Influence of Nano-Filler Concentration on Transport Properties of PVA-PEO Blend Systems

In the present study, two different PVA-PEO nanocomposite blend polymer electrolyte systems viz., System-I: [(PVA)(42.5):(PEO)(42.5):(AgNO3)(5):(PEG)(10):(Al2O3)(x)] and System-II: [(PVA)(47):(PEO)(47):(LiCF3SO3)(9):(EC)(6):(Al2O3)(x)] are prepared using solution cast technique for various Al2O3 nanofiller amounts ranging from 2 to 10 wt%. The influence of Al2O3 concentration on the transport properties of the electrolytes of both these systems is closely inspected. Here, the ionic transport number (ti) measurements of the blend specimens are carried out using ‘dc Polarization Technique’.

Transport and Morphological Properties of Gel Polymer Electrolytes Containing Mg(CF3SO3)2

Magnesium-ion conducting gel polymer electrolytes (GPEs) based on PMMA with ethylene carbonate (EC) and propylene carbonate (PC) as a plasticizing solvent were prepared via the solution casting technique. Mg(CF3SO3)2 salt was used as source of magnesium ions, Mg2+. The variation of conductivity with salt concentrations, from 5 wt.% to 30 wt.% was studied. The gel polymer electrolyte with composition 20 wt.% of Mg(CF3SO3)2 exhibited the highest conductivity of 1.27 x 10-3 S cm-1 at room temperature. The conductivity-temperature dependence of gel polymer electrolyte films obeys Arrhenius behaviour with activation energy in the range of 0.18 eV to 0.26 eV. Ionic transport number was evaluated using DC polarization technique and it reveals the conducting species are predominantly ions. It is found that the ionic conductivity and transport properties of the prepared GPEs are consistent with the X-Ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM) studies.

Electrical Conductivity of Piezoelectric Strontium Bismuth Titanate Under Controlled Oxygen Partial Pressure

Hysteresis free and linear piezoelectric behavior of SrBi4Ti4O15 (SrBIT) is very promising for precise sensors/actuators devices. Despite a quite low longitudinal piezoelectric coefficient (around 15 pC/N), its elevated ferroelectric phase transition temperature (540°C) allows its use above 300°C. Electrical conductivity at such temperatures should be kept as low as possible in order to avoid loss of piezoelectric properties or charge drifts. Under reducing conditions, however, the electrical conductivity may change considerably. The electrical conductivity of SrBi4Ti4O15 (SrBIT) has been measured under controlled oxygen partial pressure at elevated temperatures (700-900°C) from 1 atm down to 10−15atm. From 1 atm down to 10−15 atm pO2, above 700°C, the conductivity of SrBIT exhibits a -1/4 slope in log-log scale indicating n-type conductivity and an impurity controlled oxygen vacancy concentration. A conductivity minimum is observed around 0.2 atm for undoped SrBIT at 800°C. Acceptor doping (Mn) raises the minimum and flattens the conductivity curve with slope around -1/10 at 700°C, and -1/6 at 900°C. Ionic conductivity and defect ionization are discussed to account for this. Preliminary results indicate the possibility of a large, pO2 independent, region, down to 10−15atm pO2. The ionic transport number was found to be 0.42 at 800°C for undoped SrBIT and 0.75 for Mn doped SrBIT. The activation energies of undoped (1.35 eV) and Mn doped (1.44 eV) samples are close to each other as expected for a common mechanism

Defect Chemistry of “BaCuO2” II. Transport Properties and Nature of Defects

The charge transport properties of "BaCuO2" with 88:90 (Ba :Cu) cation ratio were characterized by thermopower, electrical conductivity and ionic transport number measurements in a wide range of temperature and oxygen partial pressure conditions. The nature of carriers is always represented by small polarons due to self-trapping of the electronic holes generated by the oxygen non-stoichiometry equilibrium. Some anomalies in carrier mobility as a function of temperature are shown not to be related to incomplete ionization of oxygen atoms on interstitial sites