功能陶瓷讲义-1
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Electronic Ceramics and Their Applications
X.M. Chen (陈湘明)
Department of Materials Science & Engineering, Zhejiang University, Hangzhou 310027 Tel: 87952112; E-mail: xmchen@zju.edu.cn Web: http://www.cmsce.zju.edu.cn/xmchen
功能Hale Waihona Puke Baidu瓷的学科关系
无机非金属材料 功能陶瓷 功能材料
学科基础：固体物理、固体化学、电磁学、材 料科学基础 相关学科：电子、通讯、仪器仪表等
功能陶瓷
—现代电子技术的三大物质基础之一
微电子学
固体电子学 电介质材料
光电子学
半导体材料
光电子材料
(功能陶瓷)
电子材料
Primary Contents
Elements of Dielectrics (电介质) and Ceramic Insulators Ferroelectric(铁电), Relaxor Ferroelectric(驰豫铁 电 ), Antiferroelectric ( 反 铁 电 ) Ceramics and Ceramic Capacitors(电容器) Microwave Dielectric Ceramics(微波介质陶瓷) Piezoelectric(压电) and Opto-electric Ceramics Ceramic Sensors ZnO Varistors(变阻器) Conducting Ceramics
Clausius-Mosotti Equation
Ep can be shown to be P/3e0, and Ed=0 for certain crystals of high symmetry and glasses. So that, EL= Em+ P/3e0 = Ea-Edp + P/3e0 (1.18) In more general case, it is assumed that EL= Em+ gP (1.19) in which g is the ―internal field constant‖ The dipole moment p induced in the entity can be now written as p=a EL (1.20) If it is assumed that all entities are of the same type and have a density N, then P=Np=Na(Em+ gP) (1.21) Or P/e0Em =ce= Na/e0/(1-Nag) (1.22) In the particular case for which g=1/3eo, we have the Clausius-Mosotti Equation (er-1)/(er+2)=Na/3e0 (1.23)
Since P= sP and sT=D (electric displacement) e0 E=P-D (1.8) D= e0 E+ P (1.9) If the dielectric is linear, P=ce e0 E, so that D= e0 E+ ce e0 E=(1+ ce) e0 E (1.10) where, ce is electric susceptibility, a tensor of the second rank
铁电与介电新材料(Ferroelectric and dielectric new materials) 巨介电常数材料(Giant dielectric constant materials) 非铅铁电与弛豫铁电陶瓷(Pb-free ferroelectric and relaxor ferroelectric ceramics) 微图案铁电薄膜(Micro-patterned ferroelectric thin films) 复相与多功能耦合陶瓷(Composite and multifunctional ceramics)
电位移D、电场强度E与极化强度P的 关系
For case a): E=s/e0
s - surface charge density
(1.6)
(1.7)
For case b): E=(sT-sP)/e0
sT – total surface charge density; sP – polarazation charge density
磁电复相陶瓷 (Magetoelectric composite ceramics) 多铁性材料 (Multiferroic materials) 磁性电介质(Magnetic dielectrics)
功能陶瓷的基本概念
与结构陶瓷相对应的概念，主要指具备特定的 电、磁、声、光、热等物理性能的陶瓷材料； 电子陶瓷是功能陶瓷的主体； 电子陶瓷：介电陶瓷(绝缘陶瓷)、铁电陶瓷、 反铁电陶瓷、压电陶瓷、热释电陶瓷、半导体 陶瓷、电光陶瓷、磁性陶瓷等 在电子、通讯、军事、以及家电技术中有着广 泛的应用。
Research Activities in X.M. Chen’s Group
微波介质陶瓷及其应用(Microwave dielectric ceramics and their applications)
中介电常数微波介质陶瓷新体系 低介电常数微波介质陶瓷新体系 叠层介质谐振器 可调谐介电薄膜
Brief Introduction of X.M. Chen
Was born in Hunan 1959 B.S. Dept. Mater. Sci.& Eng., Central South University in 1981 PhD Dept. Mater. Sci. & Metallurgy, The University of Tokyo in 1991 Research Scientist at Yokohama R&D Labs., Furukawa Electric Co. Ltd. (Japan), 1991-1994 Associate Professor, Dept. Mater. Sci. Eng., Zhejiang Univ. 1994-1996 Professor, Dept. Mater. Sci. Eng., Zhejiang Univ., Since 1996 Distinguished Young Scientist Foundation of NSFC in 2000 Professor of ―Changjiang Scholar Program‖ 2002 Member of International Advisory Board of MMA2000, MMA2002, MMA2006 Chairman, MMA-2004 (Inuyama, Japan) & MMA-2008 (Hangzhou, China) Member of Executive Board, Asian Electroceramics Association (AECA). Authored or co-authored more than 140 papers in pier-reviewed international journals …
载流子短程运动与位移—极化(Polarization)
电介质的基本物理概念-极化
极化-正负电荷中心偏移 偶极矩(dipole moment) p=Qdx 极化强度P P=dp/dV=Njmj
(1.1) (1.2)
mj= aj E’ (1.3) aj - polarizability of average dipole moment; E’- local electric field P=sp (surface charge density) (1.4)
Applied External Field, Internal Macroscopic Field & Local (Lorentz) Field
An individual atom or ion in a dielectric is not subjected directly to an applied field but to a local field. The internal macroscopic field Em is the resultant of applied external field Ea and depolarizing field Edp, i.e. Ea-Edp. It is assumed that the solid can be regarded as comprising identifiable polarizable entities on the atomic scale. The local field EL (or Lorentz field) differ from Em since the latter is arrived at by considering the dielectric as a continuum. EL = Em+Ep+Ed (1.17) where, Ep-the contribution from the charges at the surface of the spherical cavity (imaging for the moment that the sphere of material is removed); Ed-due to the dipoles within the boundary.
