Definite increases in the Curie point (TC) of undoped and lanthanum‐ (La‐) doped (<0.5 at.%) barium titanate (BaTiO3) ceramics sintered at elevated temperatures in the range of 1300°‐1450°C were observed. Both undoped and 0.3 at.% La‐doped BaTiO3 (chosen as a typical doping concentration to yield semiconducting materials) ceramics showed almost the same TC behavior; their TC values increased by ∼3.5°C as the sintering temperature was increased from 1300° to 1450°C. Semiconducting 0.3 at.% La‐doped materials increased in room‐temperature bulk resistivity and TC with increased sintering temperature. The bulk resistivity of the La‐doped materials, which was obtained from complex impedance analysis, increased from ∼2 omega cm for the material sintered at 1350°C to ∼6 ω cm at 1450°C. The phenomenon of bulk resistivity increase with sintering temperature was observed in the materials with a doping concentration of ≥ 0.2 at.% La, but was not observed in those doped with <0.2 at.% La. The mechanisms of TC and the bulk resistivity increase observed in the present materials with increased sintering temperature are discussed based on various models found in the literature, particularly in terms of the defect chemistry in semiconducting BaTiO3 ceramics and the influence of liquid phases present during sintering.

BaTiO, ceramics doped with La (0.01-0.84 at.%) were prepared only with the addition of La and stoichiometric Ti02. As a result, even when BaTiO, was doped with 0.53 at.% La, it could be converted to a semiconductor by sintering at 1540°C for 2 h in air and cooled slowly in the furnace. Differential thermal analysis data clearly demonstrated that the Curie point in the materials shifted toward lower temperatures with increased content of La substituted at the Ba site up to a critical concentration that varied with the sintering temperature. The obtained results suggest that the semiconducting-insulating transition for highly donor-doped BaTiO, was closely related to the incorporation of donor into the grains and to the resultant grain size, which were significantly affected by the sinterability of the BaTiO, starting powders and sintering conditions used.

Objective: To demonstrate the clinical significance of 4hour delayed gadolinium-enhanced three-dimensional fluidattenuated inversion recovery (delayed 3D-FLAIR) in patients with intralabyrinthine schwannoma (ILS). Patients: Three patients who were clinically diagnosed with ILS. Interventions: All patients underwent audiological examinations and magnetic resonance imaging (MRI) scans. The MR-protocol included axial MR cisternography, immediate gadolinium-enhanced T1-weighted sequence, and heavily T2weighted 3D-FLAIR prior to and 4 hours after the intravenous administration of gadolinium contrast medium. Main Outcome Measures: All MR images were visually inspected.Results: In all three patients with ILS, delayed 3D-FLAIR MRI demonstrated a strong signal of cochlear fluid surrounding the tumor, which highlighted a tumor region that lacked signals.Conclusions: Delayed 3D-FLAIR MRI may serve as a novel diagnostic tool for the early detection of intralabyrinthine micro-schwannoma. The findings also shed light on the pathophysiology of ILS.