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BiAlO_(3)-modified BiFeO_(3)-BaTiO_(3) high curie temperature lead-free piezoelectric ceramics with enhanced performance

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Rare Metals 2023年第11期42卷 3839-3850页

作者： Xiao-Xiao Zhou Yu-Cheng Tang He-Zhang Li Yi-Jin Hao Meng-Ping Xue Jun Pei Xiao-Yan Peng Bo-Ping Zhang School of Materials Science and Engineering University of Science and Technology BeijingBeijing100083China Department of Precision Instrument Tsinghua UniversityBeijing10084China Beijing Key Laboratory of Special Ceramics and Refractories China Iron&Steel Research Institute GroupBeijing100081China

BiFeO_(3)-BaTiO_(3)(BF-BT)lead-free piezoelectric ceramics have high piezoelectricity and high curie temperature(T_(C)),but the mixed-valence Fe ions and Bi^(3+)volatilization would promote the formation of Bi_(25)FeO_(40)/Bi_(2)Fe_(4)O_9 and oxygen vacancy,which greatly degrade the insulation properties required for polarization.In this study,it was found that the modification of BiAlO_(3)(BA)in BF-BT ceramics could effectively solve these problems,reducing the leakage current to 1×10^(-9)A·cm^(-2)and transiting the space charge-limited conduction to ohmic conduction.Because of the enhanced insulation properties and appropriate rhombohedral-pseudocubic phase ratio(C_R/C_(PC)),BF-BT-xBA ceramics in an optimized composition obtain enhanced piezoelectric performance:piezoelectric charge coefficient(d_(33))=196 pC·N^(-1),planar electromechanical coupling coefficient(k_(p))=31.1%,T_(C)=487℃and depolarization temperature(T_d)=250°C;unipolar strain(S_(uni))=0.17%and piezoelectric strain coefficient(d_(33)^(*))=335 pm·V^(-1)at 100℃.Especially,d_(33)exceeds 283 pC·N^(-1)at 233℃and d_(33)^(*)is 335 pm·V^(-1)at100℃,showing an excellent high-temperature piezoelectricity and high depolarization temperature.The results are attributed to the domain structure of rhombohedral-pseudocubic phase coexistence and its high-temperature switching behavior.This work provides a feasible and effective approach to improve the high temperature piezoelectric properties of BF-BT-xBA ceramics,making them more suitable for high temperature applications.

关键词： BiFeO_(3)-BaTiO_(3)(BF-BT) curie temperature Electrical insulation properties Piezoelectric properties Thermal stability

Magnetic properties of gadolinium and/or dysprosium substituted Sm-Co nanocomposite ribbons

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Journal of Rare Earths 2024年第6期42卷 1093-1100,I0004页

作者： Akila Raja Shampa Aich Department of Metallurgical A Materials EngineeringIndian Institute of Technology(IIT) Kharagpur721302India

The present study reported the influence of heavy rare-earth elements(Gd and/or Dy)on Sm-Co-based melt-spun ribbons.Microstructure and magnetic properties of Sm-Co-based(Sm_(1-x)RE_(x)Co_(5))ternary and quaternary systems were investigated.The X-ray diffraction,Auger spectroscopy,scanning electron microscopy(SEM)and transmission electron microscopy(TEM)analyses reveal the presence of the 1:5H and 2:17R phases in the as-spun ribbons.A high-temperature magnetic measurement reports a curie temperature(Tc)at~825 and~869 K in Sm0.6Gd0.4Co5(ribbon A)and Sm_(0.6)Gd_(0.3)Dy_(0.1)Co_(5)(ribbon B),respectively.A low-temperature magnetic measurement on Sm0.6Gd0.3Dy0.1Co5 ribbons exhibits a type-2 SR(spin reorientation)behaviour at~72 K,which arises due to the presence of the DyCo5 phase.Room temperature magnetic measurements reveal that overall magnetic measurement(OMP)is about 24 and 29.9 for ribbons A and B,respectively.Consequently,the comparative investigations profess that ribbon B shows better magnetic performance due to Dy addition with reduced grain size.This observation indicates that the Gd and Dy substituted Sm-Co magnet can be a potential magnet for high-temperature applications.

关键词： Permanent magnets Melt-spinning Heavy rare-earth curie temperature Rare earths

curie temperature of Amorphous Fe-Si-B and Fe-W-Si-B Alloys

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Rare Metals 1998年第2期17卷 2-8页

作者：王玲玲赵立华胡望宇吴力军张邦维湖南大学物理系湖南长沙湖南大学材料研究与测试中心湖南长沙中科院国际材料物理中心辽宁沈阳

オhe effects of composition, annealing temperature and time, annealing heating rate on the curie temperature of amorphous FeSiB and FeWSiB alloys were studied. The results indicate that the curie temperature of these alloys increases with the increase of the metalloid content when it is curie temperature increases with the annealing temperature and the annealing time. However, for the amorphous FeWSiB alloys with the high metalloid content, the curie temperature increases at low annealing temperature and with short annealing time, and decreases at high annealing temperature and with long annealing time. The heating rate in measuring curie temperature also influences the curie temperature of the alloys. The curie temperature is higher at lower heating rates.

关键词： curie temperature FeSiB and FeWSiB alloys Amorphous materials

Influence of Non-Magnetic Substitutional Atoms on Spontaneous Moment and curie temperature of Ce_2Co_(17) Compounds

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Journal of Rare Earths 2002年第4期20卷 273-277页

作者：胡社军刘正义 De Boer F R Buschow K H J Faculty of Materials and Energy Guangdong University of Technology Guangzhou 510643 China

The structure and magnetic properties of Ce 2Co 17-xM x(M=Ga,Al and Si) compounds for M concentrations up to x=5 were studied by means of X-ray diffraction and magnetic measurements. The experimental results show that the curie temperatures and Co spontaneous magnetization decrease significantly with increasing the addition of non-magnetic substitutional atoms, and that Si which has a minimum solid solubility in Ce 2Co 17 causes a largest reduction of curie temperature, spontaneous magnetization and moment per Co atom compared with Ga and Al.

