Chromaticity Stability Research Articles

Spectral characteristics of highly thermally stable Eu3+-doped P2O5-B2O3-ZnO-BaO glasses for tricolor WLEDs and red lasers

In this study, Eu3+doped P2O5-B2O3-ZnO-BaO (PBZB) glasses were synthesized using the melt-quenching method. Phonon sideband analysis enables the determination of the glasses' phonon energy at 1212 cm−1, which agrees with the data derived from the FTIR spectrum. Under excitation at 393 nm, the PBZB glasses all exhibit a high-purity red emission with a color purity nearly 100 % and a correlated color temperature below 4000 K, as well as their chromaticity coordinates close roughly to those of standard red light (0.67, 0.33). Optimal red emission is achieved in the PBZB glasses with a Eu2O3 concentration of 2.0 mol%. The luminescence lifetimes of Eu3+ ions, being in the millisecond range, exhibit an initial increase followed by a decrease. Based on the Inokuti-Hirayama model, the energy transfer process among Eu3+ ions is primarily driven by the d-d interactions and occurs predominantly within the clusters of the Eu3+-Eu3+ ions. Further substantiation of the high covalency and asymmetry of the Eu3+-O2− bonds is supported by the Judd-Ofelt theory calculations. The glass doped with 2.0 mol% Eu2O3 demonstrates an enhanced branching ratio, emission cross-section, gain bandwidth, and optical gain, confirming its potential for applications in high-gain lasers. Temperature-dependent emission spectra reveal the PBZB glasses' excellent thermal and chromaticity stability across 298–473 K. At 150 °C, the emission intensity at 612 nm for the 2.0 mol% Eu2O3-doped PBZB glass maintains 72 % of its initial value, with a chromaticity shift of only 4.36 × 10−3, substantially below the criteria of 0.015. Consequently, this study confirms the significant potential of 2.0 mol% Eu2O3-doped PBZB glass for applications in tricolor WLEDs and red lasers.

Conservation Measures for Media Art According to Technological Changes: Color Reproducibility Comparison for Conservation of Artwork Using Video Display

Artworks using display devices require conservation treatment due to aging or discontinuation of media. However, irreversible conservation treatment methods such as modification and change of existing media may be included, which may infringe on the right to secure the originality and maintain the identity of the work. Accordingly, a comparative study on the theoretical background and color reproduction elements was conducted to provide basic data for mid to long-term conservation to confirm the possibility of replacing works using discontinued CRT with LCD. Video art is a modern art form that uses video technology as an artistic expression medium and has technology dependence. Therefore, as the conversion of the used medium is appropriate, the materials added in the conservation process are seen as part of securing the originality in terms of ‘material conservation’. An experiment was conducted to compare the color characteristics of CRT and LCD. As a result of the experiment, it was confirmed that the luminance and chromaticity stability of LCD was relatively excellent through the measurement results of spectral distribution, chromatic change difference, background dependence, and time stability, confirming the possibility of alternative application.

Harvesting Multicolor Photoluminescence in Nonaromatic Interpenetrated Metal-Organic Framework Nanocrystals via Pressure-Modulated Carbonyls Aggregation.

Interpenetrated metal-organic frameworks (MOFs) with nonaromatic ligands provide a unique platform for adsorption, catalysis, and sensing applications. However, nonemission and the lack of optical property tailoring make it challenging to fabricate smart responsive devices with nonaromatic interpenetrated MOFs based on ligand-centered emission. In this paper, the pressure-induced aggregation effect is introduced in nonaromatic interpenetrated Zn4O(ADC)4(Et3N)6 (IRMOF-0) nanocrystals (NCs), where carbonyl groups aggregation results in O─O distances smaller than the sum of the van der Waals radii (3.04 Å), triggering the photoluminescence turn-on behavior. It is noteworthy that the IRMOF-0 NCs display an ultrabroad emission tunability of 130nm from deep blue (440nm) to yellow (570nm) upon release to ambient conditions at different pressures. The eventual retention of through-space n-π* interactions in different degrees via pressure treatment is primarily responsible for achieving a controllable multicolor emission behavior in initially nonemissive IRMOF-0 NCs. The fabricated multicolor phosphor-converted light-emitting diodes based on the pressure-treated IRMOF-0 NCs exhibit excellent thermal, chromaticity, and fatigue stability. The proposed strategy not only imparts new vitality to nonaromatic interpenetrated MOFs but also offers new perspectives for advancements in the field of multicolor displays and daylight illumination.

