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CsPbIBr2 has shown great potential in the optoelectronics field due to its well‐balanced relationship between bandgap and durability among all‐inorganic perovskites materials. However, the CsPbIBr2 thin films prepared by the traditional one‐step spin coating method suffer from unsatisfactory morphology, poor crystallinity, and high defect density, which lead to the degradation of device performance. Herein, a simple preannealing method is used to form unstable transition films which are then annealed at high temperature to obtain CsPbIBr2 perovskite films with uniform morphology, free pinholes, and strong crystallinity. The performance of the device can be effectively improved due to the reduction of defects and the optimization of the contact between functional layers. Therefore, the power conversion efficiency of 9.6% is obtained, which is nearly 100% improvement compared with that of the control device. [ABSTRACT FROM AUTHOR]

The effect of preannealing (PA) on microstructural evolution and tensile properties of a novel nickel‐based alloy GH4065 is investigated. Particularly, the study of PA in disc superalloys is reported herein for the first time. The detailed strengthening mechanisms of specimens under different heat treatment cycles are identified by electron backscatter diffraction (EBSD) and transmission electron microscope (TEM) observations. The results reveal that the PA treatment after deformation improves the homogeneity of the microstructure due to static recrystallization (SRX). Multimodal size distributions and the morphology of γ′ precipitates are found after the PA + solution + aging (PASA). Also, the distributions of secondary and tertiary γ′ precipitates are optimized due to the PA. The tensile strength of GH4065 alloy after PASA is higher than that of as‐forged (AF) alloy and solution + aging (SA) alloy attributed to the improved microstructure during PA treatment. Compared with the SA specimens, the specimens of GH4065 alloy after PASA treatment lead to significant strengthening as the yield strength increased to more than 150 MPa, which is mainly due to the contribution from annealing twins and microtwins strengthening, as well as the grain refinement and γ′ precipitation strengthening. [ABSTRACT FROM AUTHOR]

In this paper, the microstructure evolution of the 2195 Al-Li alloy under different isothermal annealing schedules and ramp heating-up heat treatments prior to solution heat treatment and the tensile properties of the aging alloy were investigated. The grain structure characteristics of the aging alloy could be influenced by the change of different heat treatment schedules prior to the solution heat treatment. Meanwhile, the mechanical properties of the aging alloy including strength, heterogeneity, and anisotropy were closely related to the grain structure characteristics. There were evident differences in the mechanical properties of aging samples, attributed to the mutual effect of grain structure evolution and texture change. Annealing at a lower temperature (300–350 °C) resulted in the growth of the grain size and the aspect ratio as well as the decrease of the deformation texture components, related to the decline of the strength and the heterogeneity. While grains refined and the deformation texture components increased as the annealing temperature rose (350–400 °C), the strength along the transverse direction decreased, and the heterogeneity increased. Fibrous and overall texture components significantly strengthened in the grain structure of aging samples treated with the low heating-up rate, resulting in a higher strength in the longitudinal direction.

Two screen printing inks were developed for the low-temperature fabrication of printed and flexible thick film negative temperature coefficient thermistors able to operate at room temperature. The first of the two screen printing inks developed utilised cobalt ferrite (CoFe2O4) as the temperature sensing material with the second ink incorporating manganese ferrite (MnFe2O4). These were then screen printed onto lithographically printed silver interdigitated electrodes with a 200 µm track and gap using a synthetic paper (Teslin) as the substrate. The inks required a 10 min curing step at 80°C. Pre-annealing of the ferrite powders before ink formulation enabled the avoidance of high-temperature processing post-fabrication typically required in industrial thermistor production. The printed thermistors were tested at a controlled constant humidity between 15 and 50°C. Both materials demonstrated typical natural logarithmic responses with high linearity and sensitivity. [ABSTRACT FROM AUTHOR]

The techniques of differential thermal analysis are frequently employed to study the kinetics of the transformation reactions and, in particular, the crystallization of the glassy alloys. The corresponding thermal data can be analyzed by the Kissinger method, which was originally derived for the study of homogeneous reactions. The consensus in the literature, in several decades, was that such applications (i.e. to heterogeneous solid state transformations) of the Kissinger method are not valid. In the present work the principal objections to the mentioned applications are addressed and alternative derivations of theoretical results are provided. These results demonstrate that the Kissinger method is valid for heterogeneous reactions of the type described by Johnson-Mehl-Avrami equation in the isothermal case. Also the isothermal and non-isothermal data on crystallization of the Cu0.10As0.40Se0.50 glassy alloy are given. The experimental results and the discussion carried out here, help to clarify the effects of incubation time in non-isothermal transformation kinetics and provide a further demonstration of validity of the generalized Johnson-Mehl-Avrami theory for the description of heterogeneous solid state transformations.Las técnicas de análisis térmico diferencial se emplean con frecuencia para estudiar la cinética de las reacciones de transformación y, en particular la de la cristalización de aleaciones vítreas. Los datos térmicos correspondientes pueden analizarse por el método de Kissinger, que se desarrolló originalmente para el estudio de reacciones homogéneas. Durante varias décadas, el consenso en la literatura fue que tales aplicaciones (es decir, a transformaciones heterogéneas de estado sólido) del método de Kissinger no eran válidas. En el presente trabajo se señalan las principales objeciones a las aplicaciones mencionadas y se da una deducción alternativa de los resultados teóricos. Estos resultados demuestran que el método de Kissinger es válido para reacciones heterogéneas del tipo descrito por la ecuación de Johnson-Mehl-Avrami en el caso isotermo. También se dan los datos de cristalización isoterma y no isoterma de la aleación vítrea Cu0.10As0.40Se0.50. Los resultados experimentales y la discusión realizada aquí, ayudan a aclarar los efectos del tiempo de incubación en la cinética de transformaciones no isotermas y proporcionan una demostración adicional de la validez de la teoría generalizada de Johnson-Mehl-Avrami para la descripción de transformaciones heterogéneas de estado sólido.

