High Temperature Solid State Research Articles

Solution Synthesis and Diffusion-Mediated Formation Pathway of NbTe4 Particles.

NbTe4 is an important material because of its fundamental low-temperature electronic behavior and its potential interest for thermoelectric, catalytic, and phase-change applications, especially as nano- and microscale particles. As a tellurium-rich group V transition metal telluride, bulk NbTe4 is typically synthesized through high-temperature solid-state or metal flux reactions and NbTe4 films can be made by sputtering and annealing, but NbTe4 is generally not amenable to the lower-temperature solution-based syntheses that yield small particles. Here, we demonstrate a solvothermal route to NbTe4 particles that is based on mainstream colloidal nanoparticle synthesis. We find that the reaction proceeds in situ through a multistep pathway that begins by first forming elemental tellurium needles. NbTe4 then deposits on the surface of the tellurium needles through a diffusion-based process. Time-point studies throughout the reaction reveal that crystallographic relationships between Te and NbTe4 define how the diffusion-based reaction proceeds and help to rationalize the morphology of the resulting NbTe4 particles. As synthesized, NbTe4 particles exhibit a surface consisting of predominantly Nb-Te and reduced NbOx species, but after storage, surface oxidation transforms these species to primarily Nb2O5 and TeO2, while the NbTe4 remains unchanged. These synthetic capabilities and reaction pathway insights for NbTe4, made using a solvothermal method, will help to advance future studies on the properties and applications of this and related tellurides.

Near-Infrared Luminescent Materials Incorporating Rare Earth/Transition Metal Ions: From Materials to Applications.

The spotlight has shifted to near-infrared (NIR) luminescent materials emitting beyond 1000 nm, with growing interest due to their unique characteristics. The ability of NIR-II emission (1000-1700 nm) to penetrate deeply and transmit independently positions these NIR luminescent materials for applications in optical-communication devices, bioimaging, and photodetectors. The combination of rare earth metals/transition metals with a variety of matrix materials provides a new platform for creating new chemical and physical properties for materials science and device applications. In this review, the recent advancements in NIR emission activated by rare earth and transition metal ions are summarized and their role in applications spanning bioimaging, sensing, and optoelectronics is illustrated. It started with various synthesis techniques and explored how rare earths/transition metals can be skillfully incorporated into various matrixes, thereby endowing them with unique characteristics. The discussion to strategies of enhancing excitation absorption and emission efficiency, spotlighting innovations like dye sensitization and surface plasmon resonance effects is then extended. Subsequently, a significant focus is placed on functionalization strategies and their applications. Finally, a comprehensive analysis of the challenges and proposed strategies for rare earth/transition metal ion-doped near-infrared luminescent materials, summarizing the insights of each section is provided.

NASICON Membrane with High Ionic Conductivity Synthesized by High-Temperature Solid-State Reaction.

In the present work, we studied the impact of excess Na addition on the structure of the standard NASICON ion conductor along with Na ion transport mechanisms. In this sense, NASICON ceramic membranes (NZSP) were prepared by a simple chemical synthesis method, the solid state reaction (SSR), using an excess of 5% Na (Na3.15Zr2Si2PO12) and an excess of 10% Na (Na3.3Zr2Si2PO12), in order to improve the conduction properties of the ceramic membrane. The characterization of the NZSP nanoparticles was performed by measuring the particle size by dynamic light scattering (DLS), the morphology of the NASICON samples pre-sintered at 1100 °C was analyzed by the SEM method (scanning electron microscope), and X-ray diffraction (XRD) analysis was used to investigate the crystal structure of samples, while the surface area was measured using the BET technique. The electrical properties (i.e., ionic conductivity) were evaluated by impedance spectroscopic methods at room temperature (RT). Following the experiments for NASICON membranes without Na excess, with 5% Na excess, and with 10% Na excess synthesized at different pressing forces and sintering temperatures, it was found that membranes with a 10% Na excess, sintered at 1175 °C for 10 h, presented a good ionic conductivity (4.72 × 10-4 S/cm).

Bioimaging and prospects of night pearls-based persistence phosphors in cancer diagnostics.

