Fast Cathodoluminescent Calcium Sulfide Phosphors

Lehmann, W.; Ryan, Frank

doi:10.1149/1.2404174

Cited by 56 publications

(16 citation statements)

References 4 publications

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“…4. Energy difference between these peaks is found to be almost the same order as reported [20,21] for the two lowest states ( 2 F 5/2 and 2 F 7/2 ) of the single 4f electron of Ce 3+ . It can, therefore, be reasonably assumed that the electronic transitions for the luminescence terminate in these two states.…”

Section: Xrd Tem Tga and Pl Studiessupporting

confidence: 78%

Luminescence and defect studies of Ce3+ doped CaS phosphor synthesized via solid state diffusion method

Singh

Rao

Zhu

et al. 2006

Materials Science and Engineering: B

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Section: Xrd Tem Tga and Pl Studiessupporting

confidence: 78%

Luminescence and defect studies of Ce3+ doped CaS phosphor synthesized via solid state diffusion method

Singh

Rao

Zhu

et al. 2006

Materials Science and Engineering: B

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“…3 Using a General Electric model XRD5 powder diffractometer with a CuK a source, we found the lattice constant of both the magnetron and e-beam deposited CaS films to be the same (within experimental error), a = 5.708 ± 0.001 A, which is slightly larger than the bulk value reported previously. 13 From the diffraction peak widths we have estimated the average crystallite size in our films.…”

Section: B Structure and Compositionmentioning

confidence: 47%

Photoluminescence and optical absorption in CaS : Eu²⁺ : Sm³⁺ thin films

et al. 1992

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The optical absorption and photoluminescence of Eu 2+ : Sm 3+ -doped CaS films have been investigated in this paper. The energy dependence of the refractive index and absorption coefficient of the film were obtained by analyzing transmission and reflection spectra of the thin film. The refractive index at low energies is very close to the bulk value for CaS (n -2.03) and decreases with increasing energy in the range of 1.2 to 2.5 eV. The energy gap of CaS : Eu 2+ : Sm 3+ thin films is found to be a direct gap with value E e = 4.48 eV. Photoluminescence studies on annealed CaS : Eu 2+ : Sm 3+ thin films showed a broad band at ~1.92 eV identified with emission from Eu ions, and a set of sharp lines corresponding to emission from Sm 3+ ions. Most of the strong features presented in the room temperature spectra are found in good agreement with previous bulk studies of CaS : Eu 2+ and CaS : Sm 3+ . The abnormal increase of the Sm 3+ photoluminescence with increasing temperature is explained by the phonon-assisted energy transfer from Eu 2+ ions to Sm 3+ ions.

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“…This is particularly important, for example, in projection television screens. There are several rare-earth activated phosphors that could be used instead of the sulfide including Y 4 (SiO 4 ) 3 :Tb 3+ , La 2 O 2 S:Tb 3+ (27), CaS:Ce 3+ (28), and SrGa 2 S 4 :Eu 2+ (29). Terbium-activated cathodoluminescent phosphors, such as La 2 O 2 S:Tb 3+ and yttrium silicate, do not provide a saturated enough green color.…”

Section: Phosphors For Cathode Ray Tubesmentioning

confidence: 99%

Phosphors

Srivastava¹,

Soules²

2000

Kirk-Othmer Encyclopedia of Chemical Technology

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PHOSPHORSLuminescence is the process of producing light in excess of thermal radiation following an excitation. A solid material exhibiting luminescence is called a phosphor. Phosphors are usually fine inorganic compound powders of a high degree of purity and a median particle size of 3-15 micrometers but may be large single crystals, used as scintillators, or glasses or thin films. Phosphors may be excited by high energy invisible uv radiation (photoluminescence), x-rays (radioluminescence), high energy electrons (cathodoluminescence), a strong electric field (electroluminescence), or in some cases infrared radiation (up-conversion), chemical reactions (chemiluminescence), or even stress (triboluminescence). Figure 1 shows the electromagnetic energy spectrum indicating some of the common energy forms that excite phosphors. Because phosphors convert the exciting energy to visible radiation, they have many everyday applications; phosphors are responsible for the light generated by fluorescent lamps, televisions, computer terminals, etc.Phosphors usually contain activator ions in addition to the host material. These ions are deliberately added in the proper proportion during the synthesis. The activators and their surrounding ions form the active optical centers. Table 1 lists some commonly used activator ions. Some solids, made up of complexes such as calcium tungstate [7790-75-2], CaWO 4 , are self-activated. Also in many photoluminescence phosphors, the primary activator does not efficiently absorb the exciting radiation and a second impurity ion is introduced known as the sensitizer. The sensitizer, which is an activator ion itself, absorbs the exciting radiation and transfers this energy to the primary activator.The optical properties of a phosphor are measured on relatively thick plaques of the phosphor powder. An important optical property for the application of the phosphor is its emission spectrum, the variation in the intensity of the emitted light versus wavelength. Fluorescent lamps must have phosphors which produce white light of high luminous efficiency and with good color rendering properties. Because individual activator centers generally emit in a relatively narrow region of the spectrum producing a colored light, more than one activator or phosphor must be used. Similarly colored televisions employ three phosphors in separate closely spaced dots; one dot contains a phosphor which emits in the blue, one in the green, and one in the red region of the spectrum. Saturated colors are needed in order for the screen to be able to reproduce nearly all colors using these emissions in different relative proportions. In other applications, such as x-ray screens, it is desirable to have an emission spectrum concentrated near the peak in the sensitivity of the receptor, such as the x-ray photographic film. The reflectance spectrum is a graph of the percentage of radiation reflected and absorbed by the powder plaque versus wavelength. The excitation spectrum gives the variation of the light output from the phos...

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Fast Cathodoluminescent Calcium Sulfide Phosphors

Abstract: not Available.

Cited by 56 publications

References 4 publications

Luminescence and defect studies of Ce3+ doped CaS phosphor synthesized via solid state diffusion method

Luminescence and defect studies of Ce3+ doped CaS phosphor synthesized via solid state diffusion method

Photoluminescence and optical absorption in CaS : Eu²⁺ : Sm³⁺ thin films

Phosphors

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Fast Cathodoluminescent Calcium Sulfide Phosphors

Abstract: not Available.

Cited by 56 publications

References 4 publications

Luminescence and defect studies of Ce3+ doped CaS phosphor synthesized via solid state diffusion method

Luminescence and defect studies of Ce3+ doped CaS phosphor synthesized via solid state diffusion method

Photoluminescence and optical absorption in CaS : Eu2+ : Sm3+ thin films

Phosphors

Contact Info

Product

Resources

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Photoluminescence and optical absorption in CaS : Eu²⁺ : Sm³⁺ thin films