Microstructures and Luminescent Properties of Sm³⁺‐Doped KSr₂Nb₅O₁₅ Prepared by Molten Salt Synthesis Method

Abstract

Recently, photochromic ceramics with luminescence modulation behavior gradually developed into a hot point in inorganic materials, and the coupling between photochromic and luminescent properties will enhance the readout rate of information and convenience. [1,2] Mainstream photochromic systems include (K 0.5 Na 0.5 )NbO 3 (KNN), [3] Na 0.5 Bi 2.5 Nb 2 O 9 (NBN), [4] Na 0.5 Bi 0.5 TiO 3 (NBT), [5] SrSnO 4 (SS), [6] BaMgSiO 4 (BMS), [7] PbWO 4 (PWO), [8] and their compounds. [9,10] Due to the stable and excellent luminescence properties of rare-earth ions dopants, [11][12][13] most of the inorganic photochromic compounds relied on the introduction of rare-earth activator to obtain luminescence properties, and realized the luminescence modulation by the resonance energy transfer from luminescent center to photochromic center. [3][4][5][6][7][8][9] KSr 2 Nb 5 O 15 (KSN) lead-free ferroelectric materials exhibit excellent multifunctional features, including dielectric, ferroelectric, thermoelectric, electro-optic, photocatalytic, and photoluminescent, photochromic areas. [14][15][16][17] Due to the typically tetragonal tungsten bronze (TTB) structure, doping modification of KSN can be flexibly executed, and there are abundant sites available for occupying with alkali, alkali-earth, and rare-earth cations. [18] The photochromic effects of KSN ceramics were reported in our previous work in 2019. [17] The absorbance (and reflectivity) of KSN ceramics could be reversibly changed by alternating the light irradiation (395 nm) and thermal treatment, which exhibit various potential applications in optical information storage and recording, optical antifake, and sensors. [7,19,20] For tungsten bronze type host, the luminescent properties of Eu 3þ -doped NaSr 2 Nb 5 O 15 , [21] Dy 3þ -doped KBa 2 Nb 5 O 15 , [22] and RE 3þ (RE ¼ La, Pr, Nd)-doped KSr 2 Nb 5 O 15 [16] have been reported, and these systems exhibited the predominance in the charge transfer transition between rare-earth activator and hosts, and good luminescent emission properties. Moreover, compared with other systems, the KSN-based materials possess the TTB type structure and significant anisotropy on the optical properties, including photochromic, luminescent, and luminescence modulation properties. [23] Based on these features, the KSNbased textured ceramics with obvious grain orientation have