Obtaining Efficiently Tunable Red Emission in Ca_3-δLn_δWO₆:Mn⁴⁺ (Ln = La, Gd, Y, Lu, δ = 0.1) Phosphors Derived from Nearly Nonluminescent Ca₃WO₆:Mn⁴⁺ via Ionic Substitution Engineering for Solid-State Lighting

Abstract

Wireless communication on the body is expected to become more important in the future. This communication will in certain scenarios benefit from higher frequencies of operation and their associated smaller antennas and potentially higher bandwidths. One of these scenarios is communication between a wristband and wearable sensors on the arm. In order to investigate the feasibility of such a scenario, propagation at 55 -65 GHz along the arm is measured for two configurations. First, for increasing separation distances along the arm, and second for a transmitter is rotationally placed around the wrist. Two channel gain models are fitted to the data and used to obtain a channel gain exponent in the first configuration and loss per angle of rotation in the second configuration. These models are relevant inputs for the design of future wearable wireless systems.

Compensation effect of electron traps for enhanced fluorescence intensity ratio thermometry performance

“…On the other hand, the Mn 4+ (r = 53 pm) prefers to replace Ga 3+ (r = 62 pm) based on the similar radius to the interstitial oxygen O (Oi) to balance the charge. 35,36 The XRD patterns of ZGO:Mn samples (Fig. 1a) match well with the standard pattern of cubic ZnGa 2 O 4 (PDF#38-1240).…”

Bi3+/Mn4+ co‐doped dual‐emission phosphors for potential plant lighting

“…However, the emission intensity of 2 E → 4 A 2g transition of Mn 4+ ions first increases with increasing Mn 4+ ion concentration, reaching a maximum luminescence intensity at y = 0.005, and then the PL intensity is decreased due to the concentration quenching effect (Figure 7B). 42 Here, the energy‐transfer efficiency from Bi 3+ ion (peak: 477 nm) to Mn 4+ ion (peak: 718 nm) is estimated using the following equation: $$\begin{equation}{\rm{\;}}{\eta _T} = \;1 - {T_S}/{T_{S0}}\end{equation}$$where T S 0 and T S are the lifetimes of the Bi 3+ ion (peak: 477 nm) in the absence and in the presence of the Mn 4+ ion (peak: 718 nm), respectively. The decay lifetimes are calculated into 505, 477, 426, 422, 406, 391, and 350 ns with growing Mn 4+ concentration, and the energy‐transfer efficiencies $${\eta _T}\;$$ are calculated to be 0%, 5.6%, 15.7%, 16.5%, 19.6%, 22.6%, and 30.7% for SLGO:0.02Bi 3+ , y Mn 4+ , 0.09Li + when y = 0, 0.003, 0005, 0.007, 0.009, 0.011, and 0.013, respectively.…”

Deep-red-emitting phosphors of Mn4+-activated tantalite for high-sensitivity lifetime thermometry and security films

“…To date, tetravalent manganese (Mn 4+ ) ions-doped materials with specific 3d 3 electron structures, which were found to give a strong deep-red emission under a broad excitation band, have attracted much attention for application in various advanced fields, such as WLEDs, fingerprint detection, plant cultivation, wide-gamut displays, luminescent thermometers, and flexible anti-counterfeiting films. [14][15][16][17][18][19][20][21][22][23][24] In particular, inorganic double-perovskite materials with octahedral sites are considered to be beneficial for the splitting of the Mn 4+ crystal field to obtain candidates with excellent lumines-cent performances, such as Gd 2 MgTiO 6 :Bi 3+ /Mn 4+ , 25 Y 2 MgTiO 6 :Mn 4+ , 26 La 3 Li 3 W 2 O 12 :Eu 3+ /Mn 4+ , 27 Ba 2 CaWO 6 : Mn 4+ , 28 La 2 ZnTiO 6 :Mn 4+ , 29 and (Ca,Sr,Ba) 2 CaWO 6 :Mn 4+ phosphors. 30 Herein, the double-perovskite structures with octahedral sites cooperating with Mn 4+ are shown to be an effective strategy for developing high-performance phosphors.…”