Low-density porous materials, so-called aerogels, with silicone networks have been developed through aqueous sol–gel systems. We found that the two-step acid-base process is suitable for the meso-scaled homogeneous hydrophobic network formations with the aid of surfactant. Optically transparent aerogels have been prepared from various organo-substituted alkoxysilanes [RSi(OR′)₃, R and R′ are organic groups] and organo-bridged alkoxysilanes (R′O)₂(CH₃)Si–R–Si(CH₃)(OR′)₂ and (R′O)₃Si–R–Si(OR′)₃. Most aerogels, poly(methylsilsesquioxane) aerogels in particular, from these precursors show mechanical flexibility against compression and bending deformations, which allows spring-back during ambient pressure drying to yield xerogels with almost the same properties with supercritically dried aerogels. In addition to these scientific works on aerogels, applications of aerogels to visual arts and designs are also discussed.

Microwave processing shows promise as a material synthesis method for metastable phases and contributes to achieve energy-efficient processes. This paper outlines the synthesis of functional ceramics under microwave electromagnetic fields in terms of solid–solid and solid–gas reactions. Microwave-assisted synthesis of functional materials, such as oxides and nitrides has been shown to save energy and reduce reaction times compared to conventional methods. Local selective heating under microwave irradiation has been experimentally demonstrated to generate significant temperature differences and microwave-induced solid–gas reactions involve a mechanism of plasma generation from gas-phase excitation, supported by emission spectroscopy.

Crack self-healing ability at high temperatures (>1000 °C) has been reported in alumina (Al₂O₃) composites dispersed with silicon carbide. For lower self-healing temperature ranges, such as 600–800 °C, titanium carbide (TiC) has been considered as a promising healing agent. However, no investigation has been conducted on Al₂O₃ containing a low volume (<15 vol %) of TiC. In this study, Al₂O₃ composites dispersed with 10 vol % of micro/nano TiC particles were prepared by a hot pressing method, then the mechanical properties and the self-healing ability were investigated. The composites were pre-cracked on the surface by a Vickers hardness tester, then annealed at 400 and 700 °C for 1–3 h to demonstrate the self-healing ability. Scanning electron microscope (SEM) observations and bending strength tests confirmed that the cracks were almost healed after annealing at 700 °C for 3 h. Characterizations by adsorption–desorption isotherm, thermogravimetry, and X-ray diffraction have pointed out that the size of TiC healing particles plays an important role on the healing rate and strength recovery of the composites.

This study verified the behavior of sample current, volumetric power dissipation, and shrinkage during flash sintering with the voltage-to-current protocol in the time frame of 90 s before and after the flash event. The volumetric power dissipation exhibited a peak value, followed by a decrease to the minimum value, and then increased asymptotically and approached a steady-state value. The discrepancy between the peak and minimum values, ΔP, increased with the limiting current value pre-set at the power supply during the heat-up stage. As ΔP increased, the degree of shrinkage progress decreased in stage III after the flash event, which is caused by the heterogeneity of shrinkage rate inside a compact. To consider the complete shrinkage amount, including stage III, in the current-to-voltage protocol, it is crucial to ensure that ΔP does not reach an excessive level when setting the maximum current.

In this study, crystalline films of α-Mn₂O₃ and Mn₃O₄ were prepared on glass substrates at 95 °C by the spin-spray method, in which aqueous solutions containing Mn²⁺ and H₂O₂ were simultaneously sprayed. The controlled preparation of α-Mn₂O₃ and Mn₃O₄ polycrystalline films and Mn₃O₄ nanorod arrays can be achieved by adjusting the H₂O₂ concentration and pH of the reaction solution. The concentration of terephthalic acid (C₈H₆O₄), a chemical probe for the hydroxyl radical (HO·), was used as an experimental parameter to investigate the main oxidizing agent in the spin-spray reaction. The generation of HO· was confirmed based on photoluminescence measurements and quenching tests, and the concentration of HO· was found to be a crucial factor for the phase formation in this study.

The photoelastic constant (PEC) of a square-shaped glass, such as very tough and fragile glasses of a mechanical nature and a very small stress-induced birefringent glass, can be successfully obtained by a heterodyne method. The merit is that the PECs can be obtained even for difficult compositions to re-form into disk-shaped, instead of the commonly used method of measuring PECs with disk-shaped glass. The PECs of square and disk-shaped glasses with the same composition can be obtained within ±0.2 × 10⁻¹² Pa⁻¹ measurement accuracy. This phenomenon could be developed into a potential glass that can be processed into square shapes with high precision but is difficult to process into disks using glass lenses and filters.

