The ion exchange properties of nanosized cerium molybdo iodate and cerium phospho iodate

Nanoparticles of cerium molybdo iodate and cerium phospho iodate, tetravalent metal acid (TMA) salts were prepared by chemical co-precipitation method.The protons present in the structural hydroxyl groups indicate good potential for TMA salts to exhibit solid state proton conduction. The samples in its protonated form weresubjected to ion exchange capacity studies. The data revealed that the samples act as agood ion exchanger

Electrical conductivity and ion exchange studies of nano sized cerium (IV) tungsto iodate — A new cation exchanger

488-490Nano particles of cerium tungsto iodate, a tetravalent metal acid salt, have been prepared by chemical co-precipitation method. The particle size of the sample has been calculated from its X-ray diffraction pattern and the average grain size is found to be 25 nm. The size is further characterized by SEM, TEM and FTIR analyses. Its dielectric behaviour at various temperatures (50<span style="mso-bidi-font-family: " times="" new="" roman""="" lang="EN-GB">°-110°C) and frequencies is also investigated. The dielectric constant values increase with the decrease in frequency and the increase in temperature. Moreover, the sample in its protonated form is subjected to ion exchange capacity studies. The data reveals that the sample works as a good ion exchanger. </span

Characterization, dielectric and optical studies of nano-cerium phospho iodate synthesized by chemical co-precipitation method

299-304Nanoparticles of cerium phospho iodate belong to the class of tetravalent metal acid (TMA) salt are synthesized by chemical co-precipitation method. The particle size obtained from X-ray diffraction spectrum is found to be in the range of 30 nm. Surface morphology is studied from SEM images. The chemical composition of the sample has been verified using EDAX. The optical studies are carried out using FTIR and UV techniques. The stretching and bending frequencies of the sample are studied using the FTIR spectrum. The optical direct band gap of the material calculated using the Tauc’s relation is found to be 3.4 eV. The dielectric behaviour of the samples is studied at various temperatures and frequencies and ac electrical conductivity is also calculated. It is found that dielectric constant decreases with increase in frequency

Characterization, dielectric and optical studies of cerium molybdo tungstate nanoparticles

893-898Nanoparticles of cerium molybdo tungstate (CMT) have been prepared by chemical co-precipitation method. The average particle size is determined from X-ray diffraction studies. The nanoparticle nature of the sample is verified using SEM, TEM and AFM images. The surface morphology of the sample is studied from SEM image. The FTIR spectrum has been used to study the stretching and bending frequencies of molecular groups in the sample. Temperature and frequency dependence of the dielectric constant and ac electrical conductivity have been investigated. The dielectric permittivities of the samples are evaluated from the observed capacitance values in the frequency range 100 Hz-1 MHz and in the temperature range 50°-110°C. It has been found that with increasing frequency, the dielectric constant decreases. The high value of dielectric constant at low frequencies may mainly be due to the space charge and rotational polarization. Also, the dielectric constant increases with increase in temperature for fixed frequencies. As the temperature increases more and more dipoles will be oriented resulting in an increase in molecular dipole moment. The ac electrical conductivity is evaluated from the permittivity studies. The absorption spectra of the sample in the UV range are recorded. From the analysis of the absorption spectra, the material is found to have a direct band gap of 3.2 eV

Clay Intercalation and its Influence on the Morphology and Transport Properties of EVA/Clay Nanocomposites

Nanocomposite membranes based on poly-(ethylene-co-vinyl acetate) copolymer (18% vinyl acetate content)and two different organomodified clays have been prepared by mechanical mixing using two roll mill method. The morphology of the nanocomposites was investigated using small angle X-ray scattering, scanning electron microscopy, and transmission electron microscopy. The mechanical and thermal studies were also performed using universal testing machine and differential scanning calorimeter, respectively. Samples with low filler content showed excellent dispersion of layered silicates resulting in a partially exfoliated structure. The diffusion and transport of organic solvents through the membranes have been investigated in detail as a function of clay content, nature of solvent and clay, and temperature in the temperature range of 28−70 °C. The influence of free volume on the transport properties of the membranes was studied using positron annihilation lifetime spectroscopy. The solvent uptake was minimum for composites with 3 wt % of filler, and it get increased with increasing filler content, which is presumably due to aggregation of clay filler at higher loading. The transport phenomenon was found to follow an anomalous mode. Activation parameters were estimated, and the molar mass between cross-links was calculated. Finally, the experimental transport data were compared with theoretical predictions