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本文把非晶La_(80)Al_(20)在真空中、不同温度及时间条件下进行退火,以及在6GPa不同温度退火40min,并对退火样品的相结构及超导性进行了研究。发现真空中,250℃退火的样品晶化成了T>4.2K,不超导的单相四方La_4Al;300℃及450℃退火的样品晶化成La_3Al,α-La、β-La及一些未知杂相,这些多相混合物的T_c<6.0K。在6GPa 300℃及以下温度退火的样品,晶化成单相六角La_4Al,其晶格常数与六角La_3Al的完全相同,这些样品的T_c>5.1K;6GPa、350℃及以上温度退火的样品,晶化成La_3Al相及新未知相H,新相H的T_c为6.3K。
In this paper, amorphous La_ (80) Al_ (20) was annealed in vacuum at different temperature and time, and annealed at different temperatures of 6GPa for 40min. The phase structure and superconductivity of annealed samples were also studied. The samples annealed at 250 ℃ were found to be crystallized into T> 4.2K, single-phase tetragonal La_4Al without superconductivity in vacuum. The samples annealed at 300 ℃ and 450 ℃ crystallized into La_3Al, α-La, β-La and some unknown heterogeneous T_c <6.0K for these multi-phase mixtures. Samples annealed at 6GPa at 300 ℃ and below crystallized into single phase hexagonal La_4Al with the same lattice constant as that of hexagonal La_3Al. T_c> 5.1K for these samples; samples annealed at 6GPa, 350 ℃ and above crystallized into La_3Al phase and the new unknown phase H, the new phase H T_c 6.3K.