摘要:

Studies of both single crystals and ceramics of samarium‐doped BaTiO3having identical compositions show that the positive temperature coefficient (PTC) electrical resistivity anomaly originates at the grain boundaries of the ceramic. The grain‐boundary region is visualized as an electron exhaustion layer, 102to 104A thick, of much higher electrical resistivity than the interior of the grain. These findings are compatible with Heywang's barrier layer model, with possible tunneling or electron wave scattering models, and with elements of Saburi's local fields mechanism. Sufficient information to point to any one model is, however, not yet availa

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1963.tb13770.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

An oxide of titanium, apparently Ti2O3, showed solid solubility in Al2O3of 1.0, 1.8, and 2.5 mole % at 1400°, 1600°, and 1700°C, respectively, when heated in hydrogen with a dew point of about ‐50°C. At the same temperatures in air, however, no indication of solid solubility (of TiO2, presumably) was found by X‐ray diffraction. It is concluded, therefore, that titania effects densification and grain growth of alumina by grain‐boundary action rather than by a defect mechanism in the corundum lattice resulting from the substitutional solution of

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1963.tb13771.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1963.tb13772.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1963.tb13773.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1963.tb13774.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY