Saburo Magari

Growth morphology of UO2, ZrO2, HfO2 and ThO2 crystallites grown from oxide plasmas

Abstract The characteristics growth morphology of UO2, ZrO2, HfO2 and ThO2 crystals grown from oxide plasmas is presented. The growth proceeds by ions from ionized plasmas on a high-temperature substrate (cathode) at temperature over 2000°C by the mechanism named “electrolysis of plasma”. Faceted UO2 crystals were obtained from a UO2 plasma, while crystals grown from the other oxide plasmas were round-shaped. When the plasma current was low, thick films of HfO2 and ThO2 were formed. Increase of substrate (cathode) heating power and of the Ar feeding rate resulted in the decrease of the density of the round-shaped crystals. When O2 was supplied, the deposits of ZrO2 and HfO2 were melted and formed a hemisphere, as a result of enhanced plasma heating.

Deposition of crystals from the plasmas of ZrO2, HfO2, ThO2, and CeO2

Deposition occurs onto a cathode from an oxide plasma generated inside a hollow oxide anode by the mechanism called the electrolysis of plasma. The temperature of the cathode is usually over 2000 °C during deposition. Deposits attain fairly large crystalline sizes (about 0.3 mm) in spite of their high deposition rates. And besides, some unusual crystals are formed. For the deposition from ZrO2, HfO2, and ThO2 plasmas, the deposition rate, growth rate, and the current efficiency increase with the plasma current (0.4–8 A) and with feeding O2 gas into the plasmas. On the other hand, heating a cathode externally or feeding Ar gas into them leads to the reduction of those rates, the current efficiency, and yield. The maximum growth rate from the ThO2 plasma is 8.4 μm/sec. Yields exceed 90% in general. Mass‐spectrometric analyses showed that the main depositing ion species is ZrO+ for the deposition from the ZrO2 plasma. Deposits obtained are usually black oxides, whose O/M (M=Zr, Hf, and Th) ratios are 1.95, 1...

Storage Tube Type Mass Spectrometer Recorder

By replacing a pen and ink recorder, a multiple trace oscillograph, an ordinary oscilloscope, and a vibrating reed electrometer by a storage tube‐type recorder, and a scintillator type ion detector, a trace of mass peaks obtained from not only various scanning speeds but also nonrepeated phenomena can be seen on the oscilloscope for a wanted duration. The mass spectrometer with this recording assembly will be useful for industrial monitoring and for research work.