GeTe is highly sought-after due to its versatility as a high-performance thermoelectric material and phase change material, as well as a ferroelectric Rashba semiconductor. Compared to most ...thermoelectric materials, it has an additional degree of freedom of rhombohedral-cubic phase transition at 673 K. At this temperature, the lattice thermal conductivity approaches a theoretical minimum due to ferroelectric instability while the high-energy Σ and low-energy L bands converge to give outstanding electronic properties. Therefore, modulation of the phase transition temperature allows simultaneous and synergistic tuning of the electronic and thermal transport properties to achieve high
zT
. In this work, Sn alloying together with Bi,Sb doping is used to suppress the phase transition to achieve a pure cubic structure with a lattice thermal conductivity of around 0.4 W m
−1
K
−1
and peak
zT
of 1.7 at 723 K with an average
zT
of 1.23 between 400 and 800 K. Furthermore, the Vickers hardness of 270 and Young's modulus of 63.5 GPa in Ge
0.4
Sn
0.4
Bi
0.02
Sb
0.12
Te are by far the highest amongst binary chalcogenides. More importantly, the high quality factor achieved in this work gives ample room for further
zT
improvements. The fundamental insights drawn from this work provide a pathway towards engineering GeTe-based alloys to achieve high
zT
at any temperature of interest.
The rhombohedral-cubic phase transition temperature of GeTe can be tailored
via
Sn-alloying, leading to high performance thermoelectric GeTe.
The two-dimensional layer of molybdenum disulfide (MoS2) exhibits promising prospects in the applications of optoelectronics and valleytronics. Herein, we report a successful new process for ...synthesizing wafer-scale MoS2 atomic layers on diverse substrates via magnetron sputtering. Spectroscopic and microscopic results reveal that these synthesized MoS2 layers are highly homogeneous and crystallized; moreover, uniform monolayers at wafer scale can be achieved. Raman and photoluminescence spectroscopy indicate comparable optical qualities of these as-grown MoS2 with other methods. The transistors composed of the MoS2 film exhibit p-type performance with an on/off current ratio of ∼10(3) and hole mobility of up to ∼12.2 cm(2) V(-1) s(-1). The strategy reported herein paves new ways towards the large scale growth of various two-dimensional semiconductors with the feasibility of controllable doping to realize desired p- or n-type devices.
Phosphide-based thermoelectrics are a relatively less studied class of compounds, primarily due to the presence of light elements, which result in high thermal conductivity and inherent stability ...problems. In this work, we present a stable phosphide–tetrahedrite, Ag6Ge10P12, which possesses the highest zT (∼0.7) among all known phosphides at intermediate temperatures (750 K). We examine the intrinsic electronic and thermal transport properties of this compound by expressing the transport properties in terms of weighted mobility (μW), transport coefficient (σE0 ), and material quality factor (B), from which we are able to elucidate that the origin of its high zT can be attributed to the platelike Fermi surface and high level of band multiplicity related to its complex band structure. Finally, we discuss the origin of the low lattice thermal conductivity observed in this compound using experimental sound velocity, elastic properties, and Debye–Callaway model, thus laying the foundation for similar stable phosphides as potentially earth-abundant and nontoxic intermediate-temperature thermoelectric materials.
GeTe as one of the most promising medium temperature thermoelectrics has progressed leaps and bounds in recent years, largely thanks to a combination of its unique electronic, thermal and structural ...properties. Despite its various advantages, a major factor standing in the way of wide commercial adoptions lies in its unreliable mechanical properties. This work reports Re doping as a strategy to drastically enhance the mechanical properties of GeTe, resulting in Vickers microhardness as high as 342.6 H v in Ge 0.88 Sb 0.10 Re 0.02 Te, which is more than double that of pristine GeTe (145 H v ). Ge 0.88 Sb 0.10 Re 0.02 Te also exhibited a Young's modulus of 64.1 GPa, substantially higher than many other binary chalcogenide thermoelectrics. The significant enhancement of GeTe in mechanical properties is mainly related to the mechanism of precipitation hardening. In addition, we found that while the electronic properties were slightly compromised with Re doping, the lattice thermal conductivity was reduced due to point defects scattering brought about by Re atoms. Therefore, a high zT value (>1.6) at 600–800 K is achieved in Ge 0.88 Sb 0.10 Re 0.02 Te. Furthermore, above 10% device efficiency can be expected for the operating temperature between 300–800 K. Such a solution to strengthen the mechanical properties of GeTe using Re doping is expected to play a major part in the push for full-scale GeTe-based thermoelectric devices.