A germanium n+/p shallow junction formed by a combination of low-temperature preannealing (LTPA) and excimer laser annealing at a low fluence of 150 mJ/cm2 for phosphorus-implanted germanium is demonstrated. The LTPA step plays a critical role in annihilating the implantation damages and significantly suppressing phosphorus diffusion during laser annealing process, resulting in a very small dopant diffusion length with high activation level of phosphorus. A well-behaved Ge n+/p shallow junction diode with a record rectification ratio of \(\sim 10^{7}\) and low leakage current density of \(8.3 \times 10^{-5}\) A/cm2 is achieved, which is greatly beneficial to the scaled Ge MOSFET technology. [ABSTRACT FROM PUBLISHER]

Fe-6·5 wt-%Si thin sheets were produced by conventional rolling and annealing processes, and the effect of preannealing before final annealing on recrystallisation texture was investigated using macro- and microtexture analysis. It is found that the suitable temperature and time of preannealing can decrease detrimental γ recrystallisation texture, resulting in an optimisation of magnetic induction. The effects of preannealing can be attributed to its weakening the dynamic advantage of γ recrystallisation nuclei with respect to others. [ABSTRACT FROM AUTHOR]

Continuous heating differential scanning calorimetry is frequently employed to study the kinetics of transformation reactions and, in particular, the crystallization of the glassy alloys. Such data are analyzed by the Kissinger method, which was originally derived for the study of homogeneous reactions. Although the consensus in the literature, over several decades, was that such applications (i.e. to heterogeneous solid state transformations) of the Kissinger method are not valid, nevertheless, by assuming that the transformation products and mechanism do not change with temperature, it is possible a valid application of Kissinger method to non-isothermal heterogeneous transformations. In this work, the principal objections to these applications are addressed and bearing in mind the quoted assumptions alternative derivations of theoretical results are provided. These results demonstrate that the Kissinger method is valid for heterogeneous reactions of the type described by the Johnson–Mehl–Avrami–Kolomogoroff equation in the isothermal case. Isothermal and continuous heating data on the crystallization of Ge0.13Sb0.23Se0.64 semiconducting alloy are presented. These experimental results and the discussion presented here help to clarify the effects of incubation time on the non-isothermal transformation kinetics and provide a further demonstration of the validity of the generalized Johnson–Mehl–Avrami–Kolomogoroff theory for the description of heterogeneous solid state transformations. [Copyright &y& Elsevier]

Two-dimensional (2D) lateral heterostructures based on transition metal dichalcogenides (TMDCs) attract great interest due to their properties and potential applications in electronics and optoelectronics, such as p-n rectifying diodes, light-emitting diodes, photovoltaic devices, and bipolar junction transistors. However, the studies of 2D lateral heterostructures have mainly focused on monolayer nanosheets despite bilayer heterostructures exhibiting higher performance in many electronic and optoelectronic devices. It remains a great challenge to synthesize lateral heterostructures with few layers. Here, we report the growth of bilayer-bilayer (bl-bl), bilayer-bilayer-monolayer (bl-bl-mo), bilayer-monolayer (bl-mo), monolayer-bilayer (mo-bl), and monolayer-monolayer (mo-mo) tungsten disulfide (WS 2 ) and tungsten diselenide (WSe 2 ) lateral heterostructures. The selenium/tungsten (Se/W) ratio of WSe 2 precursor powders and the growth atmosphere can be changed with the extension of annealing time, which influences the layer number of the heterostructures. More bilayer WSe 2 epitaxially grows at the WS 2 edge with short annealing time (high Se/W ratio), and more monolayer WSe 2 grows at the WS 2 edge with long annealing time (low Se/W ratio). The density functional theory (DFT) calculations provide an in-depth understanding of the growth mechanism. This report expands the 2D material lateral heterostructure family, which gives impetus to their applications in electronics and optoelectronics.

In this paper, the microstructure evolution of the 2195 Al-Li alloy under different isothermal annealing schedules and ramp heating-up heat treatments prior to solution heat treatment and the tensile properties of the aging alloy were investigated. The grain structure characteristics of the aging alloy could be influenced by the change of different heat treatment schedules prior to the solution heat treatment. Meanwhile, the mechanical properties of the aging alloy including strength, heterogeneity, and anisotropy were closely related to the grain structure characteristics. There were evident differences in the mechanical properties of aging samples, attributed to the mutual effect of grain structure evolution and texture change. Annealing at a lower temperature (300–350 °C) resulted in the growth of the grain size and the aspect ratio as well as the decrease of the deformation texture components, related to the decline of the strength and the heterogeneity. While grains refined and the deformation texture components increased as the annealing temperature rose (350–400 °C), the strength along the transverse direction decreased, and the heterogeneity increased. Fibrous and overall texture components significantly strengthened in the grain structure of aging samples treated with the low heating-up rate, resulting in a higher strength in the longitudinal direction. [ABSTRACT FROM AUTHOR]