Heating Transmission Electron Microscopy Research Articles

A general synthesis of inorganic nanotubes as high-rate anode materials of sodium ion batteries

Inorganic tubular materials have an exceptionally wide range of applications, yet developing a simple and universal method to controllably synthesize them remains challenging. In this work, we report a vapor-phase-etching hard-template method that can directly fabricate tubes on various thermally stable oxide and sulfide materials. This synthesis method features the introduction of a vapor-phase-etching process to greatly simplify the steps involved in preparing tubular materials and avoids complicated post-processing procedures. Furthermore, the in-situ heating transmission electron microscopy (TEM) technique is used to observe the dynamic formation process of TiO2−x tubes, indicating that the removal process of the Sb2S3 templates first experienced the Rayleigh instability, then vapor-phase-etching process. When used as an anode for sodium ion batteries, the TiO2−x tube exhibits excellent rate performance of 134.6 mA h g−1 at the high current density of 10 A g−1 and long-term cycling over 7000 cycles. Moreover, the full cell demonstrates excellent cycling performance with capacity retention of 98% after 1000 cycles, indicating that it is a promising anode material for batteries. This method can be expanded to the design and synthesis of other thermally-stable tubular materials such as ZnS, MoS2, and SiO2.

Formation of Face-Centered Cubic Phase in Ti35 Alloy Under In Situ Heating Transmission Electron Microscopy

Formation of Face-Centered Cubic Phase in Ti35 Alloy Under In Situ Heating Transmission Electron Microscopy

Microstructure-Dependent Thermal Stability of Super-Tetragonal Nanocomposite Films through In Situ TEM/EELS Study.

Smart microstructure design in nanocomposite films allows us to tailor physical properties such as ferroelectricity and thermal stability to broaden applications of next-generation electronic devices. Here, we study the thermal stability of self-assembled PbTiO3 (PTO)/PbO nanocomposite films with nano-spherical and nanocolumnar microstructures by utilizing an environmental transmission electron microscopy (TEM) combined with electron energy loss spectroscopy (EELS). The real-time study reveals that the microstructure-dependent interphase strain has an effect on the stabilization of the tetragonal phase. Compared to the nano-spherical configuration, the nanocomposite film with the nanocolumnar microstructure can maintain the giant tetragonality of ∼1.20 up to 450 °C, and the tetragonal phase is predicted to be stable at elevated temperatures > 600 °C. Moreover, the temperature-dependent EELS further demonstrates the sensitivity of the chemical bonding of Pb and Ti with O to the PTO lattice distortion, correlating the structural variation and electronic properties at different temperatures. Such in situ heating TEM study provides insights into the thermal stability of nanocomposites with different microstructures and facilitates the advancement of power electronics applications in harsh environments.

Atomic-Scale Investigation of the Reversible α- to ω-Phase Lithium Ion Charge – Discharge Characteristics of Electrodeposited Vanadium Pentoxide Nanobelts

Using an electrochemical potential pulse methodology in a mixed solvent system, electrochemical deposition of amorphous vanadium pentoxide (V2O5) nanobelts is possible. Crystallisation of the material is achieved using in air annealing with the temperature of crystallisation identified using in-situ heating transmission electron microscopy (TEM). The resulting α-phase V2O5 nanobelts have typical thicknesses of 10-20 nm, widths and lengths in the range 5-37 nm (mean 9 nm) and 15 - 221 nm (mean 134 nm), respectively. One-cycle reversibility studies for lithium intercalation (discharge) and de-intercalation (charge) reveal a maximum specific capacity associated with three lithium ions incorporated per unit cell, indicative of ω-Li3V2O5 formation. Aberration corrected scanning TEM confirm the formation of ω-Li3V2O5 across the entirety of a nanobelt during discharge and also the reversible formation of the α-V2O5 phase upon full charge. Preliminary second cycle studies reveal reformation of the ω-Li3V2O5, accompanied with a morphological change in the nanobelt dimensions. Achieving α-V2O5 to ω-Li3V2O5 to α-V2O5 reversibility is extremely challenging given the large structural rearrangements required. This phenomenon has only been seen before in a very limited number of studies, mostly employing nanosized V2O5 materials and never before with electrodeposited material. Figure 1

Thermal-Induced Alterations In Lunar Soil Grains Revealed Via In Situ TEM Heating

