单晶YSZ的Xe+离子辐照效应研究

 200keV Xe⁺离子辐照使单晶YSZ由无色透明变成紫色透明，结果表明，能量为200keV，注量为1×10¹⁷cm^-22的Xe⁺离子辐照YSZ单晶产生的损伤高达350dpa，在损伤区产生高密度的缺陷，但仍然没有发生非晶化转变。吸收光谱测试结果表明，产生吸收带的注量阈值大约为10¹⁶cm^-2。注量为1×10¹⁶cm^-2和1×10¹⁷cm^-2的样品，吸收带峰值分别位于522nm和497nm。光吸收带可能与Zr阳离子最近邻的氧空位捕获电子形成的F型色心和Y阳离子近邻的氧离子捕获空穴形成的V型色心有关。     

新型1223相高T_c超导层型铜氧化物(Tl,M)(Sr,Ba)_2Ca_2Cu_3O_z(M=Cr,V)

纯的TlSrCaCuO体系难以制备1223型超导铜氧化物,报道了合成和用粉末X射线衍射、电子衍射鉴定了一大类新型1223相高T_c超导层型铜氧化物(Tl_(1_x)M_s)(Sr_(2_y)Ba_y)Ca_2Cu_3O_x,其中M为Cr或V,包括(Tl_(0.75)Cr_(0.25)(Sr_(2_y)Ba_y)Ca_2Cu_3O_x,(Tl_(0.75)V_(0.25))(Sr_(2_y)Ba_y)Ca_2Cu_3O_x,(Tl_(1_x)Cr_x)Sr_2Ca_2Cu_3O_x和(Tl_(1_x)V_x)Sr_2Ca_2Cu_3O_5等4个系列1223相层型铜氧化物。在M存在的情况下,适量的Ba部分取代Sr,有利于(Tl,M)基1223相化合物的形成,然而,当y=0,即无Ba存在时,过量Tl对(Tl,M)基1223相化合物的形成十分必要。电阻和交流磁化率测量都显示,有Ba存在时的这些化合物超导电性T_c(ρ=0)均在100K以上,(Tl_(0.75)Cr_(0.25))(Sr_0.5Ba_1.50)Ca_2Cu_3O_x的T_c(ρ=0)可达113K,纯Sr系列掺V1223相化合物的超导电性略高于相应的掺Cr的化合物的超导电性,其中(Tl_0.75V_0.25)Sr_2Ca_2Cu_3O_x的T_c(ρ=0)可达105K。此外,作者还详细研究和讨论了M(Cr或V)量和Sr/Ba比对(Tl,M)基1223型铜氧化物形成和超导电性的影响。     

新型1223相高Tc超导层型铜氧化物(Tl,M)(Sr,Ba)2Ca2Cu3Oz(M=Cr,V)

纯的TlSrCaCuO体系难以制备1223型超导铜氧化物,报道了合成和用粉末X射线衍射、电子衍射鉴定了一大类新型1223相高T_c超导层型铜氧化物(Tl_(1_x)M_s)(Sr_(2_y)Ba_y)Ca_2Cu_3O_x,其中M为Cr或V,包括(Tl_(0.75)Cr_(0.25)(Sr_(2_y)Ba_y)Ca_2Cu_3O_x,(Tl_(0.75)V_(0.25))(Sr_(2_y)Ba_y)Ca_2Cu_3O_x,(Tl_(1_x)Cr_x)Sr_2Ca_2Cu_3O_x和(Tl_(1_x)V_x 关键词：     

Optical and structural properties of Ge-ion-implanted fused silica after annealing in different ambient conditions

Ge+ ions are implanted into fused silica glass at room temperature and a fluence of 1×10 17 cm-2 . The as-implanted samples are annealed in O2, N2 and Ar atmospheres separately. Ge0 , GeO and GeO2 coexist in the as-implanted and annealed samples. Annealing in different atmospheres at 600℃ leads each composite to change its content. After annealing at 1000℃, there remains some amount of Ge 0 in the substrates. However, the content of Ge decreases due to out-diffusion. After annealing in N2 , Si–N composite is formed. The absorption peak of GeO appears at 240 nm after annealing in O2 atmosphere, and a new absorption peak occurs at 418 nm after annealing in N2 atmosphere, which is attributed to the Si–N composite. There is no absorption peak appearing after annealing in Ar atmosphere. Transmission electron microscopic images confirm the formation of Ge nanoparticles in the as-implanted sample and GeO 2 nanoparticles in the annealed sample. In the present study, the GeO content and the GeO2 content depend on annealing temperature and atmosphere. Three photoluminescence emission band peaks at 290, 385 and 415 nm appear after ion implantation and they become strong with the increase of annealing temperature below 700℃, and their photoluminescences recover to the values of as-grown samples after annealing at 700℃. Optical absorption and photoluminescence depend on the annealing temperature and atmosphere.     

