Chemical durability, electrical and dielectric properties of the ternary system (50-x)K2O???xMnO???50P2O5 phosphate glassesAuthor(s): El Moudane M
Potassium phosphate glasses containing MnO ranging from 20 to 35 mol % have been synthesized using melt-quenching method. The amorphous nature of the samples was confirmed by XRD. The chemical durability of these studied glasses increases with MnO content. Glasses having more than 30 mol% MnO had an excellent chemical durability. The electrical and dielectric parameters were measured in the frequency range from 10 KHz to 1 MHz in the temperature range from room temperature to 550°C. It was observed that the values of ac conductivity increase with frequency. The conductivity of all the glasses increases with temperature following the Arrhenius law. Activation energy was found to increase with raise in amount of manganese oxide and decrease with the frequency. It was also observed that the values of dielectric constant and loss factor enhance and decrease respectively with increasing temperature and frequency. These results agree with a closer structure and act in a manner that manganese enters the glassy matrix as a network former character. K2O–MnO–50P2O5 glasses containing different concentrations of MnO ranging from 20 to 35 mol % have been prepared using conventional melt-quenching technique. The amorphous nature of the samples was asserted by X–ray diffraction. The chemical durability of these glasses increases with rising MnO content. Glasses containing more than 30 mol%MnO had an excellent chemical durability. The electrical and dielectric parameters were measured in the frequency range from 10 KHz to 1 MHz in the temperature range from room temperature to 550°C. It was observed that the values of ac conductivity augment on increasing frequency. The conductivity of all the glasses increases with temperature following the Arrhenius law. Activation energy was found to increase with raise in concentration of manganese oxide and decrease with the increase in the frequency. It was also observed that the values of dielectric constant and loss factor enhance with the increase in temperature and decrease with increase in frequency in all the glasses studied. These results agree with a closer structure and act in a manner that Mn2+ enters the glassy matrix as a network former character. Phosphate glass is a class of optical glasses composed of metaphosphates of various metals. Instead of SiO2 in silicate glasses, the glass forming substrate is P2O5. Dr. Alexis G. Pincus of the American Optical Company supplied aluminium phosphate glass samples for Manhattan Project-era Oak Ridge researchers, and was anecdotally called the inventor in 1945 in a Columbia University researcher's note by Aristid V. Grosse. P2O5 crystallizes in at least four forms. The most familiar polymorph (see figure) comprises molecules of P4O10. The other polymorphs are polymeric, but in each case the phosphorus atoms are bound by a tetrahedron of oxygen atoms, one of which forms a terminal P=O bond. The O-form adopts a layered structure consisting of interconnected P6O6 rings, not unlike the structure adopted by certain polysilicates. The P4O10 cagelike structure which provides the basic building block for phosphate glass formers. Phosphate glasses are highly resistant to hydrofluoric acid. With an addition of iron oxide, they act as efficient heat absorbers. Iron phosphate and lead iron phosphate glass are alternatives to borosilicate glass for immobilization of radioactive waste. Phosphate glasses can be advantageous over silica glasses for optical fibers with high concentration of doping rare earth ions. A mix of fluoride glass and phosphate glass is fluorophosphate glass. Silver-containing phosphate glass is used in phosphate glass dosimeters. It emits fluorescent light when irradiated by ultraviolet light, when previously exposed to ionizing radiation, in an amount proportional to the dose. Some phosphate glasses are bio-compatible and water-soluble and are suited for use as degradable tissue and bone scaffolds within the human body. Recent developments of phosphate glasses for a variety of technological applications, from rare-earth ion hosts for solid state lasers to low temperature sealing glasses, have led to renewed interest in understanding the structures of these unusual materials. In this review, spectroscopic and diffraction studies of simple phosphate glasses, including v-P2O5 and binary phosphate compositions, are described. Special attention is given to the structures of anhydrous ultraphosphate glasses, which have received close attention from the glass community only in the past six years. This paper investigates the dielectric properties and magnetic properties of epoxy composites with different amount of powdered iron phosphate glass (IPG) at 8.2 GHz to 12.4 GHz using microwave technique. IPG composed of 60P2O5-40Fe2O3 (mol%) was produced by conventional melt and quenching method and crushed into powder. The IPG powder was characterized using energy dispersive X-ray spectroscopy (EDS), particle size analyzer and powder X-ray diffraction (XRD). Different amount of IPG (10-70 wt%) were dispersed in the epoxy. The epoxy-IPG composites were characterized by their morphology, elemental composition and scattering parameters using scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and vector network analyzer (VNA), respectively. Reflection coefficient, |S11| increases whereas transmission coefficient, |S21| decreases with increasing IPG content in epoxy. Dielectric constant, εr' of epoxy-IPG composites were found increased with the IPG content from 3.33 to 4.69. Phosphate glasses are chemical durable compared with most silicate and borosilicate glasses. The addition of iron to phosphate glasses strengthens the chemical bonds in the glass structure and further improves the chemical durability. This property allows iron phosphate glasses to be used in hazardous wastes immobilization . Iron phosphate glasses exhibit low melting temperature (typically between 950 and 1150 °C). The batch materials of iron phosphate glasses couple well with microwave radiation. Therefore, microwave heating technique is introduced to produce iron phosphate glass . The technique is a fast and energy-saving alternative to the conventional heating technique using furnaces. The microwave radiation interacts with ions and dipoles in the batch materials, and increases their temperature to the melting point. Besides using microwave to heat the batch materials, microwave can also be used to investigate various properties of glasses.