A unified model for temperature dependent electrical conduction in polymer electrolytes

The observed temperature dependence of electrical conduction in polymer electrolytes is usually fitted with two separated equations: an Arrhenius equation at low temperatures and Vogel-Tamman-Fulcher (VTF) at high temperatures. We report here a derivation of a single equation to explain the variation of electrical conduction in polymer electrolytes at all temperature ranges. Our single equation is in agreement with the experimental dataComment: 13 pages, 2 figure

Second Order Phase Transition and Universality of Self-Buckled Elastic Slender Columns

Self-buckling is an interesting phenomenon that is easily found around us, either in nature or in objects made by human. Palm fronds which initially directed upward when they were short and turned into bending after appreciably longer is an example of the self-buckling phenomenon. We report here that the self-buckling of columns can be treated as a process of second order phase transition by considering the straight column as disorder state, the bending column as order state, and the temperature as the inverse of column length. The critical temperature corresponds to the inverse of critical length for buckling, 1/Lcr, and the deviation angle made by column free end relative to vertical direction satisfies a scaling relationship with a scaling power of 0.485. Changing of the column geometry from the vertically upward to the bending state can be considered as a transition from disorder state to order state.Comment: Accepted for publication in Journal of Taibah University for Science 23 pages, 6 figure

New Design of Potentially Low-cost Solar Cells Using TiO2/Graphite Composite as Photon Absorber

A solar cell design using the combination of titanium dioxide and graphite as active photon absorbing materials were proposed. The titanium dioxide absorbs photons of nearly ultraviolet wavelengths to produce electron hole pairs, while graphite is expected to absorb photons of longer wavelengths. Although many authors have claimed that graphite is not a semiconductor, we observed that a model of a solar cell containing titanium dioxide only as the active material behaves exactly the same as a model containing graphite only as the active material. Additionally, we observed that a model of a solar cell made using a composite of titanium dioxide and graphite as the active material had much higher efficiency than solar cells made using titanium dioxide only or graphite only active materials.Comment: 3 figure

Percolation Model for Proton Immobility in Ice

A simple Ising model and a statistical theory of gel formation in a polymer matrix were combined to explain the effect of temperature on the mobility of protons in ice. Cowin et al observed that protons in ice bulk were immobile at temperatures below 190 K, and suddenly become mobile at temperatures above 190 K [Nature 398, 405 (1999)]. We proposed here that the transport of protons is controlled by a percolation mechanism. The proton transport is facilitated by the occurrence of easily reoriented water molecules in the ice bulk. The fraction of this molecule depends on temperature and was calculated using a simple Ising model. The formation of network of these molecules which provides pathways for proton transport was calculated using a statistical theory of gel formation in a polymeric system. Our model succeeded to reproduce the variation of potential difference between the ice film surfaces with respect to temperature as observed by Cowin et al based on a soft landing experiment

Luminescent Polymer Electrolyte Composites Using Silica Coated-Y2O3:Eu as Fillers

Luminescent polymer electrolyte composites composed of silica coated Y2O3:Eu in polyethylene glycol (PEG) matrix has been produced by initially synthesizing silica coated Y2O3:Eu and mixing with polyethylene glycol in a lithium salt solution. High luminescence intensity at round 600 nm contributed by electron transitions in Eu3+ (5D0 → 7F0, 5D0 → 7F1, and 5D0 → 7F3 transitions) were observed. The measured electrical conductivity was comparable to that reported for polymer electrolyte composites prepared using passive fillers (non luminescent). This approach is therefore promising for production of high intensity luminescent polymer electrolyte composites for use in development of hybrid battery/display