Microstructure evolution of zircaloy-4 during Ne ion irradiation and annealing: An in situ TEM investigation

The microstructural evolution of zircaloy-4 was studied, including the amorphization and recrystallization of Zr（Fe, Cr）2 precipitates, and the density of dislocations under in situ Ne ion irradiation and post annealing. The results show that irradiation at a relatively high temperature and dose induces the formation of nanocrystals in pre-amorphized Zr（Fe, Cr）2 precipitates. The recrystallized nanocrystals also have the structure of hcp-Zr（Fe, Cr）2. The formation of the nanocrystals is thought to be the consequence of competition between atomistic disordering and the recrystallization of precipitates under ion irradiation. The free energy of the nanocrystal is lower than that of the amorphous state, which is another reason for the recrystallization of the precipitates. With increased annealing temperature, the density of the nanocrystals is increased. The dislocation density sharply decreases with the increase in the annealing temperature, and its size increases.     

Cluster size and substrate temperature affecting thin film formation during copper cluster deposition on a Si （001） surface

The soft deposition of Cu clusters on a Si(001) surface was studied by molecular dynamics simulations.The embedded atom method,the Stillinger-Weber and the Lennar-Jones potentials were used to describe the interactions between the cluster atoms,between the substrate atoms,and between the cluster and the substrate atoms,respectively.The Cu13,Cu55,and Cu147 clusters were investigated at different substrate temperatures.We found that the substrate temperature had a significant effect on the Cu147 cluster.For smaller Cu13 and Cu55 clusters,the substrate temperature in the range of study appeared to have little effect on the mean center-of-mass height.The clusters showed better degrees of epitaxy at 800 K.With the same substrate temperature,the Cu55 cluster demonstrated the highest degree of epitaxy,followed by Cu147 and then Cu13 clusters.In addition,the Cu55 cluster showed the lowest mean center-of-mass height.These results suggested that the Cu55 cluster is a better choice for the thin-film formation among the clusters considered.Our studies may provide insight into the formation of desired Cu thin films on a Si substrate.     

辐照诱发中间相Zr(Cr,Fe)2非晶化的原位电子显微研究

 在美国Argonne国家实验室连接有IVEM-Tandem National Facility加速器的Hitatch3000电子显微镜上，通过能量600keV及注量率为2.5×10¹²cm^-2·s^-1的Ne离子原位辐照,研究了锆-4合金中沉淀相hcp Zr(Cr,Fe)₂的重离子辐照效应，结果表明：600keV的Ne离子在350℃原位辐照至0.2dpa时，hcp-Zr(Cr,Fe)₂沉淀相的层错条纹开始消失；0.8dpa时沉淀相的电子衍射斑点大部分消失，发生明显的化学无序；2.7dpa时明场像衬度完全消失，非晶环已非常明显，表明沉淀相已经非晶化。600keV的Ne离子在350℃辐照hcp-Zr(Cr,Fe)₂相非晶化的临界损伤离位率约为2.7dpa。     

310 ℃和350 ℃下锆-4合金中沉淀相非晶化研究

用大束流加速器和透射电子显微镜研究了Zr-4合金在310 ℃和350 ℃下的质子辐照效应。当质子能量为2 MeV，在310 ℃和350 ℃下质子辐照产生原子离位损伤达5 dpa（注量率为8.5×1013 cm-2·s-1），辐照前后的明场像、高分辨相和电子衍射花样均表明:在310 ℃辐照产生原子损伤达到5 dpa，沉淀相Zr(Cr,Fe)2边缘5～10 nm的区域已经非晶化，而在350 ℃时质子辐照却没有非晶化发生。沉淀相Zr(Cr,Fe)2的元素分布图像和浓度分布表明，铁元素向基体扩散并且聚集在非晶化边界区域。