C2v Site Research Articles

Analysis of site symmetries of Er3+ doped CaF2 and BaF2 crystals by high resolution photoluminescence spectroscopy

The understanding of complex relationships between luminescent properties, local symmetry of an emitting center, and the host crystal structure provides a better insight into optical properties of materials. In this work, the alkaline earths CaF2 and BaF2 fluoride crystals doped with 0.1 mol% ErF3 were investigated. The crystals structure has been studied using a synchrotron and laboratory X-ray diffraction. The C3v and C4v sites symmetry were determined using erbium probed high resolution emission spectroscopy (HRPL) at low temperature (LT) of 10 K. The considerable difference in room temperature (RT) optical properties for CaF2 compared to BaF2 crystals was observed. Such difference in absorption intensity of 4.7 times of erbium 4G11/2 manifold in UV, and 7.5 times in green emission from 4S3/2 manifold, could be due to the distinction in the host crystals cationic radius (ΔrCa,Ba) and the dopant-host ionic radius (ΔrCa-Er, ΔrBa-Er). Those Δr differences influence the structure and lead to the following symmetry formation: In CaF2, the C4v and C3v isolated centers were identified, with the determined Er3+- F−i bond lengths of 2.734 Å and 4.735 Å respectively; In BaF2, only C3v isolated centers were identified with the determined Er3+- F−i bond lengths of 5.380 Å. The present work is the first study that takes into account correlations of optical properties, the local symmetry and the structure in mentioned fluorides crystals, and it could be a step forward in the lanthanide doped optical materials systematics.

On the Utility of Ce3+ Spin−Orbit Transitions in the Interpretation of Rate Data in Ceria Catalysis: Theory, Validation, and Application

Cerium oxide is a ubiquitous component in catalytic systems of industrial and academic interest, and the precise mechanistic function of oxygen vacancies/Ce3+ ions a persistent open question in this regard. Existing methods for quantifying vacancy densities are for the most part indirect in nature, and they either have to necessarily be applied ex situ or, if applicable in situ, are oftentimes limited in applicability or quantitative rigor. We present herein a theoretical and experimental analysis of the utility of 2F5/2–2F7/2 electronic transitions in the quantitative estimation of oxygen vacancy or Ce3+ densities. Application of crystal field theory reveals the nonforbidden nature of 2F5/2–2F7/2 transitions for Ce3+ ions present in a C3v site symmetry environment, unlike free Ce3+ ions in the gas phase that exhibit La Porte forbidden transitions between states of equivalent parity. The molar extinction coefficient for the infrared feature of interest is estimated using three reductants─H2, CO, and ethanol─and applied toward interpretation of ceria-catalyzed H2–D2 exchange and tert-butanol dehydration catalysis rate data. Linear correlations between H2–D2 exchange rates and infrared spectroscopy-derived vacancy densities point to the sole involvement of reduced domains in H2 activation steps prevalent in hydrogenation and hydrodeoxygenation catalysis. Contrastingly, areal tert-butanol dehydration rates that trend inversely with vacancy densities both in the presence and absence of α-hydrogen-containing oxygenates carrying a propensity toward stoichiometric oxidative routes suggest the participation of oxidized, not reduced domains in dehydrative turnovers producing isobutene. The nonforbidden nature of the Ce3+2F5/2–2F7/2 transition─evidenced here using symmetry considerations─likely extends beyond the C3v symmetry environment under consideration here, implying that its fortuitous appearance within the infrared region of the electromagnetic spectrum may render it amenable to quantitative application in relating local structure to catalytic function in ceria catalysis more broadly.

Preparation and characterization of antimony nanoparticles for hydrogen evolution activities

