(1. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長(zhǎng)沙 410083；
2. 中南大學(xué) 教育部有色金屬材料科學(xué)與工程重點(diǎn)實(shí)驗(yàn)室，長(zhǎng)沙 410083；
3. 中南大學(xué) 粉末冶金國(guó)家重點(diǎn)實(shí)驗(yàn)室，長(zhǎng)沙 410083)
摘 要: 建立了金屬納米微粒的結(jié)合能模型，該模型以微粒尺寸、形狀因子和密堆因子為主要參數(shù)。根據(jù)該模型計(jì)算V、Cr、Nb、Mo、Ta、W和Fe元素納米微粒的結(jié)合能。結(jié)果表明：一定形狀下，在一定的臨界尺寸時(shí)各納米微粒bcc結(jié)構(gòu)的結(jié)合能和fcc結(jié)構(gòu)的結(jié)合能相等；當(dāng)微粒尺寸大于該臨界尺寸時(shí)，bcc結(jié)構(gòu)更穩(wěn)定，小于該尺寸時(shí)，fcc結(jié)構(gòu)更穩(wěn)定。進(jìn)一步的計(jì)算表明，球形和正四面體形可以看作近正多面體形的兩個(gè)極限，多面體形微粒發(fā)生結(jié)構(gòu)轉(zhuǎn)變的臨界尺寸介于兩個(gè)極限尺寸之間，與文獻(xiàn)中報(bào)道的結(jié)果一致。
關(guān)鍵字: 金屬納米微粒；結(jié)構(gòu)穩(wěn)定性；結(jié)合能；形狀效應(yīng)；尺寸效應(yīng)
their cohesive energy
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Non-ferrous Materials Science and Engineering, Ministry of Education,
Central South University, Changsha 410083, China;
3. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China）
Abstract: A model was developed to account for the size, shape and structure dependent cohesive energy of metallic nanoparticles. The cohesive energies of V, Cr, Nb, Mo, Ta, W and Fe were calculated. The results show that the cohesive energy of nanoparticles of bcc structure is the same as that of fcc structure at the critical size and specific shape. When the nanoparticle size is larger than the critical size, the nanoparticles in bcc structure are more stable, but when the nanoparticle size is less than the critical value those in fcc structure are more stable. Furthermore, as the nanoparticles is close to the polyhedral shape, the critical size of polyhedral shape lies in the middle of spherical and tetrahedral shape, which is consistent with the experimental and other theoretical predictions.
Key words: metallic nanoparticles; phase stability; cohesive energy; size effect; shape effect
