1、BRITISH STANDARD BS EN 50324-2:2002 Piezoelectric properties of ceramic materials and components Part 2: Methods of measurement Low power The European Standard EN 50324-2:2002 has the status of a British Standard ICS 31.140 BS EN 50324-2:2002 This British Standard, having been prepared under the dir
2、ection of the Electrotechnical Sector Policy and Strategy Committee, was published under the authority of the Standards Policy and Strategy Committee on 10 October 2002 BSI 10 October 2002 ISBN 0 580 40537 0 National foreword This British Standard is the official English language version of EN 50324
3、-2:2002. The UK participation in its preparation was entrusted by Technical Committee GEL/15, Insulating materials, to Subcommittee GEL/15/3/1, Ceramics and glass, which has the responsibility to: A list of organizations represented on this subcommittee can be obtained on request to its secretary. C
4、ross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or
5、of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text;
6、 present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover
7、, an inside front cover, the EN title page, pages 2 to 26, an inside back cover and a back cover. The BSI copyright date displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date CommentsEUROPEAN STANDARD EN 50324-2 NORME EUROPENNE EURO
8、PISCHE NORM May 2002 CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B - 1050 Brussels 2002 CENELEC - All rights of exploitation in any form and b
9、y any means reserved worldwide for CENELEC members. Ref. No. EN 50324-2:2002 E ICS 31.140 English version Piezoelectric properties of ceramic materials and components Part 2: Methods of measurement - Low power Proprits pizolectriques des matriaux et composants en cramique Partie 2: Mthodes de mesure
10、 - Faible puissance Piezoelektrische Eigenschaften von keramischen Werkstoffen und Komponenten Teil 2: Meverfahren - Kleinsignal This European Standard was approved by CENELEC on 2001-12-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions
11、for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member. This European Standard exists in three of
12、ficial versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical co
13、mmittees of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.EN 50324-2:2002 2 Foreword This European Standard was prepared by the CENELEC BTTF 63-2, A
14、dvanced technical ceramics. The text of the draft was submitted to the formal vote and was approved by CENELEC as EN 50324-2 on 2001-12-01. The following dates were fixed: latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endor
15、sement (dop) 2002-12-01 latest date by which the national standards conflicting with the EN have to be withdrawn (dow) 2004-12-01 This part 2 is to be used in conjunction with EN 50324-1. _ 3 EN 50324-2:2002 Contents Page 1 Scope4 2 Symbols and units.4 3 Dimensions and finish of standard test specim
16、en5 4 Electrodes .6 5 Environmental requirements .6 6 Small signal data - Timing of measurement 6 7 Number of test specimens.6 8 Methods of measurement7 9 Determination of a complete set of material parameters - Systematic procedure15 10 Errors in calculated coefficients.23 11 Determination of the t
17、emperature coefficient of the parameters24 12 Temperature coefficients of calculated parameters.25 13 Calculation of ageing rates26EN 50324-2:2002 4 1 Scope The methods of measurement described in this European Standard are for use with piezoelectric components produced from the ceramic materials de
18、scribed in EN 50324-1 “Terms and definitions”. Methods of measurement for specific dielectric, piezoelectric and elastic coefficients are generally applicable to piezoelectric ceramics. The polycrystalline nature of ceramics, statistical fluctuations in composition and the influence of the manufactu
19、ring process, result in specified material coefficients being typical mean values. These values are provided for design information only. Piezoelectric transducers can have widely differing shapes and may be employed in a range of vibrational modes. Material parameters however, are measured on simpl
20、e test-pieces (discs, rods etc. see EN 50324-1, Figure 2) using specific geometric and electrical boundary conditions. Consequently, the results of the tests provide basic material parameters only and must only be used as a guide to the actual properties of manufactured commercial components. 2 Symb