Modern research focuses exclusively on the search for relatively inexpensive, highly efficient electrocatalytic materials for the electrocatalytic hydrogen production water splitting reactions. Antimony is a chemical element having four allotropes with three oxidation states. Antimony is a semi-metal with elemental antimony. Recently, elemental antimony (Sb) with an extensive light absorption was recognized as good electrocatalytic for hydrogen evolution reactions. This study focuses on preparation and characterization of antimony nanoparticles for hydrogen evolution activities as explored. We report the structural, optical, vibrational, electrochemical properties of the pristine antimony nanoparticles for efficient catalytic material for electrochemical water splitting applications. The prepared antimony nanoparticles revealed the rhombohedral crystal structure formation with D3d5 (R 3¯ m) space group situated on symmetry C3v sites. In Raman studies, the peak appeared at 110.67 cm−1 corresponds to in-plane longitudinal vibration (Eg) and at 147 cm−1 for out of plane vibration (A1g) for pure antimony. The synergic effect of NMP and ultrasonication yields highly homogeneous antimony nanoparticles as evidenced from morphological analysis. From electrochemical impedance analysis, the solution resistance value of Sb-NMP is 1.67 Ω, which was small in comparison to the pure Sb (1.96 Ω) and Sb-Ball (1.93 Ω) and exhibited the good conductive nature of Sb-NMP nanomaterials. From electrochemical HER analysis, we found that the Sb-NMP showed the low 246 mV@10 mA/cm2 overpotential with low 186 mV/dec Tafel slope value. Furthermore, the chronoamperometry study exposed that the electrocatalyst Sb-NMP delivered an exceptional HER performance with high stability of 80% retention for continuous three hours measurements. Therefore, this study may perhaps facilitate the growth of antimony nanoparticles which can be used as an HER catalysts for improving the electrocatalytic HER activity.

Crystal-phase-specific near-infrared photoluminescence from Er3+-doped Bi2O3 thin films

Er3+-doped Bi2O3 films were sputter deposited on Si(100) substrates at room temperature with H2O vapor as an oxygen source gas. Crystal phases appearing after postannealing in an O2 atmosphere included single-phases of α-Bi2O3, γ-Bi2O3, and δ-Bi2O3, as well as a mixed phase of α-Bi2O3 and γ-Bi2O3. Selection of the crystal phase was possible in terms of H2O pressure and postannealing temperature. Photoluminescence spectra from Er3+ ions excited at a laser wavelength of 532 nm revealed distinct spectral features specific to the crystal phases. A clear crystal-field splitting feature consisting of eight emission lines was observed in PL spectra from sufficiently oxidized α-Bi2O3:Er films, indicating that Er3+ ions occupied low-symmetry C2v sites of Bi3+. The optimum annealing temperature for optical activation of Er3+ ions was between 400 and 450 °C. The emission intensity of α-Bi2O3:Er deposited with H2O was seven times higher than that of α-Bi2O3:Er deposited with O2 probably because larger numbers of Er3+ could substitute Bi3+ sites under reduced condition. Increasing deposition temperature lowered the emission intensity due to the loss of OH and H species from the as-deposited films. The emission spectra of γ-Bi2O3:Er were featureless and its emission intensity was one order of magnitude lower than that of α-Bi2O3:Er. The low-temperature phase of δ-Bi2O3:Er turned out to be entirely emission inactive. Reactions at the interface between the Bi2O3 film and the Si substrate were promoted upon postannealing at 500 °C. The resulting Bi2SiO5:Er exhibited a weak emission spectrum with four emission lines, which reflected occupation at tetragonal Bi3+ sites in the (Bi2O2)2− layers.

Growth and characterization of ErF3 doped BaF2 crystals

ErF3 doped BaF2 crystals were obtained using the vertical Bridgman technique. Five crystals, with 0.05, 0.08, 0.1, 0.2 and 0.5 mol% ErF3 added to the starting material, have been investigated. The optical absorption spectra reveal the characteristic bands of the Er3+ ions. The distribution of Er3+ ions along the crystals was studied using the optical absorption spectrum of every samples (14–18 slices) cleaved from the as-grown crystals. The Er3+ ions are not uniform distributed along the BaF2 crystals. The segregation coefficient, k, was calculated using the so-called optical absorption method and the Scheil relationship between the dopant concentration and crystal growth conditions. The calculated segregation coefficient of the Er3+ ions ranges from 0.76 to 0.98, for ions with trigonal (C3v) sites, and from 0.6 to 0.86 for clusters, depending on the ErF3 concentration. In the investigated temperature range, only one type of dielectric relaxation has been observed. This relaxation, with activation energy of 0.54 eV is associated with trigonal NNN type (C3v) centers. The charge compensating defects were discussed taking into account both the optical absorption spectra and the calculated number of NNN dipoles whose relaxation were observed.

