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This study reports cathodoluminescence (CL) and photoluminescence (PL) properties of undoped borate Ca 3 Y 2 B 4 O 12 and Ca 3 Y 2 B 4 O 12 :x Dy 3+ (x = 0.5, 1, 2, 3, 5, and 7) synthesized by gel combustion method. Micro-X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), CL and PL under electron beam and 359 nm pulse laser excitation, respectively were used to investigate characterization and luminescence studies of synthesized samples in the visible wavelength. As-prepared samples match the standard Ca 3 Y 2 BO 4 phase that belongs to the orthorhombic system with space group Pnma (62) based on XRD results. Under electron beam excitation, this borate host shows a broad band emission from about 250 to 450 nm, peaked at 370 nm which is attributed to NBHOC. All as-prepared phosphors exhibited the characteristic PL and CL emissions of Dy 3+ ions corresponding to 4 F 9/2 → 6 H J transitions when excited with laser at 359 nm. The CL emission spectra of phosphors were identical to those of the PL spectra. Concentration quenching occurred when the doping concentration was 1 mol% in both the CL and PL spectra. The underlying reason for the concentration quenching phenomena observed in the discrete orange-yellow emission peaked at 574 nm of Dy 3+ ion-doped Ca 3 Y 2 B 4 O 12 phosphor is also discussed. According to these data, we can infer that this new borate can be used as a yellow emitting phosphor in solid-state illumination., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

La 2 MoO 6 orange-red phosphors with high efficiency incorporated with Eu, Dy and Sm have been synthesized through a gel combustion method. The influences of rare earth doping in synthesized samples were analysed by X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), and cathodoluminescence. Rare earth doped La 2 MoO 6 samples show strong emission bands in the range of 400-750 nm and optimal doping concentration for all samples was 2 mol%. La 2 MoO 6 host doped Eu ion showed intense and predominant emission peaks in 450-750 nm range. The electrical multipolar interaction contributed to the non-radiative energy transfer between Eu 3+ ions in La 2 MoO 6 host matrix. Sm doped La 2 MoO 6 host exhibited orange-red CL emission peaks at 564, 608, 652 and 708 nm La 2 MoO 6 :Dy 3+ phosphor displayed emissions at 484, 574 and 670 nm, respectively. The observed intense and sharp emission peaks indicate that La 2 MoO 6 is promising host for lanthanides doped phosphor materials in the applications of optoelectronic., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Undoped and Pr, Sm and Tb activated BaAl 2 O 4 phosphors have been synthesized by solid state reaction method and combustion method. The structure and morphological observation of the phosphor samples were monitored by X-ray powder diffraction (XRD) and environmental scanning electron microscope (ESEM) coupled to an energy dispersive X-ray spectrometer (EDS). The all diffraction peaks are well assigned to standard data card (PDF♯17-306). Emission properties of the samples were explored using light emission induced by an electron beam (i.e cathodoluminescence, CL) at room temperature (RT). Undoped BaAl 2 O 4 sample exhibits a broad defect emission from 300 to 500 nm from the aluminate defect centres. CL spectra recorded at room temperature display that the as-prepared BaAl 2 O 4 :Ln (Ln=Pr, Sm and Tb) phosphors exhibit different luminescence colors coming from different rare earth activator ions. The transition 4 G 5/2 → 6 H 7/2 located at 606 and 610 nm for Sm 3+ can occur as hypersensitive transition having the selection rule ΔJ = ± 1. For the Tb 3+ doped samples, they exhibit D45 green line emissions. The proposed luminescent mechanisms of all doped rare earth ions are also discussed., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

