Intermetallic Compounds - Intermetallic Compounds

A compound formed only from two or more metallic elements. [ I ] Electron compounds: Compounds to which the Hume-Rothery rule applies. For example, β-phase compounds (CuZn, Ag ₃ Al, etc.) have an e / a ratio ( e is the total number of valence electrons, a is the total number of atoms) of 3/2, γ-phase compounds (Cu ₅ Zn ₈ ) have an e/a ratio of 21/13, and ε-phase compounds (CuZn ₃ , AgMg ₃ , etc.) have an e/a ratio of 7/4. Examples can be seen in compounds between group 11 elements of the periodic table and multivalent elements from groups 12 to 14. [ II ] Coordination polyhedral compounds: Compounds with a close-packed atomic arrangement, with each atom coordinating to the other atoms in a dodecahedral to hexadecahedral structure. For example, there are σ-phase compounds (FeCr, FeV, and other alloy-type compounds with an atomic ratio of 1:1 between elements from groups 5, 6, and 7 to 10 of the periodic table) and Laves phase compounds ( _MgZn2 , _MgNi2 , and other compounds with a composition formula of _AB2 and an atomic radius ratio of A:B of approximately 1.2:1). [ III ] Electrochemical compounds: Compounds in which the valence is satisfied between positive and negative metals or metalloids with a large difference in electronegativity. Examples include _Mg2Pb , GaAs, and CdS. [ IV ] Compounds in which the component elements that bond with metals are I, C, Si, Ge, As, Se, etc., and interstitial compounds in which light atoms such as H, C, N, and O are inserted between the metallic bond lattice can also be included. Some of these have properties not seen in normal alloys. For example, these include III-V semiconductors (GaAs), superconducting materials (Nb ₃ Sn), hydrogen storage alloys (LaNi ₅ ), permanent magnetic materials (SmCo ₃ ), and heat-resistant alloys (Ni ₃ Al).

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

2種類以上の金属元素のみから形成される化合物．【Ⅰ】電子化合物：ヒューム-ロザリーの規則が適用されるもの．たとえば，e/a(eは価電子の合計，aは原子数の合計)が3/2のβ相化合物(CuZn，Ag₃Alなど)，21/13のγ相化合物(Cu₅Zn₈)，7/4のε相化合物(CuZn₃，AgMg₃など)である．周期表11族と多価の12～14族の元素間の化合物に例がみられる．【Ⅱ】配位多面体化合物：最密原子配列をもち，各原子は互いに12～16面体型配位構造となっている．たとえば，σ相化合物(FeCr，FeVなど，周期表5，6族-7～10族元素間の原子数比1：1の合金型化合物)，ラーヴェス相化合物(MgZn₂，MgNi₂など，組成式がAB₂で，原子半径比が，A：Bが約1.2：1のもの)などがある．【Ⅲ】電気化学的化合物：電気陰性度の差が大きい陽性と陰性の金属または半金属間で，原子価が満足されるもの．Mg₂Pb，GaAs，CdSなどが該当する．【Ⅳ】金属と結合する成分元素がI，C，Si，Ge，As，Seなどのものや，金属結合格子間に軽原子H，C，N，Oなどが入った侵入型化合物も含めることがある．これらのなかには，通常の合金にはみられない特性をもつものがある．たとえば，Ⅲ-Ⅴ半導体(GaAs)，超伝導材料(Nb₃Sn)，水素吸蔵合金(LaNi₅)，永久磁石材料(SmCo₃)，耐熱合金(Ni₃Al)などである．

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