In order to classify the white porcelains of the Tang Dynasty unearthed in Xi’an, the chemical composition, micro-morphology, and glaze color of archaeological white porcelain samples were systemically analyzed and compared with standard white fragments from Gongyi kilns (Henan Province) and Xing kilns (Hebei Province) by a series of analytical techniques including ultra-depth of field microscope, X-ray fluorescence spectroscopy and visible spectrophotometer. The results showed that most of white fragments excavated in Xi’an could be attributed to three types. There were two types that could be classified as Xing kilns and Gongyi kilns in terms of microstructure, chemical composition, and glaze color. However, some of Xi’an white porcelains presented imperfect correspondence concerning the firing process, indicating that they might neither come from Gongyi kilns nor from Xing kilns. Or another possibility is that they might be prepared by different firing protocol. Besides, the information of raw materials and firing process of white porcelains of Gongyi kilns and Xing kilns was also discussed. The purpose of this work is to provide a scientific approach to classify ancient ceramics.

Fabrication conditions, involving the introduction of intrinsic defects such as oxygen vacancies in the material, play a crucial role in the persistent luminescence (PersL) properties. In this study, Y₃Al₂Ga₃O₁₂ (YAGG):Pr³⁺ ceramic phosphors were synthesized in the air from 1400 to 1600 °C by using a solid-state reaction method. The influence of sintering temperature on luminescence properties and PersL properties was investigated. YAGG:Pr³⁺ prepared via a low sintering temperature (1400 °C) exhibits the relative strongest 5d-4f photoluminescence and PersL in the UV region of Pr³⁺ among the samples. The Thermoluminescence (TL) measurements revealed that the intensity of two strong TL peaks related to intrinsic trap centers increases with the rise in sintering temperature. A significant reduction in deep traps, associated with the oxygen vacancies in the sample sintered at 1400 °C, can be observed in the normalized TL glow curves. Consequently, the enhancement of UV PersL of Pr³⁺ was observed which may through suppressing the relaxation process from the 5d state to ¹D₂ level through the state of intrinsic defects.

TiB₂ composites with 30 wt.% TiC and 10 wt.% Ti, TiB₂ composites with only 30 wt.% TiC, and bulk TiB₂ without any additives were fabricated using the spark plasma sintering (SPS) technique at a temperature of 1500 °C, respectively. In addition, bulk TiB₂ ceramic was also fabricated at 1800 °C. The differences in densification and mechanical properties between TiB₂ composites and bulk TiB₂ ceramics were systematically investigated. The addition of TiC and Ti reduced the densification temperature from above 1800 to 1500 °C. Compared with the bulk TiB₂ ceramic (with a density of 4.38 g/cm³) sintered at 1800 °C, the TiB₂ composites exhibited enhanced sinterability, decreased grain size, increased strength and toughness, and slightly lower hardness.

To minimize nozzle cloggage during long time synthesis of nanocolloids, an Outer nozzle type Shear-Agitation Reactor (Outer SA Reactor) with unbranched flow channels was developed in this study. The Outer SA Reactor was employed to prepare ceria-zirconia solid solution (CZ) nanocolloids under the same conditions as the conventional Inner Nozzle SA Reactor. The CZ nanocolloids obtained from both reactors showed almost the same particle size (2.8 nm) and size distribution. The excellent nanocolloid synthesis capability of the Outer SA Reactor was because the regions with the highest turbulent energy were fully utilized for nucleation.

In this study, green synthesis of copper nanoparticles (CuNPs) was investigated at low temperatures without the use of harmful reagents. The starting material was a mixture of an aqueous copper nitrate solution and carboxymethyl cellulose (CMC) suspension. Subsequently, the mixture was processed 0–20 times using a high-pressure wet-type jet mill (jet mill) at a discharge pressure of 100 MPa. The number of jet milling cycles affected the shape of the precipitated particles. Transmission electron microscopy images of a sample subjected to five jet milling cycles showed that many CuNPs were precipitated and well-dispersed on the CMC surface. These precipitated CuNPs were spherical with an average particle size of 5.4 ± 1.9 nm. No CuNPs were precipitated by processing the aqueous copper nitrate solution without CMC using the jet mill at a discharge pressure of 100 MPa. This indicates that CMC acted as a reducing and stabilizing agent. In the X-ray diffraction pattern of the sample subjected to five jet milling cycles, only peaks attributed to the cellulose crystalline phase appeared and no other peaks, such as those attributed to metallic copper or copper oxide, appeared, irrespective of the copper content of the sample, which was 3.6 %. This suggests that the synthesized CuNPs were either predominantly amorphous or possessed extremely low crystallinity.

Gel-casting of ceramics is useful in fabricating near-net-shaped ceramic products owing to the use of a high solid-loading-slurry and fast curing. However, the affinity between the precursors, which can affect the viscosity of the slurry, has not been discussed or optimized using different slurry-compositions. This study proposes a novel approach to estimate the affinity between the precursors by investigating the solubility parameters (SPs) of the precursors as a function of ceramic powder, monomer, and cross-linker of the ceramic slurry in a gel-casting system. Properties of the ceramic slurries and void-structures were examined systemically by altering the molecular structure of the monomer and composition ratio of the monomer and cross-linker. The SP of the precursors exhibited a good correlation with the slurry-viscosity, porosity, and defect-volume, which play important roles in determining the mechanical strength of a sintered body.