Structure and crystal field analysis using ionoluminescence of Al2O3: Tm3+ phosphor

Structurally stable rare earth ion doped materials are attracting scientific interest for white light phosphors and laser system. α-Al2O3:Tm3+ (1 mol%) samples are synthesized by solution combustion method. Crystalline phase and structure are analyzed by X-ray diffraction (XRD) Rietveld refinement technique and it confirms multi-phases such as α-Al2O3 and TmAlO3. The average crystallite size is found to be ~125 nm. Ionoluminescence (IL) spectra of 100 MeV swift Si8+ ions irradiated Al2O3 show a sharp emission at 695 nm and a set of small humps at 678, 683 nm (N′ lines) and 708, 716, 729 nm (N lines) corresponding to Cr3+ impurity transition (2Eg→4A2g) of R lines. Emission peak at 672 nm is corresponding to Mn4+ (2E→4A2) characteristic emission. IL spectra of Tm3+ (1 mol%) doped Al2O3 exhibits Tm3+ characteristic emissions at 359.82, 397.79, 467.46, 528.01, 658.20, 757.00, 764.12 and 808.02 nm (1D2→3H6, 3P2→3H4, 1G4→3H6, 1D2→3H5, 1D2→3H4, 1D2→3F3, 1D2→3F2 and 3H4→3H6 transitions respectively) along with Cr3+ and Mn4+ impurity emissions. Further, 4f12 atomic energy configuration of Tm3+ in Al2O3 and TmAlO3 has been calculated by the crystal field theory method. Microstate energy levels of free Tm3+ ion, Tm3+ ions in C3v site of Al2O3 and Tm3+ ion in Cs site of TmAlO3 are fitted by varying the crystal field parameters. Root mean square (rms) deviation is found to be 0.30 16.41 and 18.18 cm−1 respectively. IL intensity decays with increasing ion fluence due to the formation of extended defects and local heating in host along by Si8+ ion trajectory. Irradiation-induced damage cross section of the cylindrical ion path is found to be 4.81 ± 0.20 and 5.10 ± 0.20 nm2 for undoped (695 nm) and Tm3+ doped Al2O3 (559 nm) respectively.

Electron paramagnetic resonance enhanced crystal field analysis for low point-group symmetry systems: C2v sites in Sm3+:CaF2/SrF2

We present a comprehensive spectroscopic study of C point-group symmetry sites in Sm:CaF/SrF codoped with either NaF or LiF. Data includes electron paramagnetic resonance measurements of Zeeman and hyperfine interactions for the ground state, as well as site-selective excitation and fluorescence spectroscopy up to the G multiplet. Inclusion of the EPR data allowed us to determine unique crystal-field parameters. The parameters provide information about the geometry of the sites and the nature of the interactions between the Sm dopant and the alkaline earth co-dopant.

ZnGa2-xEuxO4 nanoparticles: 10 minutes microwave synthesis, thermal tuning of Eu3+ site distribution and photophysical properties

Microwave-assisted synthesis of red-emitting ZnGa2-xEuxO4 (x = 0.005, 0.008, 0.010, 0.012, 0.015) nanoparticles is reported. Salient features of this method are: 10 min are sufficient to obtain well-crystallized, phase-pure nanoparticles; synthesis upto 2 g/batch can be accomplished with high yields (>90%) at a low temperature of 200 °C; the obtained nanoparticles are near-spherical and of ∼7 nm size as seen by HR-TEM; as-prepared nanoparticles show intense red emission at 615 nm due to the 5D0 → 7F2 transition, when excited at 395 nm. The structural and optical properties of the ZnGa2-xEuxO4 were studied by XRD, HR-TEM, FE-SEM, FT-IR and time-resolved photoluminescence (PL) spectroscopy. ZnGa1.99Eu0.01O4 nanoparticles, which showed the most intense red emission, were studied for the effect of annealing (in air) on their optical properties. Annealing at up to 1000 °C (i) enhanced crystallinity and the crystallite size increased from ∼7 nm in the as-prepared material to ∼46 nm (ii) enhanced emission intensity, and moved the CIE coordinates towards red. Photoluminescence decay curves displayed two lifetimes, implying the distribution of Eu3+ (i) on particle surface (ii) within the host lattice; the distribution gradually changes with annealing. The peak fitting of the emission spectra implies C2v site symmetry around Eu3+. A detailed Judd–Ofelt analysis has been presented. The samples annealed at 600–800 °C showed ∼58% quantum efficiency. The color purity could be increased to 87% by varying the Eu3+ content. Our report demonstrates the efficacy of swift microwave-assisted synthesis (10 min) in providing a red phosphor of high color purity suitable for LEDs and display applications.

