Temperature-Modulated Pyroelectricity Measurements of a Thin Ferroelectric Crystal with In-Plane Polarization and the Thermal Analysis Based on One-Dimensional Layer Models

A temperature-modulated pyroelectricity measurement system for a small single crystal is developed and applied to standard sample measurements performed on a thin single crystal of lithium niobate. The modulation measurement is based on the AC technique, in which the temperature of the sample is periodically oscillated, and the synchronized pyroelectric signal is extracted using a lock-in amplifier. Temperature modulation is applied by irradiating periodic light on the sample placed in the heat exchange gas. To apply this technique to the transparent reference sample, a commercially available black resin is coated on the sample’s surface to absorb the light energy and transmits it to the specimen. The experimental results are analyzed using a two-layer heat transfer model to verify the effect of the light-absorbing layer as well as the radiative temperature modulation system.

Temperature-Modulated Pyroelectricity Measurements of a Thin Ferroelectric Crystal With in-Plane Polarization and the Thermal Analysis Based on One-Dimensional Layer Models

A temperature-modulated pyroelectricity measurement system for a small single crystal is developed and applied to standard sample measurements performed on a thin single crystal of lithium niobate. The modulation measurement is based on the AC technique, in which the temperature of the sample is periodically oscillated, and the synchronized pyroelectric signal is extracted using a lock-in amplifier. Temperature modulation is applied by irradiating periodic light on the sample placed in the heat exchange gas. To apply this technique to the transparent reference sample, a commercially available black resin is coated on the sample’s surface to absorb the light energy and transmits it to the specimen. The experimental results are analyzed using a two-layer heat transfer model to verify the effect of the light-absorbing layer as well as the non-contact temperature modulation system.

CRYSTALLINE STRUCTURE AND PHYSICAL PROPERTIES OF UCo2Al3

Some intermetallic compounds which contain uranium or cerium present heavy fermion characteristics. Take, for example, in the UM 2 Al 3 ( M = Pd , Ni ) family, superconductivity and magnetism coexist and present heavy fermion behavior. This work presents the crystallographic characteristics and physical properties of a new compound of this family; the intermetallic compound UCo 2 Al 3. Our initial crystallographic studies performed in a small single crystal show that the structure is hexagonal and similar to the UNi 2 Al 3 and UPd 2 Al 3 parent compounds. The space group is P6/mmm with a=5.125 Å and c=4.167 Å crystalline parameters. Measurements of resistivity and magnetization performed on the single crystal reveal that the compound is not superconducting when measured at about 1.8 K. The compound is highly anisotropic and features related to Kondo-like behavior are observed. A weak ferromagnetic transition is observed at a temperature of about 20 K.

Second harmonic generation from CsLiB6O10-containing glass-ceramics

Glass-ceramics containing ferroelectric CsLiB6O10 crystals were prepared by heat treating Cs2O–Li2O–B2O3 glasses. Second harmonic generation (SHG) was observed from samples prepared by two-step heat treatment (nucleation and growth); however, the intensity was rather weak. On the other hand, one-step heat treatment by the addition of a small amount of TiO2 to the glass resulted in the glass-ceramics containing small single crystal-like CsLiB6O10 particles. The strongest SHG observed was comparable with that of Y-cut quartz. The preferred orientation of precipitated CsLiB6O10 crystals was attributed to the occurrence of SHG from the glass-ceramics.

Structure of Mg6SO2(OH)14 determined by micro single-crystal X-ray diffraction

The structure of hexamagnesium sulfonyl tetradecahydroxide, Mg6SO2(OH)14, has been determined with an extremely small single-crystal (ca 0.5 × 100 × 2.5 μm) using synchrotron radiation [1.00 (1) Å]. The crystal is orthorhombic with space group Ccmm (No. 63), a = 15.895 (1), b = 3.105 (1), c = 13.367 (1) Å, V = 659.64 (3) Å3 and Z = 2. The final R and wR values are 0.073 and 0.083 for 105 crystallographically independent reflections. The structure consists of MO6 octahedra and SO4 tetrahedra. The MgO6 octahedra share their edges to form zigzag sheets parallel to (100). The SO4 tetrahedron shares two of the O atoms with the MgO6 octahedra at the turning of the sheet and is statistically located with a probability of 0.5. Fine streaks observed perpendicular to the b* axis on diffraction photographs indicate that the SO4 tetrahedra are distributed at random along the a and c axes, but alternately along the b axis. All the H atoms are considered to exist in the form of OH groups.

Computer Simulation of Bending Plastic Deformation and Creation of Dislocations in Copper Thin Films

A small single crystal of copper with a notch has been bent by use of the molecular dynamics method. The bend axis was [110]. Dislocations were created near the tip of the notch and moved on (111) slip plane. Pulling a copper single crystal, half dislocations were created in such a way that the bending was compensated.