Atsushi Komura

Microwave Dielectric Properties of Ba4(Nd28/3-yRy)Ti18O54 (R = Eu, Dy, Ho, Er and Yb) Solid Solutions

We have investigated the formation and the microwave dielectric properties of the Ba4(Nd28/3-y Ry)Ti18O54 (R = Eu, Dy, Ho, Er and Yb) solid solutions in which R ions are substituted for Nd ions in Ba6-3xNd8+2xTi18O54 solid solutions with x=2/3. Based on the change of the volume of the unit cell, it was inferred that Eu, Dy, Ho and Er ions substituted into rhombic A1-sites, but Yb ions did smaller sites such as B-sites and C-sites after substituting A1-sites. The quality factor (Qf) improved as the ionic radius of substituted R ions increased. In the Eu series, the best Qf value of 10405 GHz was obtained. The temperature coefficients of the reasonant frequency (τf) in the Dy, Ho and Er series were improved by more than 50%, but the dielectric constant (er) showed only a nominal change of about 3–4 in the vicinity of 80.

Recordable Digital Versatile Disc for High Data Transfer Rate Recording

We studied the characteristics of the 4.7 GB recordable digital versatile disc (DVD-R) for a high data transfer rate higher than 44 Mbps. Using simulation, analytical pulse sequence and atomic force microscopy (AFM) measurement, we analyzed the thermal interference. We also used originally synthesized dye with low thermal interference and realized good recording characteristics with jitter values of around 8% at 66 Mbps recording and 11% at 89 Mbps recording.