The influence of the additive BaGeO3 on BaSnO3 ceramics

Abstract

DTA, XRD and sintering investigations of the system BaSnO 3 -BaGeO 3 , prepared by a mixed-oxide method, are described herein. The melting temperature of this system is about 1270 ± 5 • C. We find a partial solubility of BaGeO 3 into BaSnO 3 of the order of 6-7 mol%. Up to 50 mol% BaGeO 3 , the calcined powders (1150 • C) as well as the once-sintered samples consist of BaSnO 3 and orthorhombic BaGeO 3 at room temperature. A gradual appearance of hexagonal BaGeO 3 can be observed in calcined powders and once-sintered ceramics with a BaGeO 3 content above 50 mol%. After sintering at ≥1200 • C for more than 1 h all ceramic bodies consist of BaSnO 3 and orthorhombic BaGeO 3 . The addition of BaGeO 3 leads to a considerable reduction of the sintering temperature and to a strong densification. Sintering at 1180 • C for 10 h and an addition of only 1 mol% BaGeO 3 leads to dense ceramic bodies with cubic-like grains.

Semiconducting properties of Ge-doped BaSnO3 ceramic

“…At 1400 • C we obtain bodies with a heterogeneous grain distribution between 2.5 and 26 m (see also Ref. [33]). …”

“…Sintering at 1200 • C leads to ceramics with relative density of 82% (5.92 g/cm 3 ). A relative density of 95% (6.83 g/cm 3 ) is observed at a slightly higher temperature of 1250 • C. After sintering at 1300 and 1400 • C we obtain ceramics with relative densities of 99% [33]. SEM images of the surface of the ceramic bodies are shown in Fig.…”

“…The preparation procedure is described elsewhere [33]. Briefly, a powder with the composition of BaSn 0.99 Ge 0.01 O 3 was prepared via a conventional mixed-oxide method.…”

“…The reflectance spectra of the samples were measured using a UV-VIS-NIR 3600 Shimadzu spectrophotometer with an integrating sphere attachment. Recently, Köferstein et al [33] reported on the system BaSnO 3 -BaGeO 3 . They found a limited solid solubility of BaGeO 3 in BaSnO 3 of the order of 6-7 mol%, because of their different crystal structures.…”

“…BaGeO 3 can be also used as a sintering aid to drastically reduce the sintering temperature as reported for BaTiO 3 -based ceramics [30][31][32]. Recently, Köferstein et al [33] sintered BaSnO 3 ceramics at very low temperatures adding BaGeO 3 and they found a partial solid solubility of BaGeO 3 in BaSnO 3 .…”