Crystallization of oxide materials from molten metal hydroxides: The characterization of new high-oxidation-state bismuthates

Miscellaneous · Wed Jan 01 00:00:00 EST 1992

OSTI ID:6934065

Carlson, V A

In 1988, the discovery of superconductivity in Ba[sub 0.7]K[sub 0.3]BiO[sub 3] piqued scientific interest in the study of materials which contain the element bismuth. Specifically, high-oxidation-state bismuthates were of interest as the formal oxidation state of bismuth in Ba[sub 0.7]K[sub 0.3]BiO[sub 3] is +4.3. Although many bismuthates with a lower formal oxidation state [Bi(III)] have been studied previously, few materials which contain bismuth atoms in a higher oxidation state have been characterized. This thesis presents the synthesis and characterization of twelve new Bi(V) oxides which include seven new structure types; two new Sb(V) oxides are included also. The formulae of these materials are Li[sub 6]KBiO[sub 6], Li[sub 6]RbBiO[sub 6], Li[sub 2]Ba[sub 5]Bi[sub 2]O[sub 11], Li[sub 9]Al[sub 2]Sr[sub 4]BiO[sub 14], AlSr[sub 4]Ba[sub 2]BiO[sub 10], NaBa[sub 3]BiO[sub 6], NaSr[sub 3]BiO[sub 6], LiSr[sub 3]BiO[sub 6], Ag[sub 1[minus]x]K[sub x]Ba[sub 3]BiO[sub 6], NaSr[sub 3]SbO[sub 6], LiSr[sub 3]SbO[sub 6], Ba[sub 3]BiO[sub 5.5], Ba[sub 2]SrBiO[sub 5.5], and Sr[sub 3]BiO[sub 5.5]. All of the materials were crystallized from molten mixtures of alkali and/or alkaline-earth metal hydroxides in the temperature range 450[degrees] to 750[degrees]C. In addition, NaBa[sub 3]BiO[sub 6] and Ag[sub 1[minus]x]K[sub x]Ba[sub 3]BiO[sub 6] were found to decompose at 400 and 100[degrees]C respectively to form Na[sub 0.25]Ba[sub 0.75]BiO[sub 3] and (Ag/K)[sub x]Ba[sub 1[minus]x]BiO[sub 3]. This decomposition will be discussed also in this thesis.

• Research Organization: California Univ., Berkeley, CA (United States)
• OSTI ID: 6934065
• Resource Relation: Other Information: Thesis (Ph.D.)
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BISMUTH OXIDES
CRYSTALLIZATION
VALENCE
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
INTERMETALLIC COMPOUNDS
LITHIUM OXIDES
ALLOYS
BISMUTH COMPOUNDS
CHALCOGENIDES
LITHIUM COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
360201* - Ceramics
Cermets
& Refractories- Preparation & Fabrication