Fluorescence line narrowing and Judd-Ofelt theory analyses of [formula omitted]-doped low-silica calcium aluminosilicate glass and glass-ceramic

Eu-doped calcium aluminosilicate glass and glass-ceramic were synthesized and studied by site-selective spectroscopy. Using both broadband excitation and fluorescence line narrowing techniques, the D05→F17 emission transition was studied under resonant excitation at different wavelengths within the F07→D05 band. In order to explore the local structure of the systems, crystal-field analysis was applied assuming C2v site symmetry. Moreover, from the emission spectra of glass and glass-ceramic systems, Judd-Ofelt parameters Ωt (t = 2, 4) were considered. Transition probability (A), stimulated emission cross-section (σ), radiative lifetime (τR) and branching ratios (β) due to the transition D05→FJ7 (J = 1, 2, 3 and 4) of Eu3+ ions were evaluated in different local fields and their relative variations were discussed. The crystallization process, which converted the glass into glass-ceramic, promoted an important enhancement in the quantum efficiency, which was improved from 45% to 60%.

Ferromagnetic and antiferromagnetic orderings in wurtzite diluted magnetic nanostructures

Using a new approach based on symmetry analysis, we have determined the magnetic symmetry groups (Shubnikov groups) of ferro- and antiferromagnetic wurtzite nanostructures doped with magnetic atoms periodically distributed at cation sites as well as the direction of the spontaneous magnetic field. Quantum wells, nanorods (nanowires), nanotubes, and quantum dots have been considered. The direction of the spontaneous magnetic field is determined by magnetic atoms with higher C3v (3m) or Cs (m) site symmetry group (the site symmetry group is defined with respect to the doped nanostructure). When the magnetic-atom distribution becomes more or less disordered (Diluted Magnetic Semiconductors), it seems reasonable to assume that, in most of the cases, the symmetry in regions with a size of some wurtzite unit-cells remains close to that of a periodic one, hence possibly inducing local ferro- or antiferromagnetic properties. The regions can induce overall ferro- or antiferromagnetic states when they have common spontaneous magnetic field direction or, possibly, induce easy-magnetization direction or plane (direction or plane of maximal magnetization intensity for a given external magnetic field strength) when disorder imposes a spread of spontaneous magnetic field direction over the various regions. Of course, such an effect adds itself to magnetic properties eventually induced by grain boundaries, other crystalline phases, and defects such as vacancies, dislocations or interstitial atoms.

F−-Eu3+ charge transfer energy and local crystal environment in Eu3+ doped calcium fluoride

A series of CaF2:xEu3+ (x = 0.01–0.05) phosphors were synthesized by coprecipitation and high temperature solid-state method. Three different F--Eu3+ charge transfer (CT) bands in CaF2:xEu3+ (x = 0.01–0.05) were detected through the PL spectra. Three local crystal environments (deformed Oh octahedron, C3V, C4V) were proposed in Eu3+ doped CaF2. The broad peak at 277 nm is F- → Eu3+ CT peak, in which Eu3+ ions located deformed Oh octahedron sites, the broad peak at 312 nm is due to Eu3+ ions situating at C4v sites, also, Eu3+ ions with C3v sites can make the F- → Eu3+ CT produce a 38-nm redshift to 315 nm. Density functional theory (DFT) was performed to calculate the energy band gap(Eg) according to the three models. The calculation results consist with the experiment. The excitation peaks can be tuned in the same host through changing the local structure of Eu3+.

Site symmetry approach in the supercell model of carbon-doped ZnO bulk

Carbon-doped zinc oxide is one of promising materials for technological applications due to its ferromagnetism observed at room temperature. When using the hybrid DFT-HF Hamiltonian based on the PBE0 exchange-correlation functional for large-scale calculations on defective ZnO:C single crystal, we have shown that application of supercell model for carbon impurity located at O site of wurtzite-structured ZnO bulk results in the dependence of calculated formation energy of the point defect (Eform) on the selected site symmetry of the substituted atom in the supercell. For a more symmetric C3v site usually used for simulation of defective ZnO structures, values of formation energy per single dopant in supercell essentially exceed those evaluated for less symmetric C1 and Cs sites. On the other hand, each of these three types of Eform does not noticeably differ depending on supercell size if it is large enough to neglect lateral interaction between adjacent dopants. Influence of site symmetry on the electronic structure of C-doped ZnO is discussed too. The suggested approach can be further applied to a wide class of defects in crystalline solids allowing the detailed analysis of electron density localization in a defective crystal and more accurate reproducing the formation energy of point defect.