Impact-induced thermal modifications occur frequently in the solar system, and the microstructures of extraterrestrial samples can reveal the thermal-induced alterations that have occurred to their parent bodies. The characterization and reproduction of these sub-micron features are challenging and require new analytical techniques. The combination of a dual-beam system and transmission electron microscopy (TEM) techniques, with in situ TEM heating, is a promising method. This method can be used to systematically understand the chemical and microstructural changes in extraterrestrial samples resulting from thermal-induced alterations. To better reproduce the microstructures observed in the Chang′E-5 soil grains, a comprehensive series of TEM experiments was conducted by varying the in situ heating conditions and starting materials, including Martian meteorites and Earth samples. The experimental results showed that the nanophase iron (np-Fe0) particles, which appeared in both Fe-rich pigeonite and Fe-poor olivine, as well as the np-Fe0 content and morphology, varied with increasing heating time (0 – 90 min) at 800 °C. These results indicated that the formation mechanism of np-Fe0 particles varied in different matrices. Therefore, our established approach can reveal the thermal-induced alterations in celestial bodies and can be applied effectively for studying the formation of microscopic features in extraterrestrial bodies.

In situ multiscale probing of the synthesis of a Ni-rich layered oxide cathode reveals reaction heterogeneity driven by competing kinetic pathways.

Nickel-rich layered oxides are envisaged as key near-future cathode materials for high-energy lithium-ion batteries. However, their practical application has been hindered by their inferior cycle stability, which originates from chemo-mechanical failures. Here we probe the solid-state synthesis of LiNi0.6Co0.2Mn0.2O2 in real time to better understand the structural and/or morphological changes during phase evolution. Multi-length-scale observations-using aberration-corrected transmission electron microscopy, in situ heating transmission electron microscopy and in situ X-ray diffraction-reveal that the overall synthesis is governed by the kinetic competition between the intrinsic thermal decomposition of the precursor at the core and the topotactic lithiation near the interface, which results in spatially heterogeneous intermediates. The thermal decomposition leads to the formation of intergranular voids and intragranular nanopores that are detrimental to cycling stability. Furthermore, we demonstrate that promoting topotactic lithiation during synthesis can mitigate the generation of defective structures and effectively suppress the chemo-mechanical failures.

Advanced preparation of plan-view specimens on a MEMS chip for in situ TEM heating experiments

In situ transmission electron microscopy (TEM) is a powerful tool for advanced material characterization. It allows real-time observation of structural evolution at the atomic level while applying different stimuli such as heat. However, the validity of analysis strongly depends on the quality of the specimen, which has to be prepared by thinning the bulk material to electron transparency while maintaining the pristine properties. To address this challenge, a novel method of TEM samples preparation in plan-view geometry was elaborated based on the combination of the wedge polishing technique and an enhanced focused ion beam (FIB) workflow. It involves primary mechanical thinning of a broad sample area from the backside followed by FIB-assisted installation on the MEMS-based sample carrier. The complete step-by-step guide is provided, and the method’s concept is discussed in detail making it easy to follow and adapt for diverse equipment. The presented approach opens the world of in situ TEM heating experiments for a vast variety of fragile materials. The principle and significant advantage of the proposed method are demonstrated by new insights into the stability and thermal-induced strain relaxation of Ge Stranski–Krastanov islands on Si during in situ TEM heating.Graphical abstract

Exploring stability of a nanoscale complex solid solution thin film by in situ heating transmission electron microscopy

