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1. chinaXiv:201904.00103 [pdf]

A Novel Narrow-Band Green-Emitting Phosphor CsKNaLi(Li3SiO4)4 with the UCr4C4-Related Type Structure

师进生; 王丽丽; 孔晓颖; 李鹏; 兰学芳; 陈倩
Subjects: Materials Science >> Electronic, Optical and Magnetic Materials

我们成功合成了CsKNaLi(Li3SiO4)4:Eu2+ (CKNLLSO:Eu2+)作为UCr4C4型结构氧基家族的新成员。该荧光粉的基质化合物的晶体结构和能带结构分别通过Rieveld精修方法和密度泛函理论分析和计算。由于高度压缩和刚性的阴离子骨架,取代Cs格位的Eu2+在InGaN基紫外LED的激发下,发出了明亮的绿色荧光,半峰宽为55 nm.当温度升高到190℃时,CKNLLSO:Eu2+的稳定性仍然较好。采用浓度优化的CKNLLSO:4%Eu2+制成的LED器件发出的绿光的色坐标为(0.2320, 0.6016),相关色温为7314K。分析结果表明,这种荧光粉是一种很有前景的白光LED绿色荧光粉。

submitted time 2019-04-30 Hits905Downloads264 Comment 0

2. chinaXiv:201902.00003 [pdf]

Magnetic field-dependent reversal effect of the electromagnet- induced normal stress of magnetorheological materials

Taixiang Liu; Yangguang Xu; Ke Yang; Lianghong Yan; Beicong Huang; Zhuo Zhang; Xiaodong Jiang; Hongwei Yan
Subjects: Materials Science >> Materials Mechanics

Magnetorheological (MR) materials are a type of magnetoactive smart materials, whose physical or mechanical properties can be altered by applying a magnetic field. In usual, MR materials can be prepared by mixing magnetic particles into non-magnetic matrices. In this work, the electromagnet-induced (or non-uniform magnetic field-induced) normal stress of MR materials is studied. It shows that the stress does not vary monotonically along with the enhancement of the applied magnetic field. There exists a field-dependent reversal effect of the variation of the stress. The reversal effect is thought resulting from that the ratio of interparticle repellent of parallel magnetic particles to the particle-electromagnet attraction gets enlarged along with the enhancement of the field.

submitted time 2019-02-01 Hits683Downloads361 Comment 0

3. chinaXiv:201809.00158 [pdf]

Text_Figs_new.pdf

刘伟
Subjects: Materials Science >> Metals and Alloys

理解合金元素如何调制金属材料的弹性模量在固体物理理论及金属材料的机械性能的工程设计领域都很重要。本文采用第一性原理方法计在合金原子浓度在 0.4 到 1.85 at% 范围内 12 种铁基固溶体的弹性模量并研究合金元素对 bcc 铁基体弹性模量的机制。

submitted time 2018-09-14 Hits1228Downloads556 Comment 0

4. chinaXiv:201809.00002 [pdf]

Pressure-Induced Indirect-Direct Bandgap Crossover and Bandgap Engineering in Ductile Semiconductor Ag3PO4 with Negative Linear Compressibility

Lu, Yang; Zhu, Shengcai; Huang, Eugene; He, Yu; Ruan, Jiaji; Yan, Hao
Subjects: Materials Science >> Materials Science (General)

Silver orthophosphate (Ag3PO4) has aroused widespread interest since the discovery of visible-light-driven photocatalysis activity. However, its indirect bandgap nature at ambient becomes an obstacle to improve the photocatalysis efficiency and use in other application fields. In this study, the indirect-to-direct bandgap crossover was found during the pressure-induced phase transition from cubic to trigonal phase in Ag3PO4. The observed bandgap narrowing could be partially retained after pressure was released to ambient conditions, accelerating to efficiently utilize the solar spectrum. Moreover, Ag3PO4 was ductile like metals. Unexpectedly, this ion-conducting and ductile semiconductor photocatalyst further exhibited the negative linear compressibility (NLC) at pressure range of 7.5-25 GPa. This work, combining experimental and theoretical tools, provides an insight into the modulation mechanism of the electronic structure for silver-based semiconductors, and may broaden the applications of Ag3PO4.