Enhancement of photoluminescence properties in Na+ doped K2BaPO4F:Sm3+ phosphors

In this paper, Sm3+-activated K2BaPO4F red phosphors were prepared by a traditional solid-state reaction method. The crystal structure and emission enhancement mechanism of the materials were systematically investigated. The photoluminescence intensity, chromaticity, lifetime, and fluorescence thermal stability were evaluated in detail. The emission intensity and quantum efficiency were significantly improved by the introduction of Na + ions. The lattice parameters of the K2BaPO4F, K2Ba0.975PO4F:0.025Sm3+, and Na-doped K2Ba0.975PO4F:0.025Sm3+ phosphors were investigated through the Rietveld refinement method. With the occupation of K+ sites by Na+ ions, the reduced volume of the unit cell increased the quantum efficiency of Sm3+ ions about 2.5 times. The present work demonstrates that the modified K2-2xNa2xBa0.975PO4F:0.025Sm3+ orange-red phosphors are expected to be used in white light-emitting diodes (w-LEDs).

Synthesis, bright red-emitting and low thermal quenching behavior of europium(Ⅲ)-activated sodium borophosphate phosphor

In this work, trivalent europium (Eu3+) activators were incorporated into sodium borophosphate Na3B6PO13 via replacing Na+ ions. The large band gap is verified via the experimental diffuse reflectance data and theoretical calculations. The concentration quenching with the optimal 13 % Eu3+activators is caused by quadrupole–quadrupole interaction. A vibrant red-emitting behavior is illustrated when excited at 394 nm. For Na3B6PO13:13 %Eu3+, the low thermal quenching behavior (86 %@423 K) and good chromaticity stability (0.0073@473 K) is revealed. Finally, we utilize the red-emitting material to construct a white light-emitting diodes, producing the low correlated color temperature (4250 K) and satisfactory color rendering index (82). The title material exhibits promise for illumination application.

Two-site occupancy induced a broadband blue-emitting in Eu2+ doped Na3Ba2Ca(PO4)3 phosphor

During the process of developing commercial chips, the phosphors with single broadband emission are indispensable. In this report, a new ternary phosphate phosphor Na3Ba2Ca(PO4)3:Eu2+ has been successfully synthesized by the high-temperature solid-state reaction (HSSR) method, which shows broad emitting band in the range of 350–600 nm centered at 436 nm (FWHM ∼ 72.3 nm). The crystal structure of the Na3Ba2Ca(PO4)3 and Eu2+ doped Na3Ba2Ca(PO4)3 were determined by the Rietveld method, indicating the trigonal system with P31c space group. The selective two-site occupancy tendency of Eu2+ ions at Ba1O9 and Ca2O8 sites in the matrix was comprehensively revealed according to the split peaks (433 nm and 469 nm) at 298 K and 11 K, computational validation and fluorescence lifetime analysis of photoluminescence spectrum. Impressively, the optimal Na3Ba2Ca(PO4)3:0.02Eu2+ phosphor exhibits appropriate spectrum resemblance (SR) indexes (58.5% and 72.2%), proper thermostability (78.6%) and excellent chromaticity stability (Δx = 8.68 × 10−6 and Δy = 3.64 × 10−5). Besides, the phosphor prepared by HSSR owns the higher internal quantum efficiency of 62.1% in comparison with that synthesized by polymerizable complex (PC) method. The new phosphor can serve as a potential broadband and blue-emitting phosphor for the application of solid-state lighting and plant growth.

Optical tuning and energy transfer of single-phase white-emitting Y3TaO7:Bi3+, Eu3+ for ultraviolet converted pc-WLED with high chromatic stability

