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Process of Photoluminescence and Photostimulated Luminescence in BaFBr:Eu Phosphors

Wei CHEN (Lab. of Semiconductor Mater. Sci. , Institute of Semiconductor , Chinese Academy of Sciences , Beijing , 100083 , China)(To whom correspondence should be addressed)Mianzeng SU(Dept. of Chemistry , Peking University , Beijing , 100871 , China)

材料科学技术（英文）

The photoluminescence (PL) and photostimulated luminescence (PSL) of BaFBr:Eu phosphors are reported. In the photoluminescence of BaFBr:Eu, the emission of Eu2+ , e-h recombination and Eu3+ have been observed, while in the photostimulated luminescence only the emission of Eu2+ was observed. This phenomenon may be explained well by the suggestion of a two-band model for the host emission in which the host emission energy may transfer to Eu2+. The difference of excitation in those two processes results in different transfer rates which makes the PL and PSL emission different.

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Investigation of Instability of Lattice of Bi_2Sr_2CaCu_2O_x

Han ZHANG and Qingrong FENG (Dept. of Physics , Peking University , Beijing 100871 , China)Y.Zhao(School of Materials Science and Engineering , University of New South Wales , Sydney 2052 , NSW , Australia)F.Ritter and W.Assmus (Physikalisches Institut , J.W.Goet

材料科学技术（英文）

Bi2Sr2CaCu2Ox superconductor was studied by differential scanning calorimetry (DSC) and thermogravimetry (TG) in different atmospheres. It is discovered that there is a thermal anomaly in the DSC curve, associated with a weight loss in the TG curve before the melting of the sample. Careful thermal analysis and high temperature X-ray diffraction reveal that the thermal anomaly and the weight loss show an instability of the crystalline Iattice. By annealing the sample in oxygen and argon, respectively and then by TC measurement and thermal analysis, the coincidence of transition temperature with the instability is found. The coincidence is further confirmed by Y-doped 2212 phase.

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Photoelectrochemical Study of Passive Films on Sensitized Stainless Steel

Tianbao DU and Shenhao CHEN (Chemistry Dept. , Shandong University , Jinan 250100 , China)Maizhi YANG and Li CHEN (Chemistry Dept. , Peking University , Beijing 100871 , China)

材料科学技术（英文）

Passive films formed on sensitized stainless steel in sulphuric acid solutions have been studied using photoefectrochemical techniques. The results of the photocurrent measurement indicate that the passive films on sensitized stainless steel are characterised with n-type or p-type semiconductor in different potential regions. The difference in the photoelectrochemical behaviour can be interpreted assuming that the passive film is an iron-chromium oxide solid solution associated with various hydration degrees of the Cr(Ⅲ) oxides at various potentials

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INTERACTION OF OXIDE FILM WITH MOLTEN FLUX DURING ALUMINUM BRAZING

ZHANG Qiyun , LIU Shuqi , ZHANG Yuhua , Peking University , Beijing , China

金属学报(英文版)

The interaction of oxide film with molten flux during aluminum brazing has been studied by means of X-ray powder diffraction. The following conclusions have been deduced: The swell- ing of aluminum oxide film is caused by Li~+ inserting into the vacancies of octahedral or tetrahedral structure of 0 atom skeleton in у-Al_2O_3 . The strength of oxide film decreases as the crytallinity increases by the treating of flux containing LiF.

关键词: molten salt flux , null , null

LIQUIDUS OF SYSTEM Ag-Cu-Ge

LIU Shuqi , YI Tao , Peking University , Beijing , China

金属学报(英文版)

The diagram of Ag-Cu-Ge system was constructed from the investigation of 13 internal sec- tions by DTA heating as well as cooling curves in an atomsphere of dry N_2 . The phase dia- gram is subdivided into two pseudo-ternary systems shown as Ag-Cu-Cu_3Ge and Ag-Cu_3Ge-Ge. Both systems belong to simple eutectic type. The ternary eutectic points lie in." E_1, Ag(22.0)-Cu(58.8)-Ge(19.2), 632℃ and E_2 , Ag(44.3)-Cu(29.5)-Ge(26.2), 533℃. The three side binary systems were redetermined.

关键词: phase diagram , null , null

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