Examination of the Mass Transfer of Additive Elements in Barium Titanate Ceramics during Sintering Process by Laser Ablation ICP-MS.

The mass transfer of additive elements during the sintering of barium titanate (BaTiO3) ceramic was examined by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) in the present study. An analytical sample consisting of two pellets of BaTiO3 with different concentrations of additive elements of manganese (Mn) and holmium (Ho) as well as silicon (Si) as a sintering reagent was prepared and measured by LA-ICP-MS with small laser irradiated diameter of 10 µm to evaluate the distributions and concentrations of additive elements in order to examine their mass transfers. As results, enrichments of Mn and Si as an additive element and a sintering reagent, respectively, were observed on the adhesive surface between two BaTiO3 pellets, even though Ho did not show a similar phenomenon. The mass transfers of additive elements of Mn and Ho were also examined, and Mn seemed to show a larger mass transfer than that of Ho during the sintering process for BaTiO3 ceramics. The results obtained in this study shows the effectives of LA-ICP-MS for the future improvement of MLCCs.

Highly piezoelectric co-doped AlN thin films for wideband FBAR applications.

We report piezoelectric materials composed of charge-compensated co-doped (Mg, ß)(x)Al(1-x)N (ß = Zr or Hf) thin films. The effect of the dopant element into AlN on the crystal structure, and piezoelectric properties of co-doped AlN was determined on the basis of a first-principles calculation, and the theoretical piezoelectric properties were confirmed by experimentally depositing thin films of magnesium (Mg) and zirconium (Zr) co-doped AlN (Mg-Zr-doped AlN). The Mg-Zrdoped AlN thin films were prepared on Si (100) substrates by using a triple-radio-frequency magnetron reactive co-sputtering system. The crystal structures and piezoelectric coefficients (d33) were investigated as a function of the concentrations, which were measured by X-ray diffraction and a piezometer. The results show that the d33 of Mg-Zr-doped AlN at total Mg and Zr concentrations (both expressed as ß) of 0.35 was 280% larger than that of pure AlN. The experimentally measured parameter of the crystal structure and d33 of Mg-Zr-doped AlN (plotted as functions of total Mg and Zr concentrations) were in very close agreement with the corresponding values obtained by the first-principle calculations. Thin film bulk acoustic wave resonators (FBAR) employing (Mg,Zr)0.13Al0.87N and (Mg, Hf)0.13 Al0.87N as a piezoelectric thin film were fabricated, and their resonant characteristics were evaluated. The measured electromechanical coupling coefficient increased from 7.1% for pure AlN to 8.5% for Mg-Zr-doped AlN and 10.0% for Mg- Hf-doped AlN. These results indicate that co-doped (Mg, ß)(x)Al(1-x)N (ß = Zr or Hf) films have potential as piezoelectric thin films for wideband RF applications.