Reabsorption and color drift at high temperature hinder the high-quality application of the phosphor-converted white light-emitting diodes (pc-WLEDs) devices, thus it is urgent to develop the single-phase white-emitting phosphors with good chromatic stability. In this work, a series of color-tunable Y3TaO7:Bi3+, Eu3+ phosphors are designed by co-doping Bi3+ and Eu3+ based on the crystal structure information and energy transfer principle between Bi3+ and Eu3+, which can be adjusted to achieve single-phase white emission. By increasing the temperature to a high value of 473 K, the emission peak of Bi3+ ions still present at 470 nm in Y3TaO7:Bi3+ phosphors even when the concentration of Bi3+ ions changes, and the characteristic emission peaks of Bi3+ and Eu3+ basically maintain unchanged throughout in Y3TaO7:Bi3+, Eu3+ phosphors. Finally, the single-phased Y3TaO7:0.025Bi3+, 0.06Eu3+ phosphor was employed with ultraviolet chip to produce a warm WLED device with color rendering index of 81.5, correlated color temperature of 4165 K and the Commission International de I′Eclairage chromaticity coordinates of (0.3645, 0.3347). The results indicate that Y3TaO7:Bi3+, Eu3+ phosphors with high chromaticity stability have great application potential in full-spectrum WLEDs.

A novel red-emitting Na5W3O9F5:Eu3+ phosphor with high color purity for blue-based WLEDs

Red phosphor plays a key role in improving the lighting and display quality of phosphor-converted white light-emitting diodes (pc-WLEDs). Meanwhile, developing new luminescent matrix materials can positively contribute to the acquisition of ideal and efficient phosphors. In this work, we propose a novel red-emitting Na5W3O9F5:Eu3+ (NWOF:Eu3+) phosphor. The phase composition, morphology, electronic structure and photoluminescence properties of the NWOF:Eu3+ phosphor were systematically investigated. The EXAFS results prove that the Eu3+ dopants occupy the Na2 and Na3 sites in the NWOF host. Under 466 nm blue light excitation, NWOF:xEu3+ (0.05 ≤ x ≤ 0.25) phosphors display a dominant red emission at 607 nm and achieves a high color purity (97.44%) due to the dominant electric dipole transition (5D0→7F2) of Eu3+ ions. Impressively, this red-emitting NWOF:0.25Eu3+ phosphor exhibits relatively superior thermal stability (450 K, >50%) and excellent chromaticity stability (2.32 × 10−4 ≤ ΔE ≤ 6.23 × 10−3) from 298 K to 498 K. The activation energy for thermal quenching effect is determined to be 0.22 eV. Moreover, the pc-WLED was fabricated by coupling a 460 nm blue chip with the as-synthesized NWOF:0.25Eu3+ red phosphor and commercial YAG:Ce3+ phosphor. The optical parameters of the as-fabricated pc-WLED are also measured, and the CIE coordinates remain almost constant as the drive current increases from 20 mA to 120 mA. These results indicate that the NWOF:0.25Eu3+ red phosphors should be a suitable candidate as a red component for the preparation of pc-WLEDs.

Analysis of thermal chromaticity stability, energy transfer and colour tunablity of Dy3+-Eu3+ doped BBZL glasses for high-power W-LED applications

A family of highly thermal chromatic stable Dy3+-Eu3+ doped B2O3-Bi2O3-ZnO-Li2O (BBZL) glass samples was synthesised using the high-temperature melt quenching technique. The optical and thermal stability properties of the samples were analysed using their fluorescence spectra at various temperatures, fluorescence lifetime decay times and colour coordinates. The Dy3+-doped BBZL (BBZL: Dy) glass samples generated cold white light when exposed to ultraviolet (UV) light, while the Dy3+-Eu3+-doped BBZL (BBZL: DyEu) glass samples emitted neutral and warm white light, which can be attributed to the introduction of Eu3+ that substantially enhanced the colour rendering of samples. An overlap of the excitation-emission spectra of Eu3+ and Dy3+ indicated an energy transfer between Dy3+ and Eu3+. Under a 350 nm excitation, the fluorescence lifetime of BBZL: DyEu decreased from 0.5348 to 0.3642 ms. Using the Dexter theory, the energy transfer between Dy3+ and Eu3+ was demonstrated to be an electric dipole-electric dipole leap. The chromaticity shifts of BBZL: DyEu were 8.60 × 10−4 and 9.40 × 10−4 at 448 and 498 K, respectively, reflecting the high thermal stability of the sample chromaticity. The study demonstrated that Dy3+-Eu3+ doped borate glasses can be used as tunable luminescent materials in high-power white light-emitting diodes to mitigate the chromaticity shift in fluorescent materials at high temperatures.

