Structural and emission properties of Eu3+‐doped alkaline earth zinc‐phosphate glasses for white LED applications

Quaternary alkaline earth zinc‐phosphate glasses in molar composition (40 ? x)ZnO – 35P₂O₅ – 20RO – 5TiO₂ – xEu₂O₃ (where x=1 and R=Mg, Ca, Sr, and Ba) were prepared by melt quenching technique. These glasses were studied with respect to their thermal, structural, and photoluminescent properties. The maximum value of the glass transition temperature (T_g) was observed for BaO network modifier mixed glass and minimum was observed for MgO network modifier glass. All the glasses were found to be amorphous in nature. The FT‐IR suggested the glasses to be in pyrophosphate structure, which matches with the theoretical estimation of O/P atomic ratio and the maximum depolymerization was observed for glass mixed with BaO network modifier. The intense emission peak was observed at 613 nm (⁵D₀→⁷F₂) under excitation of 392 nm, which matches well with excitation of commercial n‐UV LED chips. The highest emission intensity and quantum efficiency was observed for the glass mixed with BaO network modifier. Based on these results, another set of glass samples was prepared with molar composition (40 ? x)ZnO – 35P₂O₅ – 20BaO – 5TiO₂ – xEu₂O₃ (x=3, 5, 7, and 9) to investigate the optimized emission intensity in these glasses. The glasses exhibited crystalline features along with amorphous nature and a drastic variation in asymmetric ratio at higher concentration (7 and 9 mol%) of Eu₂O₃. The color of emission also shifted from red to reddish orange with increase in the concentration of Eu₂O₃. These glasses are potential candidates to use as a red photoluminsecent component in the field of solid‐state lighting devices.     

Synthesis and properties of geminis with two alkyl and two phosphate headgroups

Amphipathic compounds having two phosphate groups and two long‐chain alkyl groups were prepared by a two‐step process: (a) preparation of monoalkyl phosphate from pyrophosphoric acid and dodecanol, (b) preparation of bis‐phosphoric acid from monoalkyl phosphate, (CH₃)₄NOH and 1,6‐dibromo hexane by using acetonitrile as solvent. The experimental results showed that a 5 : 10 : 2.5 molar ratio of reactants (alkyl phosphate/(CH₃)₄NOH/1,6‐dibromo hexane) and 3 h duration was the optimum for the reaction. The structure of the synthesized product was verified by analytical methods, viz. FT‐IR and ¹H‐NMR. The surface‐active and performance properties like foaming, wetting and anionic content of the disodium salt of bis‐phosphoric acid were also evaluated. The synthesized anionic gemini surfactants possessed maximum anionic content, i.e. 73.4%, and showed better water solubility, foaming and wetting ability than conventional monoalkyl phosphates.     

Cool and photocatalytic yellow ceramic pigments; from lead-tin to Cr doped scheelite pigments

The historical lead based pigments (XVII-XVIII century), the modern Ni,Sb-rutile (1939) and Pr-zircon (1961) yellow pigments as well as the novel yellow pigments based on Cr-scheelite and Mo-yttrium cerate pigments were synthesized and compared as semiconductors of high NIR reflectance (cool pigments) and with photocatalytic activity. All powders are wide band gap semiconductors (E_g=2.1–3.1?eV) with high NIR reflectance, ranging from 80% for Cr-Scheelite to 86% of Naples yellow, except Ni,Sb-rutile pigment that shows 55%. The low color performance of lead based pigments in alkyd paint and lead-free glazes along with its toxicity, discard these pigments as cool eco-friendly pigments. The Pr-zircon, Cr-scheelite and Mo-yttrium cerate pigments exhibit high NIR reflectance (R_NIR =?80–83%) and yellow coloration (b*?=?57.6–45.3) but only Pr-zircon and Cr-scheelite show color stability in alkyd paint and lead free glaze applications. Regarding to results of Orange II photodegradation test, lead based and Ni,Sb-rutile pigments inhibits the photolysis of the UV irradiation, acting as protecting agents from irradiation. The Mo-cerate shows a slight photocatalytic activity (t_1/2 =?301?min) and both Cr-scheelite and Pr-zircon pigments show a moderate activity (t_1/2 =?198 and 184?min respectively). Looking at a possible industrial application, the leaching test shows that the fluorides released by Pr-zircon (16.8?mg/g) as well as the Cr(VI) of Cr-scheelite (6?mg/g) should be treated and controlled. The Cr-scheelite solid solution Ca(Cr_xW_1-x)O₄ is stable to x?=?0.2 but its pigmenting capacity saturates at x?=?0.1.     

