Mn(IV)‐Substituted Metal(II) Hexafluorido Metallates(IV): Synthesis, Crystal Structures, and Luminescence Properties

Abstract

We synthesized 16 novel red‐emitting Mn(IV)‐substituted phosphors of the compositions MgGeF6 : Mn, MgPbF6 : Mn, CaMF6 : Mn (M=Ge, Sn, Pb, Zr, Hf), SrSnF6 : Mn, “SrTiF6 : Mn”, BaPbF6 : Mn, ZnMF6 : Mn (M=Sn, Pb, Zr, Hf), and CdMF6 : Mn (M=Pb, Hf) using a dry‐chemical fluorination process completely avoiding hydrofluoric acid. In comparison with the commonly used red‐emitter K2SiF6 : Mn (KSF) with its emission maximum at 630.8 nm, all above Ca and Sr compounds and CdHfF6 : Mn show a blue‐shift of their emission maxima, the compound SrSnF6 : Mn even by 4.2 nm down to 626.6 nm. The compounds were characterized by powder X‐ray diffraction, IR and emission spectroscopy. We additionally present the crystal structures of the unsubstituted compounds CaZrF6, CaHfF6, CaPbF6, CdZrF6, CdHfF6, and MgHfF6, which all crystallize isotypic in the NaSbF6 structure type. The compound “SrTiF6” was characterized by powder XRD and studied with evolutionary structure prediction methods, but its crystal structure could not yet be solved.

Comparative Study on Crystal Structures and Synthetic Techniques of Ternary Hafnium/Zirconium Fluorides

“…Compound 1 crystallizes in the cubic space group Fm– 3 m and is isostructural with the previously reported zirconium analogue, MgZrF 6 . The crystal structure of compound 1 was previously reported based on a Rietveld refinement of powder X-ray diffraction data by Bandemehr et al in 2021 . Herein, we report a structure solution obtained using single-crystal X-ray diffraction data.…”

“…44 The crystal structure of compound 1 was previously reported based on a Rietveld refinement of powder X-ray diffraction data by Bandemehr et al in 2021. 5 Herein, we report a structure solution obtained using single-crystal X-ray diffraction data. The structure is best described as a double ReO 3 -type structure, where the MgF 6 and HfF 6 octahedra are ordered in a NaCl fashion.…”

“…The chemistry of inorganic fluorides has been explored for many decades and, during this time, numerous synthetic routes were developed and used for the preparation of new inorganic fluorides, to determine their structures, and to investigate their physical properties . Often solid-state reactions were explored to prepare new compositions, utilizing mostly binary fluorides that were prepared by the direct fluorination of oxides or chlorides using F 2 (g). − Solution routes, also, were explored, in particular those involving condensed anhydrous HF, resulting in the discovery and characterization of a very large number of phases. − An alternative approach utilized hydrothermal routes under supercritical conditions, which permits the formation of high-quality single crystals of novel compositions and structures. − Another solution route involved molten salts, which can be used at temperatures ranging from as low as ∼150 °C to over 1000 °C, depending on the particular salt chosen. − This approach also has been extremely fruitful and has yielded many new compositions and structures. More recently, the mild hydrothermal route has become popular as it can be used for the crystallization of fluorides and/or oxyfluorides and also because it uses only small quantities of aqueous HF, which are easily handled in typical research laboratories.…”

On New Alkaline‐Earth Hexafluorogermanates as Host Structures for UV Phosphors

“…al ., [3] or as published more recently, by high temperature reactions in fluorine atmosphere of Kraus et al. [4] . Hexafluorogermanates are often functionalised as red phosphors by doping with Mn 4+ , since its allowed 2 E ‐ 4 A 2 ‐transition is promising for applications in LED lightning and displays alike [5,6] .…”

“…al., [3] or as published more recently, by high temperature reactions in fluorine atmosphere of Kraus et al. [4] Hexafluorogermanates are often functionalised as red phosphors by doping with Mn 4 + , since its allowed 2 E-4 A 2 -transition is promising for applications in LED lightning and displays alike. [5,6] Since most hexafluorogermanates so far feature singly charged cations, tetravalent manganese was the only possible activator with efficient luminescence, although BaGeF 6 was successfully doped with Ce 3 + and Tb 3 + previously.…”