Novel near-ultraviolet-excited and thermally-stable blue-emitting phosphor for healthy WLED lighting

The widespread popularity of white light-emitting diodes (WLED) lighting results in a chronic exposure to blue light, which has negative impacts on human biological functions, emotions and health. As an alternative strategy, integrating near-ultraviolet (n-UV) LED chips with high-efficiency (high quantum efficiency, chemical and thermal stability) tricolor phosphors, can easily achieve high-quality white light and diminish the so-called “blue-light hazard”. However, few blue-emitting phosphors can meet the aforementioned requirements. Herein, we report a novel n-UV excited bright blue-emitting CsBaB9O15:2%Eu2+ phosphor with high internal quantum efficiency (IQE = 68.8%) and outstanding thermal stability (94.2%@ 150 °C, 84%@ 250 °C). Impressively, this phosphor exhibits excellent chromaticity stability (Δx = 0.002, Δy = 0.012; 3.6 × 10−3 ≤ ΔE ≤ 8.1 × 10−3) from 25 to 150 °C. These remarkable thermal stability are mainly ascribed to the large band gap of host (Eg = 5.85 eV), which effectively suppresses the thermal ionization pathway of the dominant 440 nm emission in the CsBaB9O15:2%Eu2+ phosphor. A WLED device was fabricated by combining commercial phosphor Sr2Si5N8:Eu2+, green phosphor (Sr, Ba)2SiO4:Eu2+ and as-synthesized blue phosphor with a 380 nm n-UV LED chip, which exhibits high color-rendering index (CRI = 90) and low correlated color temperature (CCT = 3301 K). These results demonstrate that the outstanding CsBaB9O15:Eu2+ blue phosphor could be a candidate for next-generation healthy WLED lighting.

Lead-free perovskite variant Rb2SnCl6:Te based phosphor-sapphire composite for high-power laser-driven lighting

Lead-free perovskite variants have attracted wide interest because of the lead-free feature and broadband emission originated from self-trapped exciton (STE), which show great advantages in lighting applications. Especially the tetravalent Te-doped A2B(IV)X6 perovskite variants, which have efficient excitation in the blue range and strong emission in the yellow region as well as high photoluminescence quantum yield, is particularly suitable for solid-state lighting. Despite these fascinating properties, it is still not suitable for high-power illumination due to its poor thermal resistance and severe light saturation feature at high laser power density. Herein, we develop a lead-free perovskite variant Rb2SnCl6:Te based phosphor-sapphire composite (PSC) fused with low-melting glass through a simple screen-printing and sintering process. The as-prepared PSC shows yellow-green emission at 570 nm, due to the combination of Te luminescent center and Jahn-Teller-like STE, and exhibits a high thermal conductivity of 37.06 W m−1 K−1. Benefitted from the high thermal conductivity of the sapphire substrate, the PSC exhibits the great improvement in light saturation behavior, heat dissipation, and chromaticity stability withstand the high-power blue laser, compared to Rb2SnCl6:Te phosphor, finally contributing to an excellent PLQY of 70.3%. In addition, by combining the PSC with the blue laser, a warm white light with a CIE chromaticity coordinate of (0.368, 0.344), and a correlated color temperature of 4129 K is achieved. These results demonstrate that this simple and low-cost fabrication method is expected to be widely used for various phosphors and the PSC can own excellent application prospects in high-power laser-driven lighting.

Preparation and study of borate glass-ceramics coated γ-Ce2S3 red pigment

In this study, the core–shell wrapping structure red pigment with γ-Ce2S3 colorant as core and borate glass-ceramics as shell was prepared by low temperature self-propagating combustion method with solid sulfur as sulfur source. The effects of H3BO3 addition amount on the chromaticity and temperature stability of the coated pigment were studied. It was found that when the addition amount of nB/Ce was equal to1.40, the coated pigment with the optimal stability and chromaticity value can be obtained, and its redness value (a*) was 42.01. This coated pigment still maintained a certain redness (a*=30.86) after calcined at 680 °C for 10 min in air. This indicates that the temperature stability of borate glass-ceramics coated γ-Ce2S3 red pigment with core–shell structure can be improved from 350 °C to 680 °C.

Microscopic Imaging Technology Assisted Dynamic Monitoring and Restoration of Micron-Level Cracks in the Painted Layer of Terracotta Warriors and Horses of the Western Han Dynasty.

