Crystal Structure, Characterization, and Luminescence Properties of Mn4+‐Doped K3Nb2O4F5

This paper reports on the synthesis of the oxyfluoride compound K₃Nb₂O₄F₅ under high-pressure/high-temperature conditions. When Mn⁴⁺ is introduced into the crystal lattice, the compound exhibits red luminescence upon excitation with blue light.

Abstract

In this paper, we present the high-pressure/high-temperature synthesis and characterization of the potassium fluoridooxidoniobate K₃Nb₂O₄F₅. Single-crystal analysis revealed that the phase crystallizes in the trigonal space group m (hR18) with a=5.799(2), c=21.371(4) Å, V=622.4(4) ų and Z=3 at T=299 K exhibiting a structure type closely related to that of Ba₂RbFe₂F₉. The assignment of the anion positions to oxygen and fluorine is based on crystallographic data and BLBS/CHARDI calculations. Further characterization via EDX spectroscopy was carried out, corroborating the ratio of K to Nb. Doping of the title compound with Mn⁴⁺ was achieved in a secondary step using a ball-mill, resulting in a red phosphor material, which was additionally analyzed by luminescence spectroscopy. The emission maximum is located at λ_max=630 nm.

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