Novel tantalum phosphate Na₁₃Sr₂Ta₂(PO₄)₉: synthesis, crystal structure, DFT calculations and Dy³⁺-activated fluorescence performance

Abstract

A new tantalum phosphate, tridecasodium distrontium ditantalum nonaphosphate, NaSrTa(PO), was prepared using the high-temperature flux method. The structure can be described as a three-dimensional open framework containing isolated [Ta(PO)] units that are interlocked by Na and Sr ions. Band structure studies by the first-principles method revealed that NaSrTa(PO) is an insulator with an indirect band gap of 4.78 eV, which makes it suitable as a luminescent host matrix. A series of solid solutions, i.e. NaSrTa(PO):xDy (x = 0.01, 0.02, 0.04, 0.06, 0.08, 0.1, 0.12 and 0.14), were prepared and their photoluminescence properties studied. Under 350 nm light excitation, these emit two typical emissions of the Dy ion, i.e. the F→H transition centred at 476 nm and the F→H transition centred at 570 nm.

Rb9–xAg3+xSc2(WO4)9: a new glaserite-related structure type, rubidium disorder, ionic conductivity

“…In the given structure, each 'pinwheel' consists in our case of the ScO 6 octahedron sharing its corners with six circumjacent WO 4 tetrahedra [Fig. 3 Very similar hexagonal layers of [M 2 (TO 4 ) 9 ] dimers were also found in Cs 7 Na 5 Yb 2 (MoO 4 ) 9 (Basovich et al, 2011) and Na 13 Sr 2 Ta 2 (PO 4 ) 9 (Zhao et al, 2018). In both cases the role of 'bracing' AgO 2 dumbbells play distorted Na3O 6 octahedra, whereas the space between the layers is filled by slightly twisted Na1O 6 and Na2O 6 trigonal prisms and Cs3O 8 polyhedra in Cs 7 Na 5 Yb 2 (MoO 4 ) 9 [Fig.…”

Structure–Optical Behavior Correlation, Optimized Photoluminescence, and DFT Calculation of La7O6(BO3)(PO4)2:Sm3+ Micropowder for Solid State Lighting

“…When we increase the content of Sm 3+ ion up to x = 7%, the PL emission intensity of LNBP: x Sm 3+ micropowders present a following rise. Subsequently, it descends for the further increase of Sm 3+ -doped content because of the concentration quenching effect, which is correlated to the nonradiative energy transfer among Sm 3+ ions …”

“…Subsequently, it descends for the further increase of Sm 3+doped content because of the concentration quenching effect, which is correlated to the nonradiative energy transfer among Sm 3+ ions. 40 To further explore the mechanism of concentration quenching, the critical energy transfer distance (R c ) of Sm 3+ ion in LBPO:Sm 3+ micropowder can be estimated by using the equation presented by Blasse, 41 as below:…”