钛酸铋钠系陶瓷的共掺杂与固溶改性研究
发布时间：2019-04-04 19:38
【摘要】：钛酸铋钠Na_(0.5)Bi_(0.5)TiO_3(NBT)因其具有较高的居里温度、良好的机电耦合系数以及优异的铁电压电性能等而备受关注。另外,发现该材料还具有潜在的离子电导特性,引发了新一轮探索。而其作为铁电压电材料应用时,矫顽场较高极化困难以及漏电流较大,对其性能仍需进一步改善;作为电解质应用时,材料的电导性能也仍需进一步提高。因此,本论文通过离子掺杂及固溶改性手段对钛酸铋钠材料进行改性,以提高不同用途下材料的性能,并对陶瓷样品的微结构及电学性能进行了研究。基于离子掺杂改性原理,采用改进的固相反应工艺制备了 Na_(0.5)Bi_(0.5-x)Sr_xTi_(1-x)Ga_xO_(3-δ)陶瓷,利用X射线衍射仪、扫描电子显微镜及电学性能测试系统等测试手段,研究了Sr~(2+)、Ga~(3+)共掺杂量对NBT陶瓷的相结构、微观形貌、阻抗特性及介电性能的影响规律,并对材料的电导率进行了计算分析。结果表明:引入一定量的Sr~(2+)、Ga~(3+)后,NBT陶瓷的电导性能得到提升,在阻抗图谱中其晶粒电导与晶界电导能够明显区分,电导机制从电子电导转变为离子电导。随着Sr~(2+)、Ga~(3+)掺杂量的增加,材料的总电导率、晶粒电导率及晶界电导率均先增大后减小,当x=0.O_3时,总电导率在810℃下高达0.024S/cm,电导激活能降低至0.48eV,表明该材料在固体电解质应用方面很有潜在的应用价值。基于固溶改性方法成功制备了(1-x)Na_(0.5)Bi_(0.5)TiO_(3-x)La(Zn_(0.5)Ti_(0.5))O_3系列陶瓷,研究了该系陶瓷的相组成、微观形貌及电学性能的变化规律。结果表明:引入一定量的La(Zn_(0.5)Ti_(0.5))O_3后,NBT仍保持单一的钙钦矿结构。La(Zn_(0.5)Ti_(0.5))O_3的引入起到了细化晶粒的作用,且晶粒棱边更分明,同时对材料体系的介电性能有显著影响。随着La(Zn_(0.5)Ti_(0.5))O_3引入量的增加,材料体系的介电弥散因子增大,弛豫增强,介电弛豫激活能降低,当x=0.018时降至最低,为1.32eV。另外,La(Zn_(0.5)Ti_(0.5))O_3的引入也使得材料体系的铁电性能得到改善,随着La(Zn_(0.5)Ti_(0.5))O_3含量的增加,材料体系的矫顽场由43.4 kV/cm降低至23.7kV/cm。为了提高NBT基材料的铁电性能,在x=0.0O_3和x=0.018组分的基础上,引入0.06BaTiO_3来构建NBT的准同型相界(MPB)。结果发现:当x=0.0O_3时在电场的作用下引发的相变为不可逆相变;当x=0.018时,该相变为可逆相变,且其动态压电常数高达60pm/V。将LaGaO_3组分引入到钛酸铋钠体系中成功制备了(1-x)Na_(0.5)Bi_(0.5)TiO_(3-x)LaGaO_3系列陶瓷,结果发现:引入微量的LaGaO_3后NBT以R3c相存在,并且在引入LaGaO_3后并未观察到NBT材料的离子电导特性。随着LaGaO_3引入量的增加,材料体系的电导激活能与介电弛豫激活能均有所降低,在x=0.012时,电导激活能为1.30 eV,介电弛豫激活能为0.65 eV,并进一步探索比较了电导激活机制与介电激活机制,表明该类材料在中温段的离子传导主要以隧道传导机制进行,使其有望作为中温型固体电解质材料应用。
[Abstract]:Sodium bismuth titanate Na_ (0.5) Bi_ (0.5) TiO_3 (NBT) has attracted much attention due to its high Curie temperature, good electromechanical coupling coefficient and excellent ferroelectric properties. In addition, it is found that the material also has the potential ionic conductivity characteristics, leading to a new round of exploration. When it is used as a ferroelectric material, the coercivity field is difficult to be polarized and the leakage current is larger, so the properties of the material still need to be further improved, and as an electrolyte, the conductivity of the material needs to be further improved. Therefore, sodium bismuth titanate was modified by ion doping and solid solution modification in order to improve the properties of the materials in different applications, and the microstructure and electrical properties of ceramic samples were studied. Based on the principle of ion doping modification, Na_ (0.5) Bi_ (0.5) Sr_xTi_ (1) Ga_xO_ (3-未) ceramics were prepared by an improved solid-state reaction process, and X-ray diffractometer was used. The effects of co-doping of Sr~ (2) and Ga~ (3) on the phase structure, microstructure, impedance and dielectric properties of NBT ceramics were studied by scanning electron microscopy (SEM) and electrical properties testing system. The conductivity of the material was calculated and analyzed. The results show that the conductivity of NBT ceramics is improved by introducing a certain amount of Sr~ (2) and Ga~ (3). In the impedance spectrum, the grain conductance and grain boundary conductance can be distinguished obviously, and the conductivity mechanism changes from electronic conductivity to ionic conductivity. With the increase of doping amount of Sr~ (2) and Ga~ (3), the total conductivity, grain conductivity and grain boundary conductivity of the materials increased first and then decreased, and the total conductivity reached 0.024 S / cm at 810 鈩，
本文编号：2454103
[Abstract]:Sodium bismuth titanate Na_ (0.5) Bi_ (0.5) TiO_3 (NBT) has attracted much attention due to its high Curie temperature, good electromechanical coupling coefficient and excellent ferroelectric properties. In addition, it is found that the material also has the potential ionic conductivity characteristics, leading to a new round of exploration. When it is used as a ferroelectric material, the coercivity field is difficult to be polarized and the leakage current is larger, so the properties of the material still need to be further improved, and as an electrolyte, the conductivity of the material needs to be further improved. Therefore, sodium bismuth titanate was modified by ion doping and solid solution modification in order to improve the properties of the materials in different applications, and the microstructure and electrical properties of ceramic samples were studied. Based on the principle of ion doping modification, Na_ (0.5) Bi_ (0.5) Sr_xTi_ (1) Ga_xO_ (3-未) ceramics were prepared by an improved solid-state reaction process, and X-ray diffractometer was used. The effects of co-doping of Sr~ (2) and Ga~ (3) on the phase structure, microstructure, impedance and dielectric properties of NBT ceramics were studied by scanning electron microscopy (SEM) and electrical properties testing system. The conductivity of the material was calculated and analyzed. The results show that the conductivity of NBT ceramics is improved by introducing a certain amount of Sr~ (2) and Ga~ (3). In the impedance spectrum, the grain conductance and grain boundary conductance can be distinguished obviously, and the conductivity mechanism changes from electronic conductivity to ionic conductivity. With the increase of doping amount of Sr~ (2) and Ga~ (3), the total conductivity, grain conductivity and grain boundary conductivity of the materials increased first and then decreased, and the total conductivity reached 0.024 S / cm at 810 鈩，
本文编号：2454103
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