(Nj=number of dipoles of type j; mj=average dipole moment)
极化机理
at= as+ao+ai+ae (1.5) ae-Electronic (Atomic) Polarization;
ai -Ionic Polarization; ao-Orientation (Dipolar) Polarization; as -Space Charge or Diffusional Polarization
Chapter 1 Elements of Dielectrics and Ceramic Insulators
I. Elements of Dielectrics
物质按导电性能的分类
载流子长程运动与位移—传导、宏观电流
导体：金属、部分非金属 半导体：部分非金属单质与化合物 绝缘体 （无载流子长程运动与位移）：大部分非金 属单质与化合物 电介质（绝缘体+半导体；通常为绝缘体）
介电常数(Dielectric Constant)
Since D= sT, QT/A= (1+ ce) e0 U/h (1.11) QT =(1+ ce) e0 UA/h (1.12) C=QT/U= (1+ ce) e0 A/h (1.13) Since vacuum has zero susceptibility, C0=e0 A/h (1.14) If the space between the plates is filled with a dielectric of susceptibility ce, the capacitance is increased by a factor 1+ ce. Permittivity e of the dielectric is defined by e =e0(1+ ce) (1.15) Dielectric constant (relative permittivity) er = e /e0=1+ ce (1.16)
X.M. Chen (陈湘明)
Department of Materials Science & Engineering, Zhejiang University, Hangzhou 310027 Tel: 87952112; E-mail: xmchen@zju.edu.cn Web: http://www.cmsce.zju.edu.cn/xmchen
功能Hale Waihona Puke Baidu瓷的学科关系
无机非金属材料 功能陶瓷 功能材料
学科基础：固体物理、固体化学、电磁学、材 料科学基础 相关学科：电子、通讯、仪器仪表等
功能陶瓷
—现代电子技术的三大物质基础之一
微电子学
固体电子学 电介质材料
光电子学
半导体材料
光电子材料
(功能陶瓷)
电子材料
Primary Contents
Elements of Dielectrics (电介质) and Ceramic Insulators Ferroelectric(铁电), Relaxor Ferroelectric(驰豫铁 电 ), Antiferroelectric ( 反 铁 电 ) Ceramics and Ceramic Capacitors(电容器) Microwave Dielectric Ceramics(微波介质陶瓷) Piezoelectric(压电) and Opto-electric Ceramics Ceramic Sensors ZnO Varistors(变阻器) Conducting Ceramics
Clausius-Mosotti Equation
Ep can be shown to be P/3e0, and Ed=0 for certain crystals of high symmetry and glasses. So that, EL= Em+ P/3e0 = Ea-Edp + P/3e0 (1.18) In more general case, it is assumed that EL= Em+ gP (1.19) in which g is the ―internal field constant‖ The dipole moment p induced in the entity can be now written as p=a EL (1.20) If it is assumed that all entities are of the same type and have a density N, then P=Np=Na(Em+ gP) (1.21) Or P/e0Em =ce= Na/e0/(1-Nag) (1.22) In the particular case for which g=1/3eo, we have the Clausius-Mosotti Equation (er-1)/(er+2)=Na/3e0 (1.23)
Since P= sP and sT=D (electric displacement) e0 E=P-D (1.8) D= e0 E+ P (1.9) If the dielectric is linear, P=ce e0 E, so that D= e0 E+ ce e0 E=(1+ ce) e0 E (1.10) where, ce is electric susceptibility, a tensor of the second rank
铁电与介电新材料(Ferroelectric and dielectric new materials) 巨介电常数材料(Giant dielectric constant materials) 非铅铁电与弛豫铁电陶瓷(Pb-free ferroelectric and relaxor ferroelectric ceramics) 微图案铁电薄膜(Micro-patterned ferroelectric thin films) 复相与多功能耦合陶瓷(Composite and multifunctional ceramics)
电位移D、电场强度E与极化强度P的 关系
For case a): E=s/e0
s - surface charge density
(1.6)
(1.7)
For case b): E=(sT-sP)/e0
sT – total surface charge density; sP – polarazation charge density
磁电复相陶瓷 (Magetoelectric composite ceramics) 多铁性材料 (Multiferroic materials) 磁性电介质(Magnetic dielectrics)
功能陶瓷的基本概念
