The cooling stage of postdeposition annealing is often regarded as a passive step that preserves the structure formed at high temperature. Herein, we examined whether the cooling path affects the crystallographic texture of L10-FePt films derived from Fe/Pt multilayers on thermally oxidized Si(100). After a 240 min hold at 700 degrees C, specimens were cooled either at different nominal rates or using a switching protocol in which controlled cooling at -1 degrees C min-1 was terminated at a switching temperature Tsw, followed by natural cooling. Changing the nominal rate altered the preferred texture from (111)-dominant to (001)-enhanced. Extending controlled cooling to 200 degrees C rather than 450 degrees C increased the relative (001) diffraction contribution and narrowed the (001) rocking curve. The accompanying increase in out-of-plane loop squareness was qualitatively consistent with this structural trend. These results establish the cooling stage as an active process parameter for controlling the final L10-FePt texture.
The shape, size and spatial arrangement of magnetic grains in L10-FePt granular films containing grain boundary materials (GBMs) were investigated with regard to self-organized heat-assisted magnetic recording media. The proposed quantitative morphology indices were applied to sputter-deposited FePt 30 vol% GBM films on a (001)-textured MgO underlayer, enabling isolated grains to be distinguished from irregular coalesced grains. Isolated grains tend to exhibit a terrace-terminated morphology close to the thermodynamic equilibrium shape, appearing square-shaped in plan view. The square-grain fraction increased as the GBM melting point decreased, suggesting that the equilibrium shape developed through diffusion of Fe and Pt at grain/GBM interfaces after rapid solidification. For FePt-TiO2 and FePt-ZrO2, the lattice misfit, square-grain side length and the center-to-center spacing between grains were 8.19%, 5.25 nm and 5.78 nm, and 8.52%, 3.75 nm and 4.39 nm, respectively. The square-grain alignment extended to 10 nm & times; 25 nm in area and was limited by the grain size of the MgO underlayer.
AeM2V2O8 compounds (Ae = Sr, Ba; M = Co, Mg, Ni) have attracted attention as a new family of ferroelectric materials. In this study, the melt-solidification behaviours of SrMg2V2O8 (SMV) and BaMg2V2O8 (BMV) were investigated using a floating zone (FZ) furnace, and SMV and BMV melt incongruently, with MgO as the primary crystalline phase. The slow-cooling FZ method was then used to establish the pseudo-binary SrV2O6-MgO and BaV2O6-MgO phase diagrams and to identify the compositional ranges in which SMV and BMV crystallize as single phases. On the basis of these diagrams, BMV crystals were grown from an MgO-poor solution by the travelling-solvent FZ method. The precipitation of MgO was completely suppressed in these crystals; although a small amount of an Mg-poor secondary phase remained in the central region, the crystal grain size and transparency were improved.
The thermoelectric (TE) conversion module presented was fabricated using type-I, type-II, and type-VIII clathrates to evaluate its power-generation characteristics. This module exhibited normal current-voltage characteristics, and its energy conversion efficiency increased with increasing temperature difference, reaching approximately 10% at a temperature difference of 445 K between 297 and 742 K, where the current, output voltage, and electrical power were around 1.4 A, 0.85 V, and 1.2 W, respectively. These clathrate materials demonstrate high potential for application in high-performance TE modules. However, challenges regarding the formation of diffusion barriers and long-term stability tests remain to be addressed.
Organic hole transport materials (HTMs) must reconcile efficient charge collection with the stability of a multicomponent contact under illumination and heat. This Progress Review places three small-molecule HTM families we developed in the context of molecular design strategies reported by other groups. Conjugated-core, π -bridge, and methoxy/methylthio terminal-group modifications reveal that aggregation control, conductivity after doping, and interfacial selectivity must be optimized together. Mixed terminal functionality enabled an average power conversion efficiency of 23.6%, whereas sulfur-containing bridges substantially improved device durability at 85 °C. High initial efficiency and undoped mobility alone did not predict thermal stability or doped-device performance. The resulting design principles primarily concern chemically doped HTMs in n–i–p devices; their extension to dopant-free and inverted architectures requires validation of processing and interfacial compatibility. We distinguish observed structure–property relationships from proposed packing and passivation mechanisms and identify stable doping, interface control, and scalable film formation as priorities for practical HTMs.
