Combustion Synthesis and Photoluminescence Properties of Red-Emitting CaAlSiN3:Eu2+ Phosphor for White-LEDs

A combustion synthesis method has been developed for synthesis of Eu²⁺ doped CaAlSiN₃ phosphor and its photoluminescence properties were investigated. Ca, Al, Si, and Eu₂O₃ powders were used as the Ca, Al, Si and Eu sources. The addition of NaN₃, NH₄Cl and Si₃N₄ powders was found to increase significantly the product yield. These powders were mixed and pressed into a compact, which was then wrapped up with an igniting agent (i.e., Mg+Fe₃O₄). The compact was ignited by electrical heating under a N₂ pressure of ≤1.0 MPa. Effects of these experimental parameters on the product yield were investigated and a reaction mechanism was proposed. The synthesized CaAlSiN₃:Eu²⁺ phosphor absorbs light in the region of 200–600 nm and shows a broad band emission in the region of 500–800 nm due to the 4f⁶5d¹ → 4f⁷ transition of Eu²⁺. The sample doped with Eu²⁺ at the optimized molar ratio of 0.04 is efficiently excited by the blue light (460 nm) and generates emission peaking at ~650 nm with peak emission intensity ~106% of a commercially available phosphor, YAG:Ce³⁺(P46-Y3).The internal quantum efficiency of the synthesized phosphor was measured to be 71%, compared to 69% of the YAG:Ce³⁺ (P46-Y3).     

The pH Value Control of Morphology and Luminescence Properties of Gd2O2S: Tb3+ Phosphors

Developing rare-earth doped oxysulfide phosphors with diverse morphologies has significant value in many research fields such as in displays, medical diagnosis, and information storage. All of the time, phosphors with spherical morphology have been developed in most of the related literatures. Herein, by simply adjusting the pH values of the reaction solution, Gd₂O₂S:Tb³⁺ phosphors with various morphologies (sphere-like, sheet-like, cuboid-like, flat square-like, rod-like) were synthesized. The XRD patterns showed that phosphors with all morphologies are pure hexagonal phase of Gd₂O₂S. The atomic resolution structural analysis by transmission electron microscopy revealed the crystal growth model of the phosphors with different morphology. With the morphological change, the band gap energy of Gd₂O₂S:Tb³⁺ crystal changed from 3.76 eV to 4.28 eV, followed by different luminescence performance. The samples with sphere-like and cuboid-like microstructures exhibit stronger cathodoluminescence intensity than commercial product by comparison. Moreover, luminescence of Gd₂O₂S:Tb³⁺ phosphors have different emission performance excited by UV light radiation and an electron beam, which when excited by UV light is biased towards yellow, and while excited by an electron beam is biased towards cyan. This finding provides a simple but effective method to achieve rare-earth doped oxysulfide phosphors with diversified and tunable luminescence properties through morphology control.     

A Novel Red-Emitting Na2NbOF5:Mn4+ Phosphor with Ultrahigh Color Purity for Warm White Lighting and Wide-Gamut Backlight Displays

In this work, a novel red-emitting oxyfluoride phosphor Na₂NbOF₅:Mn⁴⁺ with an ultra-intense zero-phonon line (ZPL) was successfully synthesized by hydrothermal method. The phase composition and luminescent properties of Na₂NbOF₅:Mn⁴⁺ were studied in detail. The photoluminescence excitation spectrum contains two intense excitation bands centered at 369 and 470 nm, which match well with commercial UV and blue light-emitting diode (LED) chips. When excited by 470 nm blue light, Na₂NbOF₅:Mn⁴⁺ exhibits red light emission dominated by ZPL. Notably, the color purity of the Na₂NbOF₅:Mn⁴⁺ red phosphor can reach 99.9%. Meanwhile, the Na₂NbOF₅:Mn⁴⁺ phosphor has a shorter fluorescence decay time than commercial K₂SiF₆:Mn⁴⁺, which is conducive to fast switching of images in display applications. Profiting from the intense ZPL, white light-emitting diode (WLED) with high color rendering index of Ra = 86.2 and low correlated color temperature of T_c = 3133 K is realized using yellow YAG:Ce³⁺ and red Na₂NbOF₅:Mn⁴⁺ phosphor. The WLED fabricated using CsPbBr₃ quantum dots (QDs) and red Na₂NbOF₅:Mn⁴⁺ phosphor shows a wide color gamut of 127.56% NTSC (National Television Standard Committee). The results show that red-emitting Na₂NbOF₅:Mn⁴⁺ phosphor has potential application prospects in WLED lighting and display backlight.     

