Hierarchical pore structure mullite ceramics with macro- and meso-pores were prepared by a foam-gelcasting method and a pore-forming agent method using SiC and CaCO₃ as additives. The effect of SiC amount on the flexural strength, compressive strength and thermal conductivities of porous ceramics was also investigated. The results show that porous mullite ceramics with a lot of close pores can be fabricated via the method with mullite powder as a raw material and CaCO₃ and SiC (0-8% (mass fraction)) as additives. The as-synthesized porous mullite ceramic prepared with 4% (mass fraction) SiC has 69.9% porosity and a lowest thermal-conductivity.

Calcite, quartz and Al₂O₃ were used as raw materials to prepared anorthite coating, and improving the flexural strength of porcelain tiles via residual surface compressive stress provided by regulating the composition of the coating. The effect of binders, Al₂O₃ content, modulus of elasticity of coating and the ratio of cross section between coating and substrate were studied on the preparation of coating and improving of flexural strength. The results are as follows: when the Al₂O₃ content a is 17.5%, 1% PVA is used as binder and the sintering process is kept at 1 200 ℃ for 0.5 h, an anorthite coating with a thickness of about 80 μm can be obtained. The hardness of the samples is 630 kg/mm² and the flexural strength increased by 72.6%, from (62±3) to (107±4) MPa.

An assisted identification method with artificial intelligence was proposed to identify the dating and authenticity of ancient ceramics with banana leaf pattern. The local binary patterns (LBP) and the histogram of oriented gradient (HOG) were used to extract the characteristics of the time from the banana leaf pattern of ancient ceramics images. The intelligent chronological identification of ancient ceramics was realized through the fusion of the local binary patterns features and the histogram of oriented gradient features of banana leaf pattern, and the similarity of ornamentation was used to measure the authentic and imitative possibility of ancient ceramics. The experiment was based on the ancient ceramic image database of the museum collections. The experimental results show that the proposed method can complete the accurate identification of ancient ceramics and find out the development law of banana leaf pattern, thus assisting experts in the identification of the ancient ceramics. In addition, the similarity analysis based on ornamentation features can provide a support for the authenticity identification of ancient ceramics.

(Li_0.5Bi_0.5)_xBa_1-xBi₈Ti₇O₂₇ intergrowth bismuth layered structure lead-free piezoelectric ceramics were prepared by a solid-state reaction method. (Li_0.5Bi_0.5)²⁺ co-doping can replace Ba²⁺ doping at A site in the system to regulate the crystal structure as well as increase the Curie temperature and the application range in the high-temperature field. The introduction of (Li_0.5Bi_0.5)²+increases the piezoelectric constant d₃₃ from 8 to 18.5 pC/N, and the Curie temperature from 480 to 633 ℃. Based on the result of XRD and Raman spectra, the degree of orthogonal distortion increases. The hysteresis loops show that the remanent polarization is related to the structural distortion, and the piezoelectric constant changes in the same way. (Li_0.5Bi_0.5)_0.6Ba_0.4Bi₈Ti₇O₂₇ ceramics with the optimum comprehensive electrical properties can be used as a potential candidate material for high- temperature piezoelectric field.

0.65CaTiO₃-0.35(La_1-xCe_x)AlO₃ (CTLCA-x) microwave dielectric ceramic was successfully synthesized by the polymeric precursor method using EDTA as a chelating agent. The effects of Ce³⁺ ion doping on the microwave dielectric properties, microscopic structure and crystal structure were studied. The result indicated that the sintering temperature of CTLCA-x ceramic prepared by polymer precursor method was decreased by about 125 ℃ compared with conventional mixed solid method, a single orthorhombic phase for all the compositions can form and the unit cell volume increases linearly with the doping content x. Ce³⁺ ion dopant can increased the quality factor and dielectric constant, but the temperature coefficient of resonant frequency decreased. When x = 0.2, the optimal microwave dielectric properties of ε_r=42.7, Q×f=39 159 GHz, and τ_f= -7×10^-6/℃ for the CTLCA-0.2 ceramics could be obtained, which sintered at 1 325 ℃ for 3 h.