Inorganic persistent phosphors feature great potential for cancer diagnosis due to the long luminescence lifetime, low background scattering, and minimal autofluorescence. With the prominent advantages of near-infrared light, such as deep penetration, high resolution, low autofluorescence, and tissue absorption, persistent phosphors can be used for deep bioimaging. We focus on highlighting inorganic persistent phosphors, emphasizing the synthesis methods and applications in cancer diagnostics. Typical synthetic methods such as the high-temperature solid state, thermal decomposition, hydrothermal/solvothermal, and template methods are proposed to obtain small-size phosphors for biological organisms. The luminescence mechanisms of inorganic persistent phosphors with different excitation are discussed and effective matrixes including galliumate, germanium, aluminate, and fluoride are explored. Finally, the current directions where inorganic persistent phosphors can continue to be optimized and how to further overcome the challenges in cancer diagnosis are summarized.

Effect of the Elaboration Method on Structural and Optical Properties of Zn1.33Ga1.335Sn0.33O4:0.5%Cr3+ Persistent Luminescent Nanomaterials.

Near-infrared (NIR) persistent luminescence (PersL) materials have demonstrated promising developments for applications in many advanced fields due to their unique optical properties. Both high-temperature solid-state (SS) or hydrothermal (HT) methods can successfully be used to prepare PersL materials. In this work, Zn1.33Ga1.34Sn0.33O4:0.5%Cr3+ (ZGSO:0.5%Cr3+), a newly proposed nanomaterial for bioimaging, was prepared using SS and HT methods. The results show the crystal structure, morphology and optical properties of the samples that were prepared using both methods. Briefly, the crystallite size of the ZGSO:0.5%Cr3+ prepared using the SS method is ~3 µm, and as expected, is larger than materials prepared using the HT method. However, the growth process used in the hydrothermal environment promotes the formation of ZGSO:0.5%Cr3+ with more uniform shapes and smaller sizes (less than 500 nm). Different diameter ranges of nanoparticles were obtained using HT and ball milling (BM) methods (ranging from 25-50 nm) and by using SS and BM methods (25-200 nm) as well. In addition, the SS-prepared microstructure material has stronger PersL than HT-prepared particles before they go through ball milling to create nanomaterials. On the contrary, after BM treatment, ZGSO:0.5%Cr3+ HT and BM NPs present higher PersL and photoluminescence (PL) properties than ZGSO:0.5%Cr3+ SS and BM NPs, even though both kinds of NPs present worse PersL and PL compared to the original particles before BM. To summarize: preparation methods, whether by SS or HT, with additional grinding as a second step, can have a significant impact on the morphological and luminescent features of ZGSO:0.5%Cr3+ PersL materials.

Control of the LiFePO4 electrochemical properties via a pray-drying-assisted a solid-phase reaction route using Fe3(PO4)2 as iron precursor

Fe3(PO4)2 as iron precursor was prepared by liquid phase method with FeSO4 as iron source, and then LiFePO4(LFP) was made by high-temperature solid state reaction. The adjustment of Fe and P content is beneficial to the precise control of Fe3(PO4)2 precursor components and ensure the excellent electrochemical performance of LiFePO4 materials. It is shown that pH is very critical to the contents of iron and phosphorus in Fe3(PO4)2, and a stoichiometric ratio of high-yield Fe3(PO4)2 can be obtained at a pH of six. After Fe3(PO4)2 is mixed with Li3PO4 and glucose, high-energy ball milling and spray-drying technology are used to thoroughly mix the mixtures and control their morphology of them. The as-prepared LiFePO4 maintains the microporous spherical morphology by high-temperature solid-state method, which is formed in spray drying. At 700 °C, the LFP/C material has reaching 156, 147, 137, 128, 111, 96 mAh g−1 at 0.2 C, 0.5 C, 1 C, 5 C and 10 C rate, respectively, and after 500 long loops for 5 C, the capacity retention still maintains 49%. LFP prepared with ferrous iron phosphate as precursor has good cycling performance.

Thermionic Emission Capability of the Ba–Sc–Al–O Compound Synthesized by High-Temperature Solid-State Process

The dibarium scandium aluminum oxide (Ba2ScAlO5) is an important compound for thermionic emission in high-power vacuum devices. Herein, the high-temperature solid-state synthesis mechanism is investigated extensively to develop single-phase <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ba2ScAlO5 and evaluate its emission capacity. Barium carbonate, scandium oxide, and aluminum hydroxide are adopted as the reactants. The synthesis temperature, the intermediate phases, and the cell parameters of the final products differ from sintering the coprecipitated precursor. The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ba2ScAlO5 single-phase material can be obtained based on the nonstoichiometric mole ratio of BaO:Sc2O3:Al2O3 = 4.4:1.1:0.9. The X-ray Rietveld refinement reveals that the substitution of Sc for Al and the defects of the Ba, Sc, and O vacancies account for the nonstoichiometry and the shrinkage of cells. The test cathode impregnated with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ba2ScAlO5 doped with Ca2+ exhibits an emission capability of 6.79 A/cm2 at 900 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ }\text{C}_{\text {B}}$ </tex-math></inline-formula> in the dc mode. This work demonstrates the feasibility of obtaining <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ba2ScAlO5 with considerable emission through the high-temperature solid-state process.