Combining thin film deposition with in situ heating electron microscopy allows to understand the thermal stability of complex solid solution nanomaterials. From a CrMnFeCoNi alloy target a thin film with an average thickness of ~10 nm was directly sputtered onto a heating chip for in situ transmission electron microscopy. We investigate the growth process and the thermal stability of the alloy and compare our results with other investigations on bulk alloys or bulk-like films thicker than 100 nm. For the chosen sputtering condition and SiNx substrate, the sputter process leads to the Stranski–Krastanov growth type (i.e., islands forming on the top of a continuous layer). Directly after sputtering, we detect two different phases, namely CoNi-rich nanoscale islands and a continuous CrMnFe-rich layer. In situ annealing of the thin film up to 700°C leads to Ostwald ripening of the islands, which is enhanced in the areas irradiated by the electron beam during heating. Besides Ostwald ripening, the chemical composition of the continuous layer and the islands changed during the heating process. After annealing, the islands are still CoNi-rich, but lower amounts of Fe and Cr are observed and Mn was completely absent. The continuous layer also changed its composition. Co and Ni were removed, and the amount of Cr lowered. These results confirm that the synthesis of a CrMnFeCoNi thin film with an average thickness of ~10 nm can lead to a different morphology, chemical composition, and stability compared to thicker films (>100 nm).Impact statementExploring stability of a complex solid solution thin film by in situ heating transmission electron microscopy is a study of the thermal stability of sputtered complex solid solution thin films with thicknesses of ~10 nm. Complex solid solution materials have a promising electrocatalytic behavior due to the interplay of multi-element active sites. In order to understand their catalytic properties, it is important to identify the different structure-composition-activity correlations. Thus, our investigation helps to clarify and to understand the stability of nanoscale complex solid solution with an average film thickness of ~10 nm.Graphic abstractCombining sputter deposition with in situ heating transmission electron microscopy allows to understand the thermal stability of nanoscale complex solid solution thin films.

Observation of the Initial Stage of 3C-SiC Heteroepitaxial Growth on the Si Nanomembrane

One considerable concern in 3C-SiC growth is the different lattice constant between the 3C-SiC and Si substrate, which causes defects and strain at the interface. Although the heteroepitaxial growth has been achieved, there have been no experimental studies on the initial process of 3C-SiC growth. In this research, we directly observe heteroepitaxial growth of 3C-SiC on the (001) Si nanomembrane (Si NM) step by step. We used in situ heating transmission electron microscopy (TEM) to study the initial growth process of 3C-SiC growth at the nanoscale in a high-vacuum environment. We demonstrate the growth of 3C-SiC at the preferential (110) direction without defects. The heteroepitaxial grown 3C-SiC without defects is attributed to the bowing effect at the nanoscale to compensate for the lattice misfit. Based on these results, we proposed a new method to heteroepitaxially grow on the Si NM through in situ heating TEM study.

Facile Fabrication of CuO Nanosheets and In Situ Transmission Electron Microscopy/X‐Ray Diffraction Heating Characterization of Microstructure Evolution

CuO nanosheets (NSs) are synthesized by a one‐step template‐free solution method. The thermal characteristics are further accounted for by studying the morphological and structural evolution at different temperatures. The initial morphology and structure of the prepared CuO NSs are explored by scanning electron microscopy, energy dispersive spectrometer (EDS), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and X‐ray diffraction (XRD). These results confirm the advantages of smooth surface, and uniform and good crystalline array structure with a thickness of several tens of nanometers. During thermal analysis, in situ TEM heating is conducted from room temperature to 1120 °C, accompanied by the appearance and evolution of porous membrane areas and fusion areas. The changing process of shrinking and final disappearance is studied by in‐depth and detailed research. At the same time, in situ XRD heating from room temperature to 1100 °C and EDS analysis at 1020 °C provide auxiliary analysis of phase transition from CuO to Cu2O during in situ TEM heating.

In Situ Transmission Electron Microscopy Investigation of Melting/Evaporation Kinetics in Anisotropic Gold Nanoparticles.

We report on thermal stability and phase transition behaviors of triangular Au nanoprisms through in situ heating transmission electron microscopy. With rising temperature, Au nanoprisms exhibit fluctuating surface reconstructions at the corner regions. When a quasi-melting state is reached at the temperature below bulk melting points, the evaporation is initiated commonly at a corner with low curvature and containing sharp intersection points. The subsequent annealing process leads to the gradual evaporation, which, in the absence of thick carbon coverages, is accompanied by marked shape reconstructions. The thermal stability and evaporation behaviors are not evidently regulated by nanoprism aggregations.

