High-dielectric-constant nanograin BaTiO_(3)-based ceramics for ultra-thin layer multilayer ceramic capacitors via grain grading engineering

Four BT-based ceramic samples were prepared using a grain grading approach.The bigger-grained(~100 nm)and smaller-grained(~70 nm)BaTiO_(3)(BT)powders were mixed.The smaller-grained BT powder controlled the average grain size and guaranteed the reliability,while the bigger-grained powder enhanced the dielectric constant.Various percentages of bigger-grained BT powder were introduced to balance the average grain size and the dielectric constant.As the proportion of bigger grains increased,the dielectric constant(εr)improved significantly.The room-temperatureεr of 25%bigger-grain mixed BT(2623)was~50%higher than that of the sample with a similar average grain size without grain grading.The ceramic mixed with 15%bigger-grained BT showed comprehensive dielectric performance,which met the EIA X5R standard and provided a considerableεr of 1841 along with a low dielectric loss of 0.78%.Notably,the average grain size was 90 nm,which favors the applications in ultra-thin multilayer ceramic capacitors.

Preparation of B_(2)O_(3)-ZnO-SiO_(2)Glass and Sintering Densification of Copper Terminal Electrode Applied in Multilayer Ceramic Capacitors

B_(2)O_(3)-Zn O-SiO_(2)(BZS)glass containing Cu O with excellent acid resistance,wetting properties,and high-temperature sintering density was prepared by high temperature melting method and then applied in copper terminal electrode for multilayer ceramic capacitors(MLCC)applications.The structure and property characterization of B_(2)O_(3)-Zn O-SiO_(2)glass,including X-ray diffraction,FTIR,scanning electron microscopy,high-temperature microscopy,and differential scanning calorimetry,indicated that the addition of CuO improved the glass’s acid resistance and glass-forming ability.The wettability and acid resistance of this glass were found to be excellent when CuO content was 1.50 wt%.Compared to BZS glass,the CuO-added glass exhibited excellent wettability to copper powder and corrosion resistance to the plating solution.The sintered copper electrode films prepared using the glass with CuO addition had better densification and lower sintering temperature of 750℃.Further analysis of the sintering mechanism reveals that the flowability and wettability of the glass significantly impact the sintering densification of the copper terminal electrodes.

Mechanism of extracting palladium(Ⅱ) with cyclic sulfoxide derivatives

The extraction ability of palladium(Ⅱ) from acidic media with cyclic sulfoxide derivatives-α Dodecyl tetrahydrothiophene 1 Oxide (DTMSO), α octyl tetrahydrothiophene 1 Oxide (OTMSO) and α butyl tetrahydrothiophene 1 Oxide (BTMSO) was investigated. The extracting efficiency of cyclic sulfoxide derivatives decreased with the increasing of acidity in the lower acidity, and the efficiency became stable with the change of acidity in the higher acidity. The extraction reaction of palladium(Ⅱ)with DTMSO is exothermic, and extraction reaction of palladium(Ⅱ)is endothermic when OTMSO or BTMSO were used as extracting reagents. The coordination number was studied by slope method. The results indicate that coordination number is 2, and the composition of complex is (PdCl 2)·2RTMSO. FT IR spectra were used to analyze the structure of complex and coordinated atom in complex, Pd is coordinated with both oxygen and sulfur atom in S=O group in sulfoxide derivatives.

The microstructure and dielectric properties of titanium oxide doped with nano CuO

The TiO_(2) ceramics doped with nano CuO were fabricated by the conventional solid-state reaction method.The crystal structure,microstructure,microwave dielectric properties and lattice vibrations of TiO_(2) ceramics doped with nano CuO have been investi-gated.Nano CuO with higher sintering capability worked as flux former and effectively improved the sintering process of TiO_(2) ceramics.The microwave dielectric properties of TiO_(2) doped with nano CuO were much better than that doped with micron CuO at the same doping content.Raman spectra showed that the full width at half maximum of E_(g) mode of TiO_(2) doped with micron CuO was larger than nano CuO doped ones,which indicated a poor crystalline and a short phonon lifetime.TiO_(2) doped with 1wt.% nano CuO,sintered at 950℃ for 2h had compact and homogeneous microstructure and possessed the following dielectric properties:ε_(r)=106,Q×f=24808,τf=371ppm/℃.

Single-phase formation mechanism and dielectric properties of sol-gel-derived Ba(Ti_(0.2)Zr_(0.2)Sn_(0.2)Hf_(0.2)Ce_(0.2))O_(3) high-entropy ceramics

Single-phase Ba(Ti_(0.2)Zr_(0.2)Sn_(0.2)Hf_(0.2)Ce_(0.2))O_(3)(BTZSHC) high-entropy ceramics(HECs) with the perovskite structure were successfully prepared via the sol-gel method.The results reveal that the as-prepared ceramics exhibit a single cubic phase belonging to the Pm3 m space group.The high entropy is the driving force of the formation of single-phase ceramics.A larger entropy(ΔS_(mix)) and a negative enthalpy(ΔH_(mix)) are conducive to the formation of single-phase compounds.Herein,ΔS_(mix)=0.323 R mole-1andΔH_(mix)=43.88 kJ/mol.The sluggish-diffusion effect ensures the thermal stability of high-entropy systems.Dielectric measurements reveal that the as-prepared BTZSHC high-entropy ceramics are relaxor ferroelectrics,and the degree of relaxor(γ) is 1.9.The relaxor behavior of the as-prepared ceramics can be ascribed to the relaxation and thermal evolution of their polar units(PUs).The findings of this work provide a theoretical basis and technical support for the preparation of single-phase high-entropy ceramics.