Quantitative nanoscale mapping of three-phase thermal conductivities in filled skutterudites via scanning thermal microscopy

Abstract

In the last two decades, a nanostructuring paradigm has been successfully applied in a wide range of thermoelectric materials, resulting in significant reduction in thermal conductivity and superior thermoelectric performance. These advances, however, have been accomplished without directly investigating the local thermoelectric properties, even though local electric current can be mapped with high spatial resolution. In fact, there still lacks an effective method that links the macroscopic thermoelectric performance to the local microstructures and properties. Here, we show that local thermal conductivity can be mapped quantitatively with good accuracy, nanometer resolution, and one-to-one correspondence to the microstructure using a three-phase skutterudite as a model system. Scanning thermal microscopy combined with finite element simulations demonstrate close correlation between sample conductivity and probe resistance, enabling us to distinguish thermal conductivities spanning orders of magnitude, yet resolving thermal variation across a phase interface with small contrast. The technique thus provides a powerful tool to correlate local thermal conductivities, microstructures, and macroscopic properties for nanostructured materials in general, and nanostructured thermoelectrics in particular.

Imidazolium-Based Ionic Liquids Affect Morphology and Rigidity of Living Cells: An Atomic Force Microscopy Study

“…The cells can be considered as effective multi-layered systems, in order to take into account the complex cytoskeletal structure, 69 simulations. 70,71 For each cell condition, (exact number N of cells used for statistic is shown in Table 1), the mean Young's modulus value E, and its associated effective errors (standard deviation  and standard deviation of the mean E) have been calculated, following the procedure described in details in Ref. 61,72 The results are therefore presented as E ±  (± E).…”

Probing of Local Multifield Coupling Phenomena of Advanced Materials by Scanning Probe Microscopy Techniques

“…The versatility of SPM techniques is also able to measure the different physical properties at the same location. Thus, they are the ideal tools to study the MCP of various materials from nanometer to micrometer scales . Since the invention of the scanning tunneling microscope (STM) and atomic force microscopy (AFM), the two earliest functional modes in SPM family, a variety of techniques have been developed and widely used for characterizing different physical properties of materials.…”

“…Figure shows the basic setups of some representative SPM techniques. The most used SPM techniques include contact/noncontact/tapping‐mode AFM, conductive AFM (C‐AFM) (Figure i), Kelvin probe force microscopy (KPFM) (Figure ii), electrostatic force microscopy (EFM), magnetic force microscopy (MFM), scanning thermal microscopy (SThM), electrochemical AFM (EC‐AFM), piezoresponse force microscopy (PFM) (Figure iii), electrochemical strain microscopy (ESM), contact resonance force microscopy (CR‐FM) (Figure iv), and multifrequency AFM such as AM–FM (amplitude modulation–frequency modulation) and bimodal AFM, and many others. Some of the SPM measurements results are illustrated in Figure .…”

“…However, the major limitation of the SPM techniques is lack of structural or compositional information. A few recent studies have used ESM and SThM to indirectly map the different compositional phases of materials . SPM has also been integrated with Raman or IR spectroscopy in order to combine the advantages of high spatial resolution of SPM and the ability to quantify chemical information by Raman or IR techniques …”

Enhanced Thermoelectric Properties of Hydrothermal Synthesized BiCl3/Bi2S3 Composites

“…As such, many techniques have been used to enhance the ZT, such as nanostructures [4] , layered thermoelectric materials [5][6][7] , atomic substitution in alloys [8][9] . At the same time, many methods and theories were developed for analyzing the thermoelectric properties of composite materials, such as SThM [10] , mesomechanics combined phase field simulation [11] , and nonlinear asymptotic homogenization theories [12] . Thermoelectric materials are also combined with other energy technologies to achieve more application prospect, such as thermoelectric hybrid battery system [13] .…”