摘要 利用DSC、XRD、拉曼光谱和红外显微镜研究了富含Te的Ge 20 Se y Te 80−y 红外硫属化物玻璃(y高达8 at.%)。玻璃化转变、结晶和熔化现象的彻底非等温热动力学表征根据粒径进行。Tool-Narayanaswamy-Moynihan 模型成功地用于描述结构松弛过程;然后根据拉曼光谱检测到的特征结构单元的结构变化和运动来解释弛豫参数的组成演变。成核-生长 Johnson-Mehl-Avrami 模型和经验自催化模型用于描述 DSC 结晶数据的复杂动力学。基于XRD和显微分析,揭示了以下结晶机制:六方Te(表面定位)的初始成核-生长沉淀,然后是菱面体GeTe的本体定位自催化生长;在较高 Se 含量的情况下,在高温下会额外形成 Ge-Te-Se 晶相。为增加 Se 含量而确定的更高玻璃稳定性可能与结晶过程的部分抑制有关,但初始 Te 沉淀仍然存在,然而,一旦 Se 含量达到~4
Abstract Synthesis of tellurides and selenides of Hg, Cd, Zn, Ge, Sn and Pb at temperatures considerably below the melting point of the compounds, was studied. The reaction went to completion within a few days.
Combustion synthesis is a novel technique that utilizes the exothermic heat of a chemical reaction to maintain the reaction and to rapidly prepare materials. But, hitherto, none of unified criterion for the validation of combustion synthesis has been proposed. Herein, we proposed the conditions need to be met. In terms of kinetics, at the adiabatic temperature (Tad), the diffusion distance of atoms
燃烧合成是一种利用化学反应的放热来维持反应并快速制备材料的新技术。但是,迄今为止,尚未提出用于验证燃烧合成的统一标准。在此,我们提出了需要满足的条件。就动力学而言,在绝热温度(T ad)下,原子的扩散距离(升Ť广告)在0.1 s内应大于反应物的粒径(d), 那是, 升Ť广告≥d。对于满足T ad / T m,L的系统≥1(其中T m,L是反应物的低熔点成分的熔点),液相的存在将原子的扩散距离从纳米显着增加到数十微米,从而成为标准升Ť广告≥d简化为T ad / T m,L≥在大多数情况下为1。在热力学方面,系统需要确保反应成分处于激活状态,即T ad / T m,H ≥0.7,其中T m,H是高熔点组分的熔点。本研究提出的SHS反应标准进一步提高了对SHS反应的理论理解,并为探索二元和多组分化合物的超快合成提供了指导。
Thermal behavior of Ge20SeyTe80−y infrared glasses (for y up to 8 at.%)
作者:Roman Svoboda、Daniela Brandová、Jiří Málek
DOI:10.1016/j.jallcom.2016.04.165
日期:2016.9
Abstract The Te-rich Ge 20 Se y Te 80−y infrared chalcogenide glasses (for y up to 8 at.%) were studied by means of DSC, XRD, Raman spectroscopy and infrared microscopy. Thorough non-isothermal thermo-kinetic characterization of the glass transition, crystallization and melting phenomena was performed in dependence on the particle size. The Tool–Narayanaswamy–Moynihan model was successfully used to
摘要 利用DSC、XRD、拉曼光谱和红外显微镜研究了富含Te的Ge 20 Se y Te 80−y 红外硫属化物玻璃(y高达8 at.%)。玻璃化转变、结晶和熔化现象的彻底非等温热动力学表征根据粒径进行。Tool-Narayanaswamy-Moynihan 模型成功地用于描述结构松弛过程;然后根据拉曼光谱检测到的特征结构单元的结构变化和运动来解释弛豫参数的组成演变。成核-生长 Johnson-Mehl-Avrami 模型和经验自催化模型用于描述 DSC 结晶数据的复杂动力学。基于XRD和显微分析,揭示了以下结晶机制:六方Te(表面定位)的初始成核-生长沉淀,然后是菱面体GeTe的本体定位自催化生长;在较高 Se 含量的情况下,在高温下会额外形成 Ge-Te-Se 晶相。为增加 Se 含量而确定的更高玻璃稳定性可能与结晶过程的部分抑制有关,但初始 Te 沉淀仍然存在,然而,一旦 Se 含量达到~4
Atomic Layer Deposition of Metal Tellurides and Selenides Using Alkylsilyl Compounds of Tellurium and Selenium
germanium antimony telluride (GST) has been attempted only using plasma-assisted processes owing to the lack of appropriate tellurium precursors. In this paper we make a breakthrough in the development of new ALD precursors for tellurium and selenium. Compounds with a general formula (R3Si)2Te and (R3Si)2Se react with various metal halides forming the corresponding metal tellurides and selenides. As
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Te via Reducing the Phase‐Transition Temperature and Introducing Resonant Energy Doping
作者:Min Hong、Zhi‐Gang Chen、Lei Yang、Yi‐Chao Zou、Matthew S. Dargusch、Hao Wang、Jin Zou
DOI:10.1002/adma.201705942
日期:2018.3
GeTe with rhombohedral‐to‐cubic phase transition is a promising lead‐free thermoelectric candidate. Herein, theoretical studies reveal that cubic GeTe has superior thermoelectric behavior, which is linked to (1) the two valence bands to enhance the electronic transport coefficients and (2) stronger enharmonic phonon–phonon interactions to ensure a lower intrinsic thermal conductivity. Experimentally
具有菱形-立方相变的GeTe是有前途的无铅热电候选物。在这里,理论研究表明,立方晶格特具有优异的热电性能,这与(1)两个价带可提高电子输运系数和(2)较强的共谐声子-声子相互作用以确保较低的固有热导率有关。实验上,基于Ge 1− x Sb x在优化载流子浓度的情况下,通过进一步掺杂In可以达到2.3的创纪录高品质因数,这会引起费米能级附近的态密度失真。此外,Sb和In共掺杂降低了相变温度,从而将立方GeTe的更好的热电性能扩展到了低温。此外,电子显微镜表征还显示出晶界,高密度堆垛层错和纳米级析出物,再加上不可避免的点缺陷,导致热导率急剧下降。基础研究和实验演示为高性能无铅热电材料的开发提供了重要方向。