Synthesis, Properties and Mineralogy of Important Inorganic Materials

Warner, Terence E.

doi:10.1002/9780470976012

Cited by 37 publications

(45 citation statements)

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“…Bird's eye view, or c axis projection, of the CaWO 4 unit cell crystal structure is shown in Figure 3, which is adopted from Ref. 6 and redrawn. Five ab-planes are presented along c axis, from the top to the bottom.…”

Section: Resultsmentioning

confidence: 99%

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Pycnometric and Spectroscopic Studies of Red Phosphors Ca²⁺_(1-1.5x)WO₄:Eu³⁺_xand Ca²⁺_(1-2x)WO₄:Eu³⁺_x,Na⁺_x

Cho¹

2013

Bulletin of the Korean Chemical Society

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Red phosphors Ca (1−1.5x) Eu x WO 4 and Ca (1−2x) Eu x Na x WO 4 were synthesized with various concentrations x of Eu 3+ ions by using a solid-state reaction method. The crystal structure of the red phosphors were found to be a tetragonal scheelite structure with space group I4 1 /a. X-ray diffraction (XRD) results show the (112) . Raman spectra exhibit that, without showing any difference before and after the doping of activators to the host material CaWO 4 , all the gerade normal modes occur at the identical frequencies with the same shapes and weaker intensities after the substitution. However, the FT-IR spectra show that some of the ungerade normal modes have shifted positions and different shapes, caused by different masses of Eu 3+ ions (or Na + ions, or V Ca '' vacancies) from Ca .

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Section: Resultsmentioning

confidence: 99%

“…The host material CaWO 4 exhibits a bright blue fluorescence upon exposure to a short wavelength ultraviolet radiation (254 nm). CaWO 4 crystallizes in the tetragonal scheelite structure (space group: I4 1 /a), [2][3][4][5][6] at ambient temperature and pressure. Calcium tungstate is essentially an ionic compound.…”

Section: Introductionmentioning

confidence: 99%

Pycnometric and Spectroscopic Studies of Red Phosphors Ca²⁺_(1-1.5x)WO₄:Eu³⁺_xand Ca²⁺_(1-2x)WO₄:Eu³⁺_x,Na⁺_x

Cho¹

2013

Bulletin of the Korean Chemical Society

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“…The preparation of Egyptian blue pigment, a mixture of mostly CaCuSi 4 O 10 and SiO 2 , is a well-studied process 4,[13][14][15][16][17][18][19][20][21] . The numerous reported procedures may be categorized as either melt flux or solid-state reactions.…”

Section: Discussionmentioning

confidence: 99%

Exfoliation of Egyptian Blue and Han Blue, Two Alkali Earth Copper Silicate-based Pigments

Johnson-McDaniel

Salguero

2014

JoVE

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In a visualized example of the ancient past connecting with modern times, we describe the preparation and exfoliation of CaCuSi 4 O 10 and BaCuSi 4 O 10 , the colored components of the historic Egyptian blue and Han blue pigments. The bulk forms of these materials are synthesized by both melt flux and solid-state routes, which provide some control over the crystallite size of the product. The melt flux process is time intensive, but it produces relatively large crystals at lower reaction temperatures. In comparison, the solid-state method is quicker yet requires higher reaction temperatures and yields smaller crystallites. Upon stirring in hot water, CaCuSi 4 O 10 spontaneously exfoliates into monolayer nanosheets, which are characterized by TEM and PXRD. BaCuSi 4 O 10 on the other hand requires ultrasonication in organic solvents to achieve exfoliation. Near infrared imaging illustrates that both the bulk and nanosheet forms of CaCuSi 4 O 10 and BaCuSi 4 O 10 are strong near infrared emitters. Aqueous CaCuSi 4 O 10 and BaCuSi 4 O 10 nanosheet dispersions are useful because they provide a new way to handle, characterize, and process these materials in colloidal form.

