Thermal Behavior Of Films Research Articles

Photo-Electrical Tandem of Modulated Polyvinyl Alcohol Based Plasticized Solid Polymer Electrolyte Nanocomposite Films: Effect of Propylene Carbonate Contents

Plasticized solid polymeric electrolyte nanocomposites based on polyvinyl alcohol (PVA) incorporating Cs2CuO2 nanoparticles (NPs), electrolyte salt (LiClO4) and plasticizer (PC) were prepared via solution casting technique. The dynamic light-scattering histogram revealed that the prepared Cs2CuO2 NPs have a size in the range of 80-120 nm. The interaction between different components in PVA/Cs2CuO2/LiClO4-PC films (plasticized PVA-SPEs) were probed by FTIR, while the surface and structure were evaluated by SEM and XRD, which indicate to amorphous nature of plasticized PVA-SPEs. The thermal behavior of films was measured via TGA, where a partial decrease in the thermal stability of films was noticed with an increase of PC content in the PVA-SPEs. The highest conductivity achieved is 9.56X10-5 S/cm for PVA-SPEs containing 8wt% PC at 298K. The plasticized PVA-SPEs exhibited higher specific capacitance by two folds and photovoltaic efficiency by three folds compared to pure PVA matrix.

Application of thermal analysis and kinetic predictions to YBCO films prepared by chemical solution deposition methods

Fluorine-based chemical solution deposition routes to prepare YBa2Cu3O7-∂ films were characterized with the aid of thermal analysis techniques. Thermogravimetric analysis and X-ray diffraction were applied to characterize the main steps of the fluorine-based route: pyrolysis of the organic material and growth of the oxide. The difference between the thermal behavior of films and powders in fluorine-based chemical solution deposition route is reiterated to justify the importance of the study of films. Finally, the kinetic analysis is used to predict the mass evolution of the pyrolysis for an arbitrary temperature program with the aim to optimize this treatment to minimize film porosity and crack formation.

Thermal behaviour of films of partially neutralized poly(acrylic acid). 3: Effect of magnesium and calcium ions

AbstractPartially neutralized polyacrylates of calcium and magnesium have unexpectedly been found not to undergo thermal decarboxylation at 250°C, unlike partial polyacrylates of lithium, sodium or potassium. Reflectance infrared spectroscopy has confirmed that the partial polyacrylate of calcium is predominantly ionic but as with the magnesium compound, this does not promote decarboxylation. Further study of the partial lithium salt of poly(acrylic acid) has confirmed that lithium ions exhibit some degree of covalency, and hence are probably site‐bound. Despite this, they succeed in promoting decarboxylation. It is concluded that the main factor which prevents calcium and magnesium facilitating decarboxylation is their divalency, rather than any inherent tendency to become site‐bound. Reasons for this are discussed.

Thermal behaviour of films of partially neutralized poly(acrylic acid). 2: The influence of univalent cations

Further studies have been carried out on the thermal behaviour of partially neutralized poly(acrylic acid), using ammonium or sodium ions as the neutralizing species. It was found that, unlike the partial poly(acrylates) of lithium, sodium or potassium, partially neutralized ammonium poly(acrylate) did not undergo thermal decarboxylation on heating to 250°C. Instead, the anhydride groups, formed by reaction of the unneutralized portions of the poly(acrylic acid) macromolecule, underwent no further reaction. On the other hand, further study of the decarboxylation of 10% neutralized sodium poly(acrylate) has shown the process to be first-order in anhydride groups, with a rate constant of 2 23 × 10-3 s−1 at 250×C. A mechanism consistent with the kinetic data is proposed to account for the overall sequence leading to decarboxylation.

Thermal behavior of noncrystalline sputtered films in the system GeTe

As part of a systematic study of vapor deposited noncrystalline solid (VDNCS) sputtered films in the GeTe system, this paper reports on the thermal behavior of these films. Heating experiments were conducted on samples of various compositions throughout the NCS forming region which extends from pure Ge to at least 95 at.% Te. The crystallization temperatures of the films have been shown to be highly reproducible and sensitive to the particular NCS structure. At compositions from 70 to 95 at. % Te and at 30 at. % Te two stage crystallization was observed, in which the Te phase and Ge phase, respectively, crystallized first, followed in both cases, by crystallization of GeTe. All other compositions showed single stage crystallization in which the two phases, either GeTe + Te or GeTe + Ge, crystallized simultaneously. The possible existence of non-uniform structure in the films is indicated in the data on two stage crystallization. The relation between the crystallization temperature and the degree of disorder, or structure, of the VDNCS films is discussed with emphasis on both the composition and conditions of preparation of the films. The relevance of the current results to memory switch device research is noted.