A holmium molybdate ceramic pigment with 'allochroic effect' was prepared via mechanical activation-assisted solid-state reaction. The effects of mechanical activation mode and time as well as sintering temperature on the properties of synthesized holmium molybdate pigment were investigated by laser particle size analysis, simultaneous thermal analysis, X-ray diffraction and scanning electron microscopy, respectively. The color properties and allochroic effect of the synthesized pigments were evaluated by ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis) and colorimetry. In addition, the high-temperature stability and chemical stability of the pigments were also investigated. The results show that a sole phase of holmium molybdate can be obtained from mixed precursors ground at 1 h and sintered at 900 ℃ for 3 h, and the sintering temperature is reduced by 100 ℃, compared to that from each precursor ground separately for 2 h and then mixed or the mixed precursors unground. This is because mechanical activation pretreatment can effectively reduce the size and crystallinity of mixed precursor particles and enhance its solid-phase reaction activity, thus leading to the decrease of solid-phase reaction temperature. In addition, the pigment obtained from mixed precursors ground for 2 h has better color performance and allochroic effect under different illuminants. It is indicated that the allochroic effect of holmium molybdate pigment occurs due to the rich energy level structure of holmium ions in the visible range and the difference between relative spectral power distributions under different light sources. Meanwhile, holmium molybdate pigment can be used as a potential functional pigment in ceramic decoration and other related fields due to its high-temperature stability and chemical stability.

A glaze with a good quality and a unique decorative pattern was prepared with purple clay as a source of iron, Ca₃(PO₄)₂ and SnO₂. The effect of addition agents on the glaze color, microstructure and artistic textures was investigated by ultraviolet-visible spectroscopy, X-ray diffraction and scanning electron microscopy, and the color mechanism was analyzed. The results illustrate that the introduction of addition agents changes the chemical state of iron, and contributes to the formation of blue fancy glaze. The introduction of Ca₃(PO₄)₂ can cause the partial reduction of iron ions, leading to the glaze appearing blue and yellow, and Ca²⁺ ions promoting the separation of liquid phase to produce blue patterns. Also, the introduction of Ca₃(PO₄)₂ and SnO₂ for the increased reducibility of iron ions can increase the ratio of Fe²⁺ and Fe³⁺ ions, resulting in the glaze being blue-green, and the greater pattern and lightness value L*. The presence of Fe³⁺—O—Fe²⁺ in the vitreous is one of the color factors. The liquid separation forming the structure of the color is the auxiliary color of glaze color. The combined chemical color with structural color on the glaze becomes more colorful.

Tantalum (Ta) doped Li₇La₃Zr₂O₁₂ (Ta-LLZO) ceramics were prepared via conventional solid-state reaction. LiOH was used as a lithium source and a sintering additive for ceramics. The effect of LiOH on the microstructure and ionic conductivity of Ta-LLZO ceramics was investigated. The results show that LiOH as a lithium source can promote the formation of cubic Ta-LLZO, and LiOH as a sintering additive can effectively improve the densification of ceramics. The dense cubic garnet Ta-LLZO ceramics were obtained by sintering at 1 200 ℃ for 5 h. When the amount of the sintering additive is 6% (in mass fraction), the ionic conductivity of ceramics reaches 6.23×10^-4 S·cm^-1. It is indicated that Li₇La₃Zr₂O₁₂ prepared via solid-state reaction has a great potential in the application of all-solid-state lithium ion batteries.

In order to solve the problem for high initial frequency of unilateral lightweight phononic crystals, a phononic crystal structure of bilateral hollow asymmetric scatterers was proposed based on the local resonance mechanism. The energy band structure, transmission loss spectrum and intrinsic displacement field of phononic crystals with bilateral hollow asymmetric scatterers were calculated by the finite element method. The ultra-wide first complete band gap with an initial frequency of 79.4 Hz and a bandwidth of 1 065.2 Hz was obtained. Combined with an equivalent spring mass system, the vibration modes of the intrinsic displacement field of the marked points were analyzed, and the mechanism of band gap formation in phononic crystals of bilateral hollow asymmetric scatterers was revealed. Furthermore, effects of the geometric parameters such as notch angle of cladding, width of connecting short plate and height of hollow cylindrical scatterer on the first complete band gap were analyzed, and the geometric parameters of the phononic crystal were adjusted to control the band gap frequency. The results show that the initial frequency of the first complete band gap of the proposed bilateral asymmetric two-dimensional hollow scatterer phononic crystal effectively reduces to less than 80 Hz, and the bandwidth exceeds 1 000 Hz. Adjusting the structural parameters of phononic crystals can realize the coexistence of local resonance and the Bragg scattering band gap in a phononic crystal, which makes it possible for a single phononic crystal to regulate the low-frequency and high-frequency band gaps simultaneously.

The influences of pH value, Fe³⁺ mass concentration, and stirring rate and their interactions on the ammonium sulfate crystallization were investigated via cooling crystallization and sieving based on a response surface methodology. An average particle size quadratic orthogonal model and a variation coefficient 2FI orthogonal model were proposed. The interactions among the various factors were analyzed. The results show that pH value (A) > stirring rate (C) > Fe³⁺ ions concentration (B) is a decreased order for the parameter effects on the average particle size and variation coefficient. Their interactions have a decreased effect order (i.e., AC >BC > AB) on the average particle size and variation coefficient. When pH value is 5.5, stirring rate is 150 r/min, and Fe³⁺ ions concentration is 0.3 g/L, the average particle size and variation coefficient of the ideal crystals is 0.985 mm and 793.719, respectively.

