[Zn²⁺–Ge⁴⁺] co-substitutes [Ga³⁺–Ga³⁺] to coordinately broaden the near-infrared emission of Cr³⁺ in Ga₂O₃ phosphors

Abstract

Here, the method "chemical unit co-substitution" is used to improve the near-infrared (NIR) emission of phosphors, using [Zn2+ - Ge4+] to co-substitute [Ga3+ - Ga3+] sites to reduce crystal field...

Improving and broadening luminescence in Gd2−xAlxGaSbO7:Cr3+ phosphors for NIR LED applications

“…18 The optical band gap ( E g ) values of G 2− x A x GSO:5%Cr 3+ can be attained from the obtained DR spectra according to the Kubelka–Munk equations: 10,14,27 ( αhν ) n = A ( hν − E g )where R and α represent the reflection and absorption coefficients, respectively, hν is the photon energy, A denotes the proportional constant and n signifies the transition coefficient (for the indirect permitted transition, n = 1/2). 34 As presented in Fig. 5(b), the E g value of G 2− x A x GSO:5%Cr 3+ increases with an increase in dopant concentration of Al 3+ until it reaches the maximum when x = 0.6 and then decreases.…”

Pressure‐Induced Remarkable Spectral Red‐Shift in Mn2+‐Activated NaY9(SiO4)6O2 Red‐Emitting Phosphors for High‐Sensitive Optical Manometry

“…Surprisingly, the resulting phosphors display excellent thermal stability, in which the emission intensity at 423 K keeps around 95% of its initial value at 303 K (see Figure 3h). Besides, by the use of the following function, the corresponding activation energy (Δ E ) is evaluated [ 44,45 ] $$$$\begin{equation}I\ \left( T \right) = \frac{{{I}_0}}{{1 + A{\mathrm{exp}}\left( { - \Delta E/kT} \right)}}\ \end{equation}$$$$where the initial emission intensity is labeled as I 0 , the emission intensity at time t is denoted by I ( T ), A is a constant, and k refers to Boltzmann coefficient, where its value is 8.629 × 10 −5 eV K −1 . Through studying the experimental data by Equation (), the Δ E value for Mn 2+ in the synthesized phosphors is calculated to be around 0.275 eV (see Figure 3i).…”

“…Surprisingly, the resulting phosphors display excellent thermal stability, in which the emission intensity at 423 K keeps around 95% of its initial value at 303 K (see Figure 3h). Besides, by the use of the following function, the corresponding activation energy (ΔE) is evaluated [44,45]…”

A novel broadband near‐infrared Ca2Y3Sb3O14: Cr3+ rhombohedral pyrochlores phosphor and its application in pc‐LEDs

“…Therefore, concentration quenching is mainly achieved through exchange or electric multipolar interactions. To further clarify the interaction leading to the concentration quenching mechanism, the critical distance R c between adjacent Cr 3+ ions can be obtained using the following formula 31 : $$$$\begin{equation}{R_c} \approx 2{\left( {\frac{{3V}}{{4\pi {x_c}N}}} \right)^{1/3}}\end{equation}$$$$…”