Cracks are one of the most common issues affecting colored pottery relics; these can be divided into macroscopic cracks, recognizable by the human eye, and micron cracks, which cannot be observed by the naked eye. The gradual development of micron cracks eventually leads to large-scale cracks and the shedding of the coating layer. The repair of such micron cracks poses a key technical difficulty in restoring painted pottery remnants from the Western Han Dynasty. We attempt to solve this problem by reporting on a method that entails the use of a water-borne fluoropolymer material as the adhesive agent, as well as ultra-depth-of-field, digital microscopic imaging technology to build an operating platform for an optical imaging monitoring system. By making simulated ceramic samples, we systematically investigated the influences of water-borne fluoropolymer on chromaticity, adhesion, contact angle, surface morphology, and thermal stability of the paint layer. The results indicate that the color of the painted layer, when treated with the water-borne fluoropolymer, did not change, and the adhesion and contact angle of the painted layer were improved. Additionally, the outcomes of the SEM analysis show that the adhesion and hydrophobicity of the painted layer were improved because the water-borne fluoropolymer filled up the porous structure of the painted layer and covered the pigment particles. These findings demonstrate that aqueous, water-borne fluoropolymer can be used as an adhesive agent for micron cracks. Meanwhile, via the operating platform of the optical imaging monitoring system, the micron cracks of the painted terracotta warriors and horses from the Western Han Dynasty were successfully repaired using the water-borne fluoropolymer. The results imply that the microstructure, size, and geometric spaces of the cracks can be obtained directly utilizing microscopic imaging technology. The dynamic monitoring and imaging system described above can be employed to assist prosthetists in visualizing micro-repair operations in real time, assist with fine visual operations during the repair process, and realize dynamic video recording of the entire repair process. Our work provides a simple visualization method to repair micron-scale cracks in painted pottery relics by applying modern fluoropolymer and ultra-depth-of-field digital microscopic imaging technology.

Dual-enhancement of chromaticity and thermal stability: In-situ synthesis of core–shell γ-Ce2S3@CePO4 configuration

Non-toxic rare earth (RE) composite materials are promising and active in optoelectronic fields, such as pigment. In this work, Na ions doped γ-Ce2S3 pigments were synthesized by solid-phase vulcanization and followed by in-situ synthesis to prepare an outer layer of CePO4 film. The characterizations of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), solid state nuclear magnetic resonance (NMR) indicate that Na-doped γ-Ce2S3 and CePO4 uniformly and tightly coated core–shell structure was successfully synthesized. The thermogravimetric analysis (TG) and reflection spectrum (RS) reveal that the CePO4 coating significantly improves the colorant and thermal stability performance of γ-Ce2S3. The excellent color quality of γ-Ce2S3@CePO4 (L∗ = 45.16, a∗ = 55.94, b∗ = 44.53) is achieved and the red color (L∗ = 43.82, a∗ = 49.79, b∗ = 38.04) is still retained even if the sample is heated in air at 400 °C for 30 min.

Technologies for the Crystal LED display system

AbstractWe have developed novel active matrix driving technology integrating red–green–blue (RGB) microscale light emitting diodes (micro LEDs) and a microscale integrated circuit (micro IC) in each pixel for the Crystal LED display system. The small size and closely placed RGB subpixels of micro LEDs enabled us to achieve an outstanding contrast ratio even in a bright environment. We also achieved superior luminance linearity and chromaticity stability using accurate pulse width modulation (PWM) driving by micro ICs in the active matrix system. To integrate micro LEDs and micro ICs into a scalable display system, an additional fine‐patterned layer was applied to a conventional printed circuit board (PCB). In addition, with precise tiling technology, we could produce a large‐scale image providing an immersive visual experience.

