Study on structural, morphological, and spectral properties of LiMPO4: Eu3+, B3+(M = Zn, Sr) phosphors and latent fingerprint applications

Boron influences the melting point, crystallization, and both the optical and structural characteristics of ceramic materials. The effect of boron on the structural, morphological, and spectral properties for LiMPO4:xEu3+, yB3+ (where M = Zn or Sr and x = 3 mol%, y = 0-100 mol%) phosphors was investigated using materials fabricated with the solid-state method. In XRD results, LiZnPO4:Eu3+, B3+ series showed a single-phase structure up to 100 mol%, while LiSrPO4:Eu3+, B3+ samples exhibited a low monoclinic phase at low concentrations. In SEM micrographs, the flux effect of boron caused growth in LiMPO4:Eu3+, B3+ (M = Zn, Sr) grains sizes. As the B3+ concentration increases, PL emissions for both phosphor series increased up to 100 mol%, and the luminescence intensities increased over 8 times. Judd-Ofelt (JO) parameters (Q2, Q4) showed a slightly increasing trend for LiZnPO4:Eu3+, B3+, whilst the change in Q2 and Q4 parameters was limited for LiSrPO4:Eu3+, B3+ series. As the B3+ concentration increased, the observed lifetime (z) of LiZnPO4:Eu3+, B3+ with a bi-exponential decay decreased, whereas the z lifetime for LiSrPO4:Eu3+, B3+ with a mono exponential decay increased. The quantum efficiencies for LiSrPO4:Eu3+, B3+ phosphors varied between 89.83 %-96.78 % and exhibited approximately twice the efficiency of LiZnPO4:Eu3+, B3+. The usability of optimized LiMPO4:xEu3+, yB3+ (where M = Zn, Sr and x = 3 mol%, y = 100 mol%) phosphors was investigated for latent fingerprint applications.