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“…Scheelite CaWO 4 itself is a very efficient luminescent material at room temperature, and is used commercially as X-ray phosphor. 3,4) Terbium can be substituted for Ca 2+ in scheelite as trivalent Tb 3+ ions. The substitution of trivalent Tb 3+ for divalent Ca 2+ requires a charge compensating mechanism to maintain electrical neutrality.…”

Section: Introductionmentioning

confidence: 99%

Point Defects and Photoluminescence of Green Phosphors Ca(1-1.5x)WO4:Tbx3+ and Ca(1-2x)WO4:Tbx3+ Nax+

Cho¹

2013

Korean. J. Mater. Res.

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Two types of Tb-and Na-substituted green phosphors Ca (1-1.5x) WO 4 :and Ca (1-2x) WO 4 : were synthesized with various x values, using a solid-state reaction. The former phosphors contained both substitutional and vacancy point defects, while the later had only substitutional defects. X-ray diffraction results showed that the main diffraction peak, (112), was centered at 2θ = 28.72 o and indicated that there was no basic structural deformation caused by substitutions or vacancies. The photoluminescence emission and photoluminescence excitation spectra revealed the optical properties of trivalent terbium ions, Tb 3+. Typical transitions,F 3 , and cross relaxations were observed. Subtle differences in the photoluminescence of green phosphors were observed as a result of the point defects. The FT-IR spectra indicated that some of the ungerade vibrational modes had shifted positions and changed shapes, spreading out over a wide range of frequencies. This change can be attributed to the different masses of Tb 3+ and Na + ions and V Ca " vacancies compared to Ca 2+ ions. The gerade normal modes of the Raman spectra exhibited subtle differences resulting from point defects in Ca (1-1.5x) Tb x WO 4 and Ca (1-2x) Tb x Na x WO 4 .

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Synthesis, Properties and Mineralogy of Important Inorganic Materials

Cited by 37 publications

References 1 publication

Pycnometric and Spectroscopic Studies of Red Phosphors Ca²⁺_(1-1.5x)WO₄:Eu³⁺_xand Ca²⁺_(1-2x)WO₄:Eu³⁺_x,Na⁺_x

Pycnometric and Spectroscopic Studies of Red Phosphors Ca²⁺_(1-1.5x)WO₄:Eu³⁺_xand Ca²⁺_(1-2x)WO₄:Eu³⁺_x,Na⁺_x

Exfoliation of Egyptian Blue and Han Blue, Two Alkali Earth Copper Silicate-based Pigments

Point Defects and Photoluminescence of Green Phosphors Ca(1-1.5x)WO4:Tbx3+ and Ca(1-2x)WO4:Tbx3+ Nax+

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Synthesis, Properties and Mineralogy of Important Inorganic Materials

Cited by 37 publications

References 1 publication

Pycnometric and Spectroscopic Studies of Red Phosphors Ca2+(1-1.5x)WO4:Eu3+xand Ca2+(1-2x)WO4:Eu3+x,Na+x

Pycnometric and Spectroscopic Studies of Red Phosphors Ca2+(1-1.5x)WO4:Eu3+xand Ca2+(1-2x)WO4:Eu3+x,Na+x

Exfoliation of Egyptian Blue and Han Blue, Two Alkali Earth Copper Silicate-based Pigments

Point Defects and Photoluminescence of Green Phosphors Ca(1-1.5x)WO4:Tbx3+ and Ca(1-2x)WO4:Tbx3+ Nax+

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Pycnometric and Spectroscopic Studies of Red Phosphors Ca²⁺_(1-1.5x)WO₄:Eu³⁺_xand Ca²⁺_(1-2x)WO₄:Eu³⁺_x,Na⁺_x

Pycnometric and Spectroscopic Studies of Red Phosphors Ca²⁺_(1-1.5x)WO₄:Eu³⁺_xand Ca²⁺_(1-2x)WO₄:Eu³⁺_x,Na⁺_x