This study examines the predictive power of cognitive and affective food image components on potential tourists’ behavioral intention. Using Chinese tourists’ perception of Australia as the context, ...the study adopted a multi-method approach incorporating desktop research, surveys of food tourism stakeholders, and quantitative testing of a model using survey data. Results confirmed that (1) cognitive food image is a formative construct, (2) cognitive food image is a stronger predictor of intention than affective image, and (3) the moderating effect of food neophobia highlights the need for a destination image-building strategy to be sensitive to tourists’ food-related personality traits. Study findings validate a structural model that integrates theories regarding food image and food neophobia to explain destination food image formation. Results also offer a comprehensive formative measurement model of cognitive food image for future research.
This study addresses the conceptualization of food image and examines the role food and cuisine play in the formation of destination brand image. By tracing the destination branding literature with a ...specific focus on image and three components that influence food image formation, the authors map the current state of food image research in tourism. They then provide a dual-perspective review of food image—one that is projected and/or perceived by destination marketers and their food producers and suppliers, and the other a mental representation as perceived by tourists. The evaluation aligns the various dimensions, underlying variables, and indicators of food destination attractiveness as reflected in host–tourist perspectives. The paper offers a comprehensive conceptual framework of food tourism branding and suggests a pathway for future empirical research on destination image and branding.
Pathological Wnt pathway activation is a conserved hallmark of colorectal cancer. Wnt-activating mutations can be divided into: i) ligand-independent (LI) alterations in intracellular signal ...transduction proteins (
, β-catenin), causing constitutive pathway activation and ii) ligand-dependent (LD) mutations affecting the synergistic R-Spondin axis (
,
-fusions) acting through amplification of endogenous Wnt signal transmembrane transduction. Our aim was to exploit differential Wnt target gene expression to generate a mutation-agnostic biomarker for LD tumours.
We undertook harmonised multi-omic analysis of discovery (n=684) and validation cohorts (n=578) of colorectal tumours collated from publicly available data and the Stratification in Colorectal Cancer Consortium. We used mutation data to establish molecular ground truth and subdivide lesions into LI/LD tumour subsets. We contrasted transcriptional, methylation, morphological and clinical characteristics between groups.
Wnt disrupting mutations were mutually exclusive. Desmoplastic stromal upregulation of
may compensate for absence of epithelial mutation in a subset of stromal-rich tumours. Key Wnt negative regulator genes were differentially expressed between LD/LI tumours, with targeted hypermethylation of some genes (
,
) occurring even in CIMP-negative LD cancers.
mRNA expression was used as a discriminatory molecular biomarker to distinguish LD/LI tumours (area under the curve >0.93).
Epigenetic suppression of appropriate Wnt negative feedback loops is selectively advantageous in LD tumours and differential
expression in LD/LI lesions can be exploited as a molecular biomarker. Distinguishing between LD/LI tumour types is important; patients with LD tumours retain sensitivity to Wnt ligand inhibition and may be stratified at diagnosis to clinical trials of Porcupine inhibitors.
Resistive switching on the nanoscale is an emerging research field and Scanning Probe Microscopy (SPM) is a powerful tool for studies in this area. Under the SPM tip, the electrical field is very ...high due to the small tip radius on the order of tens of nanometers, and this can enable a range of ionic/electrochemical phenomena during the resistive switching of the materials under the SPM tip. Although the ionic/electrochemical phenomena have long been considered vital for the resistive switching of materials, a few pieces of experimental evidence, as well as the decoupling of the effects of the electrochemical processes at different stages, are still needed. In this work, we applied SPM based techniques to study resistive switching as well as the electrochemical phenomena during the resistive switching of the TiO2 thin films prepared using Pulse Laser Deposition (PLD). It was found that the reversible or irreversible electrochemical processes initiated at different voltages can promote or degrade the resistive switching behavior of TiO2. Combined with an electrical cell with environmental control, these electrochemical processes have been shown to require the involvement of moisture; the accumulation of oxygen vacancies, protons, and hydroxyls at the tip/TiO2 junction may contribute to the promoting effect of the reversible electrochemical process on resistive switching, while the oxygen vacancy ordering and the injection of protons and hydroxyls into the lattice may lead to the irreversible electrochemical process. This work provides a detailed insight into the characteristics, origins, and the effects of the electrochemical phenomena on resistive switching performance, and will provide a further understanding of the electrochemical phenomena in various functional materials.
This paper reports findings from a study into food images and the relationship with the overall perceptions of a destination. In doing so it also examines the degree to which congruence exists ...between the promotional images created by Tourism Australia and those images held by 18 major industry stakeholders. The measures are based on 40 attributes of food imagery clustered into 6 dimensions. Data derived from informants were also supported by an analysis of videos used by Tourism Australia. It was concluded a lack of consensus exists with the consequence of fragmented marketing strategies result.
•A food image framework is proposed to evaluate the host-destination food image.•Discover attributes of Australian food as a reflection of local knowledge.•Gaps occur between projected food images and actual food tourism offerings.•Reveal stakeholders' perceptions of the promotional high-end food experiences.•Stakeholders have a favourable perception of the country's diverse food culture.
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