Rare‐earth‐free Li₅La₃Ta₂O₁₂:Mn⁴⁺ deep‐red‐emitting phosphor: Synthesis and photoluminescence properties

Abstract

Li5La3Ta2O12:Mn4+ (LLTO:Mn4+) phosphors are prepared in air via high‐temperature solid‐state method and investigated for their crystal structures and luminescence properties. LLTO:Mn4+ phosphor under excitation at 314 nm shows deep‐red emission peaking at 714 nm due to the 2E→4A2 transition of Mn4+ ion. The excitation bands in the range 220 ‐ 570 nm are attributed to the Mn4+ ‐ O2‐ charge‐transfer band and the 4A2g→4T1g, 2T2g, and 4T2g transitions of Mn4+, respectively. The optimal Mn4+ ion concentration is ~0.4 mol%. The concentration quenching mechanism in LLTO:Mn4+ phosphor is electric dipole‐dipole interaction. The luminous mechanism and temperature quenching phenomenon are explained by the Tanabe‐Sugano energy level diagram and the configurational coordinate diagram of Mn4+ in the octahedron, respectively. The experimental results indicate that LLTO:Mn4+ phosphor has a potential application prospect as candidate of deep‐red component in light‐emitting diode (LED) lighting.

An Al3+-incorporated Ca2LuNbO6:Mn4+ oxide phosphor with dramatic deep-red and far-red emission bands

“…A portion of the free electrons in the low-lying excited state may instead absorb the energy released by the thermal phonon and return to the ground state ( 4 A 2g ) through the points a , b and c , which contributes to the reduction of emission intensity. 44 In order to further explore the thermal quenching characteristics, the activation energy of phosphors was calculated by using the conventional Arrhenius formula: 45 where I 0 is the emission intensity at 298 K, I (T) is the emission intensity at various temperatures ( T ) ranging from 303 to 473 K, C is a constant, Δ E is the activation energy for thermal quenching, and k is the Boltzmann constant. Fig.…”

“…A portion of the free electrons in the low-lying excited state may instead absorb the energy released by the thermal phonon and return to the ground state ( 4 A 2g ) through the points a, b and c, which contributes to the reduction of emission intensity. 44 In order to further explore the thermal quenching characteristics, the activation energy of phosphors was calculated by using the conventional Arrhenius formula: 45…”

Luminescence of Mn4+ in a Zero-Dimensional Organic–Inorganic Hybrid Phosphor [N(CH3)4]2ZrF6 for Dual-Mode Temperature Sensing

“…In recent years, luminescent materials have attracted special attention for their applications in optoelectronics, especially in the fields of temperature sensing [ 1 , 2 , 3 ]. Traditional thermometers are based on the expansion properties of liquids or metals, requiring contact with objects and heat exchange, thus leading to errors between the measured temperature and the actual temperature [ 4 , 5 ].…”

Enhancement of Mn4+ Emission by Means of Energy Transfer in Mg2Al4Si5O18:Dy3+, Mn4+ Phosphors

“…In various phosphors, rare earth ions, such as Eu 3+ , 5 Tb 3+ , 6 Sm 3+ , 7 Dy 3+ , 8 Ce 3+ 9 and Eu 2+ , 10 are used as luminescence centers universally due to their abundant transitions and emitted light with different colors. 11 Some other non-rare earth ions, such as Mn 2+ 12 and Mn 4+ , [13][14][15] also act as luminescence centers widely due to the tunable emission of Mn 2+ depending on crystal field and deep red emission of octahedral Mn 4+ . 16,17 Among various doping ions, Mn 4+ is investigated widely because Mn 4+ doped phosphors are employed to compensate the deficiency of red emission in Y 3 Al 5 O 12 :Ce 3+ based white LEDs 18,19 and to improve the efficiency of indoor plant cultivation.…”