Improvement of Emission Intensity for Near-infrared-emitting Ca₁₄Zn₆Al₁₀O₃₅:Mn⁴⁺Phosphor by Oxygen-pressure Method

Quantitative Determination of the Effective Mn4+ Concentration in a Li2TiO3:Mn4+ Phosphor and Its Effect on the Photoluminescence Efficiency of Deep Red Emission

“…The following two types of techniques are known for their enhancement of the effective Mn 4+ concentration: a charge compensation technique involving the doping of heterogeneous metal ions, M 2+ (M 2+ :Mg 2+ and Zn 2+ ) ions and Mn 4+ in aluminate hosts, 11,12 and oxygen-pressure annealing processing. 13 A Mn 2+ ion involuntarily incorporates into Al 3+ due to charge compensation when Mn 4+ is doped into Al 3+ sites in a typical CaAl 12 O 19 host, and Mg 2+ is added simultaneously to the Al 3+ site to suppress the production of Mn 2+ by charge compensation in CaAl 12 O 19 :Mn 4+ phosphors. 11 The emission intensity of Mg 2+ -codoped phosphors has been enhanced to be approximately 1.8 times larger than that of phosphors with no heterogeneous species, which is ascribed to an increase in the effective Mn 4+ concentration.…”

“…To overcome such disadvantages, the enhancement of the emission intensity excited by visible-light irradiation has been investigated using various techniques as follows: Bi 3+ –Mn 4+ energy transfer generated by Bi 3+ doping, , the modification of chemical compositions, and the control of morphology. , The improvement in the luminescence efficiency under visible-light excitation has also been investigated by suppressing lower oxidation state manganese ions, such as Mn 2+ and Mn 3+ , which can act as quenching ions for the luminescence of Mn 4+ , i.e., an increase in the “effective Mn 4+ concentration”. The following two types of techniques are known for their enhancement of the effective Mn 4+ concentration: a charge compensation technique involving the doping of heterogeneous metal ions, M 2+ (M 2+ :Mg 2+ and Zn 2+ ) ions and Mn 4+ in aluminate hosts, , and oxygen-pressure annealing processing . A Mn 2+ ion involuntarily incorporates into Al 3+ due to charge compensation when Mn 4+ is doped into Al 3+ sites in a typical CaAl 12 O 19 host, and Mg 2+ is added simultaneously to the Al 3+ site to suppress the production of Mn 2+ by charge compensation in CaAl 12 O 19 :Mn 4+ phosphors .…”

Tunable luminescence and energy transfer properties of Bi3+ and Mn4+ co-doped Ca14Al10Zn6O35 phosphors for agricultural applications

“…7 The Bi 3+ -doped gadolinium tungstate phosphor emits visible radiation from the blue to red regions and an intense near-infrared (NIR) photon centered at 976 nm has been obtained through a quantum-cutting (QC) phenomenon by codoping with Yb 3+ ions. 8 Mn 4+ activated inorganic phosphors, such as uorides, 9-11 germinates 12,13 and aluminates, [14][15][16][17] show potential in the improvement of the color rendition of white LEDs due to their broad and strong absorption in the blue region which matches well with the electroluminescence of blue LED chips. They can produce highly efficient red emission to compensate the red components in the spectrum of the YAG:Ce-GaN type white LED.…”

“…Recently, several phosphors based on the host lattice CAZO have been identied as good candidates in various photoelectricity applications with high luminescence efficiency, chemically and physically stable characteristics, ease of synthesis, and low cost of raw materials. [16][17][18][19][20] Even though the luminescent properties of rare earth ions and Mn 4+ in the host lattice CAZO have been extensively studied, blue emission luminescence from Bi 3+ in CAZO has not been observed. It is worth investigating the efficient energy transfer between the two transition metal ions Bi 3+ and Mn 4+ owing to the energy match between the 3 P 1 (Bi 3+ ) and 2 E (Mn 4+ ) levels.…”

A review on the structural dependent optical properties and energy transfer of Mn4+ and multiple ion-codoped complex oxide phosphors

“…In the crystal structure of CZAO, Ca 2+ has three different coordination environments, where two of them are coordinated to six oxygen atoms, forming a distorted octahedron, while the third is in a seven-coordinated polyhedron and the average Ca-O distance is equal to 2.498Å. 54,55 In addition, four of the ve independent positions occupied by Zn and Al are in the tetrahedral coordination, with the average Zn-O distance of 1.951Å and average Al-O distances of 1.719, 1.794 and 1.891Å, respectively. The positions are in an octahedron coordination, and the one-h positions occupied by Al and Zn are octahedral coordinations.…”