Bi底层对FePt薄膜的影响

利用磁控溅射的方法，在玻璃基片上制备了以Bi为底层的FePt薄膜，经不同温度真空热处理得到L1₀-FePt薄膜.研究了Bi做底层对FePt薄膜的有序化温度及矫顽力H_c的影响.实验结果表明：以Bi做底层的FePt薄膜在350℃实现低温有序，同时其H_c也有大幅度提高，并且可以在更大成分范围内获得H_c较高的L1₀-FePt薄膜.利用X射线光电子能谱研究了薄膜中Bi原子的分布情况，利用X射线衍射研究了薄膜的晶体学结构变化.结果表明,Bi底层在退火过程中的扩散促进了FePt薄膜有序度的升高. 关键词： 0-FePt薄膜')" href="#">L1₀-FePt薄膜 有序化温度 底层 扩散     

Spin pumping at the Co2FeAlo.sSio.5/Pt interface

Spin pumping at the Co2FeAlo.sSio.5/Pt and Pt/Co2FeAIo.sSio.5 interfaces has been studied by ferromagnetic res- onance technology （FMR）. The spin mixing conductance of the Co, FeA~o.sSio.s/Pt and Pt/Co2FeAlo.sSio.5 interfaces was determined to be 3.7~ lO19 m-2 and 2.1 ~ lO19 m 2 by comparing the Gilbert damping in a Co2FeAIo.sSio.5 sin- gle film, Co2FeAlo.sSio.s/Pt bilayer film and a Pt/Co2FeAIo.sSio.s/Pt trilayer film. Spin pumping is more efficient in the Co2FeAlosSios/Pt bilayer film than in permalloy/Pt bilayer film.     

Copolymerization and Properties of Multicomponent Crosslinked Hydrogels

A series of multicomponent hydrogels were prepared by the copolymerization of hydrophobic silicon-containing monomer 3-bis(trimethylsilyloxy) methylsilylpropyl glycerol methacrylate(Si MA) with the solvent-responsive monomers 2-hydroxyethyl methacrylate(HEMA) and N-vinyl pyrrolidone(NVP) and thermosensitive monomer N,N-dimethyl acrylamide(DMA). 2-Hydroxy-2-methyl phenyl acetone(D-1173) was chosen as UV initiator and five different dienes/triene monomers were selected as crosslinking agent in order to select the best crosslinker. The ethanol extraction experiments as well as the FTIR, DSC and TG results showed that the copolymerization was effective. The optical, permeability, and mechanical analysis results demonstrated that the obtained hydrogels were highly transparent with good oxygen permeability and mechanical properties. And the impact of crosslinker on the mechanical properties of the hydrogels was also discussed in detail. The basic results demonstrated that the obtained hydrogels had good stimuli-responsive effects to both p H value and solvent.     

乙酸铵浸提原子吸收光谱法同时测定土壤交换性盐基离子组成

采用乙酸铵浸提,研究了利用原子吸收光谱法(AAS)同时测定土壤交换性Ca,Mg,K,Na的方法。结果表明,AAS法测定交换性盐基离子组成的准确度符合参比标准的要求;66个供试土样交换性Ca和Mg平行样品相对误差分别为0.02%～3.14%和0.06%～4.06%,平均相对误差分别为1.22%和1.25%。AAS法和火焰光度法(FP)测定交换性K和Na相对误差值分别为0.06%～8.93%和0.06%～1.54%,平均相对误差分别为3.72%和0.56%。实例研究结果表明AAS同时测定土壤交换性盐基离子组成方法可靠,可真实反映农田土壤交换性能的状况。     

择优掺杂的La-Ca-Na-Mn-O体系的庞磁电阻效应

利用溶胶-凝胶法制备出择优掺杂的名义组分为La_(1-x)(Ca_(1-y)Na_y)_xMnO_3(LCNM)的多晶样品.xRD测试表明样品均为钙钛矿结构.电输运测试表明所有样品均发生金属-绝缘体转变和顺磁一铁磁转变(转变温度分别用T_m和T_c表示),转变温度随Na含量的增加而增加,但是由于Ca,Na离子间价态的不同引起的磁不均匀性,同时含Ca和Na的样品电输运曲线在T_m温度以下出现肩型鼓包,同时表现出增宽的顺磁·铁磁转变过程,磁电阻测量发现所有样品均表现出庞磁电阻(CMR)效应,但是由于磁不均匀性,y约为0.25的样品表现出两个CMR峰.     

