Evidence for a New Monoclinic Bi–La Oxide Solid Solution: Identification and Structural Relationship to the Rhombohedral Bi–Sr–O Type

✍ Scribed by M. Drache; J.P. Wignacourt; P. Conflant

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 142 KB
• Volume: 151
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.2000.8654

✦ Synopsis

As a term of the Bi+Sr+O rhombohedral type Bi 1؊y La y O 1.5 solid solution, the Bi 17 La 4 O 31.5 mixed oxide (y no. 0.19) has been investigated. Air-quenching from the high temperature domain of the 1 disordered form allows one to preserve at room temperature a metastable form of 1 . This form transforms exothermally on heating near 2003C to a new monoclinic phase. This transformation and the transition monoclinic phasePstable ordered rhombohedral 2 , which occurs at 4453C, are both irreversible on cooling for this composition. The 2 P 1 transition occurs reversibly near 6603C, under usual dynamic conditions (3003 h ؊1 ). The monoclinic cell lattice constants, a ‫؍‬ 9.492(2), b ‫؍‬ 7.951(2), c ‫؍‬ 7.028(2) A s , ‫؍‬ 104.74(1)3, lead to Z ‫؍‬ 12 for the unit formula Bi 0.81 La 0.19 O 1.5 and imply a disordered cationic sublattice. This mixed oxide appears as a term of a new variety of a wide solid solution (that will name hereafter).