Synthesis and Luminescence Characteristics of CaWO4: Eu3+ Red Phosphor for White Light Emitting Diode

White light emitting diode (LED) red phosphor Ca1−xWO4:xEu3+ (x = 0.10, 0.15, 0.20, 0.25, 0.30) was prepared by high temperature solid state method. The phase of the phosphor sample was analyzed by X-ray diffraction (XRD) and the morphological characteristics of the sample were analyzed by scanning electron microscope (SEM), and the luminescence characteristics of the sample were studied by fluorescence spectrophotometer. The results show that the synthesized samples are scheelite structure and can be effectively excited by near ultraviolet light (393 nm) and blue light (464 nm). The main emission peak is located at 615 nm, which belongs to the 5D0→7F2 transition of Eu3+. The optimum doping amount of Ca1−xWO4:xEu3+ is 25%. In addition, Ca0.75WO4: Eu3+0.25 was prepared by sol–gel method, which was compared with the same component sample prepared by high-temperature solid-state method. It was found that the phosphor prepared by high-temperature solid-state method had relatively high luminous intensity.

SrLaNaTeO6:Eu3+ red-emitting phosphors with high luminescence efficiency and high thermal stability for high CRI white LEDs

A novel single-phase trivalent europium activated red-emitting SrLaNaTeO6 phosphor was first synthesized in a process of traditional high-temperature solid-state. The phase purity, morphology, and spectroscopy of the prepared phosphor were analyzed. Under 395 nm excitation, the photoluminescence (PL) spectra of the SrLaNaTeO6:Eu3+ products mainly contained five dominant sharp peaks. The intense red emission peak at 615 nm was the typical 5D0→7F2 electric dipole transition of Eu3+. The optimum product of high quenching concentration was the SrLaNaTeO6:0.90Eu3+, which reached a high internal quantum efficiency (IQE) of 90.6%. The SrLaNaTeO6:0.90Eu3+ was estimated to have Rc of 6.57 Å and possessed high color purity of 100.0%. The phosphors exhibited excellent thermal stability and high activation energy (Ea = 0.29 eV). The prepared white light-emitting diode (WLED) had a high color rendering index (CRI) Ra of 92 and a low correlated color temperature (CCT) of 5008 K. In conclusion, the phosphors have potential as red components for WLEDs.

Immobilization of Strontium Aluminate into Recycled Polycarbonate Plastics towards an Afterglow and Photochromic Smart Window.

A transparent smart window made of recycled polycarbonate plastic (PCP) waste was prepared and immobilized with strontium aluminate phosphor nanoparticles (SAPN). It has afterglow emission, super-hydrophobicity, durability, photostability, good mechanical properties, ultraviolet protection, and high optical transmittance. To create an afterglow emission polycarbonate smart window (SAPN@PCP), recycled polycarbonate waste was integrated with various concentrations of SAPN (15-52 nm). SAP micro-scale powder was made using the solid-state high temperature method. The SAP nanoparticles were produced using the top-down method. To create a colorless plastic bulk, recycled polycarbonate waste was inserted into a hot bath. This colorless plastic was thoroughly combined with SAPN and cast to create an afterglow luminous smart window. To investigate its photoluminescence properties, spectrum profiles of excitation and emission were measured. According to the luminescence parameters, the phosphorescent colorless polycarbonate plates displayed a change in color to strong green under UV illumination and greenish-yellow in a dark box. The afterglow polycarbonate smart window displayed two emission peaks at 496 and 526 nm, and an absorption wavelength of 373 nm. Upon increasing the SAPN ratio, the hydrophobic activity, hardness, photostability, and UV protection were improved. Luminescent polycarbonate substrates with lower SAPN ratio demonstrated rapid and reversible fluorescence under UV light, while the higher SAPN content in the luminous polycarbonate substrates showed afterglow.

