Ordered Intermetallic Pt-Sn Nanoparticles: Exploring Ordering Behavior across the Bulk Phase Diagram
Ordered Intermetallic Pt-Sn Nanoparticles: Exploring Ordering Behavior across the Bulk Phase Diagram
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DOI：
10.1021/cm5007197
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发表时间：
2014-04-22
影响因子：
8.6
通讯作者：
DiSalvo, Francis J.
中科院分区：
文献类型：
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作者：
DeSario, Douglas Y.;DiSalvo, Francis J.
由于Pt-Sn的体相图包含五种不同的化合物（Pt3Sn, PtSn, Pt2Sn3， PtSn2和PtSn4），它们具有非常不同的全等或非全等熔点，因此我们选择该体系来研究通过相同的液相共还原反应制备的不同成分的金属间纳米颗粒的均匀性和结构的影响因素。用碱金属硼氢化物在四氢呋喃中还原了铂和氯化锡前驱体。在这五种成分中，只有铂锡在室温下形成有序的金属间纳米颗粒（平均畴尺寸为4.3 nm）。制备的Pt3Sn纳米颗粒采用合金FCC结构，并在200℃的低温退火下有序排列成立方Cu3Au结构，尽管它们的体积不一致熔化温度很低，但富锡成分（PtSnx，其中x = 3/ 2,2或4）在室温下形成高度无序的产物，需要在>= 200℃退火才能观察到结晶和有序。由氯化锡（II）制备的相表现出与氯化锡（IV）不同的共还原行为，后者需要更高的温度才能产生同样有序的颗粒。光谱研究表明，这种行为可能是由于在还原之前溶液中形成Pt-Sn配合物，当使用锡（II）作为前驱体时，而不是锡（IV），导致目标化学计量相的成核更加一致。讨论了退火结晶的过程。
Because the bulk phase diagram of Pt-Sn contains five different compounds (Pt3Sn, PtSn, Pt2Sn3, PtSn2, and PtSn4) with very different congruent or incongruent melting points, we chose this system to investigate factors that influence the homogeneity and structure of intermetallic nanoparticles with different compositions prepared by the same solution phase co-reduction reaction. Pt and Sn chloride precursors were reduced by alkali metal borohydrides in tetrahydrofuran. Of the five compositions, only Pt Sn forms ordered intermetallic nanoparticles (average domain size of 4.3 nm) at room temperature. As-prepared Pt3Sn nanoparticles adopt an alloy FCC structure and ordered into the cubic Cu3Au structure at the unexpectedly low annealing temperature of 200 degrees C. Despite their low bulk incongruent melting temperatures, the tin-rich compositions (PtSnx, where x = 3/2, 2, or 4), by contrast, form highly disordered products at room temperature and require annealing at >= 200 degrees C for crystallization and ordering to be observed. Phases prepared from tin(II) chloride exhibit co-reduction behavior different from that of tin(IV) chloride, the latter requiring overall higher temperatures to produce similarly ordered particles. Spectroscopic studies indicate that this behavior may be due to the formation of Pt-Sn complexes in solution prior to the reduction when tin(II) is used as a precursor, but not for tin(IV), resulting in more consistent nucleation of the target stoichiometric phases. The process of crystallization by annealing is discussed.