Preparation and morphology of magnesium borate fibers via electrospinning

Magnesium borate fibers were prepared by electrospinning technique (and following calcination) from sol–gel precursors, using polyvinyl-pyrrolidone (PVP) as processing aid. Phase-pure fibers of about 6 μm in diameter were obtained by high temperature calcination of the inorganic–organic composite mats. The samples thus prepared were characterized by means of SEM, XRD and FT-IR, respectively. The concentration of the initial solution influenced only the fiber diameter in the green samples, while the final dimension after ceramization was related to the formation of new porous fibers in a preferential direction. This phenomenon resulted from some orientation already present in the green mats, and from the softening and densification of the fibers after decomposition of the PVP. An incomplete crystallization of the samples was observed after heat treatment at 800 °C, with a residual glassy phase due to the Mg modification of the B2O3 network. Fully crystalline fibers were obtained from the mats calcined at 1000 °C.