The magnetocaloric effect and critical behavior in amorphous Gd 60Co 40-xMn x alloys.

The amorphous alloys Gd60Co40−xMnx (x = 0, 5, 10, 15) were prepared by melt spinning. The Curie temperature,T c, increases monotonously with Mn addition, ranging from 198 K for x = 0 to 205 K for x = 15, while the maximum values of −ΔSM under the applied field change from 0 to 5 T are 7.7, 7.1, 6.2 and 5.4 J·kg−1·K−1 for x = 0, 5, 10, and 15, respectively. All samples undergo a second order ferri-paramagnetic phase transition. The critical behavior around the transitiontemperature is investigated in detail, using both the standard Kouvel-Fisher procedure as well as the study of the field dependence of the magnetocaloric effect. Results indicate that the obtained critical exponents are reliable, and that the present alloys exhibit local magnetic interaction

The role of environmental justice reform in corporate green transformation: Evidence from the establishment of China’s environmental courts

Purpose: The establishment of environmental courts in China provides a good opportunity to explores the economic effects of environmental justice reform. This paper investigates how the environmental justice reform can influence corporate green transformation from the perspective of green technology innovation and explores the potential mechanisms of how the environmental courts affect green technology innovation. The heterogeneous effects of environmental courts are also considered.Methodology: Using the establishment of environmental courts in China as a quasi-natural experiment, this paper adopts a difference-in-difference (DID) method to conduct empirical test based on data on Chinese listed A-shared firms from 2004 to 2019. Moreover, this paper use propensity score matching (PSM), tobit and negative binomial regression method to address possible estimation bias.Findings: The establishment of environmental courts significantly enhances green technology innovation among enterprises. The more effective judicial enforcement and better public awareness of the environment brought by the environmental courts will increase the cost of illegality and external supervision pressure for firms, which will lead firms to innovate in green technology. Furthermore, the positive and significant effect of environmental courts on green technology innovation is more pronounced in state-owned enterprises (SOEs) and enterprises located in regions where local protectionism is more serious or regions with more ideal environmental legal system

Magnetic properties and magnetocaloric effects in GdCo9Si2 compound with multiple magnetic phase transitions

The structure and magnetic properties of polycrystalline GdCo9Si2 compound have been investigated. It has a BaCd11 structure and undergoes two magnetic phase transitions: an antiferromagnetic to ferrimagnetic transition occurring at rv93 K, and a ferrimagnetic to paramagnetic transition at 420 K, which results in a positive and a negative magnetic entropy change, respectively. The two peak values of magnetic entropy change are -0.6 and 1.1 J·kg-1 K-1 for DH ¼ 5 T. Furthermore, there exists a metal-semiconductor transition temperature (TP), below which the resistance increases with increasing temperature, while the semiconductor characteristic is observed above TP. The magnetic domain structures are characterized by stripe and grid structures 1 lm wide. Although the MCE is small for applications, its study is useful to clearly understand the nature of multiple magnetic phase transitions in the GdCo9Si2 compound

Low hysteresis and large room temperature magnetocaloric effect of Gd 5Si2.05-xGe1.95-xNi2x (2x 0.08, 0.1) alloys

Gd5Si2.05-xGe1.95-xNi2x (2x ¼ 0.08, 0.1) alloys were prepared by arc melting followed by annealing at 1273 K for 96 h. Mixed monoclinic Gd5Si2Ge2-type phase, orthorhombic Gd5Si4-type phase, and a small amount of Gd5Si3-type phase were obtained in these alloys. Gd5Si2.01Ge1.91Ni0.08 alloy undergoes a second-order transition (TC) around 300 K, whereas Gd5Si2Ge1.9Ni0.1 alloy exhibits two II I transitions including a first-order transition (TC ) at rv295 K and second-order transition (TC ) at rv301 K. Ni substitution can effectively reduce the thermal hysteresis and magnetic hysteresis while max maintaining large magnetic entropy change. The maximum magnetic entropy changes (|DSM |) of 1 -1 Gd5Si2.05-xGe1.95-xNi2x alloys with 2x ¼ 0.08 and 0.1 are 4.4 and 5.0 J kg- K, respectively, for 0–2 T, and are 8.0 and 9.1 J kg-1 K-1, respectively, for 0–5 T. Low hysteresis performance and relatively large magnetic entropy change make these alloys favorable for magnetic refrigeration applications