硅含量对Al2O3-SiO2气凝胶结构和性能的影响

研究了硅含量对Al2O3-SiO2气凝胶结构和性能的影响.结果表明,随着硅含量的增加,Al2O3-SiO2溶胶的凝胶时间逐渐延长,气凝胶密度逐渐增大.其结构逐渐由多晶勃姆石向无定形SiO2过渡.Al2O3-SiO2气凝胶同时含有Al-O、Si-O以及Al-O-Si结构,600 ℃煅烧后的物相为无定形γ-Al2O3和SiO2,1 200 ℃煅烧后为莫来石相.当硅含量为6.1wt%～13.1wt%时,适量的硅抑制了Al2O3-SiO2气凝胶的相变,其1 000℃的比表面积(339～445 m2·g-1)高于纯Al2O3气凝胶(157 m2·g-1).SEM分析表明,硅元素的加入改变了Al2O3气凝胶的结构形貌,随着硅含量的增大,Al2O3-SiO2气凝胶逐渐由针叶状或长条状向球状颗粒转变.     

应力下SmNiO_3钙钛矿氧化物薄膜材料的电导与红外光电导

稀土镍基钙钛矿氧化物RNiO_3(R为稀土元素)可以在温度触发下发生从电子游离态到局域态的金属绝缘体转变,这一特性在传感器,数据存储,调制开关等方面具有可观的应用价值.本文通过脉冲激光沉积法,在钛酸锶(SrTiO_3)、铝酸镧(LaAlO_3)单晶衬底上准外延生长热力学亚稳态镍酸钐(SmNiO_3)薄膜材料,利用薄膜与衬底间晶格失配引入界面应力,实现对SmNiO_3电子轨道结构与金属绝缘体相变温度的调节.结合电输运性质与红外透射实验的综合表征研究,论证了双向拉伸应变引起的晶格双向拉伸畸变,可以引起SmNiO_3的禁带宽度的展宽,从而稳定绝缘体相并提高金属-绝缘相转变温度.进一步结合近边吸收同步辐射实验表征,揭示了拉伸应变稳定SmNiO_3绝缘体相的本质在于Ni—O成键轨道在双向拉伸形变作用下的弱化,使得镍氧八面体中的价电子偏离镍原子从而稳定SmNiO_3的低镍价态绝缘体相.     

合成反铁磁Ni81Fe19/Co90Fe10/Ru/Co90Fe10/Ni81Fe19的研究

采用直流磁控溅射方法制备了一系列的合成反铁磁及以其为自由层的自旋阀.研究发现,在Ni₈₁Fe₁₉与Ru层之间插入适当厚度的Co₉₀Fe₁₀层后,可有效地提高合成反铁磁两磁性层间的反铁磁耦合强度,得到具有饱和场H_s更高、饱和磁化强度M_s更低、热稳定性更好的合成反铁磁.另外,以这种合成反铁磁作自旋阀的自由层时,可有效提高自旋阀的稳定性. 关键词： 合成反铁磁 退火 自旋阀     

Observation of banded spherulites and lamellar structures by atomic force microscopy

Spherulites are common structures of semi-crystalline polymers. It has been known that semi-crystalline polymers can form spherulites when crystallized from solution or from melt. A dark Maltese cross of a spherulite could be easily observed under the polarized optical microscopy (POM). Moreover, some spherulites show an additional alternating dark and bright concentric ring structure that is attributed to the regular twisting of the radial crystallite ribbons as they grow from the spherulit…     

分散液相微萃取-气相色谱-质谱法测定环境水样中5种芳香胺的含量北大核心CSCD

向5mL水样中加入0.1g NaCl,溶解后加入50μL三氯甲烷(萃取剂)和300μL丙酮(分散剂),以4 000r·min-1的转速离心2min。采用气相色谱-质谱法测定所得有机相中5种芳香胺的含量,以内标法定量。结果表明:5种芳香胺的质量浓度在一定范围内与其峰面积与内标的峰面积的比值呈线性关系,检出限(3S/N)为0.000 1～0.001 5mg·L-1。以实际空白水样为基体进行加标回收试验,回收率为94.7%～106%,测定值的相对标准偏差(n=6)均小于5.0%。