[en] Highlights: • 3 mol% Dy³⁺ doped cobalt niobate (CoNb₂O₆) compound has been synthesized by molten salt method. • The synthesized submicron CoNb₂O₆:Dy³⁺ particles were successfully incorporated into Polyamide 6 fibers by using electrospinning technique. • The smallest fiber diameter was gained from the solution including 0.1 g CoNb₂O₆:Dy³⁺ (applied voltage 38 kV, 15.5 cm distance). • Mechanical properties of the structures were highly correlated with the fiber characteristics and also fiber size (diameter) distribution. • Optical analysis of electrospun nanofibrous webs showed that the emission intensity increased by increasing CoNb₂O₆:Dy³⁺ phosphor content. - Abstract: 3 mol% Dy³⁺ doped cobalt niobate (CoNb₂O₆) compound has been synthesized by molten salt method using Li₂SO₄/Na₂SO₄ salt mixture as a flux at a relatively low temperature as compared to solid state reaction. X-ray diffraction patterns of 3 mol% Dy³⁺ doped CoNb₂O₆ compound indicated orthorhombic columbite single phase. SEM analysis revealed that Dy³⁺ doped CoNb₂O₆ has a submicron particle size. The photoluminescence of CoNb₂O₆:Dy³⁺ phosphor has exhibited in a dominant yellow emission at 579 nm with an excitation wavelength of 366 nm. The synthesized submicron phosphor particles were successfully incorporated into Polyamide 6 fibers by utilizing electrospinning technique. The average fiber diameter obtained through the process ranged between 192 ± 62 nm and 387 ± 341 nm. Mechanical characteristics of the produced nanofibrous webs were strongly influenced by the fiber morphologies and size (diameter) distribution rather than the phosphor particles incorporated into the fibers and/or located on the web. The photoluminescence of composite fiber material increased with the increasing phosphor content.