The(1−x)(0.94Bi_(0.5)Na_(0.5)TiO_(3)-0.06BaTiO_(3))-xKTaO_(3)(BNBT-xKT)lead-free ferroelectric ceramics were produced using the traditional solid-state sintering technique,and the phase structure,surface morphology,el...The(1−x)(0.94Bi_(0.5)Na_(0.5)TiO_(3)-0.06BaTiO_(3))-xKTaO_(3)(BNBT-xKT)lead-free ferroelectric ceramics were produced using the traditional solid-state sintering technique,and the phase structure,surface morphology,electrical properties were all thoroughly examined.Every ceramic has a single perovskite structure and there is no second phase,as shown by the XRD patterns and Raman spectra.Scanning electron microscopy revealed that all samples displayed dense microstructure and cubic grain.In addition,KT encourages grain growth due to the oxygen vacancies induced by doping or volatilization of ions at high temperatures.The Tm of the ceramics decreases with increasing doping levels due to oxygen vacancies acting as dipoles upon the addition of KT,and the dielectric loss of all samples is low at ambient temperature.In comparison to the pure BNBT ceramic’s bipolar strain value of 0.12%,the BNBT-2KT ceramic achieved a maximum bipolar strain of~0.506%and unipolar strain of~0.430%with the corresponding d33*up to 538 pm/V under 80 kV/cm field.Performance significantly improved as a result of this.A test of the correlation between temperature and ferroelectric properties shows that the largest strain value of the BNBT-2KT ceramic occurs at ambient temperature and that the phase change from ferroelectric to relaxor is complete.Additionally,it is discovered that the BNBT-3KT ceramic can sustain a stable strain across a broad temperature range,suggesting that it has good temperature stability.The aforementioned findings demonstrate that lead-based ceramics may be replaced with BNBT-xKT ceramics.展开更多
This paper investigates a system of 0.93Bi_(0.5)Na_(0.5)TiO_(3)–0.06BaTiO_(3)–0.01K_(0.5)Na_(0.5)NbO_(3)–xCuO(BNT–BT–KNN–xCuO,x=0-0:04 mol.%)ceramics,which were fabricated by the conventional solid-state process...This paper investigates a system of 0.93Bi_(0.5)Na_(0.5)TiO_(3)–0.06BaTiO_(3)–0.01K_(0.5)Na_(0.5)NbO_(3)–xCuO(BNT–BT–KNN–xCuO,x=0-0:04 mol.%)ceramics,which were fabricated by the conventional solid-state process through the granulation of vacuum freeze drier.The results show that the CuO doping made a significant enhancement on the piezoelectric properties of the BNT–BT–KNN ceramics.With the doping of CuO,the transition temperature between ferroelectric phase and ergodic relaxor state is reduced to near room temperature,resulting in pinched P–E loops and“sprout”shape S-E curves.For the composition with x=0.01,a high unipolar strain of 0.39%under 5 kV/mm contributes a large d^(*)33~780 pm/V at room temperature,which is competitive with the other BNT-based ceramics.展开更多
针对锂离子电池的电-热-机耦合特性,设计了一套耦合特性综合测试系统,进行了电池不同倍率充放电工况下电-热-机耦合特性的测试与分析,以探究电池电特性、形变、温度的时间演变规律与空间分布特性,可以得到电池荷电状态(state of charge,...针对锂离子电池的电-热-机耦合特性,设计了一套耦合特性综合测试系统,进行了电池不同倍率充放电工况下电-热-机耦合特性的测试与分析,以探究电池电特性、形变、温度的时间演变规律与空间分布特性,可以得到电池荷电状态(state of charge,SOC)-形变曲线具有明显的分段特性,可以辅助磷酸铁锂电池SOC估计的修正。基于该系统测试结果研究了电池充放电过程形变产生的机理,并进行了电池热膨胀系数的参数辨识。实验结果表明:高倍率放电时,在放电初期和中期电池边缘部分膨胀,放电后期收缩,而中心位置在放电初期和中期收缩,后期膨胀;低倍率放电时,电池表现为放电初期和后期整体收缩,中期整体膨胀。研究结果可为电池内部电-热-机耦合特性的理论分析与测试管理提供依据。展开更多
基金the financial sponsorship of the National Natural Science Foundation of China(52073235).
文摘The(1−x)(0.94Bi_(0.5)Na_(0.5)TiO_(3)-0.06BaTiO_(3))-xKTaO_(3)(BNBT-xKT)lead-free ferroelectric ceramics were produced using the traditional solid-state sintering technique,and the phase structure,surface morphology,electrical properties were all thoroughly examined.Every ceramic has a single perovskite structure and there is no second phase,as shown by the XRD patterns and Raman spectra.Scanning electron microscopy revealed that all samples displayed dense microstructure and cubic grain.In addition,KT encourages grain growth due to the oxygen vacancies induced by doping or volatilization of ions at high temperatures.The Tm of the ceramics decreases with increasing doping levels due to oxygen vacancies acting as dipoles upon the addition of KT,and the dielectric loss of all samples is low at ambient temperature.In comparison to the pure BNBT ceramic’s bipolar strain value of 0.12%,the BNBT-2KT ceramic achieved a maximum bipolar strain of~0.506%and unipolar strain of~0.430%with the corresponding d33*up to 538 pm/V under 80 kV/cm field.Performance significantly improved as a result of this.A test of the correlation between temperature and ferroelectric properties shows that the largest strain value of the BNBT-2KT ceramic occurs at ambient temperature and that the phase change from ferroelectric to relaxor is complete.Additionally,it is discovered that the BNBT-3KT ceramic can sustain a stable strain across a broad temperature range,suggesting that it has good temperature stability.The aforementioned findings demonstrate that lead-based ceramics may be replaced with BNBT-xKT ceramics.
基金This work is financially supported by the National Natural Science Foundation of China(51772204)the State Key Laboratory of New Ceramics and Fine Processing of Tsin-ghua University.
文摘This paper investigates a system of 0.93Bi_(0.5)Na_(0.5)TiO_(3)–0.06BaTiO_(3)–0.01K_(0.5)Na_(0.5)NbO_(3)–xCuO(BNT–BT–KNN–xCuO,x=0-0:04 mol.%)ceramics,which were fabricated by the conventional solid-state process through the granulation of vacuum freeze drier.The results show that the CuO doping made a significant enhancement on the piezoelectric properties of the BNT–BT–KNN ceramics.With the doping of CuO,the transition temperature between ferroelectric phase and ergodic relaxor state is reduced to near room temperature,resulting in pinched P–E loops and“sprout”shape S-E curves.For the composition with x=0.01,a high unipolar strain of 0.39%under 5 kV/mm contributes a large d^(*)33~780 pm/V at room temperature,which is competitive with the other BNT-based ceramics.
文摘针对锂离子电池的电-热-机耦合特性,设计了一套耦合特性综合测试系统,进行了电池不同倍率充放电工况下电-热-机耦合特性的测试与分析,以探究电池电特性、形变、温度的时间演变规律与空间分布特性,可以得到电池荷电状态(state of charge,SOC)-形变曲线具有明显的分段特性,可以辅助磷酸铁锂电池SOC估计的修正。基于该系统测试结果研究了电池充放电过程形变产生的机理,并进行了电池热膨胀系数的参数辨识。实验结果表明:高倍率放电时,在放电初期和中期电池边缘部分膨胀,放电后期收缩,而中心位置在放电初期和中期收缩,后期膨胀;低倍率放电时,电池表现为放电初期和后期整体收缩,中期整体膨胀。研究结果可为电池内部电-热-机耦合特性的理论分析与测试管理提供依据。
