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.