Predicting doped Fe-based superconductor critical temperature from structural and topological parameters using machine learning

Recently, Fe-based superconductors have shown promising properties of high critical temperature and high upper critical fields, which are prerequisites for applications in high-field magnets. Critical temperature, T c, is an important characteristic correlated with crystallographic and electronic structures. By doping with foreign ions in the crystal structure, T c can be modified, which however requires significant manpower and resources for materials synthesis and characterizations. In this study, we develop the Gaussian process regression model to predict T c of doped Fe-based superconductors based on structural and topological parameters, including the lattice constants, volume, and bonding parameter topological index H 31. The model is stable and accurate, contributing to fast T c estimations.

Surfactant-free liquid-exfoliated copper hydroxide nanocuboids for non-enzymatic electrochemical glucose detection

Effect of hydrogen bonding parameter on concentration (left) and chronoamperometry of sequential addition of glucose (right).

Structures and Ligand Field Parameters of Sm3+ Doped Tellurite Glass: Gold Nanoparticles Mediation

Controllable modifications of overall properties of rare-earth doped glasses via gold nanoparticles (Au NPs) mediation prompted gamut research interests. Such glass systems are interesting due to their technological prospects and well as fundamental understanding of surface plasmon resonance effects at metal glass interface responsible for diverse emerging attributes. This motivate us to determine the effects of varying concentration of Au NPs on the structure and ligand field parameters of samarium (Sm3+) doped zinc tellurite glass. Glass samples with composition (79-x)TeO2-20ZnO-1Sm2O3-xAuCl3, where 0 ≤ x ≤ 0.10 mol% are prepared using melt quenching method. X-ray diffraction pattern of all glasses confirmed their amorphous nature. Transmission electron microscopic images verified the existence of Au NPs in a glass matrix matrix with an average size of 10.52 nm. Two surface plasmons resonance band of gold are probed at 652 and 715 nm. Using the UV-Vis absorption spectral data, quantities such as nephelauxetic ratio, bonding parameter and Racah parameters are evaluated. Both bonding parameter and nephelauxetic ratio revealed a reduction with increasing concentration of Au NPs, where decrease in the ionic bonding between Sm3+ and surrounding ligand have clearly indicated an enhancement in the covalency. The values of Racah parameters are decreased as the concentration of Au NPs are increased. The observed reduction in the nephelauxetic function is attributed to the weakening of the localized d-electrons aroused from overlapping d-orbital and ligand orbital. Furthermore, the Raman spectra displayed the structural modification in terms of TeO4 trigonal bipyramidal (tbp) unit, where many TeO4 tbp units are converted into their TeO3 trigonal pyramid (tp) counterparts. Raman bands are found to be located around 102-105 cm-1, 420-424 cm-1, 657-661 cm-1 and 729-736 cm-1. Results are analyzed and compared. Present glass composition is asserted to be useful for the development of photonic devices.

Bondability and Strength Evaluation of Gold Ball Bond Using Nanoindentation Approach

The evaluation of the strength and bondability of gold, Au ball bond requires a new approach to provide a more detail data. Nanoindentation test was used as a new approach to evaluate the strength distribution and bondability of Au ball. Au ball bonds that experienced different value of wire bonding parameter namely bonding force, bonding time, bonding power, and stage temperature were used as samples for the present analysis. The distribution of strength based on hardness and reduced modulus values located at the bonding area of Au ball bonds were found to be related with the values of the wire bonding parameter. Nanoindentation test was found to be a suitable approach to analyze and evaluate the bondability of Au ball bond in a localized and detailed manner. In addition, the responsible mechanism for the thermosonic Au wire bonding can be identified and analyzed by using the results obtained from the nanoindentation test.

Understanding the Role of Ultrasonic Welding in Wire Bonding

Wire bonding is the dominant chip interconnection method. Ultrasonic energy is the most important bonding parameter effecting the quality and the reliability of the intermetallic weld. Understanding the mechanism enabling weld formation is a key factor in maintaining the reliability and productivity that wire bonding provides.