Synthesis and characterization of Cr-doped diopside ceramics

A series of ceramics in the system CaO–Cr2O3–MgO–SiO2 was synthesized via solid-state high temperature sintering at 1000, 1100 and 1200 °C. The resulting ceramics were examined by powder X-ray diffraction, scanning electron microscopy, infrared and electron paramagnetic resonance spectroscopy. The color characteristics were measured spectrophotometrically. It was found that under the synthesis conditions multiphase ceramics were obtained which contain diopside, wollastonite, magnesiochromite, cristobalite, tridymite and periclase in various proportions. The synthesized ceramics are gray, gray-green and green in color, depending on the content of Cr additive, temperature of furnace and phase composition.

Influence of graphene oxide and carbon nanotubes on physicochemical properties of bone cements

The influences of graphene oxide (GO) and carboxyl functionalized multi-wall carbon nanotubes (f-MWCNTs) on mechanical and biological performances bone cements used as the bone substitute are investigated. The bioresorbable and bioceramics were prepared of calcium sulfate diydrate, tetra calcium phosphate and dicalcium phosphate dihydrate is fabricated by a solid-state high temperature process. Then the bioceramic is mixed with carboxymethyl cellulose, gelatin and nanocarbons. The addition of 0.5 wt% f-MWCNT and 1 wt% GO is found to increase the compressive strength of the resultant nanocomposite by %50 and %55, respectively, in comparison to that of the bare bone cement. 1 wt% GO incorporated bone substitutes had the optimum mechanical properties which had compressive modulus and compressive strength of 1.9 ± 0.3 and 35.8 ± 0.5 MPa, respectively. Moreover, GO is found to be more effective than f-MWCNT in stabilizing pH. The degradation rate of the bone cement is stabilized through GO incorporation but increased by incorporating f-MWCNT. Bone substitutes up to 1 wt% nanocarbons exhibit biocompatibility and MC3T3-E1 pre-osteoblasts were mineralized after 14 days of cell culture. The results demonstrate that the physicochemical properties of the nanocomposites are significantly affected by the concentration and surface properties of nanocarbons.

Synthesis, phase composition and characterization of Co-diopside ceramic pigments

Ceramic pigments in the system CaO – CoO – MgO – 2SiO2 were synthesized through solid-state high temperature sintering at 1000, 1100 and 1200 °C. The starting compositions were determined from the stoichiometric mineral diopside, following the expression CaO.xCoO.(1-x)MgO·2SiO2, where x = 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.5, 0.7 and 0.9. The effect of sintering temperature and initial cobalt concentration on the phase composition and colour were studied by powder X-ray diffraction analysis, scanning electron microscopy (SEM), infrared (FT-IR), ultraviolet–visible - (UV–Vis) and electron paramagnetic resonance (EPR) spectroscopy. Poly-phase ceramics were obtained depending on synthesis parameters, which in addition to Co-diopside, may contain wollastonite, Co-åckermanite – Ca2(Co, Mg)Si2O7, Co-olivine – CoMgSiO4, Co-monticellite – Ca(Mg, Co) SiO4, and cristobalite. Quantitative ratios of detected mineral phases and the degree of cobalt isomorphic substitution were determined by applying Rietveld refinement approach. Trends and consistencies were outlined revealing that concentration of cobalt in the initial synthesis batch and its isomorphous incorporation in the crystal structure of diopside affect the structural perfection of the cation polyhedra. This fact obviously plays a key role in controlling the amount of the main constituent phase in the run-product. Ceramics of highest diopside content and lowest measured degree of structural distortion were only formed at 1200 °C and initial cobalt concentration in the range x = 0.2–0.3. These samples are pink in colour and have the highest value of red coordinate in the CIELab system due to Co2+ ions in octahedral coordination in diopside structure.