(Na_0.535K_0.48)Nb_0.91Sb_0.09O₃+x%CaO-B₂O₃ (NKNS-xCB) lead-free piezoelectric ceramics were fabricated by conventional and microwave heating processes. The prepared samples were characterized by X-ray diffraction, differential scanning calorimetry and scanning electron microscopy, and the effects of dopant content and heating process on the phase structure and properties of as-prepared ceramics were also investigated. The results reveal that the duration used to synthesize NKNS ceramic powder by microwave heating process is 1/6 of that by conventional heating process. The duration of microwave heating process is only 3/4 times shorter than that of conventional heating process for the fabrication of NKNS-xCB ceramic, and the samples prepared by microwave heating process have a greater density and better electrical properties. The excellent piezoelectric properties (i.e., d₃₃=225 pC/N, k_p=40.2%, and ε_r=647) are obtained for the sample with x=0.50 fabricated by microwave heating process at 1 020 ℃ for 30 min, indicating that microwave heating is a promising method for the fabriction of NKN-based lead-free piezoelectric ceramic.

Silver (Ag) was coated on the surface of nano-sized BaTiO₃ powder by a chemical coating method, and BaTiO₃@Ag composite ceramic was prepared by a solid-state method. The effect of Ag content on the composition, fracture surface microstructure, dielectric properties, and impedance spectroscopy of ceramics were investigated. The results indicate that BaTiO₃@Ag composite ceramic is a core-shell structure, and the main phase is a pure perovskite phase. BaTiO₃@Ag composite ceramic contains fine and homogeneous grains. The dielectric constant and loss decrease with increasing of Ag content and the δ_min is 0.004 87. The curie peaks widen, and the diffusion factor γ increases from 1.08 to 1.42. The thermal stability is improved due to the Ag introduction. The temperature stability coefficient decreases from 0.194 0 to 0.004 8. In addition, the dielectric relaxation of BaTiO₃@Ag composite ceramic occurs at 200 ℃. The conductance activation energy and relaxation activation energy determined by impedance spectroscopy show that the relaxation phenomena occurs due to the short jump of the defective dipoles, which are formed by the conducting electrons generated from the double ionization of the oxygen vacancy and the surrounding ions.

Graphite felt (GF) was modified with a silica sol via thermal treatment to improve its hydrophilicity and electrochemical activity. The surface morphology, microstructure, and electrochemical performance of the modified samples were investigated. The results show that GF electrodes after modification have a better hydrophilicity, a greater specific surface area and more oxygen functional groups. The amount of C—O on the GF surface as the catalytic active sites for vanadium redox couples is 4.18% when the amount of silica sol is 50% (mass fraction). The VRFB based on GF modified with 50% silica sol by thermal treatment has coulombic efficiency of 95.58%, voltage efficiency of 86.07% and energy efficiency, of 92.35% at a current density of 40 mA/cm², which is increased by 10.93%, 9.16% and 3.22%, respectively, compared to the VRFB based on unmodified GF.

Y-, Fe co-doped CaZrO₃ (Y_0.08Ca_0.92Zr_1-xFe_xO_3-δ (x=0.3, 0.4, 0.5)) was synthesized by solid state reaction method. The crystal phase composition, microstructure, oxygen ionic conductivity, total conductivity and sensing properties were investigated. The result suggests that a highly orthorhombic perovskite structure and the increase of Fe-doped amount is unfavorable for the formation of single orthorhombic perovskite structre. The total electrical conductivity and ionic conductivity increase with Fe-doped amount increasing. The oxygen sensor shows good limiting current plateau in the range of 800-950 ℃. The linear relationship between limiting current (lgI_L) and 1 000/T can described as follows: lgI_L =3.215-2.101 3×(1 000/T)and the activation energy of oxygen ion is 0.417 eV. At 750 ℃、1.0%≤x(O₂)≤7.5%, the relationship between limiting current (I_L) and oxygen amount (x(O₂)) can be expressed: I_L= 7.047 6+3.875 1×x(O₂).