Probing Site Symmetry Around Eu3+ in Nanocrystalline ThO2 Using Time Resolved Emission Spectroscopy

ThO2:Eu3+ nanoparticles were synthesized at 300°C by combustion route using urea as a fuel and characterized by thermogravimetric/differential thermal analysis, X‐ray diffraction, transmission electron microscopy, and photoluminescence techniques. To investigate the effect of annealing temperature, as synthesized powder were heated further at 500°C, 700°C, and 900°C. It was observed that extent of asymmetry around Eu3+ at 700°C/900°C is very high as compared to as‐prepared or 500°C annealed sample. Based on the time resolved emission spectroscopic investigations, it was inferred that two different types of Eu3+ ions were present in the ThO2 nanoparticles. In ThO2 structure, Eu3+ ions occupy two sites; cubic (Oh) and noncubic (<C2v) as can be confirmed from our emission studies. Short‐lived species T1 (~1.3–3.4 ms) predominates at higher annealing temperature arises because of Eu3+ ions occupying noncubic (<C2v) sites without inversion symmetry, whereas long‐lived species T2 (~4.6–6.6 ms) can be ascribed to Eu3+ ions occupying cubic sites (Oh) with inversion symmetry.

Study of crystal-field excitations and infrared active phonons in the multiferroic hexagonal DyMnO3

In hexagonal DyMnO3, Dy3+ crystal-field excitations are studied as a function of temperature and applied magnetic field. They are complemented with the measurements of infrared active phonon frequency shifts under applied magnetic field at T = 4.2 K. Between TN = 68 K and T = 10 K, the absence of Dy3+ Kramers doublet splittings at either the C3 or the C3v site symmetries indicates that the Mn3+ magnetic order effective exchange field has no component parallel to the c-axis at either site. Below T = 10 K, the ground state Kramers doublet splits under the Dy3+ internal effective field as well as the applied magnetic field. Also, relatively strong infrared active phonon energy shifts are observed in magneto-infrared reflectance measurements at T = 4.2 K, allowing the calculation of the induced electric polarization changes as a function of the applied magnetic field. Such changes are associated with a large magnetoelectric effect in DyMnO3, arising from a charge transfer between Dy3+ and apical oxygen ions.

Comparative structural and photoluminescent study of Eu3+-doped La2O3 and La(OH)3 nanocrystalline powders

Eu3+-doped La2O3 nanocrystalline powder was prepared by polymer complex solution method and further used for preparation of Eu3+-doped La(OH)3. Structural and optical characterization was carried out by powder X-ray diffraction and photoluminescent spectroscopy. XRD measurements confirmed the formation of hexagonal La2O3 and its recrystallization into La(OH)3 in a humid atmosphere. Excitation spectra show redshift of host lattice and charge transfer emission bands in La(OH)3 while bands that correspond to Eu3+f–f transitions are placed at same wavelengths in both samples. Photoluminescence spectra recorded over the temperature range from 10K to 300K show that intensities of emission lines in Eu3+-doped La2O3 do not depend on temperature as much as in La(OH)3 sample. Observed dominant 5D0→7F2 and markedly visible 5D0→7F0 emissions in doped La2O3 indicate that Eu3+ ion is located in a structural site without an inversion center. On the other hand, in Eu3+-doped La(OH)35D0→7F0 transition is barely visible while 5D0→7F2 is not prominent, and with temperature drop three 5D0→7FJ (J=1, 2, 4) transitions become almost of the same intensity. In both La2O3 and La(OH)3 structures Eu3+ ion replaces La3+ in non-centrosymmetric C3v and C3h crystallographic sites, respectively, and difference in symmetry of the crystal field around europium ion is explained by comparing shape and volume of these sites. Decay times of the 5D0- level recorded over the temperature range 10−300K revealed that emission lifetime values in La2O3 (~0.7ms) are almost two times higher than in La(OH)3 (~0.4ms), and unlike in La2O3, lifetime in La(OH)3 is temperature dependent.

