Study Of Hydrogen Sensitive Property Of LaNi₅Thin Film Prepared By Magnetron Sputtering

Nowadays, hydrogen energy is widely known due to its high calorific value and being environmentally friendly and producing more energy per unit weight than any other fuel. However, hydrogen is easily leaked during transport or use or storage. Therefore, there is increasing demand for hydrogen sensor in numerous applications as the extensive use of hydrogen in great areas such as fuel cell, rocket fuels for spacecraft, neon and xenon production and semi-conductor processing for microelectronics.LaNis intermetallic compound is a well-known hydrogen storage alloy with high capacity to absorb rapidly and reversibly near atmospheric pressure in room temperature. However, the survey showed that there were a few of reports about LaNi5as hydrogen sensor metrical and most research about LaNi5focused on powder and bulk. LaNi5thin film as hydrogen sensor metrical is higher sensor than LaNis bulk and powder because the response mechanism of LaNi5depends on electrical resistance.In this paper, the intermetallic compound LaNi5thin film was prepared by means of radio-frequentncy magnetron sputtering. LaNi5thin film was deposited on Ni thin film which was deposited on silicon commercial wafers with (100) orientation as buffer layer. Sputtering conditions were varied to study their influence on the LaNi5thin film crystal structure. The crystal structure of the as-deposited thin film was probed by X-ray diffraction (XRD). The result showed that crystallization of the LaNi5thin films was attained on the condition of substrate temperature350℃,500W power,0.6Pa and target polar distances35mm, and LaNi5(101) growth in preferred orientation at substrate temperature500℃or500W power. Then the LaNi5film after surface treatment was made the transducer and tested sensitive performance on the platform in the self-developed. The results were that LaNi5alloy has the ability of absorption and release hydrogen directly after700℃annealing, and response time and recovery time is short, the hydrogen sensitive response characteristics is good. Compared with600℃annealing and surface coated Pt method,700℃annealing treatment is more conducive to the hydrogen sensitive performance of LaNi5film.The surfaces morphologies of samples before and after annealed were analyzed by atomic force microscopy; the structures and surfaces element of samples before and after annealed were studied by X-ray diffraction and X-ray photoelectron spectroscopy. The results showed that specific surface area of LaNi5film increased, and a surface La2O3-Ni structure was formed after annealed, which is benefit of hydrogen sensitive characteristics. This paper explained the reason of resistant increasing with hydrogen absorbing and resistant decreasing with hydrogen desorbing.