硼化鉭

硼化鉭（化學式：TaB，TaB₂）是鉭和硼組成的化合物，它的硬度極高。

性質[編輯]

TaB和TaB₂薄片和晶體的維氏硬度為30GPa。^[1]^[2]^[3] 在700℃以下時，這些物質很耐氧化和酸腐蝕，性質是穩定的。^[1]^[3]

TaB₂與大多數二硼化物（AlB₂, MgB₂等）具有相同的六方形結構。^[4] 這些硼化物具有以下分類空間：TaB（正交晶系，碘化亞鉈（英語：Thallium(I) iodide）型，CMCM），Ta₅B₆ （Cmmm）, Ta₃B₄ （Immm）, TaB₂ （六方晶系, 二硼化鋁型，P6/mmm）。^[3]

製取[編輯]

採用區域熔煉法可製得TaB，Ta₅B₆，Ta₃B₄或TaB₂單晶（直徑約1cm，長度約6cm）。^[2]^[3]

使用TaCl₅-BCl₃-H₂-Ar混合氣體在540~800°C範圍內時沉積硼化鉭薄片。在源氣流量比（BCl₃/TaCl₅）為6，溫度在600°C以上時沉積TaB₂（單晶）。在BCl₃/TaCl₅ = 2/4 ，溫度在600-700°C時沉積TaB（單晶）。^[1]

以NaBH₄和Ta₂O₅為原料，在700~900°C下，摩爾質量比M:B為1:4時，在氬氣中還原30分鐘，就可以合成TaB₂。^[5]

Ta₂O₅ + 6.5 NaBH₄ → 2 TaB₂ + 4 Na(g,l) + 2.5 NaBO₂+ 13 H₂(g)

參考文獻[編輯]

^ ^1.0 ^1.1 ^1.2 Motojima, Seiji; Kito, Kazuhito; Sugiyama, Kohzo. Low-temperature deposition of TaB and TaB2 by chemical vapor deposition. Journal of Nuclear Materials (Elsevier BV). 1982, 105 (2-3): 262–268. ISSN 0022-3115. doi:10.1016/0022-3115(82)90383-x.
^ ^2.0 ^2.1 Otani, S; Korsukova, M.M; Mitsuhashi, T. Floating zone growth and high-temperature hardness of NbB2 and TaB2 single crystals. Journal of Crystal Growth (Elsevier BV). 1998, 194 (3-4): 430–433. ISSN 0022-0248. doi:10.1016/s0022-0248(98)00691-5.
^ ^3.0 ^3.1 ^3.2 ^3.3 Okada, Shigeru; Kudou, Kunio; Higashi, Iwarni; Lundström, Torsten. Single crystals of TaB, Ta5B6, Ta3B4 and TAB2, as obtained from high-temperature metal solutions, and their properties. Journal of Crystal Growth (Elsevier BV). 1993, 128 (1-4): 1120–1124. ISSN 0022-0248. doi:10.1016/s0022-0248(07)80109-6.
^ Chen, Xing-Qiu; Fu, C. L.; Krčmar, M.; Painter, G. S. Electronic and Structural Origin of Ultraincompressibility of5dTransition-Metal DiboridesMB2(M=W, Re, Os). Physical Review Letters (American Physical Society (APS)). 2008-05-16, 100 (19): 196403. ISSN 0031-9007. doi:10.1103/physrevlett.100.196403.
^ Zoli, Luca; Galizia, Pietro; Silvestroni, Laura; Sciti, Diletta. Synthesis of group IV and V metal diboride nanocrystals via borothermal reduction with sodium borohydride (PDF). Journal of the American Ceramic Society. 2018-01-23, 101 (6): 2627–2637 [2020-07-22]. doi:10.1111/jace.15401. （原始內容存檔 (PDF)於2019-05-04）.

[TaB-1] 1.0 ^1.1 ^1.2 Motojima, Seiji; Kito, Kazuhito; Sugiyama, Kohzo. Low-temperature deposition of TaB and TaB2 by chemical vapor deposition. Journal of Nuclear Materials (Elsevier BV). 1982, 105 (2-3): 262–268. ISSN 0022-3115. doi:10.1016/0022-3115(82)90383-x.

[otani-2] 2.0 ^2.1 Otani, S; Korsukova, M.M; Mitsuhashi, T. Floating zone growth and high-temperature hardness of NbB2 and TaB2 single crystals. Journal of Crystal Growth (Elsevier BV). 1998, 194 (3-4): 430–433. ISSN 0022-0248. doi:10.1016/s0022-0248(98)00691-5.

[okada-3] 3.0 ^3.1 ^3.2 ^3.3 Okada, Shigeru; Kudou, Kunio; Higashi, Iwarni; Lundström, Torsten. Single crystals of TaB, Ta5B6, Ta3B4 and TAB2, as obtained from high-temperature metal solutions, and their properties. Journal of Crystal Growth (Elsevier BV). 1993, 128 (1-4): 1120–1124. ISSN 0022-0248. doi:10.1016/s0022-0248(07)80109-6.

[4] Chen, Xing-Qiu; Fu, C. L.; Krčmar, M.; Painter, G. S. Electronic and Structural Origin of Ultraincompressibility of5dTransition-Metal DiboridesMB2(M=W, Re, Os). Physical Review Letters (American Physical Society (APS)). 2008-05-16, 100 (19): 196403. ISSN 0031-9007. doi:10.1103/physrevlett.100.196403.

[5] Zoli, Luca; Galizia, Pietro; Silvestroni, Laura; Sciti, Diletta. Synthesis of group IV and V metal diboride nanocrystals via borothermal reduction with sodium borohydride (PDF). Journal of the American Ceramic Society. 2018-01-23, 101 (6): 2627–2637 [2020-07-22]. doi:10.1111/jace.15401. （原始內容存檔 (PDF)於2019-05-04）.

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