Key Engineering Materials Vol. 508

Abstract: Single Crystalline Langatate (La₃Ta_0.5Ga_5.5O₁₄, LTG) Has Been Widely Used in Piezoelectric Sensors for High Temperature Applications because of its Structural Stability at High Temperature. however, in the Recent Experiment, an Increase of Electrical Conductivity Has Been Also Observed at the Intermediate Temperature Region Ranges from 300 to 700°C. Also, in Theoretical Calculations, Penta-Valent Ta Vacancy Can Be Easily Generated and Influence Resistivity Degradation of the Crystal. In this Study, to Elucidate the Ta Vacancy Effects on Electrical Conductivity of LTG and Recently Proposed Ba-Based P321 Crystal such as BTGS and BTAS, Electrical Conductivity of those Materials Were Calculated and Compared by Utilizing Boltzmann Transport Theory. The Calculated GW Band Gaps of Perfect BTGS and BTAS (5.94 Ev and 6.69 Ev, Respectivily) Were much Larger than that of LTG (5.36 Ev). Also, at Intermediate Temperature (1000K), the Calculated Electrical Conductivity of LTG with V'''''Ta (in Kröger-Vink Notation [13]) Was around Twelve Times Higher than the Conductivity of BTGS and BTAS with Ta Vacancy.

Abstract: The Emission Characteristic of Copper Ionic Lines Requiring Large Excitation Energies Was Investigated in Low-Pressure Laser-Induced Plasma Spectroscopy (LP-LIPS), when Argon Was Employed as Plasma Gas. The Excited Mechanism of the Ironic Lines Whose Electron Transitions Were Assigned to the 3d⁹5s-3d⁹4p Configuration Was Understood from the Time-Resolved Spectra of Copper. The Emission Intensity of the Copper Emission Lines, Measured in a Time-Resolved Mode, Was Extremely Dependent on the Kind of Copper Lines and the Upper Energy. Generally, their Emission Intensities Dramatically Decreased with the Duration Time, along with the Recombination as Well as the De-Excitation of Copper Ions Requiring Larger Kinetics Energy which Mainly Were Produced in a Hot Breakdown Plasma. The Emission Behavior Excited from the 3d⁹5s-3d⁹4p Transition, such as the Cu II 254.4 nm and the Cu II 276.9 nm Lines, Was Generally Similar to that from 3d⁹4p-3d⁹4s Transition, although their Excitation Energies Were Different. This Effect Would Result from a Common and Dominant Ionization /excitation Mechanism, which Was Collision Energy Transfer from Energetic Particles such as Fast Electrons.

Abstract: We Review Our Dynamical Property Measurements of Rattling Phonons in Type-I Clathrate Compounds, the Quasi-on-Center Ba₈Ga₁₆Ge₃₀ (BGG) and Off-Center Ba₈Ga₁₆Sn₃₀ (BGS), Using a Terahertz Time-Domain Spectrometer. The Lowest-Lying Vibrational Modes of Rattling Ba Ions in the Oversized Cage Show Anomalous Temperature Dependence in their Spectra. For BGG, the Temperature Dependence Is Mostly Consistent with a Local Anharmonic Potential Approximation that Predicts Softening towards Low Temperature. On the other Hand, for BGS, a Single Broad Peak of Off-Center Rattling Phonons Splits into Two Subpeaks below 120 K, and, with Further Lowering Temperature, the Spectra Show Anomalous Broadening. While the Splitting Can Be Understood by the Double Well Potential, the Linewidth Broadening Must Be Attributed to some Relevant Interactions with such Excitations as Acoustic Phonons and Doped Carriers.

Abstract: The Inverse Spin-Hall Effect (ISHE), Conversion of Spin Currents into Charge Currents, Has Recently Been Observed in Paramagnetic Metal/Ferrimagnetic Insulator Bilayer Films by Means of the Spin Pumping. Here we Investigate the ISHE Induced by the Spin Pumping on Pt/Ti/Y₃Fe₅O₁₂ and Pt/Ti/BiY₂Fe₅O₁₂ Films, where the Y₃Fe₅O₁₂ (BiY₂Fe₅O₁₂) and Pt Layers Are Separated by Thin Ti Layer. In these Systems, we Measured Electric Voltage due to the ISHE in Pt/Ti/Y₃Fe₅O₁₂ (BiY₂Fe₅O₁₂) Systems at Room Temperature. The Experimental Results Show that the ISHE Signal Disappears in the Pt/Ti/Y₃Fe₅O₁₂ (BiY₂Fe₅O₁₂) Systems. These Results Indicate that the Spin Pumping between Y₃Fe₅O₁₂ (BiY₂Fe₅O₁₂) and Ti Layer Is Suppressed. This Method Enables us to Suppress the Spin Currents without Non-Magnetic Insulators.

Abstract: The Packing Features of Mackay and Pseudo Mackay Clusters in Al Based Approximants to Icosahedral Phases Are Surveyed. The Cubic Approximants of α-AlMnSi, AlReSi, and α-(Al,Si)CuFe Indicate Typical Mackay Clusters Composed by the Dense Icosahedral Shell Packing. On the other Hand, the Cubic Approximants of α-Alcuru and α-(Al,Si)CuFe and the Non-Cubic Approximants of Ir₉Al₂₈, χ-AlPdRe, and R-AlPdCo Shows so-Called Pseudo Mackay Clusters in which the Icosahedral Packing Feature Is Disappeared at their First Shells. The Distorted First Shells Represent a Variation of Pseudo Mackay Clusters, which Could Be Classified into Three Subgroups Based on the Symmetry.

Abstract: Deformation Characteristics in High-Purity Si Crystals Subjected to Bending Tests Were Studied. Specimens Were Deformed at the Temperatures Higher than 800°C without Brittle Fracture under Application of a High Stress up to 350 Mpa. Stress-Strain Behavior and the Yield Stresses Depend on the Temperature and the Strain Rate. The Results Were Discussed in Terms of the Dislocation Dynamics and Dislocation Mobility to Provide Fundamental Knowledge for Wafer Manufacturing.

Abstract: In this Research a Method for Computer Simulation Model of Composite Materials, which Are Reinforced by Multi-Size Particles, Is Introduced. All Particles Are Embedded in the Matrix Randomly. Composite of Different Particle Volume Fraction Were Simulated and Visualized. Statistic Results Shows that the Particles Disperse Distribution Are Uniform which Could Be Used in the Further Study of Composite.