The widespread use of thermoelectric technology is constrained by a relatively low conversion efficiency of the bulk alloys, which is evaluated in terms of a dimensionless figure of merit (zT). ThezTof bulk alloys can be improved by reducing lattice thermal conductivity through grain boundary and point-defect scattering, which target low- and high-frequency phonons. Dense dislocation arrays formed at low-energy grain boundaries by liquid-phase compaction in Bi0.5Sb1.5Te3(bismuth antimony telluride) effectively scatter midfrequency phonons, leading to a substantially lower lattice thermal conductivity. Full-spectrum phonon scattering with minimal charge-carrier scattering dramatically improved thezTto 1.86 ± 0.15 at 320 kelvin (K). Further, a thermoelectric cooler confirmed the performance with a maximum temperature difference of 81 K, which is much higher than current commercial Peltier cooling devices.

In analyzing zT improvements due to lattice thermal conductivity (κL) reduction, electrical conductivity (σ) and total thermal conductivity (κTotal) are often used to estimate the electronic component of the thermal conductivity (κE) and in turn κL from κL = ∼ κTotal − LσT. The Wiedemann-Franz law, κE = LσT, where L is Lorenz number, is widely used to estimate κE from σ measurements. It is a common practice to treat L as a universal factor with 2.44 × 10−8 WΩK−2 (degenerate limit). However, significant deviations from the degenerate limit (approximately 40% or more for Kane bands) are known to occur for non-degenerate semiconductors where L converges to 1.5 × 10−8 WΩK−2 for acoustic phonon scattering. The decrease in L is correlated with an increase in thermopower (absolute value of Seebeck coefficient (S)). Thus, a first order correction to the degenerate limit of L can be based on the measured thermopower, |S|, independent of temperature or doping. We propose the equation: L=1.5+exp−|S|116 (where L is in 10−8 WΩK−2 and S in μV/K) as a satisfactory approximation for L. This equation is accurate within 5% for single parabolic band/acoustic phonon scattering assumption and within 20% for PbSe, PbS, PbTe, Si0.8Ge0.2 where more complexity is introduced, such as non-parabolic Kane bands, multiple bands, and/or alternate scattering mechanisms. The use of this equation for L rather than a constant value (when detailed band structure and scattering mechanism is not known) will significantly improve the estimation of lattice thermal conductivity.

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Recent reports on epitaxial BiFeO 3 films show that the crystal structure changes from nearly rhombohedral ("R-like") to nearly tetragonal ("T-like") at strains exceeding ≈-4.5%, with the "Tlike" structure being characterized by a highly-enhanced c/a ratio. While both the "R-like" and the "T-like" phases are monoclinic, our detailed x-ray diffraction results reveal a symmetry change from M A and M C type, respectively, at this "R-like"-to-"T-like" transition. Therefore, the ferroelectric polarization is confined to different (pseudocubic) planes in the two phases. By applying additional strain or by modifying the unit cell volume of the film by substituting Ba for Bi, the monoclinic distortion in the "T-like" M C phase is reduced, i.e. the system approaches a true tetragonal symmetry. Therefore, in going from bulk to highly-strained films, a phase sequence of rhombohedral(R)-to-monoclinic("R-like" M A )-to-monoclinic("T-like" M C )-totetragonal(T) is observed. This sequence is otherwise seen only near morphotropic phase boundaries in lead-based solid-solution perovskites (i.e. near a compositionally induced phase instability), where it can be controlled by electric field, temperature, or composition. Our results now show that this evolution can occur in a lead-free, stoichiometric material and can be induced by stress alone.3

A simple and scalable process was developed for the synthesis of highly crystalline magnetite nanocrystals embedded in a carbon matrix using low cost starting materials; the resulting nanocomposite showed a very high specific capacity of 863 mA hg(-1) in the initial cycle and high capacity retention of 90% after 30 cycles.

The molecular composition of two shale oils (from U.S. Western and Russian Slanet mines) was studied using 15 T Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) coupled with electrospray ionization (ESI) and atmospheric pressure photoionization (APPI). Together, these techniques allowed for the identification of ∼30 000 chemical components. The class and double-bond equivalence (DBE) distributions of the shale oils were compared to those of conventional oil. N x classes were abundant in U.S. Western shale oil, and O x and NO x class compounds were in the Russian Slanet shale oil. The observed class distribution matched well with the high nitrogen content of U.S. Western shale oil and the high oxygen content of Russian Slanet shale oil. Aromatic hydrocarbon was significantly less abundant in the shale oils than in conventional oil. Following studies of the major components, structures were suggested in accordance with the DBE distribution of each class. The DBE distributions of the N1 and aromatic hydrocarbon classes were lower in the shale oils than in conventional oil. O2 compounds with DBE = 1 were abundant in the shale oils, whereas O2 compounds with DBE = 3−4 predominated in conventional oil. These findings combined with the previously reported results suggest that shale oil resembles less biodegraded oil.

Purpose Creating superior customer experience quality is important to firm success, but the link between customer experience quality and customer-to-customer interaction quality – a critical component of customer experience quality in mass service settings – has seldom been spotlighted. This paper aims to propose and test a theoretical model of the relationship among three types of customer-to-customer interaction quality (friend-interaction, neighboring customer-interaction and audience-interaction) and customer experience quality. They also examine these variables’ effects on customer citizenship behavior in mass service settings. Design/methodology/approach The authors collected data through a self-administered survey. The proposed relationships were tested using structural equation modeling. Findings Friend-interaction and audience-interaction quality perceptions significantly influence customer experience quality, with neighboring customer-interaction quality perception significant only for low communication quality. We find that enhancing customer experience quality is crucial to promoting citizenship behavior in mass service settings. Practical implications Neighboring customer-interaction quality perception has a significant effect on customer experience quality, particularly in a low communication quality situation. Therefore, service marketers should provide effective neighboring customer-interaction management schemes to enhance experience quality together with friend-interaction and audience-interaction management schemes when customers experience low communication quality. Additionally, service marketers should focus on enhancing communication quality only when anticipating low neighboring customer-interaction quality. Originality/value The findings highlight the effects of three types of customer-to-customer interaction quality on customer citizenship behavior through experience quality perception in mass service settings, and the effect of neighboring customer-interaction quality perception on customer experience quality, moderated by communication quality.

The high temperature thermoelectric performances of Zr 0.