Papers by Author: Jin Liang Huang

Abstract: Ba₂Ti₉O₂0 ceramics were prepared with different additives of B₂O₃ by liquid coating method and solid phase mix method. The sintering behavior, phase structure and dielectric properties of ceramics were investigated by X-ray diffraction, scanning electron microscopy and inductance-capacitance resistance analysis. The liquid coating method can reduce the amount of sintering aid and minimized the negative impact of sintering aid on dielectric properties. A ceramic composite which could be sintered well at 900°C for 3h and showed good dielectric properties of εr=42,tanδ=0.002 and TCF=-4ppm/°C（1MHz）was obtained when 1.0mol/l H₃BO₃ was added to the Ba₂Ti₉O₂₀ ceramic.

Abstract: AlN/epoxy (AlN/EP) composites were fabricated by casting method. The effects of the AlN content on microstructure, thermal conductivity and thermal expansion properties of composites were investigated. The results indicate that with the AlN content increasing, the thermal conductivity increase, while the coefficient of thermal expansion (CTE) decreases. When the volume fraction of AlN is 25%, the thermal conductivity is 0.507 W/m•K, which is about 2.5 times higher than that of the epoxy matrix, while the coefficient of thermal expansion is 53.7 ppm/°C. The thermal conductivity results obtained were also analyzed using the Maxwell-Eucken model to explain the effect of AlN fillers on the formation of thermal conductive networks.

Abstract: (Bi1.5Zn0.5)(Zn0.5Nb1.5)O7 (BZN) ceramic samples were prepared by solid state reaction, In order to reduce the sintering temperature of BZN ceramic we have used liquid coating technology to dope CuO by precursor solution of CuSO4. The sintering behavior, microstructures, phase structures, and dielectric properties were studied. The process reduces the amount of sintering aid and minimized the negative impact of sintering aid on dielectric properties. A ceramic composite which could be sintered well at 900°C and showed good dielectric properties of εr=161,tanδ=0.005 and TCF=-398ppm/°C（1MHz）was obtained when 0.5mol/l CuSO4 was added to the (Bi1.5Zn0.5)(Zn0.5Nb1.5)O7 ceramic.

Abstract: BaO-Sm2O3-4TiO2 (abbreviated BST) ceramic powder was prepared by the conventional solid-state reaction method. The effects of doping ZnO-2B2O3-7SiO2 (abbreviated ZBS) glass by sol-gel method on the sintering behaviors, microstructure, phase composition and dielectric properties of BST ceramics were investigated. The experimental results reveal that the main phase of samples doped with ZBS glass is tungsten bronze structure type BaSm2Ti4O12 phase, a litter Sm2Ti2O7 phase is also observed. The sintering tenperature of BST ceramics is remarkably reduced from 1350°C to 1050°C and the good dielectric properties of εr=60.2，tanδ=0.004，τf=-7.9ppm/°C were obtained for BST ceramics doped with 6wt% ZBS glass by sol-gel method sintered at 1050°C for 3h.

Abstract: Anisotropic BaBi₄Ti₄O15 powder was synthesized by a molten salt synthesis (MSS) method in K₂SO₄-Na₂SO₄ flux and the effects of different process parameters such as calcining temperature, and ratio of salt to reactant (R) on the phase formation and morphology of anisotropic BaBi₄Ti₄O₁₅ particles were also investigated. The as-synthesized powder calcined at 850-950°C exhibits a single tetragonal BaBi₄Ti₄O₁₅ phase. The morphology of BaBi₄Ti₄O₁₅ powder could be adjusted by changing the synthesis conditions. The average particle size (APS) of BaBi₄Ti₄O₁₅ powder increased with R changing from 0.8 to 1.0, while it decreased with further increasing of R to 1.2. In addition, the APS increased with increasing calcining temperature and it showed an Arrhenius dependence on the temperature. The corresponding apparent activation energy for particle growth is 31.9kJ/mol for calcining temperature of 850-1000°C.