submitted time 2018-09-03 Hits996Downloads493 Comment 1

5. chinaXiv:201801.00700 [pdf]

Morphogenesis of nacreous aragonite tablets: lessons from domed sheet nacre

Zhang, Gangsheng
Subjects: Materials Science >> Materials Chemistry

生物矿化领域的研究者普遍接受珍珠层板片是由非晶质碳酸钙(ACC)纳米颗粒相变而成。然而,这些纳米颗粒在三维空间是如何排列的及如何相变的仍未清楚。本文首次报道了一种新类型不成熟板片,即“枝晶状板片”。这种板片发育在翡翠贻贝珍珠层中。通过与颗粒状板片形貌进行对比,我们发现ACC纳米颗粒通常自组装成垂直的团簇且相变成垂直定向的文石小晶体。这种小晶体与无机成因的文石晶体的平衡形状相同。最重要的是,我们首次发现文石板片与层间有机膜(ILM)呈高的接触角(99-126度)。这表明ILM对ACC纳米颗粒是非润湿的。这种非润湿性可能对珍珠层的形貌成因有重要影响。

submitted time 2018-01-27 Hits1486Downloads768 Comment 1

6. chinaXiv:201711.02640 [pdf]

金掺杂降低碳纳米管接触电阻的实验研究

刁加加,; 常春蕊,; 张志明,; 张好强,; 孙红婵,; 安立宝
Subjects: Materials Science >> Materials Science (General)

降低与金属之间的接触电阻是碳纳米管在微纳电子领域获得应用的前提,掺杂金纳米粒子可有效降低碳纳米管的接触电阻。本文采用高温焙烧在碳纳米管表面构造缺陷和亲水基团,然后将碳纳米管在氯金酸水溶液中超声浸泡以吸附氯金酸,再在氢气气氛下加热还原氯金酸为金。扫描电子显微(SEM)图片表明碳纳米管被成功地掺杂了金纳米粒子,X射线能量散射谱(EDS)和X射线光电子谱(XPS)表明金是唯一掺杂在碳纳米管上的粒子。掺杂后碳纳米管的拉曼光谱中G带波数降低说明对碳纳米管掺杂金为N型掺杂。N型掺杂剂将电子转移给邻近的碳原子,使碳纳米管中的电子数量增加,进而增强了碳纳米管的导电性。利用介电电泳法将碳纳米管组装到一对金电极之间,并使用精密电感电容电阻(LCR)测试仪实时测量。结果表明碳纳米管与金电极之间的接触电阻较掺杂前得到了有效改善,电阻值最大可降低近50%。

submitted time 2017-11-21 From cooperative journals:《材料研究学报》 Hits16920Downloads1030 Comment 0

7. chinaXiv:201711.02643 [pdf]

石蜡/硅藻土定型相变材料的结构和热性能

赵思勰,; 晏华,; 李云涛,; 汪宏涛,; 胡志德
Subjects: Materials Science >> Materials Science (General)

以硅藻土为载体、以石蜡为相变材料,用溶剂蒸发法制备出石蜡/硅藻土定型相变材料(PA/D-PCMs),使用SEM、FT-IR、TGA、DSC等手段对其微观结构和热性能进行了表征。结果表明:硅藻土对石蜡的毛细管力及两者之间形成的氢键能阻碍液态石蜡的渗出,使PA/D-PCMs具有很高的热稳定性,硅藻土的二级孔洞限制了部分石蜡的结晶。硅藻土内部有许多互相连通的导热通道,增强了石蜡的导热效果并提高了蓄放热速率。随着石蜡含量的增大PA/D-PCMs的X、Y和Z轴传热通道上声子的散射作用更剧烈,使其导热系数降低,但是具有更高的结晶度和相变潜热。为了保证PA/D-PCMs的结构稳定和良好的热性能,石蜡的最佳质量分数为45%。

submitted time 2017-11-21 From cooperative journals:《材料研究学报》 Hits16369Downloads991 Comment 0

