形状の異なる焦電結晶積層体によるX線発生挙動および放電特性

タンタル酸リチウム単結晶を積層させたユニットの焦電特性に基づく放電およびX 線発生挙動について，結晶形状および真空度による相違を検討した．大気下での室温～400Kの温度変化サイクルに伴う放電現象はいずれも積層型結晶ユニット側面で観察された．放電回数は同一形状の板状単結晶を使用したユニットの方が形状不揃いの結晶を同一枚数積層させたときより5 倍多く，側面に絶縁グリースを塗布すると大幅に抑制された．放電は積層した板状結晶の間隙で起こり，加熱時には数秒から1 分間の短時間のスパイク状のX線が繰り返し発生した．X線の最高エネルギーは1Paと10-4Paでは相違なかったが，やや1Paの方がスパイク状X線の発生頻度が高かった．スパイク状のX 線発生および放電挙動の要因について議論した．

Three types of stacked LiTaO3 single crystal units were assembled to investigate effects
of shape of the single crystal and degree of ambient pressure on X-ray emission and discharge behavior based on the pyro electricity. Every instantaneous emission of visible light due to discharge occurred at the side of stacked crystals during heating and cooling cycle between room temperature and 400 K under atmospheric pressure. Discharge frequency on a stacked unit made of equal-sized four pieces (type-A) was five times more than that on a unit made of irregularlysized pieces (type-C). Discharge occurred possibly at narrow gap between two pieces of platelike single crystal. During heating process up to ca. 400 K under 1 or 10 - 4 Pa, spike-like X-ray emission for a few seconds through one minute occurred repeatedly on both type-A and -C units. The maximum energy of emitted X-ray was independent on both degree of vacuum and shape of stacked plate-like LiTaO3 single crystal. Discharge on type-A unit was suppressed by coating of stacked crystals with dielectric grease whereas high voltage generated on the coated unit. Origin of spike-like X-ray emission and discharge on stacked LiTaO3 units was discussed.

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