Optical transmittance and energy storage properties of potassium sodium niobate glass-ceramics

In this work, 0.8(K2O-Na2O-2Nb2O5)-0.2((1-x)B2O3-xP2O5) (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) glass-ceramics have been fabricated. The effects of P2O5 on the microstructure and properties of the glass-ceramics were comprehensively studied. The addition of P2O5 promotes the transition of the glass network structure from a negatively charged [B∅4]- tetrahedron to an electrically neutral [BP∅4] tetrahedron. With the increase of P2O5 content, the formation of K2B4O7 is inhibited, with major phase of Na0.9K0.1NbO3 and minor phase of K2B4O7. It is found that the band gap width of the glass-ceramics increases from 3.34 eV to 3.52 eV firstly and then decreases to 3.43 eV. The grain size of the glass-ceramics decreases from 150 nm to 50 nm. High optical transmittance (63%), large discharge energy density (4.58 J/cm3) and large energy storage efficiency (98%) have been simultaneously obtained for K2O-Na2O-Nb2O5-B2O3-P2O5 glass-ceramics, which are potential for the applications of the transparent pulse capacitors.