Broadband Near-Infrared Luminescence in Lead Germanate Glass Triply Doped with Yb3+/Er3+/Tm3+

This paper deals with broadband near-infrared luminescence properties of lead germanate glass triply doped with Yb³⁺/Er³⁺/Tm³⁺. Samples were excited at 800 nm and 975 nm. Their emission intensities and lifetimes depend significantly on Er³⁺ and Tm³⁺ concentrations. For samples excited at 800 nm, broadband emissions corresponding to the overlapped ³H₄ → ³F₄ (Tm³⁺) and ⁴I_13/2 → ⁴I_15/2 (Er³⁺) transitions centered at 1.45 µm and 1.5 µm was identified. Measurements of decay curves confirm reduction of ³H₄ (Tm³⁺), ²F_5/2 (Yb³⁺) and ⁴I_13/2 (Er³⁺) luminescence lifetimes and the presence of energy-transfer processes. The maximal spectral bandwidth equal to 269 nm for the ³F₄ → ³H₆ transition of Tm³⁺ suggests that our glass co-doped with Yb³⁺/Er³⁺/Tm³⁺ is a good candidate for broadband near-infrared emission. The energy transfer from ⁴I_13/2 (Er³⁺) to ³F₄ (Tm³⁺) and cross-relaxation processes are responsible for the enhancement of broadband luminescence near 1.8 µm attributed to the ³F₄ → ³H₆ transition of thulium ions in lead germanate glass under excitation of Yb³⁺ ions at 975 nm.     

Synthesis and Characterization of LaNi0.5Ti0.5O3 and La2NiTiO6 Double Perovskite Nanoparticles

In the present work, LaNi_0.5Ti_0.5O₃ and La₂NiTiO₆ nanoparticles were synthesized by the modified Pechini method. LaNi_0.5Ti_0.5O₃ was calcined at 1073 K for 17 h or 100 h, while La₂NiTiO₆ was calcined at 1273 K for 135 h. The double perovskite calcined at 1073 K for 17 h presented orthorhombic symmetry with Pbnm space group, mean particle size was 31.9 ± 1 nm, random ordering of Ni²⁺ and Ti⁴⁺ cations, Néel temperature close to 15 K, and magnetic moment of 1.29 μB. By increasing the calcination time, this material showed the same symmetry and space group, a mean particle size of 50.7 ± 2 nm, short-range ordering of Ni²⁺ and Ti⁴⁺ cations, Néel temperature around 12 K, and magnetic moment of 0.96 μB. La₂NiTiO₆ presented a monoclinic crystal structure, with P2₁/n space group, mean particle size of 80.0 ± 5 nm, rock salt ordering of Ni²⁺ and Ti⁴⁺, Néel temperature of approximately 23 K, and magnetic moment of 2.75 μB.     

Synthesis of Green-Emitting (La,Gd)OBr:Tb3+ Phosphors

Green-emitting phosphors based on lanthanum-gadolinium oxybromide were synthesized in a single phase form by the conventional solid state reaction method, and photoluminescence properties of them were characterized. The excitation peak wavelength of (La_1-xGd_x)OBr:Tb³⁺ shifted to the shorter wavelength side with the increase in the crystal field around the Tb³⁺ ions by doping Gd³⁺ ions into the La³⁺ site, and, as a result, the green emission intensity was successfully enhanced. The maximum emission intensity was obtained for (La_0.95Gd_0.05)OBr:5%Tb³⁺, where the relative emission intensity was 45% of that of a commercial green-emitting LaPO₄:Ce³⁺,Tb³⁺ phosphor.     

