BaTiO3単結晶のマイクロ波焦電気特性
1964 年 33 巻 6 号 p. 407-412
詳細
1964 年 33 巻 6 号 p. 407-412
Pyroelectric current induced by irradiation of modulated microwave of 9300 Mc/s frequency is observed on a single crystal of BaTiO3 mounted in a wave guide. The resultant pyro-electric current density is given by
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The numerical value of the rate dPs/dT of the crystal is about 1×10-8 coulomb/cm2/°C at room temperature, and when heated uniformly in a microwave electric field, the rate of temperature rise is given by
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where B is a constant relating to the heat flow from the crystal, α a constant, mainly determina-ble by physical properties of the crystal, and W(t) the incident microwave power as a function of time.
As for the characteristics of pyro-current, slowly varying current that is induced by sinusoidally modulated power of very low frequency is measured with an electrometer provided with a pen recor-der, and quickly varying current that is found at the time when incident power is modulated or switched on is observed with a synchroscope combined with a pre-amplifier. The characteristics observed at low power levels conform to those expected of the temperature changes in the crystal estimated with a few functional forms of W(t). However, when the incident microwave power reaches a certain value in the range of several hundred milliwatts, the pyro-electric effect disappears suddenly with simultaneous generation of noise, the cause of which is the disordered domain structure in the crystal.