Role of rare earth on the Mn3+ spin reorientation in multiferroic Ho1-xLuxMnO3

The role of rare earth ion R3+ in spin reorientation and magneto dielectric response is investigated by substitution of non-magnetic smaller ionic radii Lu3+ in multiferroic hexagonal HoMnO3. The XRD analysis suggests that the dopant may preferably goes to C3V site up to 1/3rd of the composition in order to reduce the lattice distortion. We suggest that the R3+ ion at C3 site could play a strong role in spin reorientation than the C3V site. The observation of TSR even in LuMnO3 precludes the role of rare earth magnetic moment in driving the spin reorientation. Surprisingly, the magneto dielectric response of HoMnO3 is dominated by the rare earth RO8 dipoles. The oppositely oriented RO8 dipole at the C3V and C3 determines the magneto dielectric response in various magnetic phases reaffirming the site specific substitution. Thus, site specific doping could be a way to enhance the magnetoelectric coupling strength.

Eu3+ probe ion for rare-earth dopant site structure in sol–gel derived LiYF4 oxyfluoride glass–ceramic

Sol–gel route using metal alkoxides and trifluoroacetic acid as precursors has been used to prepare oxyfluoride glass–ceramic containing Eu3+-doped LiYF4 nanocrystals of about tens of nm size embedded in a silica matrix through controlled crystallization at higher temperatures of the xerogel. Photoluminescence spectra and decay curves recorded in the Eu3+-doped LiYF4 polycrystalline pellet and glass ceramic have been discussed using group-theoretical arguments. In the glass–ceramic Eu3+ ions are embedded dominantly inside the LiYF4 nanocrystals most probably as Eu–O center and/or dimer centers in low symmetry (C2v) sites; oxygen ions were incorporated in their neighborhood during the glass ceramization.

Study of the Defect Structure and Crystal-Field Parameters of α-Al2O3:Yb3+

The methods currently used for studying the defect structure of laser host crystals doped with transition metal or rare-earth ions have several drawbacks or limitations. This study proposes an alternative approach for obtaining optimized impurity structures using molecular dynamics calculation in conjunction with the superposition model. This new approach is specifically applied to a system named α-Al2O3:Yb3+, in which the simulated defect structure is used to fit the superposition model parameters directly onto the observed energy levels. Such an approach provides predicted values of crystal-field parameters, Zeeman splitting g-factor, and hyperfine structure constants. Moreover, the C3v site symmetry is found to be a good approximation for the actual C3 site of Yb3+, as doped in an α-Al2O3 crystal.

Study of magnetodielectric effect in hexagonal Ho1−xDyxMnO3

The magnetodielectric studies on hexagonal Ho1−xDyxMnO3 reveal an overall enhancement of magnetoelectric coupling upon Dy3+ substitution. However, the magnitude of the enhancement is varied with doping level x. Magnetodielectric response is larger for x = 0.1 and it started decreasing with further increase in x. We suggest that the specific site (C3V site) substitution of higher ionic radii Dy3+ in the structure could play a key role in defining magnetoelectric coupling strength through structural distortion. The evolution of c/a ratio which is a measure of distortion in the hexagonal lattice agrees well with the observed percentage change in the dielectric constant which in turn substantiates the role of lattice distortion on the enhancement in magnetodielectric effect.

Optical characterization and crystal field calculation of Er3+ in AlN epilayers

We report on cathodoluminescence (CL) characterization and crystal field (CF) energy levels calculation of Er3+ ions doped in AlN hosts having different morphologies. The CL spectra of crystalline AlN:Er epilayers grown by molecular beam epitaxy and subsequently implanted with erbium were compared with amorphous AlN:Er3+ in situ doped with erbium grown by rf sputtering on (100) silicon. The high resolution CL spectra show a great similarity of Er3+ ion 4f-shell emission line pattern between all studied AlN:Er3+ samples. Assuming that Er3+ ion substitute for Al3+ ion in C3V site symmetry, the majority of emission lines were attributed to transitions between 4F9/2, 4S3/2, 2H11/2, 4F7/2, 2H9/2 and 2P3/2 excited multiplets to the 4I15/2 Stark energy levels. Simulations are carried out using Bkq crystal field parameters determined using electrostatic point charge modelstatic point charge model (PCEM) and crystal field theory. The simulations involved 23 Stark levels resulted in an average r.m.s deviation of 3.8cm−1. The comparison between the CL spectra of c-AlN:Er3+ epilayers grown on sapphire and silicon with amorphous AlN:Er3+ grown on silicon leads to a discussion on the effect of the substrate on the spectral feature of studied crystalline AlN:Er3+ epilayers.