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Fabrication and Research on Lead-free (Ba, Sr)TiO3 Based Ceramics

Author: LiYuanLiang
Tutor: QuYuanFang
School: Tianjin University
Course: Materials Science
Keywords: Barium strontium titanate Yttria Magnesia Dielectric properties Doping modification
CLC: TQ174.1
Type: Master's thesis
Year: 2005
Downloads: 165
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Abstract


Barium carbonate, strontium carbonate and titanium dioxide as the raw material, first synthesized in 1080 ℃ Ba1-xSrxTiO 3 powder and then adding a dopant such as yttrium oxide, magnesium oxide and manganese dioxide, prepared Ba1 -xSrxTiO 3 -based ceramics, the sintering temperature 1260 ℃ 1 320 ° C, and incubated for 2 hours. This paper studies the impact of yttrium oxide and magnesium oxide doped amount and conditions of Ba1-xSrxTiO 3 -based ceramic performance. Using the the XRD test the lattice structure of the sample, and the morphology of the sample was observed by SEM. Automatic LCR Meter 4425, YY 2811 type at 1KHz sample dielectric properties were tested under ambient conditions. The volume of the sample density, resistivity and other properties were also tested. The experimental results show that, (A), with increasing molar content of strontium ions, the dielectric constant of the sample, the temperature change rate of loss and dielectric decreases the breakdown field strength increases. (B) With the increase of the Y3 ion doping amount, reduced the lattice constant of the sample increases, the increase in the amount of lattice distortion with the yttrium ions doped also showed the same law, when yttrium the doping amount of ions is more than 0.6 mol%, the sample lattice distortion to the minimum. Under ambient conditions, the increase of the doping amount of the yttrium ions, the dielectric constant of the sample first increases and then decreases, and when the doping amount of the yttrium ions is more than 0.5 mol%, the reduced amplitude; Meanwhile the ranking of the specimen sample dielectric loss beginning decreases rapidly, and then, after the process of undergoing a slow decrease only slightly increased, the doping amount of change can be reduced to a minimum of the the sample dielectric loss as a function of yttrium ions 0.0015; The inside temperature of a downward trend; With the increase in the amount of yttrium ions doped sample breakdown field strength first increased with increasing amount of yttrium ions doped, then there are some fluctuations, followed by a downward trend. (C), with the doping of MgO becomes large, the dielectric coefficient of the temperature change rate tends to be smaller, the minimum value of 46.50% is obtained when the percentages of 2.20% in the quality of MgO; obvious pressure peak effect of MgO; MgO doped heteroaryl can effectively inhibit the growth of crystal grains. (D), the initial join the MgO obvious impact the ceramic dielectric properties of the effect of a Ba1-xSrxTiO3 group. Dielectric constant to 5860; losses significantly increased by an order of magnitude, the highest reach 123 × 10 -4 ; dielectric coefficient of the rate of change of the minimum of up to 40.00%. (E) the process conditions, mainly forming pressure, sintering temperature and holding time of the sample dielectric properties, but the experiment to determine the optimum forming pressure, sintering temperature and time.

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