbO2, V6O13, I2 and TMAI iodine complex. Amongst these, better discharge characteristics along with thermodynamic and chemical stability of the cell were offered by TMAI iodine complex based cathode. Beside these, it provided short-circuit current, capacity and energy density of the order of 5 mA 4.5 mAh and 2.67 Wh/kg respectively due to the presence of highly active iodine, which is not free in TMAI compared to the cathode made of simply I2.