聚合鑽石奈米棒

聚合鑽石奈米棒英語:Aggregated diamond nanorods,又稱鑽石奈米棒聚合體,簡稱ADNR),是一種奈米級晶型鑽石,又稱奈米鑽石(nanodiamond)或超鑽石(hyperdiamond)。聚合鑽石奈米棒是於2003年由石墨的壓縮製得的,也就是那次發現它比一般的鑽石要硬得多,[1]這使得它成為已知最硬的材料。後來,富勒烯的壓縮也製得了這種物質,並證實這是已知最硬和最難壓縮的材料,等溫體積彈性模量為491GPa,而一般鑽石的模量為442–446 GPa;這些數據是從X射線衍射數據中得出的,並說明聚合鑽石奈米棒的密度比普通鑽石高0.3%。[2]同一個研究小組後來說:「聚合鑽石奈米棒的硬度和楊氏模量與天然鑽石相當,但具有更優的耐磨性。」 [3]

硬度

純鑽石的<111>晶面(垂直於立方體對角線的平面)用奈米鑽石刻劃測試時的硬度為167±6 GPa,而奈米鑽石樣品本身用奈米鑽石刻劃測試時硬度達到了310GPa。[4]然而,這種測試只在刻劃工具比測試樣品更硬時才能得出正確結果。也就是說,奈米鑽石的真實硬度可能略小於310 GPa。

製備

 
富勒體粉末(掃描電子顯微鏡所攝)

聚合鑽石奈米棒可由壓縮富勒體(英語:fullerite,富勒烯的一種固態形式)粉末製得,與上文所述方法有些類似。一種方法使用了金剛石壓腔,在不加熱的情況下對其施加大約37GPa的壓力。[5]另一種方法是,將富勒體先用較小的壓力(2–20GPa)壓縮,然後加熱到300–2500 K的溫度。[6][7][8][9]聚合鑽石奈米棒的超高硬度可能在上世紀90年代就有研究者報導。[4][5]這種材料是一系列相互連接的鑽石奈米棒所構成,各奈米棒直徑為5至20奈米,長度大約為1微米

參見

參考文獻

  1. ^ Irifune, Tetsuo; Kurio, Ayako; Sakamoto, Shizue; Inoue, Toru; Sumiya, Hitoshi. Materials: Ultrahard polycrystalline diamond from graphite. Nature. 2003, 421 (6923): 599–600. doi:10.1038/421599b. PMID 12571587. 
  2. ^ Dubrovinskaia, Natalia; Dubrovinsky, Leonid; Crichton, Wilson; Langenhorst, Falko; Richter, Asta. Aggregated diamond nanorods, the densest and least compressible form of carbon. Applied Physics Letters. 2005, 87: 083106. Bibcode:2005ApPhL..87h3106D. doi:10.1063/1.2034101. 
  3. ^ Dubrovinskaia, Natalia; Dub, Sergey; Dubrovinsky, Leonid. Superior Wear Resistance of Aggregated Diamond Nanorods. Nano Letters. 2006, 6: 824. Bibcode:2006NanoL...6..824D. doi:10.1021/nl0602084. 
  4. ^ 4.0 4.1 Blank, V. Ultrahard and superhard phases of fullerite C60: Comparison with diamond on hardness and wear (PDF). Diamond and Related Materials. 1998, 7: 427. Bibcode:1998DRM.....7..427B. doi:10.1016/S0925-9635(97)00232-X. 
  5. ^ 5.0 5.1 Blank, V; Popov, M; Buga, S; Davydov, V; Denisov, V; Ivlev, A; Marvin, B; Agafonov, V; Ceolin, R. Is C60 fullerite harder than diamond?. Physics Letters A. 1994, 188: 281. Bibcode:1994PhLA..188..281B. doi:10.1016/0375-9601(94)90451-0. 
  6. ^ Kozlov, M. Superhard form of carbon obtained from C60 at moderate pressure. Synthetic Metals. 1995, 70: 1411. doi:10.1016/0379-6779(94)02900-J. 
  7. ^ Blank, V. Ultrahard and superhard carbon phases produced from C60 by heating at high pressure: structural and Raman studies. Physics Letters A. 1995, 205: 208. Bibcode:1995PhLA..205..208B. doi:10.1016/0375-9601(95)00564-J. 
  8. ^ Szwarc, H; Davydov, V; Plotianskaya, S; Kashevarova, L; Agafonov, V; Ceolin, R. Chemical modifications of C under the influence of pressure and temperature: from cubic C to diamond. Synthetic Metals. 1996, 77: 265. doi:10.1016/0379-6779(96)80100-7. 
  9. ^ Blank, V. Phase transformations in solid C60 at high-pressure-high-temperature treatment and the structure of 3D polymerized fullerites. Physics Letters A. 1996, 220: 149. Bibcode:1996PhLA..220..149B. doi:10.1016/0375-9601(96)00483-5. 

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