Near infrared-stimulated heating behaviors and ultra-high temperature sensitivity in Bi2Ti2O7:Yb3+/Ho3+ nanofibers

Monitoring temperature without contact has been paid much attention in industrial production and scientific research. Here, a series of Bi2Ti2O7:Yb3+/Ho3+ compounds (4:1, 6:1, 8:1, 10:1, 15:1, 20:1) with high temperature sensitivity were prepared via an electrospinning route. The crystal, morphology and elemental distribution were characterized by XRD, SEM and TEM. A general strategy for temperature sensing properties through inspecting the upconversion spectra was reported. It is demonstrated that the nanofibers exhibit intense and high purity green emission and the emission bands are situated at 540 nm, 665 nm and 750 nm, which was ascribed to 5F4/5S2→5I8, 5F5→5I8 and 5F4/5S2→5I7 transitions, respectively. The maximum relative sensitivity is calculated to be 2.44% at 498 K, obtained from the temperature-dependent spectra by recording in the range of 298–498 K. The samples also provide excellent repeatability and chromaticity stability. More remarkably, the optical heating ability that monitors the temperature change of the tissue injected with the Bi2Ti2O7:Yb3+/Ho3+ nanofibers were investigated. The temperature rises about 15 K after being irradiated by 808 nm laser with the pump power of 0.97 W/cm2 for 15 min. All the results highlight that the novel Bi2Ti2O7:Yb3+/Ho3+ compounds have great potential for temperature-sensing and photothermal therapy.

The photoluminescence, thermal properties and tunable color of bright green-emitting Ba3Sc(BO3)3:Ce3+/Tb3+ phosphors via efficient energy transfer

The single-phase Ba3Sc(BO3)3:Ce3+/Tb3+ samples were synthetized via high-temperature solid-state reaction. X-ray diffraction (XRD), Rietveld refinement and transmission electron microscopy (TEM) were used for characterizing the morphology and phase purity of Ba3Sc(BO3)3. The photoluminescence emission (PL) and excitation (PLE) spectra, lifetime decay behavior and thermal stability of the Ba3Sc(BO3)3:Ce3+/Tb3+ phosphors were discussed in detail. Site occupation of Ce3+ ions in Ba2+ and Sc3+ sites were explained through Gaussian fitting and Van Uitert empirical equation. All these properties are closely related to the intrinsic crystallization structure of the Ba3Sc(BO3)3 matrix, which is discussed in detail in this paper. Compared with Ba3Sc(BO3)3:1%Tb3+ sample, the luminous intensity of Tb3+ increased about 3.2 and 4.1 times for Ba3Sc(BO3)3:2%Ce3+,1%Tb3+ monitored at 342 and 313 nm, respectively. Energy transfer (ET) mechanism of Ce3+→Tb3+ were dipole-dipole interactions and quadrupole-quadrupole interactions at Ce3+(1) and Ce3+(2) sites, respectively. The temperature-dependent PL spectra of Ba3Sc(BO3)3: Ce3+,Tb3+ illustrated that this phosphor possesses excellent thermal stability and chromaticity stability. Finally, a white LED device was prepared via the combination of the n-UV chip (365 nm), commercial blue BAM:Eu2+ phosphor, green Ba3Sc(BO3)3:2%Ce3+,6%Tb3+ phosphor and commercial red Sr2Si5N8:Eu2+ phosphor, which showed bright warm-white light. These conclusions proved that the green Ba3Sc(BO3)3:2%Ce3+,6%Tb3+ phosphor is desirable for white LED applications.

Design and preparation of a type of γ-Ce2S3@c-SiO2-coated red pigment with a plum pudding mosaic structure: The effect of pre-sintering temperature on pigment properties

In this study, amorphous SiO2 (a-SiO2) gel powder was prepared by an acid-base two-step catalytic sol-gel method and pre-burned at different temperatures (150 °C, 400 °C, 600 °C, and 800 °C) to obtain mesoporous formed by the accumulation of a-SiO2 nanoparticles, in which CeO2 was coated to form CeO2@a-SiO2. The CeO2@a-SiO2 obtained by the above-mentioned method was used as a precursor, a crystalline silica-(c-SiO2) coated γ-Ce2S3 (γ-Ce2S3@c-SiO2) red pigment with a plum pudding mosaic structure was obtained by sulfidation at 900 °C in CS2 atmosphere, and calcination at 1300 °C in an Ar-protected atmosphere. A systematic study examined the influence of different pre-sintering temperatures on the morphology and microstructure of the precursor particles along with the chromaticity and thermal stability of the coated pigment. The results reveal that at a pre-sintering temperature of 400 °C, the surface area and pore volume of the precursor reached maximum values of 274 m2/g and 0.27 cm³/g, respectively, while the average aperture reached 3.49 nm. Under this experimental condition, the obtained coated pigment exhibited the highest chromaticity values of L* = 30.46, a* = 37.73, and b* = 26.41. At these values, and following calcination at 900 °C for 10 min in air, the pigment still maintained a bright-red color (L* = 27.61, a* = 29.06, and b* = 17.25); this indicates that the plum pudding mosaic-type γ-Ce2S3@c-SiO2 red pigment can increase the thermal stability of γ-Ce2S3 from 350 °C to 900 °C. It shows that mesoporous SiO2 can be applied to novel fields of coated pigments by structural design and high-temperature calcination.

