Rare Earth‐Activated Niobates

Abstract

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The Synthesis, Properties, and Applications of Columbite Niobates (M2+Nb2O6): A Critical Review

“…In a study at RT of the incorporation of Ln 3+ with Na + as a charge compensating species into the Ca 1− x Cd x Nb 2 O 6 solid solution led to considerable host emission, whereas the incorporation of Eu 3+ showed only the characteristic red emission. The cadmium‐rich members were found to be superior in the study 123 . Brittain and Mcallister 131 also investigated luminescence in the Eu 3+ doped (Ca/Cd)Nb 2 O 6 system, with samples excited by an Ar ion laser at 350 nm and 9 K. CdNb 2 O 6 produced a very intense luminescence, with >40 peaks between 526–709 nm, independent of Eu 3+ concentration up to a maximum of 12% substitution, and it was shown that a single Eu 3+ emitting site existed at Cd sites.…”

“…All the phosphors in the solid solution series Ca 1− x Cd x Nb 2 O 6 showed a broad emission band at 470 nm (for excitation at 285 nm). The presence of five cadmium 4 d electrons enables them to participate in the O 2− to Nb 5+ charge transfer, which enhances the luminescence intensity 123 luminescence properties. The PL spectra of self activated pure CdNb 2 O 6 , excited at 272 nm, have a broad and strong blue emission band maximum at 460 nm 124 …”

Synthesis of blue-luminescent CaNb₂O₆ by using a biphasic liquid method at low temperatures

“…5) Among them, CaNb 2 O 6 is known as its interesting luminescence properties arising from electronic transitions between O 2p band and Nb 4d band of the NbO 6 units in the crystal structure. CaNb 2 O 6 itself shows strong blue luminescence upon excitation with ultraviolet (UV) light, 6), 7) and it also works as a host crystal for doping activator ions. 8), 9) In the former self-activated CaNb 2 O 6 , the ordering of the NbO bonding influences strongly the intensity of luminescence.…”