Enhanced Photodegradation of p-Nitrobenzoic Acid by Binary Mixtures with Ba2+/TiO2 and MCM-41

A novel Ba(II)/TiO₂–MCM-41 composite was synthesized using binary mixtures with Ba²⁺/TiO₂ and MCM-41, and Ba²⁺ as a doping ion of TiO₂. The specific surface area and pore structure characterizations confirm that a mesoporous structure with a surface area of 341.2 m²/g and a narrow pore size distribution ranging from 2 to 4 nm was achieved using Ba(II)/TiO₂–MCM-41. Ba(II)/TiO₂ particles were synthesized into 10–15 nm particles and were well dispersed onto MCM-41. The diffraction peaks in the XRD patterns of TiO₂–MCM-41 and Ba(II)/TiO₂–MCM-41 were all attributed to anatase TiO₂. By taking advantage of MCM-41 and Ba²⁺, the photocatalytic performance of Ba(II)/TiO₂–MCM-41 was remarkably enhanced by suppressing its rutile phase, by lowering the band gap energy, and by facilitating the dispersion of TiO₂. Therefore, the photodegradation efficiencies of p-nitrobenzoic acid (4 × 10⁻⁴ mol/L) by various photocatalysts (60 min) under UV light irradiation are arranged in the following order: Ba(II)/TiO₂–MCM-41 (91.7%) > P25 (86.3%) > TiO₂–MCM-41 (80.6%) > Ba(II)/TiO₂ (55.7%) > TiO₂ (53.9%). The Ba(II)/TiO₂–MCM-41 composite was reused for five cycles and maintained a high catalytic activity (73%).     

Synthesis,Characterization and Biodistribution of GdF3:Tb3+@RB Nanocomposites

Herein we report the development of a nanocomposite for X-ray-induced photodynamic therapy (X-PDT) and computed tomography (CT) based on PEG-capped GdF₃:Tb³⁺ scintillating nanoparticles conjugated with Rose Bengal photosensitizer via electrostatic interactions. Scintillating GdF₃:Tb³⁺ nanoparticles were synthesized by a facile and cost-effective wet chemical precipitation method. All synthesized nanoparticles had an elongated “spindle-like” clustered morphology with an orthorhombic structure. The structure, particle size, and morphology were determined by transmission electron microscopy (TEM), X-ray diffraction (XRD), and dynamic light scattering (DLS) analysis. The presence of a polyethylene glycol (PEG) coating and Rose Bengal conjugates was proved by Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG), and ultraviolet–visible (UV-vis) analysis. Upon X-ray irradiation of the colloidal PEG-capped GdF₃:Tb³⁺–Rose Bengal nanocomposite solution, an efficient fluorescent resonant energy transfer between scintillating nanoparticles and Rose Bengal was detected. The biodistribution of the synthesized nanoparticles in mice after intravenous administration was studied by in vivo CT imaging.     

Red,Green, and Blue Photoluminescence of Ba2SiO4:M (M = Eu3+, Eu2+, Sr2+) Nanophosphors

Divalent europium doped barium orthosilicate is a very important phosphor for the production of light emitting diodes (LEDs), generally associated to the green emission color of micron-sized crystals synthesized by means of solid-state reactions. This work presents the combustion synthesis as an energy and time-saving preparation method for very small nano-sized Ba₂SiO₄ particles, flexibly doped to acquire different emission energies. The size of the resulting spherical nanoparticles (NPs) of the green emitting Ba₂SiO₄:Eu²⁺ was estimated to about 35 nm applying the Scherrer equation and further characterized with aid of atomic force microscopy (AFM) as well as scanning electron microscopy (SEM). This phosphor is able to build homogeneous luminescent suspensions and was successfully down-sized without changing the optical properties in comparison to the bulk phosphors. Besides the X-ray diffraction (XRD) analysis and the different types of microscopy, the samples were characterized by luminescence spectroscopy. Undoped Ba₂SiO₄ NPs are not luminescent, but show characteristic red emission of the ⁵D₀ → ⁷F_J (J = 0–4) electronic transitions when doped with Eu³⁺ ions. Moreover, these orthosilicate nanoparticles generate blue light at low temperatures due to impurity-trapped excitons, introduced by the partial substitution of the Ba²⁺ with Sr²⁺ ions in the Ba₂SiO₄ lattice causing a substantial distortion. A model for the temperature behavior of the defect luminescence as well as for their nature is provided, based on temperature-dependent luminescence spectra and lifetime measurements.     

