Observation of intrinsic emission in β-BiNbO₄available for excitation of both UV light and high energy irradiation

Abstract

β-BiNbO4 with a high temperature triclinic form was prepared via a high-temperature solid-state reaction ceramic method. Structural refinement and surface characteristic studies were performed. The optical absorption, and electronic calculation of the band structures and density of states were also studied. β-BiNbO4 ceramic has an indirect transition with a band energy of 3.05 eV. The valence band is dominated by O-2p states whereas the conduction band has predominantly Nb 4d and Bi 6s character. The intrinsic luminescence properties of β-BiNbO4 were reported, and present a blue emission band peak at 435 nm under the excitation of UV light. The β-BiNbO4 ceramic presents scintillation properties under high energy irradiation. The luminescence was studied via the combinations of the color centers, band calculation and energy transfer from NbO6 to Bi(3+) in the lattices. The thermal quenching and activation energy for the luminescence were reported. β-BiNbO4 has potential applications in photoluminescence and scintillation materials.

Optical Properties and Growth Mechanism of La3Ga5.5Nb0.5O14 Macroporous Ceramic

“…The intensity of the emission peak reduced rapidly and nearly disappears when the temperature increased from 77 to 300 K. The quenching of the emission peak should be attributed to two reasons for thermal quenching effect in macroporous La3Ga5.5Nb0.5O14 ceramic. The one is that non-radiative transition results in the heat by transfer of energy to phonons in the lattices; another one is that the elections could be trapped by any possible defects in the lattices; and it is well known that the trap centers in niobate complexes, which could have an important quenching effect on luminescence [27, 28].…”

Rare‐Earth‐Ion Doped Bi1.5ZnNb1.5O7 Photochromics: A Fast Self‐Recoverable Optical Storage Medium for Dynamic Anti‐Counterfeiting with High Security

“…Such long-wavelength absorption edge cannot be simply ascribed to the VB→CB host absorption, since the host charge transfer (CT) from the filled 2p-orbitals of O 2− to the empty 4d-orbitals of Nb 5+ in [NbO 6 ] 7− groups (i.e., O 2− ─Nb 5+ → O − ─Nb 4+ ) is usually located at 260-280 nm as demonstrated in many niobate compounds. [52][53][54] It also cannot be designated to the metal-to-metal charge transfer (MMCT) from Bi 3+ to Nb 5+ , i.e., Bi 3+ ─Nb 5+ → Bi 4+ ─Nb 4+ , which is theoretically calculated at 310 nm (Supporting Information Note). Thereupon, we supposed it is induced by the oxygen vacancy, and very likely the oxygen vacancy related defect clusters (e.g., [NbO 5 •V •• O ]).…”

Combined experimental and DFT approach to BiNbO4polymorphs

“… 1 The presence of distorted Bi-ions with lone pair 6s electron promotes facile stereochemical activity. 7 The sp coupling resulting from the mixing of O-2p and Bi-6s lone-pair orbitals facilitates the optically generated charge carrier mobility enhancement and hole effective mass reduction, thereby improving photocatalytic performance. 8 Moreover, Bi being a heavier element ( Z = 83) tends to induce strong spin–orbit coupling and large dynamic Born charges in materials.…”