关键词： rare earths Ce 2Co 17 compounds curie temperature spontaneous magnetization

Relating atomic local structures and curie temperature of NdFeB permanent magnets:an X-ray absorption spectroscopic study

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Rare Metals 2018年第11期37卷 983-988页

作者： Mu-Nan Yang Hang Wang Yong-Feng Hu Liu-Yi-Mei Yang Aimee Maclennan Bin Yang Institute of Engineering Research Jiangxi University of Scienceand Technology Canadian Light Source University of Saskatchewan

Relationship between atomic local structures and curie temperature of NdFeB permanent magnets was investigated semi-quantitatively using synchrotron radiation technique. Fe K-edge X-ray absorption spectroscopy(XAS) was employed to study the local structure of Fe atoms for samples before and after doping Dy, Tb or Gd. It is found that the bond lengths and coordination numbers are changed. Thus, the exchange interaction between Fe atoms increases with Dy, Tb or Gd doping, resulting in the improvement of curie temperature of NdFeB permanent magnets. The doping effect is proven by experimental measurement of the magnetic properties. Microstructural characterization using scanning electron microscopy(SEM) was also used to further analyze the effect of different rare earth elements doping on curie temperature of NdFeB permanent magnets.

关键词： Permanent magnet Synchrotron radiation X-ray absorption fine structure Crystal structure curie temperature

PHASE COMPONENT AND curie temperature OFNd_4(Fe_(1-x)Cr_x)_(77.5)B_(18.5)ALLOYS

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Acta Metallurgica Sinica(English Letters) 1997年第1期10卷 71-73页

作者： B.X. Gu J.R. Zhang B.G. Shen and H Wang (Department of Physics, Nanjing University, Nanjing 210093, China)(State Key Lab. of Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China)(Department of Physics, Southeastern Universit Nanjing Univ Nanjing China

The phase component and curie tempemture of Nd4(Fe1-xCrx)77.5B18.5 (0 0.1. The magnetic measurement shows that curie temperutures of Fe3B and Nd2Fe14B phases decrease with increasing Cr content. The influence of the ... 详细信息

关键词： Nd_4(Fe_(1-x)Cr_x)_(77.5)B_(18.5)alloy phase component curie temperature

ANOMALOUS EFFECT OF PRESSURE ON THE curie temperature IN MECHANICALLY ALLOYED Fe-Ni INVAR

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Acta Metallurgica Sinica(English Letters) 2007年第3期20卷 205-209页

作者： X.H. Wei F. Ono Department of Electronic Science Huizhou University Huizhou 516007 China Department of Physics Okayama University 3-1-1 Tsushima-Naka Okayama 700-8530 Japan

Measurements of magnetic susceptibility in mechanically alloyed Fe-Ni Invar alloys were taken under pressures up to 7.5GPa. The rate of decrease in the curie temperature for 700℃ annealed specimen was larger than that annealed at 1000℃. This result can be explained by considering the fact that the width of the concentration fluctuation becomes larger in the specimen annealed at lower temperature.

关键词： invar alloy Fe-Ni, mechanical alloying curie temperature

Critical temperature below the curie temperature of ferroelectric ceramics PZT

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Journal of Advanced Dielectrics 2021年第1期11卷 40-46页

作者： D.V.Kuzenko Science&Technology Center“Reaktivelektron”of the National Academy Science of Ukraine Bakinskikh Komissarov Street 83049 DonetskUkraine

The article presents the results of research the pre-transitional features of the behavior of solid solutions based on lead zirconate-titanate.The presence of a“special”critical temperature T_(d)on the temperature dependences of the permittivityε(T)and the remanent polarization P_(r)(T),preceding the temperature of the paraelectric phase transition at the curie temperature T_(C),is noted.In the temperature range Ttemperature range T_(d)temperature range T_(d)temperatures T_(d)

关键词： PZT depolarization domain structure critical temperature curie temperature

MAGNETIC MOMENT,curie temperature AND SPIN WAVE EXCITATION FOR AMORPHOUS Fe_(90-x)Si_xZr_(10) ALLOYS

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Acta Metallurgica Sinica(English Letters) 1991年第7期4卷 31-36页

作者： SHEN Baogen ZHANG Zhiying GUO Huiqun ZHAO Jiangao

The magnetization curves at 1.5 K and thermomagnetic curves for amorphous Fe_(90-x)Si_xZr_(10)(x=0,4,7 and 10)alloys prepared by the drum spinning technique have been measured with an extracting sample magnetometer.It is obtained that the average magnetic moment,,per magnetic atom and curie temperature,T_c,in the amorphous FeSiZr alloys increase with increasing Si content.The and T_c are found to be quite small,compared with amorphous FeSiB alloys.This unusual behavior is suggested to be due to the presence of the Fe—Fe antiferromagnetic interactions.The temperature dependence of magnetization at lower temperature is in accordance with Bloch's T^(3/2) law.Calculation shows that the spin wave stiffness constant,D,increases with increasing Si content from 0.37 meV·nm^2 for x=0 to 0.538 meV·nm^2 for x=10.The values ofindicate that the range of the exchange interaction is roughly the mean atomic distance of nearest neighbours.

关键词： amorphous FeSiZr alloys magnetic moment curie temperature spin wave excitation