Regulating Luminescence Thermal Quenching of Praseodymium-Doped Niobo-Tantalate Phosphor through Intervalence Charge Transfer Band Displacement

Abstract

Pr 3+ -related intervalence charge transfer (IVCT) bands are a research hotspot owing to their amelioration in the luminescence thermal quenching of Pr 3+ -activated phosphors. Here, a typical IVCT band displacement strategy via a topological chemical scheme is reported to optimize the luminescence thermal quenching performance of praseodymium-doped niobo-tantalate. The substitution of Ta 5+ ions for Nb 5+ ions reduces the valenceweighted average cation optical electronegativity and increases the bond lengths of the activator (Pr 3+ ) to the ligand cations (Nb 5+ and Ta 5+ ) via adjusting the crystal structure, leading to an increase in the IVCT energy level position from 3.521 to 4.139 eV. The increase in the IVCT energy level leads to an increase in the number of electrons located in the Pr 3+ 3 P 0 energy level, which compensates for the emission of 1 D 2 during warming. Especially, the energy gap value of the IVCT band is positively correlated with the thermal quenching activation energy ΔE 2 . ΔE 2 increases, the crossover point rises, and the nonradiative transition decreases, further enhancing the Pr 3+ 1 D 2 emission. At 503 K, the 1 D 2 emission integral intensity increases from 14 to 224% relative to the 303 K original integral intensity. This IVCT band displacement strategy can be used as a scheme for designing antithermal quenching luminescence materials.

Recent progress on modulating luminescence thermal quenching properties of Bi3+-activated phosphors

“…Once the crystal structure is determined, the luminescence thermal quenching properties of the phosphor can be strongly influenced by the chemical substitution of cations in the host cations and cations in ionic complexes. 32 As shown in Fig. 5, the environment around Bi 3+ is affected by the chemical substitution of the host cations and/or cations in ionic complexes, which affects the nephelauxetic effect and crystal-field splitting of Bi 3+ .…”

Enhanced thermally stable performance of Pr3+-doped vanadate phosphor by inhibiting the intervalence charge transfer quenching channel

“…[14][15][16] Moreover, due to the electron transfer between different metal ions, the trivalent Pr 3+ ion can undergo metal-to-metal charge transfer with transition metal ions (Mn + ), forming a low-location charge transfer state, i.e., intervalence charge transfer (IVCT). [17][18][19][20][21] The IVCT mechanism can affect the electron distribution of the 4f electronic group state of Pr 3+ , 22 leading to red emission from the 1 D 2 state by reducing the electron population of the 3 P 0 state. 23 This mechanism has been demonstrated in compounds, including closed-shell transition metal ions, such as titanates and vanadates.…”

“…, intervalence charge transfer (IVCT). 17–21 The IVCT mechanism can affect the electron distribution of the 4f electronic group state of Pr 3+ , 22 leading to red emission from the 1 D 2 state by reducing the electron population of the 3 P 0 state. 23 This mechanism has been demonstrated in compounds, including closed-shell transition metal ions, such as titanates and vanadates.…”