TEM specimens from potassium niobate single crystals were observed while being heated in a TEM. DWs and dislocations were observed; the DWs were mobile. In certain cases the DWs became pinned by the dislocations, at least for a short time, most likely due to interaction of strain fields. Both phase changes were observed with accompanying rapid appearance of new domain patterns.
Germanium antimony telluride has been the most used and studied phase-change material for electronic memory due to its suitable crystallization temperature, amorphous to crystalline resistance contrast, and stability of the amorphous phase. In this work, the segregation of Ge in a Ge2Sb2Te5 film of 30 nm thickness during heating inside the transmission electron microscope was observed and characterized. The Ge2Sb2Te5 film was deposited using sputtering on a Protochips Fusion holder and left uncapped in atmosphere for about four months. Oxygen incorporated within the film played a significant r…
The rich phase diagram of bulk Pr$_{1-x}$Ca$_{x}$MnO$_3$ resulting in a high tunability of physical properties gave rise to various studies related to fundamental research as well as prospective applications of the material. Importantly, as a consequence of strong correlation effects, electronic and lattice degrees of freedom are vigorously coupled. Hence, it is debatable whether such bulk phase diagrams can be transferred to inherently strained epitaxial thin films. In this paper, the structural orthorhombic to pseudo-cubic transition for $x=0.1$ is studied in ion-beam sputtered thin films an…
Recrystallisation phenomena in an ultrafine-grained Al-Mg-Si alloy revealed by correlative in situ EBSD and TEM heating
Graz University of Technology（格拉茨工业大学）；Graz Centre for Electron Microscopy (FELMI-ZFE)（格拉茨电子显微镜中心）；Montanuniversität Leoben（莱奥本矿业大学）；Institute of Aeronautics and Space, Brazilian Air Force（巴西空军航空与航天研究所）
On the Feasibility of Extreme Heating Rates in SEM using MEMS Heater Platforms
National Centre for Nano Fabrication and Characterization (DTU Nanolab), Technical University of Denmark (DTU)（丹麦技术大学纳米制造与表征国家中心（DTU Nanolab））；Technical University of Denmark（丹麦技术大学）；Chair of Materials Engineering of Additive Manufacturing, Technical University of Munich（慕尼黑工业大学增材制造材料工程讲席）
Contemporary powder-based polycrystalline nickel-base superalloys inherit microstructures and properties that are heavily determined by the thermo-mechanical treatments during processing. Here, the influence of a thermal exposure alone to an alloy powder is studied to elucidate the controlling formation mechanisms of the strengthening precipitates using a combination of atom probe tomography and in-situ neutron diffraction. The initial powder comprised a single-phase supersaturated gamma only; from this, the evolution of gamma-prime volume fraction and lattice misfit was assessed. The initial …
Characteristic photoluminescence (PL) of nanodiamonds (ND) of very different origin (detonation, HPHT, extracted from meteorite) was studied in situ at high temperatures in the range 20-450C. Luminescence was excited using 473 nm laser and recorded in the range 500-800 nm. In contrast to decrease of point defect PL in bulk diamond with temperature, we found that the nanodiamond luminescence related to ND surface defects increases almost an order of magnitude upon heating to 200-250 C. The observed effect reveals that water adsorbed on ND surfaces efficiently quenches photoluminescence, water d…
Understanding quantitatively the heating dynamics in magnetic tunnel junctions (MTJ) submitted to current pulses is very important in the context of spin-transfer-torque magnetic random access memory development. Here we provide a method to probe the heating of MTJ using the RKKY coupling of a synthetic ferrimagnetic storage layer as a thermal sensor. The temperature increase versus applied bias voltage is measured thanks to the decrease of the spin-flop field with temperature. This method allows distinguishing spin transfer torque (STT) effects from the influence of temperature on the switchi…
Aluminum-germanium nanowires (NWs) thermal activated solid state reaction is a promising system as very sharp and well defined one dimensional contacts can be created between a metal and a semiconductor, that can become a quantum dot if the size becomes sufficiently small. In the search for high performance devices without variability, it is of high interest to allow deterministic fabrication of nanowire quantum dots, avoiding sample variability and obtaining atomic scale precision on the fabricated dot size. In this paper, we present a reliable fabrication process to produce sub-10 nm Ge quan…
Glassy carbon is a graphene-rich form of elemental carbon obtained from pyrolysis of polymers, which is composed of three-dimensionally arranged, curved graphene fragments alongside fractions of disordered carbon and voids. Pyrolysis encompasses gradual heating of polymers above 900 degree C under inert atmosphere, followed by cooling to room temperature. Here we report on an experimental method to perform in situ high-resolution transmission electron microscopy (HR-TEM) for the direct visualization of microstructural evolution in a pyrolyzing polymer in the 500-1200 degree C temperature range…
A dedicated in situ heating setup in a scanning electron microscope (SEM) followed by an ex situ atomic force microscopy (AFM) and electron backscatter diffraction (EBSD) is used to characterize the nucleation and early growth stages of Fe-Al intermetallics (IMs) at 596 °C. A location tracking is used to interpret further characterization. Ex situ AFM observations reveal a slight shrinkage and out of plane protrusion of the IM at the onset of IM nucleation followed by directional growth. The formed interfacial IM compounds were identified by ex situ EBSD. It is now clearly demonstrated that th…
Understanding the interplay between the structure, composition and opto-electronic properties of semiconductor nano-objects requires combining transmission electron microscopy (TEM) based techniques with electrical and optical measurements on the very same specimen. Recent developments in TEM technologies allow not only the identification and in-situ electrical characterization of a particular object, but also the direct visualization of its modification in-situ by techniques such as Joule heating. Over the past years, we have carried out a number of studies in these fields that are reviewed i…
High-resolution in situ analysis of biomass pyrolysis by combining quantitative synchrotron $μ$CT and 3D particle-resolved simulations
Stanford University（斯坦福大学）；Lawrence Livermore National Laboratory（劳伦斯利弗莫尔国家实验室）；University of Illinois at Urbana-Champaign（伊利诺伊大学厄巴纳-香槟分校）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；SLAC National Accelerator Laboratory（SLAC国家加速器实验室）
Dissipation inevitably occurs in first order phase transitions, leading to the irreversible heating. Conversely, the irreversible heating effect could be a clue for the first order phase transition. We measured the temperature change at the magnetic-field-induced alpha-theta phase transition of solid oxygen. The significant temperature increase from 13 to 37 K, amounting to 700 J/mol, is observed due to the irreversible heating at the first order phase transition. We argue that the hysteresis loss of the magnetization curve and the dissipative structural transformation account for the irrevers…
