Photoemission and energy gap of MgWO4 particles connecting as nanofibers synthesized by electrospinning-calcination combinations

Mixtures of magnesium acetate tetrahydrate ((CH3COO)2Mg·4H2O), ammonium tungstate tetrahydrate ((NH4)6W7O24·4H2O), and poly(vinyl alcohol) with the molecular weight of 72,000 were electrospun through a +15 kV direct voltage to form fibers on ground flat aluminum foils. The electrospun fibers of 1.5, 3.0, and 4.5 mmol of each starting material containing 1.3 g poly(vinyl alcohol) were further calcined at 500-700 °C for 3 h constant length of time. At 500 and 600 °C calcination, both monoclinic and anorthic phases of MgWO4 particles with different sizes connecting as fibrous assemblies were detected. Upon increasing the calcination temperature to 700 °C, only monoclinic phase of facet nanoparticles interconnecting along the fibrous axes with 4.19 eV indirect band gap and 461 nm photoemission was synthesized. In the present research, formation of MgWO4 molecules as well as nucleation and growth of nanoparticles was also proposed.

► MgWO4 fibers as a semiconducting material. ► A lab-made electrospinning equipment enables us to form as-spun fibrous precursor. ► The precursor was further calcined at 700 °C for 3 h to synthesize MgWO4. ► It was composed of particles with different sizes connecting as fibrous assemblies. ► A promising material for a number of technological applications.