Transparent ceramics have various potential applications such as infrared (IR) windows/domes, lamp envelopes, opto-electric components/devices, composite armors, and screens for smartphones and they can be used as host materials for solid-state lasers. Transparent ceramics were initially developed to replace single crystals because of their simple processing route, variability in composition, high yield productivity, and shape control, among other factors. Optical transparency is one of the most important properties of transparent ceramics. In order to achieve transparency, ceramics must have highly symmetric crystal structures; therefore, the majority of the transparent ceramics have cubic structures, while tetragonal and hexagonal structures have also been reported in the open literature. Moreover, the optical transparency of ceramics is determined by their purity and density; the production of high-purity ceramics requires high-purity starting materials, and the production of high-density ceramics requires sophisticated sintering techniques and optimized sintering aids. Furthermore, specific mechanical properties are required for some applications, such as window materials and composite armor. This review aims to summarize recent progress in the fabrication and application of various transparent ceramics.

Materials development and potential applications of transparent ceramics: A review

Understanding the structure-property relationship and optimizing properties of phosphors for use in lighting and scintillation fields is an important materials challenge. In this work, we investigated the effects of the pH value of the coprecipitating solution adjusted by the concentration of NH4OH(aq) on the structure and optical properties of the obtained La2Hf2O7 nanoparticles (NPs). The obtained NPs stabilize in the ideal pyrochlore structure, but the extent of ordering increased with an increase in the pH value used. The NPs prepared at pH = 12.1 displayed the best optical performance owing to the balance of the crystallinity, agglomeration, and surface defects. On the basis of density functional theory (DFT) calculations, the origin of violet-blue emission in undoped La2Hf2O7 NPs was attributed to defect states in the electronic band gap arising due to oxygen defects. For the La2Hf2O7:Eu3+ NPs, the Eu3+ dopants possess low symmetry and their occupancy is more favorable at the LaO8 site. DFT calculations further justify the complete host-to-dopant energy transfer and origin of the most intense red emission observed experimentally. Understanding the interplay of the experimental and theoretical results thus is a very useful general approach for improving the efficiency of luminescent materials.

Correlating Structure and Luminescence Properties of Undoped and Eu3+-Doped La2Hf2O7 Nanoparticles Prepared with Different Coprecipitating pH Values through Experimental and Theoretical Studies.

Remediation techniques for uranium removal from polluted environment - Review on methods, mechanism and toxicology.

In recent years, nanocrystalline materials with grain size below 100 nm have attracted much interest due to their excellent chemical, physical, and optical properties. This review focuses on the irradiation effects of nanocrystalline materials. It has been generally believed that nanocrystalline materials have a great potential to increase irradiation resistance in the future reactor because of a large fraction of grain boundaries or interfaces that could absorb and annihilate mobile defects which produced during irradiation. Some calculation results and experiment results revealed that nanocrystalline materials can enhance irradiation resistance, while some reports showed that nanocrystalline materials exhibit worse irradiation resistance, or even amorphous at a lower irradiation dose compared with their bulk materials. During the irradiation process, the grain growth dominated by irradiation dose, thermal effect or defects was also disputed. Irradiation is also an important tool to tailor the grain size, phase structure and physical properties of the materials.

Irradiation effects on nanocrystalline materials

High temperature and high strength Y2Zr2O7 flexible fibrous membrane for efficient heat insulation and acoustic absorption

A facile solvothermal method for high-quality Gd2Zr2O7 nanopowder preparation

As efficient and stable nuclear waste forms, single-phase uranium (U6+)-incorporated La2Zr2O7 nanoparticles were designed and synthesized in an air atmosphere. To obtain a high U loading, divalent ...

Uranium-Incorporated Pyrochlore La2(UxMgxZr1-2x)2O7 Nuclear Waste Form: Structure and Phase Stability.

Yttrium-stabilized zirconia (Y0.08Zr0.92O1.96, YSZ) nanocrystalline powders were prepared by co-precipitation methods. Different precipitants (ammonium hydroxide, ammonium bicarbonate, oxalic acid, and urea) were used to study the effects of precipitants on co-precipitation synthesis of YSZ nanocrystalline powders. Thermogravimetric analysis-differential scanning calorimetry, powder X-ray diffraction, Fourier-transform infrared, scanning electron microscope, energy-dispersive spectrometer, Brunauer–Emmett–Teller, Barrett–Joyner–Halenda, and X-ray photoelectron spectroscopy analysis methods were employed to investigate the thermal decompositions, phase evolutions, micro-morphologies, surface areas, and elements analysis of the synthesized YSZ precursor powders or nanoparticles. Although different precipitants were used, the calcined products at 600 °C have nearly identical chemical compositions. The crystallization temperature of the precursor powders to evolve to cubic phase is the lowest (about 400 °C) when ammonium hydroxide is used as a precipitant, while it is about 500 °C in the case of other three types of precipitants (ammonium bicarbonate, oxalic acid, and urea) that were used. Ammonium bicarbonate cannot precipitate ZrO2+ effectively in the solution, resulting in the formation of cubic Y0.18Zr0.82O1.91 at 1000 °C. Despite the time-consuming co-precipitation process, urea was proved to be the optimal precipitant in terms of the fabrication of nanocrystalline YSZ powders with designed Y/Zr/O molar ratio, large surface area, small crystallite size, and well dispersion.

Wei Han

Papers

A facile solvothermal method for high-quality Gd2Zr2O7 nanopowder preparation

Uranium-Incorporated Pyrochlore La2(UxMgxZr1-2x)2O7 Nuclear Waste Form: Structure and Phase Stability.

The effects of precipitants on co-precipitation synthesis of yttria-stabilized zirconia nanocrystalline powders

Optimization of ball-to-powder weight ratio toward to highly transparent LaGdZr2O7 ceramics processing by solid reactive sintering

Microwave-assisted synthesis of uranium doped Y2Zr2O7 transparent ceramics as potential near-infrared optical lens