Hongwei QIN
,
Jifan HU
,
Juan CHEN
,
Hongdong NIU
,
Luming ZHU
,
Zhuo WANG
材料科学技术（英文）
by Tb in (La1-xTbx)0.67Sr0.33MnO3, the room temperature magnetoresistance △R/R0 drops at first, then undergoes an increase near x≈0.1, and finally drops again. The value of room temperature magnetoresistance at a field H=12 kOe for (La1-xTbx)0.67Sr0.33MnO3 is -3.56%. The enhancement of the room temperature magnetoresistance induced by an appropriate Tb substitution in (La1-xTbx)0.67Sr0.33MnO3 is correlated with the shifts of the Curie temperature and metal-insulator temperature to near room temperature. The drop of the room temperature magnetoresistance at large Tb doping-contents may be due to its lower TC and TMI far from the room temperature.
关键词:
Magnetoresistance
,
null
,
null
,
null
席俊华
,
季振国
,
刘坤
,
王超
,
杜鹃
无机材料学报
doi:10.3724/SP.J.1077.2006.01506
利用溶胶-凝胶法结合高温热处理在硅衬底上制备了掺Mn硅酸锌薄膜, 用XRD、SEM、UV-Vis吸收谱和PL谱测试了样品的结晶性能与光学性能, 并分析了热处理温度对掺Mn硅酸锌薄膜的结晶性能和光学性能的影响. 实验结果发现, ZnO的适量存在对掺Mn薄膜的发光有增强作用. 进一步的分析认为, 这一现象的机理可由G.G. Qin提出的量子约束-发光中心 (QCLC) 模型进行解释, ZnO中受激发的电子和空穴通过隧穿效应到达硅酸锌基体中复合发光, 从而增强发光强度.
关键词:
硅酸锌
,
ZnO
,
photoluminescence
,
quantum confinement-luminescence center
Materials Research Bulletin
Through analysis of the latest experimental results reported in the literature and obtained in our laboratory, we have extended our previous quantum confinement/luminescence center model for the photoluminescence mechanism of porous Si and of nanometer-silicon-particle-embedded Si oxide films (G.G. Qin and Y.Q. Jia, Solid State Commun. 86, 559 (1993)). We consider that there are three main types of competitive photoexcitation/photoemission processes and that the process in which photoexcitation occurs in the nanometer silicon particles (NSPs) while photoemission occurs in the luminescence centers (LCs) in the SiOx layers very close to the NSPs is usually the major one. We discuss under what conditions the other two types of processes will dominate. We believe that the extended quantum confinement/luminescence center model is a physical model that is suitable for the photoluminescence from silicon oxide films embedded with NSPs or nanometer Ge particles (NGPs), as well as from oxidized porous Si. (C) 1999 Elsevier Science Ltd.
关键词:
oxides;luminescence;defects;blue-light emission;visible luminescence;optical-properties;nanocrystals;mechanism;dependence;sio2-films;absorption;spectra;defects
Physical Review B
In response to the comment by Wang and Qin, we have rewritten our equation (22) following the coordinate system of Dina, et al. [J. Wuhan Univ. (Nature Science Edition) 3, 23 (1992)]. According to the thermodynamic stability condition and the experiment of Capitan et al., we have chosen the new parameters of the phason elastic constants. Based on this, we have recalculated the coefficients of the expressions on the vibrational denty of states and the specific heat of the icosahedral Al-Nin-Pd quasicrystal. Our results are still in agreement with the experimental data measured by Walti et al. [Phys. Rev. B 57, 10 504 (1998)]. It demonstrates that our method is useful for dealing with the low-temperature vibrational excitation of icosahedral quasicrystals.
关键词:
quasi-crystals;diffuse-scattering
席俊华
,
季振国
,
刘坤
,
王超
,
杜鹃
无机材料学报
doi:10.3321/j.issn:1000-324X.2006.06.038
利用溶胶-凝胶法结合高温热处理在硅衬底上制备了掺Mn硅酸锌薄膜,用XRD、SEM、UV-Vis吸收谱和PL谱测试了样品的结晶性能与光学性能,并分析了热处理温度对掺Mn硅酸锌薄膜的结晶性能和光学性能的影响.实验结果发现,ZnO的适量存在对掺Mn薄膜的发光有增强作用.进一步的分析认为,这一现象的机理可由G.G.Qin提出的量子约束-发光中心(QCLC)模型进行解释,ZnO中受激发的电子和空穴通过隧穿效应到达硅酸锌基体中复合发光,从而增强发光强度.
关键词:
硅酸锌
,
氧化锌
,
光致发光
,
量子约束-发光中心
刘守平
,
周上祺
,
王佳眉
,
任勤
腐蚀学报（英文）
用金相显微镜、扫描电镜、X射线衍射仪和X射线能谱仪对天然气井油管悬挂器腐蚀失效进行了检测分析，并对天然气井油管悬挂器用35CrMo钢进行了盐雾试验，结果表明，天然气中的水和CO2是引起腐蚀的主要介质，腐蚀产物主要是FeCO3，高速天然气冲刷和钢中的非金属夹杂加剧了腐蚀的速度.
CORROSION FAILURE ANALYSIS OF AN OIL TUBE USED IN NATURAL GAS WELL
LIU Shou-ping,ZHOU Shang-qi,WANG Jia-mei,REN Qin
Chongqing University
A failed oil tube used in natural gas well was examined by optical microscope,scanning electron microscope ,X-ray diffractometer and X-ray spectrometer.Corrosion behavior of 35CrMo steel samples of the oil tube were investigated by means of salt spray tests in the laboratory.The results show that CO2 and H2O are primary factors in the corrosion of oil tube.The corrosion product is FeCO3,non-metallic inclusions in the steel and erosion of natural gas fluid played an important role in accelerating the corrosion.
oil tube;
natural gas well；
35CrMo steel；
failure analysis；
corrosion
关键词:
悬挂器
,
null
,
null
,
null
X. Chang
,
K. Qin and Y.L.Lu Orthodontic Department of Stomatology College
,
China Medical University
,
Sheny ang 110001
,
China
金属学报(英文版)
proach change of CGRP with time in periodontal ligaments of rats in magnetic field, maxillae of 28 Wistar rats of 6 7 weeks were placed in magnetic fields of permanent magnets Nd 2 Fe 4 B. Changes of CGRP with t ime in maxillary periodontal ligaments of the rats were studied by immunohistochemistry. The result showed that: magnetic field had dynamic effect and some promotional effect on recove?E F F E C T O F M A G N E T I C F I E L D O N C A L C I T O N I N G E N E- R E L A T E D P E P T I D E I N P E R I O D O N T A L L I G A M E N T S O F R A T S X. Chang , K. Qin and Y. L. Lu Orthodontic Department of Stomatology College , China Medical University , Shenyang 110001 , China Manuscript received 24 June 1999 In order to approach change of C G R P with tim e in periodontal liga m ents of rats in m agneticfield , m axillae of 28 Wistar rats of 6 7 weeks w ere placed in m agnetic fields of per m anentm agnets Nd 2 Fe4 B. Changes of C G R P with tim e in m axillary periodontal liga ments of therats were stu died by i m m unohistoche mistry . The result sho wed that : m agnetic field had dy na m ic effect an d so m e pro motional effect on recovering and reconstruction of the periodontaltissues in it . This provided a better theoretical evidence for clinical use of per m anent m agnets .
关键词:
per m anent m agnet Nd 2 Fe4 B
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null
,
null
,
null
