Miyoshi Haradome

Oscillation phenomenon in ThO2‐doped SnO2 exposed to CO gas

In the ThO2‐doped SnO2 a new self‐oscillation phenomenon has been found only when it is exposed to CO gas. This phenomenon is related to the environmental CO gas concentration, substrate temperature, and applied voltage. The oscillation is extremely senstivie to the concentration of CO gas, especially in the region of 0.2‐0.3%.

New oscillation phenomena in VO2 crystals

New oscillation phenomena in VO2 crystals were observed. The oscillation is generated in the temperature region of the crystal transition, and its voltage and frequency depend upon the ambient temperature. The waveform of the oscillation is a rectangular pulse.

H/sub 2/S gas detection by ZrO-doped SnO/sub 2/

The authors report on the fabrication of H/sub 2/S gas sensors made of SnO/sub 2/ mixed with ZrO/sub 2/. Their sensitivities, responses, and selectivities to H/sub 2/S are presented. A 10-p.p.m. concentration of H/sub 2/S gas changes the sensor resistivity to a value 300 times lower than that for air around 175 degrees C. The sensors exhibit highly selective detection of H/sub 2/S in an atmosphere containing H/sub 2/S and H/sub 2/. The mechanism of the reaction between the sensors and H/sub 2/S are also discussed. >

Some unique aspects on ThO2‐doped SnO2 exposed to H2 gas

In ThO2‐doped SnO2 exposed to H2 gas, the remarkable phenomenon like the increase of sample resistivity has been found in spite of n‐type semiconductors. This phenomenon depends on the gas concentration, the sample temperature, and also the history of the samples. In samples sintered at 600 °C, it appears remarkably at the sample temperature below 240 °C and above 250 ppm of the gas concentration.

Stability and deterioration mechanism of thick film resistors

Abstract Life test stability and failure mechanism of RuO 2 -based thick film resistors at elevated temperature and high humidity have been examined. It is found that the change of resistance under high humidity conditions is caused mainly by reaction of RuO 2 + x H 2 O → RuO 2 : x H 2 O, and that the resistance value of RuO 2 :Ag:Glass in the high temperature conditions mainly due to oxidation of Ag, and that initial drift and internal strain in the resistors tend to be influenced by the firing conditions. In the case of the resistors having conductive component of solid solution of RuO 2 and other metals (exp. Bi 2 Ru 2 O 7 ), the resistors have little resistance drift and are stable.