Aluminum oxycarbides were prepared via a carbothermal reduction of alumina in vacuum at 1 300 - 1 500 ℃. The results indicate that the temperature required for the formation of aluminum oxycarbides from the carbothermal reduction of alumina in vacuum is lower than that in argon, a large amount of Al₄O₄C can be formed at 1 300 ℃, and the main component of the condensation products is Al₄O₄C, which is independent of the reaction extent of the raw materials. The condensation products consisting mainly of Al₄O₄C with a small amount of Al₄C₃ can be obtained under optimum conditions (i.e., n(α-Al₂O₃)∶n(C) of 2∶3, reaction temperature of 1 400 ℃ and reaction time of 20 min). It is confirmed that Al₄O₄C can be formed in two stages, i.e., alumina reacts with carbon to generate the gases containing aluminum Al₂O, Al and CO at higher temperatures, and the condensates mainly consisting of Al₄O₄C form at lower temperatures.

KTa_1-xNb_xO₃ crystal doped with 0.15% (in mole fraction) Fe was prepared by a top-seeded solution growth method. The dielectric properties, electric-field-induced strain distribution, component distribution and domain structure of Fe∶KTN crystal were characterized. The results show that digital holography is a promising method to measure the spatial distribution of strain, and the electric-field-induced strain properties of KTN crystal present a uneven distribution. At room temperature, the maximum strain of crystal is 0.05% when the applied electric field is 435 V/mm, while the strain value is near 0.02% 3/4 area of crystal. There is a relationship among strain distribution, component distribution and domain structure of Fe∶KTN crystal. The domain structure of crystal in the region with less Nb content is smaller and the electric-field-induced strain is greater when the room temperature is lower than the Curie temperature.

Hierarchical ZSM-5 zeolite was synthesized by a seed-assisted dry-gel conversion method, and the effects of seed amount, deionized water amount and crystallizing time on the structure and morphology of hierarchical zeolite were investigated. The results show that the crystallization rate of zeolite is increased with seed addition. Amorphous silica-aluminium gel can directly dissolve in the water film condensing on the seed surface and rapidly grew into ZSM-5 nano-zeolite near the seed. Simultaneously, nano-zeolites aggregate and some mesoporous channels are formed between the nano-crystals. The size of nano-zeolite and the resulting mesoporous pores can be adjusted by seed amount, deionized water amount and crystallizing time. The catalytic stability of the resulting hierarchical ZSM-5 zeolite is improved by nearly 5 times, compared with the conventional zeolite in the isomerization of styrene oxide to phenylacetaldehyde.

A ratiometric fluorescent probe was constructed with carbon quantum dots (CQDs) and europium ions (Eu³⁺) as a fluorophore for the visual detection of teracycline (TC). In this ratiometric probe, CQDs/Eu³⁺ has an intense blue fluorescence peak at 439 nm and a weak red fluorescence peak at 616 nm under the excitation of 380 nm wavelength. The fluorescence peak intensity of CQDs at 439 nm gradually decreases based on the inner filter effect. The fluorescence intensity of Eu³⁺ at 616 nm increases due to an antenna effect with the addition of TC. The experimental factors, such as CQDs and Eu³⁺ ratio, response time, stability, etc., were optimized. The results show that the ratio fluorescent probe has a specific recognition ability for TC. A linear relationship between the fluorescence intensity ratio(F₆₁₆/F₄₃₉) and different concentrations of TC (0-50 μM) was established with a detection limit of 0.68 µM. With the addition of TC, the color of the ratio fluorescent probe solution under ultraviolet light gradually changes from blue to red and is used for the detection of TC in milk with the recoveries ranging from 92.5% to 1 14.8%. In addition, a TC test paper was also prepared, which can be quickly used for a visual test paper detection of TC.

BaZrO₃/Al₂O₃ composite molds were prepared via sintering at 1 600 ℃ for 8 h with BaZrO₃ as a surface coating material and Al₂O₃ as a backup coating material. The phase composition and microstructure of the interfacial bonding layer between the face and back layers before and after hydration were investigated by optical microscopy, X-ray diffraction, and scanning electron microscopy with energy dispersive spectroscopy. The hydration process and damage mechanism of the interfacial bonding layer in the mold were analyzed. The effect of mold damage on the directional solidification of TiAl alloy was also investigated via directional solidification tests. The results show that BaZrO₃ and Al₂O₃ generate BaAl₂O₄ at BaZrO₃/Al₂O₃ interface during the high-temperature sintering process; and BaAl₂O₄ generates Ba(AlO(OH)₂)₂, Ba₂Al₄(OH)₁₆ and Ba₃(Al(OH)₆)₂ after hydration, leading to the grain volume change to destroy the intergranular bonding force, the generation of cracks in the mold and the failure of the mold. In the directional solidification process, the generated cracks become a channel for melt penetration of TiAl alloy, resulting in a melt leakage from the mold and the appearance of heterogeneous crystals in the directionally solidified TiAl alloy castings.