High-temperature air fluidization improves cooking and eating quality and storage stability of brown rice

Brown rice contains many valuable active ingredients; but due to its long cooking time, hard texture, heavy rice bran taste, and short shelf life, it is not widely accepted by consumers. Herein, we developed a novel processing technology so-called high-temperature air fluidization (HTAF) to treat brown rice. The effects of the HTAF treatment at 120 °C, 130 °C, and 140 °C for 60 s at a feed rate of 80 kg/h on the quality of brown rice were investigated. The results showed that the treatment with HTAF caused fissures to form on the surface and the interior of brown rice, and these fissures appeared to facilitate the penetration of water into the rice kernels during soaking. The optimal HTAF treatment temperature was 130 °C, the water adsorption of HTAF-treated brown rice at 130 °C (TBR-130) was increased to 25.3% after soaking for 160 min, which was higher than that of white rice and untreated brown rice (UBR; 13.7%). The optimal cooking time for TBR-130 was also 5 min shorter than that for UBR. The results further showed that TBR-130 had a larger degree of volume expansion compared to that of UBR, and cooked TBR-130 had softer texture than cooked UBR. The cohesiveness and sensory quality of TBR-130 were also higher than those of UBR, and the content of flavor compounds in TBR-130 was similar to that of white rice. HTAF caused no obvious damages to the main active components or nutritional components of TBR-130. Finally, TBR-130 had better chromaticity and higher storage stability than UBR. These results demonstrate that the HTAF treatment can improve cooking and eating quality and storage stability without causing obvious damages to nutritional quality of brown rice. This technology may play important roles in an attempt to promote the use of brown rice as staple foods.

Preparation, characterization, and properties of a Ba2+–Sm3+ co-doped γ-Ce2S3 red pigment

In this study, Ba2+–Sm3+ co-doped γ-Ce2S3 (abbreviated as γ-[Ba,Sm]-Ce2S3) red pigments were synthesized by the coprecipitation method with a composition of n(Ba)/n(Ce1−xSmx) = 0.1(molar ratio, x = 0, 0.01, 0.03, 0.05, and 0.10 mol). The corresponding vulcanized products, γ-[Ba,Sm]-Ce2S3 red pigments (abbreviated as S.Smx), were prepared using CS2 as a sulfur source at 850 °C for 150 min. The effect of the Sm3+ doping content on the phase composition, chromaticity, and thermal stability of Ba2+–Sm3+ co-doped γ-Ce2S3 was systematically investigated by FE-SEM, EDS, XRD, Raman spectroscopy, HR-TEM, XPS, CIELAB colorimetry, and TG-DTA. The results show that a pure γ phase can be obtained for S.Smx, when x is varied from 0 to 0.10 mol at 850 °C. With an increase in the Sm3+ content, the band gap of γ-[Ba,Sm]-Ce2S3 increased from 2.12 to 2.14 eV, which resulted in a color change from red to red-orange. The chromaticity value of the pigments increased from L∗ = 31.84, a∗ = 30.95, b∗ = 23.63, and C∗ = 38.94 (S.Sm0.00) to L∗ = 34.63, a∗ = 35.36, b∗ = 38.88, C∗ = 52.55 (S.Sm0.01), which indicates that Ba2+–Sm3+ co-doping can effectively increase the chromaticity value. The S.Sm0.01 sample still exhibited a pure γ-phase and showed excellent red color (L∗ = 33.18, a∗ = 33.74, b∗ = 36.69, and C∗ = 49.84) after the heat treatment at 400 °C for 10 min in air, which indicated that Ba2+–Sm3+ co-doping successfully increased the thermal stability of the S.Sm0.01 red pigment. S.Sm0.01 has excellent chromaticity and good thermal stability, which expands the number of methods for preparing γ-Ce2S3 red pigment and shows a considerable market potential.