K3WOF7:Mn4+ ‒ A red oxyfluoride phosphor.

K 3 WOF 7 :Mn4+ was synthesized via a solid-state synthesis route. Main feature of the structure is a quasi-isolated [WOF 5 – unit. When excited by blue light K 3 WOF 7 :Mn4+ exhibits a red luminescence. • Solid-state synthesis of oxyfluoride phosphor K3WOF7:Mn4+ in two facile steps. • Single-crystal structure determination reveals novel structure type of K3WOF7 with [WOF5]‒ as main units. • Luminescence analysis shows line emission spectrum with maximum wavelength of 627 nm. • Temperature dependent luminescence spectra show a good thermal stability up to 75 °C. Synthesis of K 3 WOF 7 :Mn4+ was accomplished via a facile two-step solid-state method. Characterization of the material was carried out by means of single-crystal and powder X-ray diffraction, energy dispersive X-ray spectrometry, as well as luminescence spectroscopy. The substance crystallizes in the monoclinic crystal system in space group P 2 1 / c (no. 14) with the lattice parameters a = 884.2(1), b = 1379.9(1), c = 679.7(1) pm, and β = 93.04(1)°. The crystal structure features a quasi-isolated [WOF 5 − building block as its main motif. The material exhibits a red luminescence under excitation with blue light. The maximum-intensity emission line is located at λ max ≈ 627 nm and the CIE1931 coordinates of the phosphor are 0.689 and 0.310 for x and y , respectively. [ABSTRACT FROM AUTHOR]