Structure and Photoluminescence Properties of Dy3+ Doped Phosphor with Whitlockite Structure

Whitlockite has the advantages of a low sintering temperature, high stability, and a low fabrication cost, and it is widely used as the host for luminescent material. In this study, Ca_1.8Li_0.6La_0.6−x(PO₄)₂:xDy³⁺ phosphor was prepared by the high-temperature solid-state method, and its structure, composition, and luminescence properties were systematically studied. The results showed that a new whitlockite type matrix was prepared by replacing Ca²⁺ in whitlockite with monovalent and trivalent cations. The prepared phosphors belonged to a hexagonal crystal system with a particle size in the range of 5–20 μm. Under the excitation of 350 nm UV light, the samples emitted white light, and there were mainly two stronger emission peaks at 481 nm in the blue band and 573 nm in the yellow band, which correspond to the electron transitions at ⁴F_9/2→⁶H_15/2 and ⁴F_9/2→⁶H_13/2 of Dy³⁺, respectively. The optimal doping concentration of Dy³⁺ in Ca_1.8Li_0.6La_0.6(PO₄)₂ matrix was 0.03 (mol%). The main mechanism of concentration quenching in the sample was dipole–dipole energy transfer. When the temperature was 130 °C, the luminescence intensity of the samples was 78.7% of that at 30 °C, and their thermal quenching activation energy was 0.25 eV. The CIE coordinates of the sample at 30 °C were (0.2750, 0.3006), and their luminescent colors do not change with temperature. All the results indicate that Ca_1.8Li_0.6La_0.6−x(PO₄)₂:xDy³⁺ phosphor is a luminescent material with good luminescence performance and thermal stability, which shows a promising application in the field of LED display.     

The Effect of Fluorides (BaF2, MgF2, AlF3) on Structural and Luminescent Properties of Er3+-Doped Gallo-Germanate Glass

The effect of BaF₂, MgF₂, and AlF₃ on the structural and luminescent properties of gallo-germanate glass (BGG) doped with erbium ions was investigated. A detailed analysis of infrared and Raman spectra shows that the local environment of erbium ions in the glass was influenced mainly by [GeO]₄ and [GeO]₆ units. Moreover, the highest number of non-bridging oxygens was found in the network of the BGG glass modified by MgF₂. The ²⁷Al MAS NMR spectrum of BGG glass with AlF₃ suggests the presence of aluminum in tetra-, penta-, and octahedral coordination geometry. Therefore, the probability of the ⁴I_13/2→⁴I_15/2 transition of Er³⁺ ions increases in the BGG + MgF₂ glass system. On the other hand, the luminescence spectra showed that the fluoride modifiers lead to an enhancement in the emission of each analyzed transition when different excitation sources are employed (808 nm and 980 nm). The analysis of energy transfer mechanisms shows that the fluoride compounds promote the emission intensity in different channels. These results represent a strong base for designing glasses with unique luminescent properties.     

Effect of Ceramic Formation on the Emission of Eu3+ and Nd3+ Ions in Double Perovskites

Herein, the structure, morphology, as well as optical properties of the powder and ceramic samples of Ba₂MgWO₆ are presented. Powder samples were obtained by high temperature solid-state reaction, while, for the ceramics, the SPS technique under 50-MPa pressure was applied. The morphology of the investigated samples showed some agglomeration and grains with a submicron size of 490–492 µm. The theoretical density and relative density of ceramics were calculated using the Archimedes method. The influence of sample preparation on the position, shape, and character of the host, as well as dopants emission was investigated. Sample sintering enhances regular emission of WO₆ groups causing a blue shift of Ba₂MgWO₆ emission. Nonetheless, under X-ray excitation, only the green emission of inversion WO₆ group was detected. For the ceramic doped with Eu³⁺ ions, the emission of both host and dopant was detected. However, for the powder efficient host to activator energy, the transfer process occurred, and only the magnetic dipole emission of Eu³⁺ was detected. The intensity of Nd³⁺ ions of Ba₂MgWO₆ powder sample is five times higher than for the ceramic. The sintering process reduces inversion defects and creates a highly symmetrical site of neodymium ions. The emission of Ba₂MgWO₆:Nd³⁺ consists of transitions from the ⁴F_3/2 excited level to the ⁴I_J multiplet states with the dominance of the ⁴F_3/2→⁴I_11/2 one. The spectroscopic quality parameter and branching ratio of Nd³⁺ emission are presented.     

