Growth and Magnetism of MnxGe1−x Heteroepitaxial Quantum Dots Grown on Si Wafer by Molecular Beam Epitaxy
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Self-assembled MnGe quantum dots (QDs) were grown on Si (001) substrates using molecular beam epitaxy with different growth temperatures and Ge deposition thicknesses to explore the interaction among Mn doping, Ge deposition, the formation of intermetallics, and the ferromagnetism of QDs. With the introduction of Mn atoms, the QDs become large and the density significantly decreases due to the improvement in the surface migration ability of Ge atoms. The growth temperature is one of the most important factors deciding whether intermetallic phases form between Mn and Ge. We found that Mn atoms can segregate from the Ge matrix when the growth temperature exceeds 550 °C, and the strongest ferromagnetism of QDs occurs at a growth temperature of 450 °C. As the Ge deposition thickness increases, the morphology of QDs changes and the ferromagnetic properties decrease gradually. The results clearly indicate the morphological evolution of MnGe QDs and the formation conditions of intermetallics between Mn and Ge, such as Mn5Ge3 and Mn11Ge8.Keywords:
Magnetism
Deposition
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Atmospheric temperature range
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The present work explores the growing behavior of the intermetallic layer in the Mg‐Si system. Following achievements have been obtained in our investigation: (i) A complete wetting concept is proposed for the lateral spreading of the intermetallic layer. (ii) In contrast to the stoichiometric property for the intermetallic phase in the phase diagram, the authors show that concentration gradients are able to be established in the kinetic process. (iii) Contrary to the reported growth behavior, d ∝ t 0.25–0.5 in other intermetallics, the authors find a transition from d ∝ to d ∝ t with an increase of the temperature, where d is the thickness of the intermetallic layer and t is the time.
Stoichiometry
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The Fe-Al intermetallic compound powders were fabricated by mechanical alloying and heat treatment process. In this research, the phase composition and microstructure of the Fe-Al intermetallic compound powders produced by different milling time and heat treatment at 800oC and 1000oC were investigated. The XRD patterns results showed that the Fe-Al intermetallic compound powders were fabricated by mechanical alloying for 60h. After heat treatment at 800oC and 1000oC, the Fe-Al intermetallic compound powders transformed into the Fe3Al powders. With the increase of milling time, the mechanical alloying extent of Fe-Al intermetallic compound powders would be increased remarkably, and the particles sizes decreased remarkably. The microstructure showed that the mean particles size of the Fe-Al intermetallic compound powders after milling for 60h was rather fine and about 4-5μm. The microstructures showed that mean particles size of the Fe3Al intermetallic compound powders produced by heat treatment at 800oC and 1000oC was also about 4-5μm.
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In this era, intermetallic technology going to take a broad advantage with its presence in high-temperature processing materials. This chapter gives a brief idea of the intermetallic compound. This chapter shows how their presence can improve the materials' properties. Various structures of the intermetallic compound and their classification have been discussed. Applications in aerovehicle industries, automobile industries, and electrical industries have been stated here.
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The intermetallic compound layers in solder bumps have the brittle feature and can easily fracture under thermal or mechanical loading. Therefore, the intermetallic compound is an issue for the fracture reliability of the solder bumps. In this work, the intermetallic compound growth before and after high temperature storage tests was investigated. The experiment results revealed that the solder bumps with nickel layers could reduce the intermetallic compound growth rate. The nickel layer, which was added in between Cu and SnAg for top solder bumps, was an important factor controlling the intermetallic compound thickness. It was hard to tell the intermetallic compound thickness at time zero; at the time of 147 hours, the intermetallic compound grew to 3.25 µm; at the time of 294 hours, the intermetallic compound grew to 5.25 µm. However, the solder joints were still in good condition.
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AbstractAbstractThe growth kinetics of intermetallic compound layers formed between Sn–5Bi–3.5Ag solder and Cu substrate were investigated at temperatures between 70°C and 200°C for 0 to 60 days. A quantitative analysis of the intermetallic compound layer thickness as a function of time and temperature was performed. Diffusion couples showed a composite intermetallic layer comprised of Cu6Sn5 and Cu3Sn. The growth of intermetallic compounds followed diffusion controlled kinetics and the layer thickness reached only 10 μm after 60 days of aging at 150°C. The apparent activation energies calculated for the growth of the total intermetallic compound (Cu6Sn5 + Cu3Sn), Cu6Sn5 and Cu3Sn intermetallic are 88.6, 84.3 and 70.28 kJ mol-1, respectively.
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Brittleness
Ductility (Earth science)
Powder Metallurgy
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Abstract Interfacial reactions and mechanical properties between the Cu and Pb-free solders, Sn-3.0Ag-0.5Cu and Sn-58Bi with addition of 0.1 to 1.0 wt.% Pb are investigated in this study. Two kinds of intermetallic compounds, scallop-shaped Cu 6 Sn 5 and plane layered Cu 3 Sn phases, were found in both Sn-3.0Ag-0.5Cu + Pb/Cu and Sn-58Bi + Pb/Cu couples. The intermetallic compound thickness increased with longer reaction times, higher reaction temperatures and greater Pb contents. The Cu 6 Sn 5 phase was the thicker intermetallic compound in the Sn-3.0Ag-0.5Cu + Pb/Cu couple. However, in the Sn-58Bi + Pb/Cu system, the Cu 3 Sn phase is the thicker intermetallic compound. Experimental results indicate that the higher Pb concentration in Sn-3.0Ag-0.5Cu or Sn-58Bi solders reduces the alloy liquidus temperature and increases the thickness of the intermetallic compound. Thicker intermetallic compounds reduce the mechanical strength of the solder joint.
Liquidus
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