Optical properties of novel luminescent nacre‐like epoxy/graphene nanocomposite coating integrated with lanthanide‐activated aluminate nanoparticles

Nacre structure has aragonite polygonal tablets, tessellated to generate separate layers, and exhibits adjacent layers and tablets within a layer bonded by a biopolymer. Herein, we report the development of nacre-like organic/inorganic hybrid nanocomposite coating consisting of epoxy tablets as well as rare-earth activated aluminate and graphene oxide tablet/tablet interfaces. The lanthanide-activated aluminate was prepared by the high temperature solid-state approach followed by the top-down technology to provide the phosphor nanoparticles (PNPs). Graphene oxide nanosheets were prepared from graphite. The prepared epoxy/graphene/phosphor nanocomposites were applied onto mild steel. Covalent bonds were formed between epoxy polymer chains resin and graphene oxide nanosheets. Those interface interactions results in tough surface, high tensile strength, and excellent durability. The usage of phosphor in the nanoparticle form guaranteed no agglomerations were produced throughout the hardening procedure by allowing better distribution of PNPs in the nacre-like matrix. The generated nacre-like substrates displayed reversible fluorescence. The excitation of the white colored nacre-like coats at 367 nm results in a green emission band at 518 nm as designated by CIE Lab and photoluminescence spectra. Various analysis methods were utilized to inspect the surface structure and elemental composition of the nacre-like coats. An improved hydrophobicity and mechanical characteristics were detected with increasing the phosphor concentration. Due to the astonishing characteristics of the prepared nacre-like composite paint, both ceramics and metals can benefit from the current simple strategy.

On the nanoindentation behavior of a TiC layer formed through thermo-reactive diffusion during hot pressing of Ti and cast iron

Hot pressing of pure Ti and cast iron under vacuum formed a ∼15 µm wide TiC-layer through the thermo-reactive diffusion process. Nanoindentation testing of the TiC-layer revealed average hardness and elastic modulus values of ∼35 GPa and ∼400 GPa, respectively. High-resolution indentation mapping indicated hardness change across the boundary with peak values observed within the TiC-layer. Solid state high temperature diffusion holds significant potential for developing uniform hard coatings on pure Ti/Ti-alloys.

Colour‐switchable and photoluminescent polyvinyl chloride for multifunctional smart applications

Recycled polyvinyl chloride (PVC) waste was used to prepare transparent materials with long-lasting phosphorescence, photochromic activity, hydrophobicity, strong optical transmission, ultraviolet (UV) light protection, and stiffness. Lanthanide-activated aluminate (LaA) microparticles were prepared using a high temperature solid-state procedure, and were subjected to top-down grinding technology to produce lanthanide-aluminate nanoparticles (LaAN). Laminated PVC bottles were shredded into a transparent plastic matrix, which was combined with LaAN and drop casted to produce smart materials for various applications. Smart windows and photochromic film for smart packaging can be made from recycled PVC waste by immobilizing it with various ratios of LaAN. Long-lasting phosphorescent translucent PVC smart windows and films need LaAN to be evenly dispersed in PVC without clumping. Different analytical methods were used to assess the material's morphological structure and chemical composition. Photoluminescence and decay spectra were all used to investigate the luminescence characteristics. In addition, the mechanical performance was studied. According to Commission Internationale de l'Éclairage laboratory colour measurements, this transparent PVC smart material becomes bright green under UV rays and turns a greenish-yellow in the dark. The PVC luminescence was observed to exhibit apparent emission bands at 429 and 513 nm when excited at 367 nm. Improvements were monitored in UV shielding and hydrophobicity when increasing the phosphor concentration. LaAN-immobilized PVC exhibited reversible photochromism. The present approach can be applied to various applications such as anticounterfeiting films for smart packaging, smart windows, and warning light marks.

(Digital Presentation) Sol-Gel Based Synthesis Route for High Capacity Disordered Rocksalt (DRX) Oxyfluoride Cathodes

The cost and energy density of commercial Li-ion batteries (LIBs) are largely limited by the cathode. Currently, the LIB cathode market is dominated by intercalation type layered transition metal oxides of the general form LiNixMnyCo1-x-yO2 (NMC). As the LIB market continues to grow, there is an increasing risk of over-reliance on cobalt and nickel, which not only leads to increased cost and resource depletion, but also raises ethical concerns related to the cobalt mining industry. Hence, there is an urgent need to develop new cathodes based on earth abundant materials. Disordered rocksalt (DRX) oxides and oxyfluorides have emerged as a promising candidate for next generation LIB cathodes due to their high energy density and ability to utilize low-cost, earth abundant elements such as Mn and Ti. Studies have shown that anionic substitution of oxygen with fluorine enhances electrochemical performance and cycling stability of DRX cathodes. DRX cathodes are traditionally synthesized using high temperature solid-state and high energy mechanochemical routes. While these methods have yielded promising cathodes, they face challenges with fluorine substitution and process scalability. Keeping this in mind, the goal of this research is to develop alternate synthesis routes to prepare DRX oxyfluoride cathodes and identify key structure – property correlations to optimize cathode performance. Our team recently developed a sol-gel based approach to synthesize Li1.2MnxTi0.8-xO2-yFy (y=0-0.2; x=0.4-0.6) DRX oxides and oxyfluorides. This presentation will discuss recent development related to the synthesis, structure, and performance of these cathodes Acknowledgements This research was conducted at Oak Ridge National Laboratory, managed by UT Battelle, LLC, for the U.S. Department of Energy (DOE) and is sponsored by the Office of Energy Efficiency and Renewable Energy (EERE) through the Vehicle Technologies Office (VTO).