A series of novel apatite-based Ca 2 Y 8 (SiO 4 ) 6 O 2 phosphors doped with Ce 3+ and Tb 3+ were synthesized by a solid-state reaction method at different calcination temperatures and times. The comparative results of thermal analysis (TG-DTA), FTIR, X-ray diffraction (XRD) and environmental scanning electron microscope (ESEM) reveal that the firing temperature for Ca 2 Y 8 (SiO 4 ) 6 O 2 :Ce 3+ , Tb 3+ was optimized to be 1200°C. The systematic studies on the influences of thermal treatment conditions on photoluminescence (PL) and cathodoluminescence (CL) properties were also reported. The excitation spectra of Ca 2 Y 8 (SiO 4 ) 6 O 2 :Ce 3+ , Tb 3+ exhibited one strong excitation band at 325nm. The PL and CL results indicated that the violet-blue emission intensities about 400nm from the Ce 3+ and efficient green emission at 544nm from Tb 3+ were highly dependent on the calcination conditions., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Several ZnB 2 O 4 powder samples having dopants concentrations of 0.1, 0.01, 0.04wt% Ce and La were prepared using the nitric acid method via the starting oxides. Several complementary methods such as powder X-ray diffraction (XRD), thermal analyses environmental scanning electron microscopy (ESEM), Radioluminescence (RL) and Cathodoluminescence (CL) techniques were used. Unique luminescence properties of Ce doped ZnB 2 O 4 powder samples are reported for the first time. A new luminescence bands appearing in red part of the spectrum and having all the characteristics of Ce 3+ were obtained from RL results. Changing the Ce and La concentration of 0.01-0.1wt% leads to an increase in RL and CL intensities of Ce 3+ and La 3+ ions and also CL emission spectra of ZnB 2 O 4 show gradual shift towards longer wavelength. When we compare the luminescence intensity of the samples it is seen that Ce doped ZnB 2 O 4 has the highest intense whereas La doped ZnB 2 O 4 has the lowest one. However, emission spectra of both Ce and La doped samples kept unchanged., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Here, we report our results referring to the preparation of Ce doped Y2.22MgGa2Al2SiO12, Y1.93MgAl4SiO12 and Y2.22Gd0.75Ga2Al3O12 using solid state reaction at high temperature. Several complementary methods (i.e. powder x-ray diffraction (XRPD), energy dispersive analysis of X-rays (EDX), scanning electron microscopy (SEM) and Fourier transforms infrared spectroscopy (FTIR)) were studied to examine the effects of the synthesis procedure on the morphology and structure. XRD analyses revealed that all compounds include yttrium aluminate phase with garnet structure. Cathodoluminescence (CL), radioluminescence (RL) and photoluminescence (PL) measurements were carried out for clarification of relationship between host lattice defects and the spectral luminescence emissions. Luminescence emission of phosphors is peaked at 530nm assigned to 5d-4f transitions of the dopant Ce(3+) ions with a broad emission band in 400-700nm range. Under electron irradiation, the emission spectrum of Ce doped (YGd)3Ga2Al3O12 is well defined and has a characteristic fairly narrow and sharp emission band peaking at 312nm and 624nm corresponding to transition of (6)P7/2 →(8)S7/2 and (6)GJ→(6)PJ (Gd(3+)), respectively. We suggest some of phosphors might be excellent phototherapy phosphor materials under electron excitation., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

In this study, structural and luminescence properties of magnesium borate of the form MgB4O7 doped with Tm and Na were investigated by X-ray diffraction (XRD), Raman spectroscopy and cathodoluminescence (CL). The morphologies of the synthetised compounds exhibit clustered granules and road-like materials. As doping trivalent ions into a host with divalent cations requires charge compensation, this effect is discussed. The CL spectra of undoped MgB4O7 shows a broad band emission centred around 350 nm which is postulated to be produced by self-trapped excitons and some other defects. From the CL emission spectrum, main emission bands centred at 360, 455, 475 nm due to the respective transitions of (1)D2→(3)H6,(1)D2→(3)F4 and (1)G4→(3)H6 suggest the presence of Tm(3+) ion in MgB4O7 lattice site. CL mechanism was proposed to explain the observed phenomena which are valuable in possibility of the developing new luminescent materials for different applications. In addition, the experimental Raman spectrum of doped and undoped MgB4O7 were reported and discussed., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The present study describes cathodoluminescence (CL) properties of CaSnO3 phosphors doped with Eu(3+), Tb(3+) and Dy(3+) synthesized by a solid-state method. X-ray diffraction (XRD) patterns confirm that CaSnO3 sintered at 1200°C exhibits orthorhombic structure. The evidence and rationale for two strong broad emission bands appeared at 360 and 780nm for undoped CaSnO3 are presented. The CL measurements exhibit that the 4f-4f emissions from (5)D4→(7)F6 (490nm), (5)D4 →(7)F5 (544nm), (5)D4 →(7)F4 (586nm) and (5)D4 →(7)F3 (622nm), assigned to possible transitions of Tb(3+) ions are seen. The strongest one, observed at 544nm, due to its probability of both magnetic and electric transitions make the sample emission green. Emissions at 480, 574, 662 and 755nm were detected for the CaSnO3:Dy(3+) and attributed to the transitions from the (4)F9/2 to various energy levels (6)H15/2, (6)H13/2, (6)H11/2 and (6)H9/2+(6)F11/2 of Dy(3+), respectively. CL spectra of Eu doped CaSnO3 reveal that there is a strong emission peak appeared at 615nm due to the electric dipole transition (5)D0→(7)F2 (red). Finally, our results show that the rare earth doped CaSnO3 have remarkable potential for applications as optical materials since it exhibits efficient and sharp emission due to rare earth ions., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Microscopes offer a limited depth of focus which precludes the observation of a complete image of a three-dimensional (3D) object in a single view. Investigations, by a variety of researchers, have led to the development of extended depth of focus algorithms for serial optical slices of microscopic 3D objects in recent years. However, to date, no quantitative comparison of the different algorithms has been performed, generally leaving the evaluation to the subjective qualitative appreciation of the observer. In this paper we use three different tests for extended depth of focus algorithm evaluation and test 10 different algorithms, some of them have been adapted (by us) for a series of optical slices. However, the main contribution of the paper is a new improved algorithm for computing the extended depth of focus.