ZrO₂ ceramics were brazed with Ni-Ti filler metal. The microstructure of the joint and the effect of holding time on the interfacial microstructure and mechanical property were investigated. The results show that TiO+Ni₂Ti₄O layer is formed at the interface of ceramic and filler metal at 1 350 ℃ for 10 min. TiO distributes as a discontinuous layer next to the ceramic, while Ni₂Ti₄O is a continuous layer. The center of brazing seam consists of NiTi and Ni₃Ti. TiO decreases and finally disappears, the thickness of Ni₂Ti₄O layer increases with the increase of holding time. Some cracks appear in Ni₂Ti₄O layer when the holding time is 40 min. The shear strength of the joints firstly increases and then decreases with increasing holding time. The shear strength of the joint reaches the maximum value of 88.7 MPa when the holding time is 30 min.

A [Pb(Zr_0.53Ti_0.47)O₃](PZT) sol was prepared by Sol-gel method, and the stability of PZT sol was tracked and characterized for 120 days. Through the pH value evolving with time test, it was found that the pH value was kept in the range of 4.81 to 5.52. The analysis showed that particle size distribution ranged from 1.3 to 17.1 nm, and Zeta potential ranged from -10.23 to -17.57 mV, which indicates the prepared PZT sol had good storage stability. By means of thermogravimetry-differential scanning calorimetry, thermogravimetric infrared analysis, X-ray diffraction and X-ray energy spectrum analysis, it is found that the thermal decomposition process of PZT sol can be divided into three stages; According to transmission electron microscopy (TEM) and selected area electron diffraction (SAED) analysis, it can be seen that the exposed crystal face groups of the heat-treated products are (110) and (101). Finally, the thermal decomposition mechanism and kinetics of PZT sol were studied by thermogravimetry-derivative thermogravimetry method, combined with Flynn-Wall-Ozawa method, Achar method and Satava method, the results show that: the activation energy in the first stage E_α=58.24 kJ·mol^-1, following the first-order Mample single-line rule; the activation energy in the second stage E_α=171.46 kJ·mol^-1, following three-dimensional diffusion (Jander); and the activation energy in the third stage E_α=319.56 kJ·mol^-1, following the phase boundary reaction shrinkage cylinder rule.

The potassium sodium niobate (KNN) single crystal was successfully prepared by the seed-free solid-state crystal growth method, and the effect of cooling rate on the structure and electricity properties of KNN single crystal was systematically studied. The results show that optimizing the cooling rate can promote the growth of single crystals, and it is easy to grow single crystals with larger sizes; when the cooling rate is lower, the crystal surface is flatter and the quality of the crystal is higher; The effect of the crystal structure of the single crystal is small; when the temperature reduction rate is 2.0 ℃/min, the prepared potassium-sodium niobate piezoelectric single crystal exhibits excellent piezoelectric properties, and its positive piezoelectric coefficient d₃₃ reaches 510 pC/N, the inverse piezoelectric coefficient d^*₃₃ is 1 425 pm/V, and the crystal also has a lower dielectric loss tanδ=0.02, a higher Curie temperature T_C=416 ℃, and a larger remanent polarization P_r=20 μC/cm². This shows that the potassium-sodium niobate-based single crystals grown by seed-free solid-state crystal growth method by optimizing the cooling rate is a promising piezoelectric ferroelectric single crystal material and has great potential application value.

Tm^- and Ho^- codoped yttrium aluminum garnet (YAG) nanopowders were prepared by the sol-gel method, and a transparent ceramic was prepared from the obtained powders. X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and fluorescence spectroscopy were used to analyze the synthesized nanopowders and transparent ceramic. The results show that after calcination at 900 ℃, the nanopowders formed the crystal phase of YAG, and the characteristic peaks in the range of 785 to 398 cm^-1 correspond to vibrations of the unique lattice of YAG. After preparing the transparent ceramic, a compact structure was achieved. In the range of 1.97-2.03 μm, the transmittance was greater than 84%. After excitation by a 780 nm pumped light source, stable laser emission at a wavelength of 2.03 μm was produced.

