Preparation and study of magnetic properties of silico phosphate glass and glass-ceramics having iron and zinc oxide

Highly crystalline superparamagnetic iron oxide nanoparticles (SPION) in a silica matrix

“…These magnetic properties arise both from the atoms which reside on the surface of the nanoparticles, and from the finite number of atoms in the nanoparticle crystalline core. It has been shown that particle size, morphology, defects, core-shell and dipolar interactions have a large influence on the magnetic properties of the samples [1,56,62,63,65,[67][68][69][70][71][72][73][74]. Moreover, the finite size and surface effects are usually masked by the presence of particle size distribution and by a magnetic interaction between the particles, and it is very difficult to distinguish the real contribution of finite size and surface effects on the magnetic properties.…”

“…Consequently, preparation of the magnetic nanoparticles requires several tasks, such as control of the size and size distribution of the particles, control of the morphology and crystallinity, and prevention of the agglomeration. Different preparation methods have been developed in order to obtain desirable samples and physical properties: hydrothermal, sol-gel, solvothermal, mechanochemical, polyol process, co-precipitation, template, thermal decomposition, spray pyrolysis, chemical vapour deposition, carbothermal reduction, electro-precipitation, microwave plasma synthesis, ␥-irradiated water-in-oil microemulsion, melt quench technique, microemulsion and reverse microemulsion technique [1,48,59,62,68,70,[73][74][75][76][77][78][79][80]. Among them the sol-gel method has been shown to be very useful for preparation of iron oxide nanoparticles dispersed in an amorphous silica matrix.…”

Some recent studies on glass/glass-ceramics for use as sealants with special emphasis for high temperature applications

“…Glass-ceramics display a large number of useful properties that include high chemical durability, resistance to thermal and mechanical shocks and the possibility of tuneable thermal expansion coefficient (TEC) [6][7][8]. As a result, glass-ceramics find wide ranging application in cookware, telescope mirror  supports, hermetic sealing, etc [9][10][11][12]. The thermophysical properties of glass-ceramics are a function of not only the composition but also the crystallization heat treatment.…”

“…Therefore, for various applications, the compositions, nucleating agents (to crystallize the desired phases) and heat treatments must be judiciously optimized to obtain materials with the necessary thermo-physical properties. In this article we review sealing of glass-to-metal/alloy and glassceramics-to-metal/alloy with a focus on some recent sealing glass-ceramic development [1][2][3][11][12][13]. One of the recent applications of glass-ceramics, which places great demand on materials performance, is sealing of solid oxide fuel cells (SOFCs) using glass/glassceramics, to effectively channel fuel and oxidant (commonly air) [14][15][16][17][18][19][20].…”

Structural and surface studies on calcium phospho-silicate glass-ceramics containing zinc and iron oxide

“…Zinc is also known to prolong chemical durability of glass, by retarding its dissolution and reaction in aqueous solutions, and thus improving the mechanical properties of the implant [13]. The addition of zinc to iron containing glass may lead to the formation of zinc ferrites, which enhance the magnetic properties, thus, a number of glass systems containing iron and zinc have also been studied and developed [14,15]. Sing et al [16] observed an increase in the apatite-forming ability of ZnO containing glass-ceramic samples with the evolution of Zinc ferrites in the glass-ceramics.…”