8. chinaXiv:201711.02644 [pdf]

水不溶性铝源合成金属有机骨架MIL-53(Al)及其对洛克沙胂的吸附

侯书亮,; 卢慧宫,; 顾逸凡,; 马小亮,; 吴一楠,; 王颖,; 李风亭
Subjects: Materials Science >> Materials Science (General)

以氧化铝、氢氧化铝、勃姆石为水不溶性金属源,用水热法合成了金属有机骨架MIL-53(Al)。使用SEM、XRD、氮气吸附和TGA表征了产物的形貌和结构,并与用传统水溶性硝酸铝合成的MIL-53(Al)对比。结果表明:使用三种水不溶性金属源都能合成典型的金属有机骨架材料MIL-53(Al)。用水热法制备的MIL-53(Al)产物的BET比表面积都在700~1000 m2/g。结果还表明,使用三种水不溶性金属源合成的MIL-53(Al)骨架的柔性(flexibility)与用常规铝硝酸盐合成的MIL-53(Al)不同。使用氧化铝合成的MIL-53(Al)常温下的孔道主要呈现大孔(lp)结构且骨架刚性较强。与使用其他铝源合成的MIL-53(Al)相比,用氧化铝合成的MIL-53(Al)对洛克沙胂有较好的吸附去除效果,吸附过程符合二级动力学模型。

submitted time 2017-11-21 From cooperative journals:《材料研究学报》 Hits13839Downloads1060 Comment 0

9. chinaXiv:201711.02646 [pdf]

聚醚改性MQ树脂增强聚氨酯弹性体

卢秋影,; 姜宏伟
Subjects: Materials Science >> Materials Science (General)

在聚氧化丙烯多元醇(PPG)和二苯基甲烷二异氰酸酯(MDI)组成的交联聚氨酯(CPU)体系的基础上添加聚醚改性MQ树脂(E-MQ),制备出E-MQ树脂增强的浇注型聚氨酯弹性体。结果表明:E-MQ树脂与CPU有良好的相容性,制备出的E-MQ增强弹性体具有良好的力学性能。当E-MQ树脂用量为8%(E-MQ树脂占聚氨酯弹性体总质量分数)时增强聚氨酯弹性体的拉伸强度可达20.8 MPa,比CPU基础样提高22.4%,撕裂强度为82 kNm-1,邵尔A硬度为82度。

submitted time 2017-11-21 From cooperative journals:《材料研究学报》 Hits14400Downloads990 Comment 0

10. chinaXiv:201711.02645 [pdf]

11.5CrNbTi和15Cr0.5MoNbTi超纯铁素体不锈钢的循环蠕变行为

应彩虹,; 陈立佳,; 刘天龙,; 郭连权
Subjects: Materials Science >> Materials Science (General)

对11.5CrNbTi和15Cr0.5MoNbTi超纯铁素体不锈钢进行650℃应力控制循环蠕变实验,研究了最大外加应力处引入的保持时间对铁素体不锈钢的循环蠕变变形和断裂行为的影响。结果表明:保持时间的延长使这两种不锈钢的最小循环蠕变速率增大,循环蠕变寿命和循环断裂周次减少。在相同的条件下,15Cr0.5MoNbTi不锈钢的循环蠕变抗力优于11.5CrNbTi不锈钢。这两种不锈钢的循环蠕变断裂模式均为穿晶断裂,随着保持时间的延长断口表面的蠕变孔洞增多,蠕变损伤作用增强。这两种不锈钢循环蠕变后的微观组织均为亚晶,位错的滑移和交滑移是循环蠕变的主要变形机制。

submitted time 2017-11-21 From cooperative journals:《材料研究学报》 Hits14318Downloads932 Comment 0

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