钼、钨掺杂磷酸盐防锈颜料的氧化还原性能

以硫酸为支持电解质,在水-1,4-二氧六环混合溶剂中,用循环伏安法研究了掺钼、钨及复合掺杂的磷酸盐颜料的氧化还原特性,分析了掺杂钼和钨的氧化还原能力和可逆性,讨论了单一和复合掺杂对磷酸盐氧化还原性的影响。结果表明,掺钼的磷酸盐氧化性强于掺钨的磷酸盐;不论是正磷酸锌还是三聚磷酸铝,都可以通过掺杂钼和其他的金属离子来改善其氧化还原性,掺杂一种金属离子的性能优于掺杂两种金属离子。     

Synthesis and characterization of (Pr,Ce)-ZrSiO4 ceramic pigments: The properties of the pigments and the effect of Ce

A series of (Pr, Ce)-ZrSiO₄ ceramic pigments were synthesized and characterized using XRD, SEM, EDS, XPS, XRF, colorimeter, and a UV-VIS-NIR spectrometer. The prepared pigments were mainly composed of the zircon phase and were well crystallized. Only a specific amount of Pr was incorporated into the ZrSiO₄ lattice. Compared with Pr, Ce was almost completely incorporated into the ZrSiO₄ lattice and was homogeneously distributed within the pigment particles. The dopant Ce reduced the amount of Pr dissolved in the ZrSiO₄ lattice and thus caused the b* values of the samples to decrease slightly. Meanwhile, the presence of Ce induced an apparent increase in red tone in the samples. The enhanced red tone resulted primarily from an increase in the absorption of light with wavelengths between 500 and 565 nm. High-temperature stability analysis demonstrated that it is feasible to improve the tone of Pr-ZrSiO₄ pigment by doping with Ce.     

Improved coloristic properties and high NIR reflectance of environment-friendly yellow pigments based on bismuth vanadate

Herein, fine powders of yellow pigments based on BiVO₄ were successfully prepared in two crystalline forms, tetragonal zircon-structured and monoclinic scheelite-structured, through a ethylene glycol-assisted method subjected to a thermal treatment at two different temperatures. The obtained materials were brightly colored with different hues of yellow, exhibited high reflection in the near-infrared region and showed visible luminescence under excitation by UV light. The new preparation method had a considerable effect on chromatic properties of the prepared scheelite-structured BiVO₄ pigments. The sample with the most vivid and bright shade of yellow was found to have the L^*a^*b^* and L^*C^*_ab h^*_ab color coordinates of (87.28, 0.37, 91.53) and (87.28, 91.53, 89.79), which are indicative of exceptionally good chromatic properties superior and/or comparable to those of other inorganic yellow pigments, both commercially available and recently described. In addition, the NIR reflectance of this powder was very high (≥?80%).     

Physico-chemical properties of ceramic pigments for high-temperature application

Heat resistant coatings are required primarily for stacks, exhaust pipes, reactors, space crafts and similar equipments that are permanently or occasionally exposed to elevated temperatures. High-temperature coatings are generally based on silicone resin with ceramic and metallic pigments. In this study, iron oxide, cobalt oxide (thermo chromic compound) and aluminum oxide are used for the preparation of four new types of coloured pigments. The thermal resistant characteristics of these ceramic pigments were studied by differential thermal analysis, thermo gravimetric analysis and differential scanning calorimetric analysis. These ceramic pigments are found to be thermally stable up to 400 °C.     

十二烷基磷酸单酯抗静电性能研究

按照GB/T 16801-1997中的方法对十二烷基磷酸单酯的抗静电性能进行研究,考察了十二烷基磷酸单酯钾盐、钠盐、三乙醇胺盐以及未中和的磷酸单酯对聚酯布的抗静电性能,结果表明:钾盐和未中和的磷酸单酯对聚酯布的抗静电效果较好。在确定了使用钾盐和未中和的磷酸单酯作为抗静电剂的条件下,考察了它们的质量浓度对聚酯布抗静电性能的影响,结果表明:当单酯钾盐的质量浓度为4 g/L,单酯为6 g/L时,对聚酯布的抗静电性能较好。在单酯钾盐的质量浓度为4 g/L,单酯为6 g/L时,考察了它们对聚酯布、棉布和腈纶布的抗静电效果,结果表明:它们对腈纶布的抗静电效果都好于其他2种布。在考察了十二烷基磷酸单酯的抗静电性能后,对其抗静电机理进行了探讨。     