Structural and Luminescence Behavior of Nanocrystalline Orthophosphate KMeY(PO4)2: Eu3+ (Me = Ca,Sr) Synthesized by Hydrothermal Method

KMeY(PO₄)₂:5% Eu³⁺ phosphates have been synthesized by a novel hydrothermal method. Spectroscopic, structural, and morphological properties of the obtained samples were investigated by X-ray, TEM, Raman, infrared, absorption, and luminescence studies. The microscopic analysis of the obtained samples showed that the mean diameter of synthesized crystals was about 15 nm. The KCaY(PO₄)₂ and KSrY(PO₄)₂ compounds were isostructural and they crystallized in a rhabdophane-type hexagonal structure with the unit-cell parameters a = b ≈ 6.90 Å, c ≈ 6.34 Å, and a = b ≈ 7.00 Å, c ≈ 6.42 Å for the Ca and Sr compound, respectively. Spectroscopic investigations showed intense ⁵D₀ → ⁷F₄ transitions connected with D₂ site symmetry of Eu³⁺ ions. Furthermore, for the sample annealed at 500 °C, europium ions were located in two optical sites, on the surface of grains and in the bulk. Thermal treatment of powders at high temperature provided better grain crystallinity and only one position of dopant in the crystalline structure. The most intense emission was possessed by the KSrY(PO₄)₂:5% Eu³⁺ sample calcinated at 500 °C.     

Red Y2O3:Eu-Based Electroluminescent Device Prepared by Atomic Layer Deposition for Transparent Display Applications

Y₂O_3:Eu is a promising red-emitting phosphor owing to its high luminance efficiency, chemical stability, and non-toxicity. Although Y₂O₃:Eu thin films can be prepared by various deposition methods, most of them require high processing temperatures in order to obtain a crystalline structure. In this work, we report on the fabrication of red Y₂O₃:Eu thin film phosphors and multilayer structure Y₂O₃:Eu-based electroluminescent devices by atomic layer deposition at 300 °C. The structural and optical properties of the phosphor films were investigated using X-ray diffraction and photoluminescence measurements, respectively, whereas the performance of the fabricated device was evaluated using electroluminescence measurements. X-ray diffraction measurements show a polycrystalline structure of the films whereas photoluminescence shows emission above 570 nm. Red electroluminescent devices with a luminance up to 40 cd/m² at a driving frequency of 1 kHz and an efficiency of 0.28 Lm/W were achieved.     

Synthesis and Characterization of Li2MgGeO4:Ho3+

In this work, the synthesis and characterization of Li₂MgGeO₄:Ho³⁺ ceramics were reported. The X-ray diffraction measurements revealed that the studied ceramics belong to the monoclinic Li₂MgGeO₄. Luminescence properties were analyzed in the visible spectral range. Green and red emission bands correspondent to the ⁵F₄,⁵S₂→⁵I₈ and ⁵F₅→⁵I₈ transitions of Ho³⁺ were observed, and their intensities were significantly dependent on activator concentration. Luminescence spectra were also measured under direct excitation of holmium ions or ceramic matrix. Holmium ions were inserted in crystal lattice Li₂MgGeO₄, giving broad blue emission and characteristic 4f-4f luminescent transitions of rare earths under the selective excitation of the ceramic matrix. The presence of the energy transfer process between the host lattice and Ho³⁺ ions was suggested.     

Facile Synthesis of g-C3N4/TiO2/Hectorite Z-Scheme Composite and Its Visible Photocatalytic Degradation of Rhodamine B

A novel g-C₃N₄/TiO₂/hectorite Z-scheme composites with oxygen vacancy (Vo) defects and Ti³⁺ were synthesized by so-gel method and high temperature solid phase reaction. This composite exhibited high visible photo-catalytic degradation of rhodamine B (RhB). The apparent rate constant of g-C₃N₄/TiO₂/hectorite was 0.01705 min⁻¹, which is approximately 5.38 and 4.88 times that of P25 and g-C₃N₄, respectively. The enhancement of photo-catalytic efficiency of the composites can be attributed to the great light harvesting ability, high specific surface area and effective separation of electrons(e⁻) and holes(h⁺). The F element from Hectorite causes the formation of Vo and Ti³⁺ in TiO₂, making it responsive to visible light. The effective separation of e⁻ and h⁺ mainly results from Z-scheme transfer of photo-produced electrons in g-C₃N₄/TiO₂ interface. The composites can be easily recycled and the degradation rate of the RhB still reached 84% after five cycles, indicating its good reusability.     

Reaction of tris(bipyridine)ruthenium(III) with hydroxide and its application in a solar energy storage system

Irradiation of Ru(bipy)₃²⁺ (bipy = 2,2′-bipyridine) with light below 560 nm results in the formation of a charge-transfer excited state potentially capable of reducing water to dihydrogen with concomitant production of Ru(bipy)₃³⁺. The latter may be reduced by hydroxide [Formula: see text] to form dioxygen and regenerate the starting complex. The use of these reactions in a cell designed to bring about the photochemical decomposition of water is proposed.     

