Abe, Kiyoshi

Inoguchi, Toshio

Murata, Akira

Tanaka, Tetsuro

Kyoto University Research Information Repository

Title Study on High Dielectric Constant Ceramics. (XX) : TuningFork and Vidrating Reed Driven by BaTiO₃ CeramicsAuthor(s)Abe, Kiyoshi; Tanaka, Tetsuro; Inoguchi, Toshio; Murata,AkiraCitationBulletin of the Institute for Chemical Research, KyotoUniversity (1953), 31(6): 421-423Issue Date1953-11-30URL http://hdl.handle.net/2433/75381RightType Departmental Bulletin PaperTextversionpublisherKyoto University        5. Study on High Dielectric Constant Ceramics. (XX)        Tuning Fork and  Vidrating Reed Driven by BaTiO3 Ceramics       Kiyoshi ABE, Tetsuro TANAKA, Toshio INOGUCHI and Akira MURATA                               (Abe Laboratory)    Tuning fork oscillators of electromagnetic type are generally used. In the osci-llator of this type constituent material of vibrator must have following properties:    i) Temperature coefficient of natural frequency is zero or very small.    ii) It must be ferromagnetic.    Furthermore, vibrator must be fixed relatively to magnets, and clearance between fork and magnets must be invariant.    In the tuning fork of piezoelectric type, such conditions are not always necessary. The idea of tuning fork driven by piezoelectric element adhered on fork surface may not be a new one. But there have never been brought in practical use, because the quartz crystal has high impedance and Rochelle salt etc. are not reliable in respect to their mechanical strength and hygroscopicity. By using BaTiO3 ceramics, these defects can be removed and all the difficulties in electromagnetic type are decreased or overcome and the apparatus can be made more simpler and smaller.    Experiments have been carried out upon several samples of this type, and com-paratively good results were obtained which will be described here.    Piezoelectric Type Tuning Fork:    In the electromagnetic type, electromagnetic attractive force acts at the loop of vibration in parallel to the motion of the vibrator. But in piezoelectric type, as piezoelectric element is directly adhered on vibrator surface and their electrostrictive force work in parallel to the surface, it is considered that the most suitable position, where piezoelectric element is to be situated, is the nodal point of vibration. As the points that have minimum amplitude were found to be situated at P,G in Fig. 1 by                                        t1:1                                                Lgj    0ce) 0  ,h Fig.- 1.Fig. 3. the measurement of amplitude distribution on the surface, BaTiO3 plate which has silver electrodes on both surface were adhered on these points. Phosphor-bronze (421 ) strips were soldered directly on electrodes of P,G as current feeders, and P is to be  connected to plate  circuit and G to grid circuit of oscillator (Fig. 2). Elements 6337 6F6                                                                                             I.                                                                                     se-                                                   Sklter        TQPhd were polarized under high voltage D.0 source before use. Fundamental vibration can be excited when both elements' are polarized in the same' ditection, and P and G are in the same phase. When sothe'phase difference exisf between them, higher harmo-nic vibrations can be excited. Siipporting' devibe'of this fork' becoine very easy, because there is nothing to be' fixed =relatively. ` ' Freg iency deviation due to the adhe-rence of the elements was ne"gli'sible`°small, as the mas`s of 'the'piezoelectric elements were very small 'compared to that` ` of vibrator`.'r''     Piezoelectric Type Vibrating 'Reed    The idea to produce a°tuiiing forik -of 'peZoeIectric type inay' be 'applied similarly to a vibrating reed' of thesane`"type:`'"In this'case,- as the inode of'vibration is very simple, method and the position where' °eleinen'ts Must be ` 'adhered are easily deter-Mined. Resonant • frequehey`bf °the Vibrat ng'reed' is' represented by the following equation as is well known;           am  t E              ~12 al~p where Z length in cm, t : thickness in cm,                = 4.73 for fundamental vibration. Nodal points are deterrriined .by: the following equation :                0:2242 Z,'0.7758 1 where l, is distance_between node and one end.    Two types of supporting system were examined as shown in Fig. 3 :    (A) Fixed at the npdal, points- of vibrator by 4 screws which have needle point.     (B) I3anged at' the':nodal - point of vibrator by 4 springs to frame.    Dimensions and frequency of tested samples are shown in the following table.    Sample Materiall(mm) t(mm)' h'(mm) f(1cc) Type 'of Supporting ' No. 1 Steel72.4 `' 4.016.2 4.01 (A)   No. 2 it56.5 5.012.7 8.01it   No. 3 Elinvar40.0 3.148.97 9.405(B) ( 422 )   Size of BaTiO3 elements were 8 x 8 x 0.5  (mm) for No. 1, No. 2 and 3 x 5 x 0.3 (mm) for No. 3. - In every ease, they were operated very successfully. As in the case of tuning fork, fundamental vibration was excited when two elements are in the same phase, and if proper phase difference is given harmonic vibration was ex-cited. Q value of vibrator was abowt 2000 -- 5000, and in (B) type Q was greater than (A) type. Internal loss was about 20 db in every case. -------------------------------------------------•        6. Study on High Dielectric Constant Ceramics. (XXI) BaTiO3 Ceramics as a Material of Dielectric Amplifier Kiyoshi ABr and Tetsuro TANAKA                               (Abe Laboratory)    It was known that dielectric amplification using ferroelectric property is possible according to the same principle as the Magnetic amplifier using ferromagnetic pro-perty, and such amplifier has attracted much attention since BaTiO3 ceramics were found out However, few reports and, data on dielectric amplifier, the production of materials or the application of amplifier, were published. Recently, the characteris-tics especially concerning amplification in dielectric properties of BaTiO3 ceramics, were inspected and the experimental results were put in order mathematically in our                                          laboratory.    As the permittivity is affected by d-c bias most sensitively near Curie temperature, it is desirable for the material of amplifier to have the Curie point at room temper-ature. Such materials are easily made by mixing titanate of Sr, Zr or Sn in BaTiO3 because the Curie point :decreases in proportion to the quantityof Sr, Zr or Sn. The materials having such', characteristics that the permittivity is not largely influenced by the temperature, ,haVe been made already. The characteristics of permittivity to d-C'bias were measured about the materials having sharp temperatUre characteristics (A-kind material) and flat temperature characteristics (B-kind material), and results were compared with theoretical ones.    Characteristics of permittivity to d-c bias:    The characteristics of permittivity to d-c bias will be mathematicaly represented by assuming,the,suitable equation to the saturation characteristics of ferroelectric materials. Many equations representing saturation characteristics have been present-ed, from which two equations suitable for BaTiO3 ceramics were selected. E = aD bD3(1) E = a sinh (13D)(2) ( 423 )

Study on High Dielectric Constant Ceramics. (XX) : Tuning Fork and Vidrating Reed Driven by BaTiO₃ Ceramics

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Study on High Dielectric Constant Ceramics. (XX) : Tuning Fork and Vidrating Reed Driven by BaTiO₃ Ceramics

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