Enhanced luminescence of manganese in singly doped white light zinc phosphate glass

On the basis of a kind of zinc phosphate oxynitride glass matrix with a broadband blue light, a series of manganese single-doped glasses were obtained. A broader red emission with the higher intensity belonging to the Mn²⁺ ion was observed in this glass matrix. The mechanism of the emission from Mn²⁺ ions was clarified through Mn³⁺ as an “energy acquisition probe” to replace complex dynamic luminescence discussion, which was a fit explanation for the differences in luminescence behavior of Mn ions in prepared glasses at different degrees of redox. The research results indicated that the prepared manganese-doped glass was a potential candidate as phosphor-converted white-light-emitting diodes. An encapsulated white-light-emitting diode device based on this glass with 276 nm ultraviolet chip was achieved. It showed the CIE values of (0.33, 0.35), high CRI (Ra = 86), and low color temperature (5228 K).     

Synthesis and characterization of lithium calcium phosphate ceramics

The crystal structure, thermal, dielectrical, alternating current conductivity and microstructure properties of lithium calcium phosphate ceramics synthesized by the sol–gel method were investigated. The average crystallite size, crystallinity, activation energy and enthalpy of crystallization of Ca₁₀Li(PO₄)₇ ceramics were determined. The X-ray diffraction (XRD) results indicated that the apatitic structure belonging to HAp was transformed fully to Ca₁₀Li(PO₄)₇ phase with the addition of Li. The Avrami exponents of the samples suggest that the crystallization mechanism is based on the surface nucleation and one-dimensional growth. It was found that the alternating current conductivity mechanism of the ceramics is controlled by the hopping motion involving a translational motion with a sudden hopping. The dielectric constant of the samples shows a small increase with increasing amount of Li.     

X‐ray absorption spectroscopy study of synthetic cobalt blue pigments similar to Kangxi blue and white porcelain

A series of cobalt blue pigments, which were synthesized based on the chemical compositions of the blue pigments in Kangxi blue and white porcelain, were investigated by Co, Mn, and Fe K‐edge and L_2,3‐edge X‐ray absorption spectroscopy to determine the oxidation states and species of the elements and to discern their impact on the blue color. The results reveal that Co is bivalent and mainly located at tetrahedral sites, which is the main parameter controlling the blue color. Mn is mainly present as Mn²⁺, or Co_xZn_1‐xAl₂O₄ and Fe is mainly present as Fe³⁺. In particular, Fe³⁺ substitutes the Al in CoAl₂O₄ and occupies octahedral sites with a high Mn content. All the synthetic cobalt blue pigments can form a solid solution with various end‐members or an intermediate solution spinel. The spectroscopic determination of the oxidation states and speciation of Co, Mn, and Fe furthers understanding of the coloration of blue pigments in blue and white porcelain.     

磷酸锌微粉的合成及应用

结合制备磷酸锌微粉的研究工作概述了磷酸锌Zn3(PO4)2.nH2O微粉的合成原理、合成进展。阐明了磷酸锌用作防锈颜料应用机理、用途。提出了间接法合成磷酸锌无需粉碎,产品达到微细级标准的反应条件。     

Synthesis of black pigments containing chromium from leather sludge

The black ceramic pigments with spinel structure have been prepared by using Cr-rich leather sludge in this paper. The washed Cr-rich leather sludge calcined at 1100 °C for 1 h as chromium oxide precursor (named as CA) was mixed with an appropriate proportion of other industrial metallic oxides, followed synthesizing black ceramic pigment by sintering. Both non-washed and washed sludge fired at 1100 °C were characterized by X-ray fluorescence (XRF) in order to determine their chemical compositions and X-ray diffraction (XRD) analysis to confirm that CA mainly contains Cr₂O₃ crystal phase. The results show that CA could be used as a source of chromium to prepare black pigment. The crystalline phases of obtained pigments were characterized by XRD. Furthermore, the morphology as well as the composition of pigments was investigated by scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS). The color coordinates of pigments were examined and compared with the commercial pigments based on CIE-L* a* b* values measured using UV–vis spectroscopy. The obtained pigments sintered at 1200 °C with 35–55 wt% content of CA possess the excellent black spinel structure and color effect. Under optimized conditions, the pigment has low average spectral reflectance (7%).     

