Photoluminescence and conductive properties of CaEuNbMoO₈ solid‐solution ceramics

Abstract

Solid‐solution ceramics show a potential in the field of electronic devices. In particular, it is necessary to investigate the photoluminescence and conductive properties of CaEuNbMoO8 (CENMO) solid solution ceramics. It is demonstrated that the sintered ceramics appear as CaMoO4 phase with scheelite structure. The results of X‐ray photoelectron spectroscopy show that the abnormal reduction of Eu3+→Eu2+ occurs in the ceramics, which is due to the formation of VCa′′$V_{Ca}^{^{\prime\prime}}$ vacancy caused by the substitution of Ca2+ by Eu3+, making it act as electron donors. The change of local symmetry of Eu3+ ions in ceramics results in a strong red fluorescence, and the charge transition between Eu, Nb, and Mo ions and O ions in the host lattice results in the near‐ultraviolet (near‐UV) excitation. As a result, CaEuNbMoO8 ceramic materials have promising applications in both near‐ultraviolet excited light‐emitting diodes and thermistors.

Structure modulation for synergistically optimizing photoluminescence and conductive property in EuNbO4–CaMoO4 ceramics

“…This structure is formed by solid solution of CaMoO 4 and EuNbO 4 of ABO 4 type and appears as a more stable scheelite‐type CaMoO 4 phase, such as CaEuNbMoO 8 solid‐solution ceramics. This unique solid‐solution structure allows CaEuNbMoO 8 to operate at higher temperatures (up to 1150°C) and to be more sensitive to temperature change (material constants up to 16955 K) 11 . In addition, Ca–Eu–Nb–Mo–O also has the property of emitting red fluorescence by near‐UV excitation 12,13 .…”

“…This unique solid-solution structure allows CaEuNbMoO 8 to operate at higher temperatures (up to 1150 • C) and to be more sensitive to temperature change (material constants up to 16955 K). 11 In addition, Ca-Eu-Nb-Mo-O also has the property of emitting red fluorescence by near-UV excitation. 12,13 For example, Ca 4 Eu x Gd 1−x NbMo 4 O 20 and CaEu x La 1−x NbMoO 8 fluorescent materials emit strong red light at 615 nm originating from 5 D 0 -7 F 2 , under excitation enters into the charge transition excitation with 240-350 nm, the 5 L 0 state with 394 nm as well as the 5 D 2 state with 464 nm.…”