Preparation and Properties of Sr3B2O6:Dy3+, Eu3+ White Phosphors Using the High-Temperature Solid-State Method

Preparation and Properties of Sr3B2O6:Dy3+, Eu3+ White Phosphors Using the High-Temperature Solid-State Method

Immobilization of lanthanide doped aluminate phosphor onto recycled polyester toward the development of long-persistent photoluminescence smart window.

Smart window can be defined as switchable material whose light transmission is altered upon exposure to light, voltage, or heat. However, smart windows are usually produced from expensive and breakable glass materials. Herein, transparent smart window with long-persistent phosphorescence, high optical transmittance, ultraviolet (UV) protection, rigid, high photostability and durability, an d superhydrophobicity was developed from recycled polyester (PET). Recycled polyester waste (RBW) was simply immobilized with different ratios of lanthanide-doped aluminate nanoparticles (LdAN) to provide a long-persistent phosphorescent polyester smart window (LdAN@PET) with an abili ty to persist emitting light for extended time periods. The solid-state high temperature technique was used to prepare lanthanide-doped aluminate (LdA) micro-scale powder. Then, the top-down technique was applied to afford the corresponding LdAN. Recycled shredded recycled polyester bottles were charged into a hot bath to provide a clear plastic shred bulk, which was then well-mixed with LdAN and drop-casted to provide long-persistent luminescent smart window. In order to improve the phosphor dispersion in the PET bulk, LdAN was synthesized in the nanoparticle form which was characterized utilizing transmission electron microscopy (TEM). For better preparation of translucent smart window of long-persistent phosphorescent polyester, LdAN must be homogeneously dispersed in the PET matrix without agglomeration. The morphology and chemical composition were studied by Fourier-transform infrared (FTIR) spectra), X-ray fluorescence (XRF) analysis, scanning electron microscopy (SEM), and energy-dispersion X-ray spectroscopy (EDX). In addition, spectral profiles of excitation and emission, and decay and lifetime were used to better understand the photoluminescence properties. The hardness properties were also investigated. The developed phosphorescent transparent polyester smart window demonstrated a color switch to intense green underneath UV irradiation and greenish-yellow under darkness as verified by CIELab color parameters. The afterglow polyester smart window showed an absorption wavelength at 365 nm and two phosphorescence intensities at 442 and 512 nm. An enhanced UV protection, photostability and hydrophobic activity were detected. The luminescent polyester substrates with lower LdAN ratios demonstrated rapid and reversible fluorescent photochromic activity beneath the UV light. The luminescent polyester substrates with higher LdAN contents displayed long-persistent phosphorescence afterglow. The current strategy can be simply applied for the production of smart windows, low thickness anti-counterfeiting films and warning signs.

Synthesis and study of ferri-diopside ceramic pigments

The article reports the mineralogical composition, structural features and changes in color parameters of iron-containing diopside pigments. The source of SiO2 in these pigments was SiO2nH2O with a particle size in the range of 2–7 m, which is much more reactive than conventionally used quartz sand. A series of ceramic pigments on the basis of stoichiometric diopside in the system CaO–Fe2O3–MgO–SiO2 was synthesized via solid-state high temperature sintering at 1000, 1100 and 12000C. The resulting ceramic pigments were examined by powder X-ray diffraction, infrared spectroscopy, electron microscopy, electron paramagnetic resonance and Mössbauer spectroscopy. The color characteristics were measured using spectrophotometry method. It was found that multiphase ceramic pigments were obtained under the synthesis conditions, which contain diopside, wollastonite, cristobalite, akermanite and periclase in various proportions. The synthesized ceramic pigments are brown and beige in color, depending on the content of Fe2O3 additive, firing temperature and phase composition. The synthesized pigments can be used for staining of ceramic glazes.