Silver nanowire (Ag NW)@TiO₂ core-shell composite structure photocatalysts with different loading ratios were prepared by a hydrothermal method. The organic dye Rhodamine B (RhB) was used as a target degradation product to evaluate its visible light catalytic activity. The results show that the calcined core-shell structure is still Ag NWs and TiO₂ crystals. The core-shell structure reduces the bandgap of TiO₂ and can achieve its excitation in the visible range. When a molar ratio of TiO₂ to Ag NW is 84%, the maximum photocatalytic activity can be obtained, and the degradation rate of RhB can reach 82.2%. The main active oxide in the degradation is superoxide radical. The structure has a good stability without oxidation or phase transition after more than 263 d of storage.

Y₂O₃:xBi³⁺ (x=0.05-1.0% (mole fraction)) phosphors were synthesized by a solid-phase reaction route. Effect of Bi³⁺ concentration on the phase composition, microstructure and photoluminescence (PL) performance was investigated. The results show that the lattice parameter and cell volume of Y₂O₃ host increase with the increase of Bi³⁺ concentration. In addition, the phosphors are equiaxed grains, and the grain size increases gradually from 250 to 600 nm with the Bi³⁺ concentration increasing. The emission spectra of Y₂O₃:Bi³⁺ phosphors excited by ultraviolet light (λ_EX=335 nm) are composed of three broadband emission spectra centered at 370 nm, 410 nm and 483 nm. The ultraviolet-emission at 370 nm and blue-light emission at 410 nm appear due to ³A_u→¹A_g and ³E_u→¹A_g electron transitions of S₆ sites of Bi³⁺, respectively. The blue-green emission at 483 nm occurs due to ³B→¹A electron transition of C₂ sites of Bi³⁺. The Y₂O₃:0.25%Bi³⁺ phosphor shows the optimal PL performance. The concentration quenching occurs when Bi³⁺ concentration is higher than 0.25% due to the dipole-dipole interaction between Bi³⁺ ions. The color coordinate of Y₂O₃:0.25%Bi³⁺ is (0.159 2, 0.218 1), and the color rendering index Ra is 69.27, indicating that the as-synthesized blue-green phosphors have a broad application prospect in the field of white light-emitting diode.

(Ba_0.97Eu_0.03)(Mg_(1-x)/3Nb_2(1-x)/3Zr_x)O₃ phosphors were prepared via a solid-state route. The crystal structure and luminescent properties were investigated. A phase structure transformation from hexagonal to cubic occurs as Zr⁴⁺ content (x) increases to 0.05, thus weakening the luminescence properties. When x>0.05, the crystal structure is cubic. The introduction of Zr⁴+into the phosphor increases the tilting of BO₆ octahedron, which makes the energy level split and broadens the bonding energy range of B—O bond, thus enhancing the absorption of near ultraviolet (NUV) light and increasing the intensity of charge transfer band (CTB). The CTB intensity increases the sensitization effect of the host on Eu³⁺ and improves the luminescent properties in NUV and blue light regions. The chromaticity coordinate of the phosphor shifts from (0.658, 0.342) to (0.642, 0.358) due to Zr⁴⁺ substitution, indicating its potential application in the excitation of NUV (395 nm) LED chips.

Fe³⁺ doped α-Al₂O₃ particles with average sizes of 12 nm, 82 nm, and 229 nm and the same Fe content were prepared by a chemical precipitation method. The lattice parameters, microstructure, energy gap, and the luminescence performance were investigated. The results show that Fe³⁺ doped α-Al₂O₃ particles with different sizes are pure α-Al₂O₃ phases. The energy gap decreases and the lattice parameters first decrease and then increase with increasing the particle size. The lattice parameters of the sample with an average particle size of 12 nm are a=b=0.478 3 nm, c=1.304 7 nm, the energy gap is 4.06 eV, and the sample exhibits a good luminescence performance under 305 nm excitation. Moreover, Fe³⁺ doped α-Al₂O₃ nanoparticles with an average particle size of 12 nm disperse well and have a narrow size distribution (5-55 nm), and can form a stable colloid suspension in ultrapure water.

