【摘要】 利用固相反应法在700℃—1000℃不同的温度下、空气中烧结Co3O4和TiO2混合物,制备了（Co₃O₄）_x/3（TiO₂）_1-x（0<x≤0·1）样品,所有的烧结样品均表现出顺磁行为,但经500℃氢退火后均表现出室温铁磁性.X射线衍射（XRD）分析显示,在所有样品中均存在钙钛矿相CoTiO3,说明Co3O4与TiO2反应形成了CoTiO3;同时,在700℃低温和900℃以上的高温烧结样品中分别观察到了单相的锐钛矿和金红石相结构.经高低温烧结的样品在500℃氢退火后,CoTiO3相消失,锐钛矿相的Co_xTi_1-xO_2-δ形成.X射线光电子能谱（XPS）分析显示,氢退火样品中的Co以+2氧化价态存在,同时没有观察到金属态的Co,这说明氢退火样品中的室温铁磁性不是源于金属Co颗粒的形成,而是与钙钛矿结构的CoTiO3相的消失和锐钛矿型的Co_xTi_1-xO_2-δ相的形成有关.（Co3O4）x/3（TiO2）1-x（0<x≤0·1）样品中的室温铁磁性可能源于锐钛矿型的Co_xTi_1-xO_2-δ相的本征铁磁性,伴随着结构相变而产生的Co离子之间的铁磁交换相互作用或许是样品室温铁磁性产生的根本原因.更多还原

【Abstract】 Paramagnetic （Co-3O-4）- x/3 （TiO-2）- 1-x （0<x≤0.1） samples were fabricated by sintering Co-3O-4 and TiO-2 from 700 ℃ to 1000 ℃ in air. X-ray diffraction （XRD） results showed that perovskite CoTiO-3 existed in all samples. Anatase phase was also detected in samples sintered at 700 ℃ and when sintering the mixture at above 900 ℃, rutile phase formed with anatase phase disappearing. All samples exhibited room-temperature ferromagnetism （RTFM） after being hydrogenated in 10% H-2/Ar mixed atmosphere for 1 hour at 500 ℃. X-ray photoelectron spectroscopy （XPS） showed that Co existed in the +2 formal oxidation state, and no Co clusters were detected. XRD showed that CoTiO-3 disappeared and a new phase Co_xTi_1-xO_2-δ formed after hydrogenation. It is suggested that hydrogenation causes the phase transformation from CoTiO-3 to Co_xTi_1-xO_2-δ . RTFM of the sample originates from the intrinsic ferromagnetism of Co_xTi_1-xO_2-δ . The exchange interaction between Co 2+ occurring with the phase transformation may be the essential reason for RTFM.更多还原