Quasicrystals with a primitive icosahedral structure and a quasilattice constant of 5.1215 Å have been synthesized in a binary Cd–Ca system. The thermal stability of the quasicrystal has been investigated by in situ high-temperature x-ray powder diffraction using synchrotron radiation. It is demonstrated that the binary CdCa quasicrystal is thermodynamic stable up to its melting temperature. The linear thermal expansion coefficient of the quasicrystal is 2.765×10−5 K−1.

The amorphous-to-quasicrystalline phase transformation in a Zr65Al7.5Ni10Cu7.5Ag10 metallic glass has been investigated by monitoring the quasilattice constant and the composition of quasicrystalline particles in the samples annealed in vacuum at 663 K for various times. It is found that the quasilattice constant decreases with annealing time and saturates after 90 min while the zirconium and silver contents in quasicrystalline particles differ from those in the remaining amorphous matrix. The results provide evidence that the amorphous-to-quasicrystalline phase transformation in the Zr65Al7.5Ni10Cu7.5Ag10 metallic glass is a nonpolymorphous reaction.

Abstract-Connectivity in smart devices is increasingly realized by wireless connections. The remaining reason for using connectors at all is for charging the internal battery, for which wireless power transfer is an alternative. Two industry standards, AirFuel and Qi, exist to support compatibility between devices. This work is focusing on the AirFuel standard, as it is operating at a higher frequency (6.78 MHz), than the Qi standard, and therefore allows smaller passive components, including the coupling coils. Whereas gallium-nitride (GaN) devices are being widely used on the transmitter (Tx) side, this work uses low voltage GaN transistors on the receiver (Rx) side to allow synchronous rectification and soft switching, thereby achieving high efficiency. After analyzing adequate Class-DE rectifier topologies, a Class-DE full-bridge 5 W rectifier using 15 V GaN transistors are designed and implemented. The experimental results show an efficiency above 80 % over a wide operating range and a peak efficiency of 89 %, at an arbitrary alignment of Tx and Rx coils with 3 cm distance between them.

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