Excited States of 3d³ Electrons in K₂SiF₆:Mn⁴⁺ Red Phosphor Studied by Photoluminescence Excitation Spectroscopy

Abstract

This paper reports on a study of the photoluminescence excitation (PLE) spectra of Mn4+-activated K2SiF6 phosphor at 20 and 300 K. Measurements of the PLE spectra show that the sharp red emissions (2Eg →4A2g) at ∼630 nm are most efficiently excited by irradiation into the spin-allowed transitions 4A2g →4T2g (∼460 nm) and 4A2g →4T1g (∼360 nm). The first efficient excitation band 4A2g →4T2g is structureless at 300 K but shows a sharp origin and some oscillatory peaks at 20 K. A Fourier transform technique is used for analyzing such oscillatory peaks. The second excitation band 4A2g →4T1g shows a structureless shape even at a low temperature (20 K). The third excitation band with a peak at ∼250 nm is very weak and could be assigned as the 4A2g →4T1g transition. The direct excitation of the 2Eg state is also found to produce the sharp red emissions at ∼630 nm with a negligibly small offset in the configurational coordination. The Franck–Condon analysis makes it possible to accurately determine the zero-phonon line energies in the 3d3 electron transitions of the MnF6 2- octahedron.

Influence of Isostatic Pressure on the Elastic and Electronic Properties of K2SiF6:Mn4+

“…Here, the transition energy from 2 E to 4 A2, Eem, is calculated by an energy gap between the up-spin and down-spin t2g states within a one electron approximation to avoid complicated calculations considering multielectron effects to obtain total electronic energy difference between the 2 E and 4 A2 states. The calculated Eem value at zero pressure is 2.74 eV, which is larger than the experimental value of 1.99 eV [9]. This overestimation is derived from the method to obtain Eem.…”

“…With minimum emission beyond 650 nm, the emission spectrum of KSF:Mn 4+ is suitable for supplying the red photons necessary to produce white light with high efficacy (lumens per watt) and color rendering index (CRI) in pc-LEDs. Given its commercial importance, detailed analyses of the spectroscopic properties, such as absorption and emission spectra, electronic and geometric properties of KSF:Mn 4+ were performed [8][9][10] and recently this red phosphor was commercialized [11].…”

Optical spectroscopy of ZnSiF6·6H2O:Mn4+ red phosphor

“…The third weak structure at $270 nm in the R spectrum may be due to transition from a p-type antibonding orbital on a fluorine ion to the non-bonding T 2g orbital on the Mn 4þ ion [20][21][22] or from the ground state ( 4 A 2g ) to the third excited state ( 4 T 1g ) of Mn 4þ ions. 23 The sharp red emissions in the $630 nm spectral region are generated by the 2 E g ! 4 A 2g transitions.…”

“…Such a phonon replica-like structure is interpreted by a vibronic progression of the fundamental frequency combined with an unsymmetrical vibration of the MnF 2À 6 octahedron superimposed on the electronic transition. 23 The second excitation band at $370 nm in the PLE spectrum can also be assigned as the spin-allowed transitions ( 4 A 2g ! 4 T 1g ).…”

Deep-red emission of Mn4+ and Cr3+ in (Li1−xAx)2MgTiO4 (A=Na and K) phosphor: Potential application as W-LED and compact spectrometer

“…Meanwhile, the luminescence properties the Mn 4+ /Cr 3+ co-doped phosphor have also been investigated. (JCPDS#89-7118) [27] has a cubic rock salt structure belonging to Fm-3m 225 vibration modes for the 3d 3 electrons when Mn 4+ is of octahedral structure [28][29][30] . However, the abnormal red effect, which may cause the seemingly broadened emission of Mn 4+ [7] .…”