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New toxic-metal-free sustainable yellow pigments have been developed in scheelite-type solid solutions: [(Li0.33Ca0.33La0.33)xBi1-x][MoxV1-x]O4. The developed pigments show a structural transition from monoclinic to tetragonal scheelite-type structures upon the substitution of LiCaLaMoO4 into the BiVO4 system. The absorption edge is gently blue-shifted from the parent BiVO4 by widening the bandgap upon the incorporation of various metal ions such as Li, La, Ca, and Mo into the lattice, allowing different intense yellow hues to be produced. The typical pigment [(LiLaCa)0.198Bi0.8][Mo0.2V0.8]O4 showed the most vivid yellow hue with a b* value of 78.32, which is comparable to the commercial Sicopal yellow (b* = 76.9). Further, the developed toxic-metal-free pigments have high near-infrared reflectance, making them sustainable as eco-friendly cool colorants for paint and plastic formulations. [ABSTRACT FROM AUTHOR]

Abstract: A new series of color tunable from yellow to near white emitting phosphors, La3SbO7:xBi3+, yEu3+ were prepared using a conventional solid state method and its structural, morphological, absorbance and photoluminescence properties and lifetime measurements were carried out to analyze the phosphor characteristics. The La3SbO7:Bi3+ phosphors crystallize into a phase pure weberite type structure with good particle morphology. Upon UV light excitation at 315 nm, these phosphors show broad band emission in the blue green region centered near 517 nm owing to the 3P1‐1S0 transitions of the Bi3+ activator. Critical emission quenching of La3SbO7:xBi3+ samples was observed at x = 0.04. Eu3+ is co‐doped with La3SbO7:0.04Bi3+ blue green phosphor to incorporate the red component to make a full color emission phosphor. The effective energy transfer from Bi3+ to Eu3+ ions has been assessed using Dexter's theory indicating resonance type through dipole‐quadrupole interaction. Further the decreasing trends in lifetime measurements confirm the existence of energy transfer process from Bi3+ to Eu3+. The near white light emitting phosphor La3SbO7:xBi3+, yEu3+ can be realized by adjusting the concentrations of the Bi3+ and Eu3+ with chromaticity coordinates: (0.30,0.48). The above results suggest that the developed phosphor could be potential to be used as a single phase white emission phosphor for n‐UV LED applications. [ABSTRACT FROM AUTHOR]

Multifunctional materials are developed in BiV1-xNbxO4 solid solutions via structural variations. A citrate gel route has been employed to synthesize these materials followed by calcination at various temperatures leading to fine particles. The effects of niobium doping over the structural variation and its influence on the optical properties are assessed by powder X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-Vis-NIR spectroscopy. These solid solutions exhibit superior coloristic properties which are comparable to commercially available yellow pigments. These materials also show remarkable reflectance in the NIR region which makes them potential candidates for cool roof applications. A notable methylene blue dye degradation property is observed in Nb5+ doped BiVO4 under sunlight irradiation. [ABSTRACT FROM AUTHOR]

Y-doped Bi2MoO6 was synthesized by the conventional ceramic method in order to assess its potential as ceramic pigment. The optimized colorants were characterized for their structural as well as optical properties. The Bi(2-x)YxMoO6 materials absorb the visible and the ultraviolet light under 500 nm efficiently, which is originated in the transition from the valence band consisting of the O 2p orbitals to the conduction band derived from the primary Mo 4d orbitals in MoO6 octahedra and the secondary Bi 6p orbitals. The absorption edge of the pigments is red shifted by yttrium doping, and as a result, the pigments display colors from pale yellow to yellow. The effective yellow hue was observed for BiYMoO6, which imparted good coloration to plastics. The synthesized pigments were found to be interesting alternatives to existing toxic yellow pigments. [ABSTRACT FROM AUTHOR]

New inorganic pigments based on fluorite solid solutions, Ce0.95M xPr0.05− xO2 (M=Zr and Sn; x ranges from 0 to 0.05) have been prepared by the conventional solid-state route with a goal of preparing environmentally benign colorants. The pigments obtained displayed better color characteristics than that of Ce0.95Pr0.05O2 system showing colors from brick red to dark brown. The coloring mechanism is based on the introduction of an additional electronic energy level of unpaired 4f electron of the praseodymium ion into the cerianite band. Further, the cosubstitution of Zr or Sn in Ce0.95Pr0.05O2 system raises the slope of the absorption edge with a blue shift resulting in enhanced lightness. Their applicability for wide spread use, chemical and thermal stability, and capacity to produce pigmentation in plastics, has been investigated. These findings suggest that the developed red pigments may form a viable and potential alternative to traditional toxic red pigments such as cadmium sulfoselenide. [ABSTRACT FROM AUTHOR]

New yellow inorganic pigments, (BiV)1-x(YNb)xO4 with high NIR reflectance were synthesized by a conventional solid-state reaction method. The effect of isovalent dopants, namely, Y3+ and Nb5+ on BiVO4 samples was characterized using powder X-ray diffractometer, scanning electron microscope, UV-vis-NIR diffuse reflectance spectrometer, and CIE 1976 L*a*b* color scales. The prepared pigments exhibit brilliant yellow colors with significant enhancement of NIR reflectance to 90.8% when compared to undoped BiVO4 at the 1100nm range. Further, the solid solutions allow fine tuning of the band gap displaying various yellow colors. The lattice distortion and reduction in particle size are responsible for the enhancement of the pigment characteristics. The above results indicate that these yellow pigments have potential to be used as cool colorants for roofs and automotives as energy-saving coatings. [ABSTRACT FROM AUTHOR]

New scheelite-based environmentally friendly yellow pigments with the general formula, (BiV)x(CaW)1-xO4 (x=0.2, 0.4, 0.6, and 0.8) have been synthesized by a solid-state route. The resulting colorants were characterized for their structural as well as optical properties. The color parameters, L*, a*, and b* values have been significantly improved in the solid solutions of (BiV)x(CaW)1-xO4 over those of BiVO4. Further, the solid solutions allow fine tuning of the optical band gap resulting in various shades of yellow. The synthesized pigments were found to be interesting alternatives to existing toxic yellow pigments. [ABSTRACT FROM AUTHOR]

New scheelite-based environmentally friendly yellow pigments with the general formula, (BiV)x(CaW)1-xO4 (x=0.2, 0.4, 0.6, and 0.8) have been synthesized by a solid-state route. The resulting colorants were characterized for their structural as well as optical properties. The color parameters, L*, a*, and b* values have been significantly improved in the solid solutions of (BiV)x(CaW)1-xO4 over those of BiVO4. Further, the solid solutions allow fine tuning of the optical band gap resulting in various shades of yellow. The synthesized pigments were found to be interesting alternatives to existing toxic yellow pigments. [ABSTRACT FROM AUTHOR]

New inorganic pigments Ce1-(x+y)TixPryO2 (x ranges from 0.05 to 0.195 and y ranges from 0.005 to 0.15) based on CeO2-TiO2-Pr6O11 solid solutions have been synthesized by solid-state route with a goal of preparing environmentally secure red colorants. Characterizations using XRD, UV-vis spectroscopy and CIE 1976 color coordinates assessment reveals the formation of pigments displaying colors ranging from brick red to dark brown. The coloring mechanism is based on the introduction of additional electronic level of energy in the cerianite forbidden band from the unpaired 4f electron of lanthanide ion. [ABSTRACT FROM AUTHOR]