Thermal Stability and Radiation Tolerance of Lanthanide-Doped Cerium Oxide Nanocubes

The thermal and radiation stability of free-standing ceramic nanoparticles that are under consideration as potential fillers for the improved thermal and radiation stability of polymeric matrices were investigated by a set of transmission electron microscopy (TEM) studies. A series of lanthanide-doped ceria (Ln:CeOx; Ln = Nd, Er, Eu, Lu) nanocubes/nanoparticles was characterized as synthesized prior to inclusion into the polymers. The Ln:CeOx were synthesized from different solution precipitation (oleylamine (ON), hexamethylenetetramine (HMTA) and solvothermal (t-butylamine (TBA)) routes. The dopants were selected to explore the impact that the cation has on the final properties of the resultant nanoparticles. The baseline CeOx and the subsequent Ln:CeOx particles were isolated as: (i) ON-Ce (not applicable), Nd (34.2 nm), Er (27.8 nm), Eu (42.4 nm), and Lu (287.4 nm); (ii) HMTA-Ce (5.8 nm), Nd (6.6 nm), Er (370.0 nm), Eu (340.6 nm), and Lu (287.4 nm); and (iii) TBA-Ce (4.1 nm), Nd (5.0 nm), Er (3.8 nm), Eu (7.3 nm), and Lu (3.8 nm). The resulting Ln:CeOx nanomaterials were characterized using a variety of analytical tools, including: X-ray fluorescence (XRF), powder X-ray diffraction (pXRD), TEM with selected area electron diffraction (SAED), and energy dispersive X-ray spectroscopy (EDS) for nanoscale elemental mapping. From these samples, the Eu:CeOx (ON, HMTA, and TBA) series were selected for stability studies due to the uniformity of the nanocubes. Through the focus on the nanoparticle properties, the thermal and radiation stability of these nanocubes were determined through in situ TEM heating and ex situ TEM irradiation. These results were coupled with data analysis to calculate the changes in size and aerial density. The particles were generally found to exhibit strong thermal stability but underwent amorphization as a result of heavy ion irradiation at high fluences.

In situ TEM observation on the ferroelectric‐antiferroelectric transition in Pb(Nb,Zr,Sn,Ti)O3/ZnO

AbstractCeramic composites of (1‐x)Pb0.99{Nb0.02[(Zr0.57Sn0.43)0.937Ti0.063]0.98}O3 (PNZST)/xZnO were recently reported to exhibit exceptionally high pyroelectric coefficients near human body temperature due to the ferroelectric‐antiferroelectric transition of the matrix grains. In the present work, a comparative study is conducted on two composites of x = 0.1 and 0.4 with in situ heating transmission electron microscopy (TEM). The results verify the presence of strain field in the PNZST grain adjacent to a ZnO particle and the stabilized ferroelectric phase at room temperature in the composite of x = 0.1. During heating, the ferroelectric matrix grain transforms to the antiferroelectric phase, contributing to the pyroelectric effect. In the composite of x = 0.4, high‐angle annular dark‐field imaging combined with energy‐dispersive X‐ray spectroscopy reveal the existence of both ZnO and Zn2SnO4. The formation of Zn2SnO4 indicates that Sn in the PNZST matrix grain is selectively extracted, and decomposition of the perovskite phase has taken place. The decomposition products in the form of fine particles are observed to facilitate the nucleation of the antiferroelectric phase and restrict the motion of the phase boundary during heating. The larger amount of ZnO and Zn2SnO4 and the decomposition of the PNZST perovskite phase are suggested to be responsible for the much lower pyroelectric coefficient in the x = 0.4 composite.

Photoelectric response characteristics of a novel translucent one-dimensional MAPbI<sub>3</sub>·DMF single crystal material