21、ols and units All material constants and equations appearing in this standard are given according to the International System of Units (SI-units). Table 1 lists the symbols and, where appropriate, shows the units associated with the physical quantities designated by the symbols. Table 1 - List of sy
22、mbols and their units Symbol Meaning SI-unit A Area m 2 c Ageing rate See note c ij Elastic stiffness constant N/m 2 C Capacitance F C T Free capacitance F d Diameter m d ij Piezoelectric charge (strain) constant C/N or m/V e ij Piezoelectric stress constant C/m 2or N/Vm E i Component of the electri
23、c field strength V/m E m Measuring field strength V/m f Frequency Hz f a Antiresonance frequency (zero reactance) Hz f m Frequency of minimum impedance Hz f n Frequency of maximum impedance Hz f p Parallel resonance frequency Hz (maximum resistance) f r Resonance frequency Hz f s Motional (series) r
24、esonance frequency Hz (maximum conductance) f 1 Frequency at first overtone Hz f 3 Frequency at third overtone Hz g ij Piezoelectric voltage (stress) constant m 2 /C or Vm/N 5 EN 50324-2:2002 Table 1 - List of symbols and their units (continued) Symbol Meaning SI-unit J 0 (z) Bessel function of firs
25、t kind and zero order J 1 (z) Bessel function of first kind and first order J m (z) Modified Bessel function of first order k eff Effective electromechanical coupling factor k 31 Transverse coupling factor k 33 Longitudinal coupling factor k 15 Shear coupling factor k p Planar coupling factor k t Th
26、ickness coupling factor l Length m M Figure of merit n Overtone order N t Frequency constant for thickness mode Hzm N p Frequency constant for radial mode Hzm Q m Mechanical quality factor R i Isolation resistance S i Strain component s ij Elastic compliance constant m 2 /N t Thickness m TC Temperat
27、ure coefficient K -1 T i Stress component N/m 2 Tan d Dielectric dissipation factor Tan m Mechanical dissipation factor v Sound velocity m/s w Width m Z Impedance r Relative frequency spacing ij Absolute permittivity o Permittivity of free space F/m Temperature C C Curie temperature C Phase angle De
28、nsity Mg/m 3 e Resistivity m E Planar Poissons ratio Angular frequency rads/sec NOTE Ageing rate is commonly expressed as % per decade. 3 Dimensions and finish of standard test specimen The surface of standard test specimens for characterisation of piezoceramics for transducers should have an averag
29、e roughness R a 1 m before electroding and deviations from flatness and parallelism of the surfaces should not exceed 50 m per length. The geometric dimensions of standard test specimens should correspond to the ratios indicated in Figure 2 of EN 50324-1.EN 50324-2:2002 6 At smaller ratios of the ge
30、ometric dimensions of the piezoceramic parts, deviations of the respective vibration modes appear, only allowing imprecise characterisation of the piezoceramic. Thickness shear vibrators with rectangular electrode faces have to be polarized in the direction of the long edge. 4 Electrodes The electro
31、des for measurement (and for operation) are deposited by firing on of precious metal pastes (e.g. Ag, AgPd, Au), electroless plating (e.g. Ni, NiAu), vacuum coating: evaporation, sputtering (e.g. Ni, CuNi, Au). 5 Environmental requirements The electrical measurements shall be carried out at temperat
32、ures between 20 C and 25 C. Before each electrical measurement (after electroding), the test specimen must be stored at these temperatures for at least 24 hours. The test specimen shall be clean and dry. During measurement, the relative humidity of air in the test laboratory shall be below 65 %. 6 S
33、mall signal data - Timing of measurement The material parameters specified for piezoelectric ceramics (dielectric and electromechanical properties) require essentially linear relationships between the components of mechanical stress and strain on the one hand and of electric field strength and displ
34、acement or polarization on the other hand. The material parameters are therefore only valid for a limited range of input level (under measurement and operating conditions). The limits of linear behaviour can vary significantly between piezoelectric ceramics of different composition. The dielectric a
35、nd electromechanical parameters of piezoelectric ceramics are subject to a natural ageing on the basis of the physical phenomenology. Therefore the parameters have to be measured at a defined time not earlier than 24 h after poling. The parameters have to be corrected for measurements in longer inte