Kirigami-inspired highly stretchable nanoscale devices using multi-dimensional deformation of monolayer MoS2

Two-dimensional (2D) layered materials, such as MoS2, are greatly attractive for flexible devices due to their unique layered structures, novel physical and electronic properties, and high mechanical strength. However, their limited mechanical strains (<2%) can hardly meet the demands of loading conditions for most flexible and stretchable device applications. In this paper, inspired from Kirigami, ancient Japanese art of paper cutting, we design and fabricate nanoscale Kirigami architectures of 2D layered MoS2 on a soft substrate of PDMS using a top-down fabrication process. Results show that the Kirigami structures significantly improve the reversible strechability of flexible 2D MoS2 electronic devices, which is increased from 0.75% to ~15%. This increase in flexibility is originated from a combination of multi-dimensional deformation capabilities from the nanoscale Kirigami architectures consisting of in-plane stretching and out-of-plane deformation. We further discover a new fundamental relationship of electrical conductance and large strain in MoS2 Kirigami structures through both experimental work and finite element simulation. Results show that the electrical conductance of the stretchable MoS2 Kirigami is closely related to its different stages of structural evolutions under strain: e.g., elastic stretching; then a combination of elastic stretching and out-of-plane buckling; and finally stretching and structural damage. This method provides a new opportunity to fabricate highly flexible and stretchable sensors and actuators using different types of 2D materials

The Preparation of High Saturation Magnetization and Low Coercivity Feco Soft Magnetic Thin Films via Controlling the Thickness and Deposition Temperature

FeCo thin films with high saturation magnetization (4 &pi;Ms) can be applied in high-frequency electronic devices such as thin film inductors and microwave noise suppressors. However, due to its large magnetocrystalline anisotropy constant and magnetostrictive coefficient of FeCo, the coercivity (Hc) of FeCo films is generally high, which is detrimental to the soft magnetic properties. Meanwhile, the thickness and deposition temperature have significant effects on the coercivity and saturation magnetization of FeCo films. In this paper, FeCo thin films with different thicknesses were prepared by magnetron sputtering at different temperatures. The effects of thickness and deposition temperature on the microstructure and magnetic properties of FeCo thin films were systematically studied. When the film thickness increases from 50 nm to 800 nm, the coercivity would decrease from 309 Oe to 160 Oe. However, the saturation magnetization decreases from 22.1 kG to 15.3 kG. After that, we try to further increase the deposition temperature from room temperature (RT) to 475 &deg;C. It is intriguing to find that the coercivity greatly decreased from 160 Oe to 3 Oe (decreased by 98%), and the saturation magnetization increased from 15.3 kG to 23.5 kG (increased by 53%) for the film with thickness of 800 nm. For the film with thickness of 50 nm, the coercivity also greatly decreased from 309 Oe to 10 Oe (decreased by 96%), but the saturation magnetization did not change significantly. It is contributed to the increase of deposition temperature, which will lead to the increase of grain size and the decrease of the number of grain boundaries. And the coercivity decreases as the number of grain boundaries decreases. Meanwhile, for the thicker films, when increasing the deposition temperature the thermal stress increases, which changes the appearance of (200) texture, and the saturation magnetization increases. Whereas, it has a negligible effect on the orientation of thin films with small thickness (50 nm). This indicates that high-temperature deposition is beneficial to the soft magnetic properties of FeCo thin films, particularly for the films with larger thickness. This FeCo thin film with high saturation magnetization and low coercivity could be an ideal candidate for high-frequency electronic devices