Abstract: The sintering behaviors and microwave dielectric properties of the (Ca0.3La0.4/3)(Li0.25Nd0.25)TiO3 (abbreviated CLLNT) ceramics doped by small amounts of ZnOB2O3- SiO2 glass and LiF were investigated in this paper. The combination adding of ZnO-B2O3- SiO2 glass and LiF improved the densifications of the CLLNT ceramics and the sintering temperature of the CLLNT ceramics were efficiently lowered from 1400°C to 1000°C. Especially, the 4.0wt% ZnO-B2O3-SiO2 glass and 1.0wt% LiF doped CLLNT ceramic sintered at 1000°C for 3h has optimum microwave dielectric properties of Kr=97, Q×f=1286GHz, and TCF=43 ppm/°C, which enable it a suitable candidate for LTCC applications.

Abstract: BaBi4-xLaxTi4O15 (BBLT) ceramics were prepared by conventional solid phase sintering ceramics processing technology. The crystal structure and the microstructure were detected by X-ray diffraction (XRD) and scanning electron microscope (SEM). The XRD analyses show that La3+ ions doping did not change the crystal structure of BBT ceramics. The sintering temperature increased from 1120°C to 1150°C with increasing Lanthanum content from 0 to 0.5, but it widened the sintering temperature range from 20°C to 50°C and refined the grain size of the BBT ceramic. Additionally, polarization treatment was performed and finally piezoelectric property was measured. As a result, the piezoelectric constant d33 of the 0.1at.% doped BBLT ceramics reached its highest value about 22pc/N at polarizing electric field of 8kV/mm and polarizing temperature of 120°C for 30min.

Abstract: Textured SrBi2Nb2O9 (SBN) ceramics were fabricated by templated grain growth (TGG) method. The plated-like SBN particles with shape anisotropy prepared by molten salt method were used as the templates. The SBN powders prepared by conventional solid (CS) reaction were used as matrix powders. It was found that the textured SBN ceramics can be obtained by TGG method. The grain orientation (Lotgering factor, f) increased with the increase of sintering temperature and content of the templates. The textured SBN ceramics with f=0.86 could then be obtained after sintering at 1300 °C for 3 h with 20wt.% templates. The relative density keeps rising with increasing temperature until it reaches a peak value 91.22% at the sintering temperature 1300°C, after which it decreases.

Abstract: BaBi4Ti4O15 ceramics was prepared by molten salt synthesis method (MSS) and conventional solid phase process (CS). The phase of reaction products and the microstructure were detected by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results show that the evident anisotropic flake structure of BaBi4Ti4O15 powder prepared by MSS was obtained at 850°C and the level of anisotropy of BaBi4Ti4O15 powder decreased with increasing temperature. After calcined at 950°C, sintering in the range of 1100~1170°C, the sintering temperature and the maximum permittivity of BaBi4Ti4O15 ceramics prepared by MSS at same frequency was lower than those prepared by CS. Additionally, the apparent degree of orientation was obtained and the lotgering factor (f) calculated according to the XRD results showed a value of 0.63.

Abstract: The cubic pyrochlore phase Bi1.5ZnNb1.5O7 nanopowder was successfully synthesized by the hydrothermal method (HTM) from the starting materials: Bi(NO3)3·5H2O, ZnO, Nb2O5 and the mineralizer: KOH. The XRD patterns prove that the cubic pyrochlore phase Bi1.5ZnNb1.5O7 nanopowder can be obtained by HTM, and TEM photographs show that the powders present the regularly granular shape, when the hydrothermal reactions were conducted at synthesis temperatures 140~220°C and reaction time for 6~48h. The crystalline sizes of the powders were calculated by the Scherrer equation to be about 43~49nm. The crystalline sizes decreased both with the increase in synthesis temperature and the prolonged reaction time until they reached to the minimum size about 43nm at 220°C for 24h.However, they tended to increase when the reaction time was above 24h.