Ti-Al₂O₃ composite samples were prepared using sintered alumina and metallic titanium as the raw materials and phenolic resin as the binder. The samples were placed in a graphite crucible and sintered in a carbon tube furnace at 1 600 ℃ in flowing nitrogen. The phase evolution of the sintered samples was analyzed. The results showed that titanium firstly reacted with nitrogen to form titanium nitride. When the content of titanium reached 12%, it can also be fully nitrided. The titanium nitride formed was mostly a flaky structure, and the rest was whisker-like. A small amount of carbon monoxide in nitrogen atmosphere can diffuse into the sample, and form a stable titanium carbonitride solid solution. For samples with 3% titanium, the strength of the sample with 3% graphite decreased by 50%. Similar titanium carbonitride solid solution was formed in Ti-Al₂O₃ samples with and without graphite. Al₅O₆N was found in the corundum sample, but not in Samples with titanium. Alumina can exist stably in the Ti-Al₂O₃ samples with metal titanium added. The phase evolution mechanism model of Ti-Al₂O₃ samples was established.

In order to solve the problem of high porosity of refractory castables due to the poor water wettability, graphite flakes (GF) were coated by TiC using titanium powders (Ti) via self-propagating high-temperature synthesis (SHS). The phase composition and microstructure of the products were investigated by X-ray diffraction, scanning electron microscopy and energy dispersive spectrometry. The water wettability of TiC-coated GF (CT) was evaluated by Zeta potential measurement, sedimentation test and water contact angle measurement, respectively. The results show that TiC coating with a continuous and uniform thickness of 763 nm is formed on the GF surface. Compared to uncoated GF and the sample with n(GF):n(TiC)=1:1 (GT) prepared by mechanical mixing, the sample CT has the maximum Zeta potential value, no delamination occurs when the sample CT disperses in water, and the contact angles with water is 26°. In addition, the physical properties, oxidation resistance and slag corrosion resistance of Al₂O₃-MgO refractory castables with GF, GT, and CT as well as castables without graphite (labled as CGF, CGT, CCT, and C0, respectively) were also determined. The apparent porosity of CCT castable is 13.4%, which is 39.37% and 11.26% lower than that of CGF and CGT castables, respectively. The decarbonized depth of CCT castable is 8.0 mm, which is 14.89% and 8.05% lower than that of CGF and CGT castables, respectively. The slag corrosion area of CCT castable is 29% , which is 19.44%、6.45% and 3.33% lower than that of C0, CGF and CGT castables, respectively.

Industrial silica bricks were obtained in tunnel kiln by sintering at 1450 ℃ with crystalline silica as a raw material, and lime milk and iron scale as binders. The creep in compression tests was carried out on 7 fired bricks with different residual quartz contents according to the standard GB/T 5073—2005. The results show that the test can be divided into three stages from room temperature to the end of creep according to the change of deformation rate. The distinct expansion stage occurs from room temperature to 900 ℃, and the expansion is positively correlated to the residual quartz content. The distinct shrinkage stage appears from 900 to 1 450 ℃, and the shrinkage is negatively correlated to the residual quartz content. The creep tends to be steady at 1 450 ℃, and the samples with a low residual quartz content show a better stability. The creep curve of silica brick obtained based on GB/T 5073 is not consistent with the expansion or contraction during the whole heating process. At the creep temperature (i.e., ≤1 470 ℃), cristobalite will translate to tridymite, and the samples with a low residual quartz content tend to be negative (i.e., shrinkage), while those with a high residual quartz content are positive (i.e., expansion). The residual quartz content has an influence on the creep process. It could be questionable to evaluate creep high-temperature performance of silica brick just according to GB/T 5073—2005 creep test method.