<p indent=0mm>Organic halide perovskites have broad application prospects in photoelectric detector due to their excellent photoelectric properties. Moreover, there has been growing interest in applying halide perovskites to semitransparent photovoltaics to achieve the highest combination of transparency and efficiency. In this paper, we aimed to prepare high-performance materials which are suitable for translucent optoelectronic devices using new preparation methods and explore the potential properties of these materials. We successfully synthesize a type of translucent linear MAPbI₃·DMF single crystal material with controllable size and good stability in atmospheric environment using the anti-solvent method. Toluene, which is often used as one of the surfactants to control the morphology of the perovskite films, was used as an anti-solvent in this paper. The growth of the one-dimensional (1D) single crystal wires was regulated by the control of the adsorbed toluene molecular at the interface, promoting the [PbI₆]⁴⁻octahedral unit in the precursor to assemble into a chain structure along the 1D direction. In addition, we could control the width and length of the single crystal wires via a slow cooling process. The width can reach tens of microns, and the length of the single crystal wires can be the centimeter level. The crystal structure of the transparent wire was analyzed using single crystal X-ray diffraction (XRD). The material exhibited a good 1D chain structure with an infinitely extended single edge-sharing octahedral lead halide chain {PbI₃}⁻ surrounded by CH₃NH₃⁺ (MA) and <italic>N</italic>,<italic>N</italic>-dimethylformamide (DMF). Through XRD characterization of the crystal structure after keeping the material at room temperature in air (~25°C, humidity ~40%) for a long time, we found that the single-crystal wire showed good stability in air. In addition, <italic>in situ </italic>heating XRD and <italic>in situ</italic> heating transmission electron microscopy (TEM) analyses showed that the morphology and crystal structure of the semi-transparent perovskite remained stable at 90°C, indicating that this material has good thermal stability. Further, an ultraviolet-visible absorption spectroscopy test showed that this material could absorb photons at <sc>300–800 nm,</sc> indicating that the obtained single crystal wire could absorb both ultraviolet and visible light. The material also exhibited a strong transmission effect for photons with wavelengths ranging from 500 to <sc>784 nm,</sc> indicating that the material has the semi-transparent property. According to the absorption spectrum, the transparency was calculated, and it was found that the transparency of single crystal materials increased in the range of more than <sc>500 nm,</sc> further implying that they have excellent translucence properties. Photoluminescence (PL) spectrum test showed that the single crystal material could emit <sc>~780 nm</sc> of fluorescence under laser irradiations of 409 and <sc>633 nm.</sc> Furthermore, using the Tauc plot method, we determined that this material has a bandgap of <sc>~1.58 eV,</sc> which is consistent with the PL test. In addition, this material shows good responsivity <sc>(7.13 A W^–1)</sc> with a response time of <sc>9.95 ms,</sc> making it suitable for photodetector applications. The good stability and photoelectric properties make this linear single crystal material an ideal candidate for the core absorbent layer of semi-transparent photodetector devices. This research work is expected to provide a reference for the development of transparent perovskite materials with high stability and good photoelectric properties.

In situ TEM observations of thickness effect on grain growth in pure titanium thin films

Ultrafine-grained materials have a strong tendency to transform into coarse-grained materials due to the high density of grain boundaries at elevated temperature. In this study, pure titanium was processed by high-pressure torsion for 10 turns to give an ultrafine-grained (UFG) structure with an average grain size of ~96 nm. The recrystallization behavior of the UFG Ti was investigated by in-situ transmission electron microscopy (TEM). It is found that the gradient microstructures with average grain size ranging from ~129 nm to ~655 nm are formed under in-situ TEM heating up to 800 °C for 30 min. The Kossel-Möllenstedt (K-M) fringes in a convergent-beam electron diffraction (CBED) pattern were used to provide an accurate measure of the sample thicknesses. The results demonstrate that grain growth is significantly suppressed in the UFG pure Ti thin film compared to bulk material. Mechanism analysis shows the combined effects of driving force and drag force on grain boundary migration is the primary cause of the grain growth inhibition in the UFG pure Ti thin film.

Microstructural evolution in self-catalyzed GaAs nanowires during in-situ TEM study

The microstructural evolutions in self-catalyzed GaAs nanowires (NWs) were investigated by using in situ heating transmission electron microscopy (TEM). The morphological changes of the self-catalyst metal gallium (Ga) droplet, the GaAs NWs, and the atomic behavior at the interface between the self-catalyst metal gallium and GaAs NWs were carefully studied by analysis of high-resolution TEM images. The microstructural change of the Ga-droplet/GaAs-NWs started at a low temperature of ∼200 °C. Formation and destruction of atomic layers were observed at the Ga/GaAs interface and slow depletion of the Ga droplet was detected in the temperature range investigated. Above 300 °C, the evolution process dramatically changed with time: The Ga droplet depleted rapidly and fast growth of zinc-blende (ZB) GaAs structures were observed in the droplet. The Ga droplet was completely removed with time and temperature. When the temperature reached ∼600 °C, the decomposition of GaAs was detected. This process began in the wurtzite (WZ) structure and propagated to the ZB structure. The morphological and atomistic behaviors in self-catalyzed GaAs NWs were demonstrated based on thermodynamic considerations, in addition to the effect of the incident electron beam in TEM. Finally, GaAs decomposition was demonstrated in terms of congruent vaporization.