新一代磷酸锌系防锈颜料--磷酸铝锌的合成和应用

采用磷酸、氢氧化铝、氧化锌为原料,利用共沉淀直接法合成新一代磷酸锌系防锈颜料——磷酸铝锌,并对产品的防锈性能进行了初步的探讨和研究。实验结果显示其防锈性能及成本优于传统的磷酸锌。     

Synthesis and properties of blue zirconia ceramic based on Ni/Co doped Ba0.956Mg0.912Al10.088O17 blue pigments

Novel blue pigments based on Ba_0.956Mg_0.912Al_10.088-xNi_xO₁₇ (0 ≤ x ≤ 0.3) and Ba_0.956Mg_0.912Al_10.088-xCo_xO₁₇ (0 ≤ x ≤ 0.3) solid solutions were successfully synthesized by solid state method. The XRD results confirmed the structure of the as-synthesized sample belongs to hexagonal β-alumina structure with the space group of P6₃/mmc. The d-d electron transitions in Ni²⁺/Co²⁺ tetrahedral sites in the visible light range are the reason for the blue colors. Then, the as-prepared blue oxides were sintered with ZrO₂ powders at 1400 °C to prepare blue zirconia ceramic materials. Based on XRD and SEM analysis, the pigment phase is stable after high-temperature sintering with ZrO₂, and a clear grain boundary is observed. The XCT results indicate the prepared blue ceramics are dense and very small pores are rarely distributed inside the blue zirconia ceramic body. Additionally, the mechanical properties of the fabricated blue ceramics were maintained compared to pure ZrO₂ ceramic.     

Functionally graded calcium phosphate bioceramics: An overview of preparation and properties

Bone tissue is composed of organic and inorganic phases with porous and dense regions, which can make it to be considered as a functionally graded body. Therefore, developing an advanced engineering implant with gradual variation in composition or structure that can fulfill the requirement for hard tissue replacement was enthusiastically followed by different researchers. The present paper overviewed the recent investigations on the 3 main types of functionally graded calcium phosphates used for bone substitution. The products features, challenges in preparation procedures and future perspectives were discussed.     

中国“入世”后铬系颜料及生产企业的前景

论述了国内外铬系颜料的简况和发展方向,国内生产企业现状及“入世”后面临的形势及对策,并将作好一切准备迎接新的挑战。     

纳米磷酸锌颜料的合成及其数据挖掘技术

借助均匀试验设计、回归分析、网格优化法等普通的软件，在纳米磷酸锌合成中应用数据挖掘技术，结果发现：如果没有微波辐射，室温固相反应也可以合成磷酸锌纳米晶体。     

乳液聚合法包覆酞菁蓝的制备及性能研究

在超细可聚合分散剂/酞菁蓝分散体中添加共聚单体和引发剂,采用乳液聚合法对酞菁蓝进行包覆。考察了共聚单体结构及用量、引发剂用量、反应温度和时间对包覆酞菁蓝性能的影响。结果表明,与甲基丙烯酸甲酯(MMA)和丙烯酸丁酯(BA)相比,苯乙烯(St)是较佳的包覆共聚单体,当St质量为颜料质量的20%,过硫酸铵(APS)质量为St与烯丙氧基壬基苯氧基丙醇聚氧乙烯磺酸铵(ANPS)总质量的1.0%,于70～80℃反应2 h时,所制备包覆酞菁蓝的粒径较小,稳定性较高。与未聚合分散体相比,包覆酞菁蓝的耐热稳定性、耐酸碱稳定性和离心稳定性均有明显提高,FTIR和TEM照片表明,酞菁蓝表面包覆了聚合物,且包覆酞菁蓝粒度分布更均匀。     

Synthesis and coloring properties of novel Ni-doped tialite pigments

Novel Ni-doped Al₂TiO₅ emerald green ceramic pigments were successfully synthesized for the first time. Several characterization techniques (XRD, XPS, SEM, TEM, UV–Vis, and automatic colorimeters) were used to determine the phase composition and stability of the pigments, as well as the valence state of the doped nickel ion. The results show that nickel ion replaces the Al³⁺ in the aluminum titanate lattice in the form of Ni²⁺, which reduces the distortion of the octahedral structure. Ni-doping of the aluminum titanate lattice produces an excellent coloring effect and significantly promotes the synthesis and stabilization of aluminum titanate. The novel pigments have excellent color stability while maintaining exceptional coloring performance and thermal stability in a base glaze synthesized at 1200 °C. These pigments show considerable potential for high-temperature applications.