Nonstoichiometric LaO0.65F1.7 Structure and Its Green Luminescence Property Doped with Bi3+ and Tb3+ Ions for Applying White UV LEDs

Red–green–blue phosphors excited by ultraviolet (UV) radiation for white light LEDs have received much attention to improve the efficiency, color rendering index (CRI), and chromatic stability. The spectral conversion of a rare-earth ion-doped nonstoichiometric LaO_0.65F_1.7 host was explored with structural analysis in this report. The nonstoichiometric structure of a LaO_0.65F_1.7 compound, synthesized by a solid-state reaction using La₂O₃ and excess NH₄F precursors, was analyzed by synchrotron X-ray powder diffraction. The crystallized LaO_0.65F_1.7 host, which had a tetragonal space group of P4/nmm, contained 9- and 10-coordinated La³⁺ sites. Optical materials composed of La_1−p−qBi_pTb_qO_0.65F_1.7 (p = 0 and 0.01; q = 0–0.2) were prepared at 1050 °C for 2 h, and the single phase of the obtained phosphors was indexed by X-ray diffraction analysis. The photoluminescence spectra of the energy transfer from Bi³⁺ to Tb³⁺ were obtained upon excitation at 286 nm in the nonstoichiometric host lattice. The desired Commission Internationale de l’Eclairage (CIE) values of the phosphors were calculated. The intense green La_0.89Bi_0.01Tb_0.1O_0.65F_1.7 phosphor with blue and red optical materials was fabricated on a 275 nm UV-LED chip, resulting in white light, and the internal quantum efficiency, CRI, correlated color temperature, and CIE of the pc LED were characterized.     

Red-Emitting Hybrid Based on Eu3+-dbm Complex Anchored on Silica Nanoparticles Surface by Carboxylic Acid for Biomarker Application

Luminescent organic-inorganic hybrids containing lanthanides (Ln³⁺) have been prominent for applications such as luminescent bio-probes in biological assays. In this sense, a luminescent hybrid based on dense silica (SiO₂) nanospheres decorated with Eu³⁺ β–diketonate complexes using dibenzoylmethane (Hdbm) as a luminescent antenna was developed by using a hierarchical organization in four steps: (i) anchoring of 3-aminopropyltriethoxysilane (APTES) organosilane on the SiO₂ surface, (ii) formation of a carboxylic acid ligand, (iii) coordination of Eu³⁺ to the carboxylate groups and (iv) coordination of dbm⁻ to Eu³⁺. The hybrid structure was elucidated through the correlation of thermogravimetry, silicon nuclear magnetic resonance and photoluminescence. Results indicate that the carboxylic acid-Eu³⁺-dbm hybrid was formed on the surface of the particles with no detectable changes on their size or shape after all the four steps (average size of 32 ± 7 nm). A surface charge of −27.8 mV was achieved for the hybrid, assuring a stable suspension in aqueous media. The Eu³⁺ complex provides intense red luminescence, characteristic of Eu^{3+ 5}D₀→⁷F_J electronic transitions, with an intrinsic emission quantum yield of 38%, even in an aqueous suspension. Therefore, the correlation of luminescence, structure, particle morphology and fluorescence microscopy images make the hybrid promising for application in bioimaging.     

Energy Structure and Luminescence of CeF3 Crystals

The results of the calculation of the energy band structure and luminescent research of CeF₃ crystals are presented. The existence of two 5d1 and 5d2 subbands of the conduction band genetically derived from 5d states of Ce³⁺ ions with different effective electron masses of 4.9 m_e and 0.9 m_e, respectively, is revealed. The large electron effective mass in the 5d1 subband facilitates the localization of electronic excitations forming the 4f-5d cerium Frenkel self-trapped excitons responsible for the CeF₃ luminescence. The structure of the excitation spectra of the exciton luminescence peaked at 290 nm, and the defect luminescence at 340 nm confirms the aforementioned calculated features of the conduction band of CeF₃ crystals. The peculiarities of the excitation spectra of the luminescence of CaF₂:Ce crystals dependent on the cerium concentration are considered with respect to the phase formation possibility of CeF₃.