Formation of&amp;nbsp;Face-Centered Cubic&amp;nbsp;Phase in Ti35 Alloy Under &lt;i&gt;in situ&lt;/i&gt; Heating Transmission Electron Microscopy

A thermally induced hexagonal close-packed (HCP) to face-centered cubic (FCC) phase transition was investigated in an α-type Ti35 alloy with twinned structure by in situ heating transmission electron microscopy (TEM) and ab initio calculations. TEM observations indicated that the HCP-Ti to FCC-Ti transition occurred both within matrix/twin and at the twin boundaries in the thinner region of the TEM film, and the FCC-Ti precipitated as plates within the matrix/twin, while as equiaxed cells at twin boundaries. Ab initio calculations showed that the formation of FCC-Ti was related to the contamination of interstitial atoms such as oxygen.

Understanding the formation of (Al,Si)3Sc and V-phase (AlSc2Si2) in Al-Si-Sc alloys via ex situ heat treatments and in situ transmission electron microscopy studies

Scandium (Sc) containing Al-Si model alloys were heat-treated at various temperatures to determine the interaction between Si and Sc. The (Al,Si)3Sc phase was formed at ~350 °C and V-phase (AlSc2Si2) was observed to form at above ~450 °C, as determined from x-ray diffraction and selected area electron diffraction. Hardening of the alloys was observed due to the formation of coherent, nanoscale (Al,Si)3Sc precipitates; whereas significant softening was observed upon the formation of coarse V-phase. Herein, the V-phase is studied in detail and has for the first time been revealed to have a rod morphology. The Transmission electron microscopy (TEM) allowed for the determination of six new orientation relationships (ORs) with the α-Al matrix for the V-phase. Additionally, in situ TEM heating experiments at 550 °C revealed that the formation of V-phase occurs due to a nucleation and growth mechanism following the dissolution of Si particles and nanoscale (Al,Si)3Sc precipitates.

Probing One-Dimensional Oxygen Vacancy Channels Driven by Cation-Anion Double Ordering in Perovskites.

Visualizing the oxygen vacancy distributions is highly desirable for understanding the atomistic oxygen diffusion mechanisms in perovskites. In particular, the direct observation of the one-dimensional oxygen vacancy channels has not yet been achieved in perovskites with dual ion (i.e., cation and anion) ordering. Here, we perform atomic-resolution imaging of the one-dimensional oxygen vacancy channels and their structural dynamics in a NdBaCo2O5.5 double perovskite oxide. An in situ heating transmission electron microscopy investigation reveals the disordering of oxygen vacancy channels by local rearrangement of oxygen vacancies at the specific temperature. A density functional theory calculation suggests that the possible pathway of oxygen vacancy migration is a multistep route via Co-O and Nd-Ov (oxygen vacancy) sites. These findings could provide robust guidance for understanding the static and dynamic behaviors of oxygen vacancies in perovskite oxides.

In-situ TEM study of the crystallization sequence in a gold-based metallic glass

The composition Au49Ag5.5Pd2.3Cu26.9Si16.3 (at.%) is of interest as the basis for the development of gold-based bulk metallic glasses for application in jewellery. In-situ heating in transmission electron microscopy (TEM) and differential scanning calorimetry (DSC, both conventional and fast) are used to obtain a comprehensive characterization of the decomposition on heating a melt-spun glass of this composition. Linking TEM with DSC over a range of heating rates 0.083‒2000 K s‒1, allows the sample temperature in the TEM heating stage to be calibrated. On heating up to melting, the glass decomposes in up to four stages: (1) complete transformation to single-phase nanocrystalline (Au,Cu)7Si; (2) grain growth of this phase; (3) precipitation of (Pd,Ag)Si, reducing the supersaturation of silicon in the (Au,Cu)7Si matrix; (4) with the precipitate phase remaining stable, decomposition of the matrix to a mixture of (Au,Ag)8Cu2, AuCu and Cu3Au phases. At all stages, grain diameters remain sub-micrometre; some of the stable nanocrystalline microstructures may themselves be of interest for applications. The characterization of the decomposition can assist in the optimization of the glass composition to improve tarnish-resistance, while retaining adequate glass-forming ability, formability in thermoplastic processing, and resistance to crystallization. For materials in general, the close correlation of in-situ TEM and DSC results should find wide use in characterizing complex transformation sequences.