Incommensurately Modulated Crystal Structure and Photoluminescence Properties of Eu2O3- and P2O5-Doped Ca2SiO4 Phosphor

Abstract

We prepared four types of Eu 2 O 3 -and P 2 O 5 -doped Ca 2 SiO 4 phosphors with different phase compositions but identical chemical composition, the chemical formula of which was (Ca 1.950 Eu 3+ 0.013 0.037 )(Si 0.940 P 0.060 )O 4 ( denotes vacancies in Ca sites). One of the phosphors was composed exclusively of the incommensurate (IC) phase with superspace group Pnma(0β0)00s and basic unit-cell dimensions of a = 0.68004(2) nm, b = 0.54481(2) nm, and c = 0.93956(3) nm (Z = 4). The crystal structure was made up of four types of β-Ca 2 SiO 4 -related layers with an interlayer. The incommensurate modulation with wavelength of 4.110 × b was induced by the long-range stacking order of these layers. When increasing the relative amount of the IC-phase with respect to the coexisting β-phase, the red light emission intensity, under excitation at 394 nm, steadily decreased to reach the minimum, at which the specimen was composed exclusively of the IC-phase. The coordination environments of Eu 3+ ion in the crystal structures of βand IC-phases might be closely related to the photoluminescence intensities of the phosphors.

P-Doped α-Ca2SiO4 and (Si, P)-Codoped CaO with Special Defect Microstructures and Luminescence due to an Enhanced Solid Solution by a Pulsed Laser Ablation Condensation Route

“…Various doped systems in Ca 2 SiO 4 : {Nd 3+ ; Dy 3+ ; (Ce 3+ , Li + ); Tb 3+ ; Sm 3+ ; Eu 2+ ; Eu 3+ ; (P 5+ , Eu 3+ )} are summarized in Table so as to compare them with our system. In the case of inorganic phosphors, the luminescence wavelength changes according to both the luminescent center ion and its coordination environment at the site occupied in the host crystal.…”

“…For example, the high-temperature phase α can be stabilized by the doping of Ge, P, and Ba . Nevertheless, the stabilizer could induce point defects and novel superstructures with specific luminescence properties. , The stabilization and related properties are, however, only suitable for the bulk system, and there are few studies on Ca 2 SiO 4 in the nanoscale, especially for the metastable α-phase.…”

Thermally Induced Morphological and Structural Transformations on Eu2+/Eu3+-Coactivated Calcium Silicate Nanophosphors

“…A previous study, by Nakano et al. demonstrated that mixed phases existed as the β- and γ-phases in Ca 2 SiO 4 , with a rise of the β-phase noted at high temperature sintering. , Conclusively, sintering at various high temperatures could cause the observable changes in phosphors’ crystal structures, presumably affecting their photoluminescence properties.…”

“…, with a rise of the β-phase noted at high temperature sintering. 28,29 Conclusively, sintering at various high temperatures could cause the observable changes in phosphors' crystal structures, presumably affecting their photoluminescence properties. 4b), a comparison with Figure 4a (before sintering) reveals that the particles manifest a consistent spherical morphology, with diameters falling within the 30−50 nm range.…”

Europium-Doped Calcium Silicate Nanoparticles as High-Quantum-Yield Red-Emitting Phosphors

“…In this study, we have synthesized calcium silicate using various-sized silica nanoparticle precursors via a hydrothermal method. Dicalcium silicate (Ca 2 SiO 4 ) has many applications as a host material in photoluminescence (PL) due to its affordability, accessibility, chemical stability, thermal resistance, and simple preparation. − Doping or co-doping of rare-earth ions to the silicate crystal is the prominent strategy for enhancing their luminescence properties. − Among various rare-earth elements, europium of two valence states (Eu 3+ , Eu 2+ ) exhibits magnificent luminescence. As most studies use Eu 2+ -doped Ca 2 SiO 4 as bluish-green-emitting phosphors, red-luminescent Ca 2 SiO 4 :Eu 3+ phosphors remain understudied. ,,, To the best of our knowledge, the luminescence of Eu 3+ -doped Ca 2 SiO 4 red-emitting phosphors has yet to be discussed in detail.…”