36、rvals after poling, bearing in mind the ageing rates determined according to clause 11. The parameters of piezoelectric ceramic parts designed as transducers for practical application should be measured within the second decade of ageing, normally 30 days after poling. 7 Number of test specimens The
37、 characteristic material parameters shall be determined on a minimum of 10 test specimens. 7 EN 50324-2:2002 8 Methods of measurement 8.1 Determination of relative permittivity and dielectric dissipation factor The relative permittivity of piezoceramic materials is determined by measurement of the c
38、apacitance by means of capacitance measuring meters at f = (1 000 200) Hz and E m 1 V/mm. The dissipation factor tan results from the same measuring procedure. The Curie temperature Cresults from the maximum of temperature dependent capacitance. This maximum is generally far above the operating temp
39、erature range (see 9.2.2 and 11). 8.2 Determination of the electromechanical properties 8.2.1 Dynamic method of measurement The determination of the electromechanical coupling factors, frequency constants, and the mechanical quality factor is made in principle by dynamic methods of measurement, that
40、 is the excitation of piezoelectric vibrators to vibration modes at mechanical resonance. The value of excitation voltages shall be corresponding to a maximum field strength of 0,01 V/mm in general. The dynamic methods of measurement are based on the impedance diagram (Figure 1) and the admittance d
41、iagram respectively of the equivalent circuits of a piezoelectric resonator. Figure 1 - Vector impedance diagram of a piezoceramic transducer Three pairs of characteristic frequencies which are significant for the specification of the piezoelectric activity are shown in Figure 1. Resistance R Reacta
42、nce X ind. cap. f f n f f f p f m f s f r f a Z n Z mEN 50324-2:2002 8 The frequencies f m , f s , f rand f n , f p , f arespectively coincide (to a first approximation) for a low- loss piezoelectric resonator, that is one with a figure of merit 20 k l k Q M 2 eff 2 eff m = (1) This is true of all p
43、iezoceramics with k eff 0,4 andQ m 80 or k eff 0,2 and Q m 500 (all material groups except type 800) and can be used in the same way for the determination of the electromechanical coupling factors. Determination of the frequency pair f s , f p , is only possible with complex measurements. The typica
44、l characteristics of the measured impedance vs. frequency of a piezoceramic transducer are shown in Figure 2. log |Z|f f m f r f s f n f a f p Figure 2 - Measured impedance of a piezoceramic transducer The use of impedance phase analyzers for the “impedance method“ results in the frequency pair f m
45、, f n , the frequencies at impedance minimum and maximum and for the “phase method“ in the frequency pair f r , f a , the frequencies at zero phase angle, = 0. For practical uses, these parameters can be approximated with the frequency pair f sand f pin all piezoceramics except type 800. The use of
46、simple ac voltage divider circuits is permissible, when the test specimen is in the series arm (for f msee Figure 3a) or in the shunt arm (for f nsee Figure 3b), fulfilling the condition R t|Z| maxrespectively. 9 EN 50324-2:2002 a) f = f m b) f = f n Figure 3 - Determination of the frequencies f man
47、d f nby the impedance method 8.2.2 Determination of electromechanical coupling factors The electromechanical coupling factors can be calculated directly from the mathematical relationships of the characteristic frequencies of the respective vibration mode (see 9.2.4.2). Alternatively, to a first app
48、roximation, the electromechanical coupling factors may be determined from the relative frequency spacing p s p r f f f = (2) The use of the relative frequency spacing rcorresponds with the determination of the effective electromechanical coupling factor k effby the relationship k ff f eff 2 p 2 s 2
49、p 2 = (3) This relationship is valid for all vibration modes and supplies the value for the dynamic electromechanical coupling factor. The difference in the material coupling factors, which have to be calculated according to the exact relations, results from the elastic boundary conditions of the various vibration modes. Material coupling factors (see equations (37) to (44) are determined