与结构陶瓷相对应的概念，主要指具备特定的 电、磁、声、光、热等物理性能的陶瓷材料； 电子陶瓷是功能陶瓷的主体； 电子陶瓷：介电陶瓷(绝缘陶瓷)、铁电陶瓷、 反铁电陶瓷、压电陶瓷、热释电陶瓷、半导体 陶瓷、电光陶瓷、磁性陶瓷等 在电子、通讯、军事、以及家电技术中有着广 泛的应用。
Research Activities in X.M. Chen’s Group
微波介质陶瓷及其应用(Microwave dielectric ceramics and their applications)
中介电常数微波介质陶瓷新体系 低介电常数微波介质陶瓷新体系 叠层介质谐振器 可调谐介电薄膜
Brief Introduction of X.M. Chen
Was born in Hunan 1959 B.S. Dept. Mater. Sci.& Eng., Central South University in 1981 PhD Dept. Mater. Sci. & Metallurgy, The University of Tokyo in 1991 Research Scientist at Yokohama R&D Labs., Furukawa Electric Co. Ltd. (Japan), 1991-1994 Associate Professor, Dept. Mater. Sci. Eng., Zhejiang Univ. 1994-1996 Professor, Dept. Mater. Sci. Eng., Zhejiang Univ., Since 1996 Distinguished Young Scientist Foundation of NSFC in 2000 Professor of ―Changjiang Scholar Program‖ 2002 Member of International Advisory Board of MMA2000, MMA2002, MMA2006 Chairman, MMA-2004 (Inuyama, Japan) & MMA-2008 (Hangzhou, China) Member of Executive Board, Asian Electroceramics Association (AECA). Authored or co-authored more than 140 papers in pier-reviewed international journals …
载流子短程运动与位移—极化(Polarization)
电介质的基本物理概念-极化
极化-正负电荷中心偏移 偶极矩(dipole moment) p=Qdx 极化强度P P=dp/dV=Njmj
(1.1) (1.2)
mj= aj E’ (1.3) aj - polarizability of average dipole moment; E’- local electric field P=sp (surface charge density) (1.4)
Applied External Field, Internal Macroscopic Field & Local (Lorentz) Field
An individual atom or ion in a dielectric is not subjected directly to an applied field but to a local field. The internal macroscopic field Em is the resultant of applied external field Ea and depolarizing field Edp, i.e. Ea-Edp. It is assumed that the solid can be regarded as comprising identifiable polarizable entities on the atomic scale. The local field EL (or Lorentz field) differ from Em since the latter is arrived at by considering the dielectric as a continuum. EL = Em+Ep+Ed (1.17) where, Ep-the contribution from the charges at the surface of the spherical cavity (imaging for the moment that the sphere of material is removed); Ed-due to the dipoles within the boundary.
(Nj=number of dipoles of type j; mj=average dipole moment)
极化机理
at= as+ao+ai+ae (1.5) ae-Electronic (Atomic) Polarization;
ai -Ionic Polarization; ao-Orientation (Dipolar) Polarization; as -Space Charge or Diffusional Polarization
Chapter 1 Elements of Dielectrics and Ceramic Insulators
I. Elements of Dielectrics
物质按导电性能的分类
载流子长程运动与位移—传导、宏观电流
导体：金属、部分非金属 半导体：部分非金属单质与化合物 绝缘体 （无载流子长程运动与位移）：大部分非金 属单质与化合物 电介质（绝缘体+半导体；通常为绝缘体）
介电常数(Dielectric Constant)
Since D= sT, QT/A= (1+ ce) e0 U/h (1.11) QT =(1+ ce) e0 UA/h (1.12) C=QT/U= (1+ ce) e0 A/h (1.13) Since vacuum has zero susceptibility, C0=e0 A/h (1.14) If the space between the plates is filled with a dielectric of susceptibility ce, the capacitance is increased by a factor 1+ ce. Permittivity e of the dielectric is defined by e =e0(1+ ce) (1.15) Dielectric constant (relative permittivity) er = e /e0=1+ ce (1.16)