Disorders and oxygen vacancies in p‐type Sn2B2O7 (B = Nb, Ta): Role of the B‐site element. Issue 2 (20th October 2022)

• Record Type: Journal Article
• Authors: Samizo, Akane; Minohara, Makoto; Kikuchi, Naoto; Ando, Kenta; Mazuka, Yuta; Nishio, Keishi
• Is Part Of: Journal of the American Ceramic Society. Volume 106:Issue 2(2023)
• Page Start: 1540
• Page End: 1546
• Publication Date: 2022-10-20
• Subjects: defects -- oxides -- pyrochlore -- semiconductors -- X‐ray methods; Ceramics -- Periodicals; 620.1405
• DOI: 10.1111/jace.18830
• Languages: English
• ISSNs: 0002-7820

Abstract

Abstract: Sn2 Nb2− x Ta x O7 ( x = 0.0–2.0) with pyrochlore structure is a promising material for p‐type oxide semiconductors. A systematic study of its Nb/Ta ratio indicated that the hole–generation efficiency of the Nb end (Sn2 Nb2 O7 ) was an order of magnitude lower than that of the Ta end (Sn2 Ta2 O7 ). Although this occurs due to differences in oxygen‐vacancy formation, the origins of the hole–generation efficiencies remain unclear due to limited information on local and global crystal‐structure disorders in pyrochlore Sn2 Nb2 O7 and Sn2 Ta2 O7 . In this study, the crystal structures of Sn2 B2 O7 (B = Nb, Ta), composed of BO6 octahedra and Sn4 O tetrahedra, were investigated using X‐ray absorption spectroscopy and X‐ray diffraction. A detailed investigation of the local and global crystal structures indicated a larger amount of disorder in the Sn4 O tetrahedra in Sn2 Nb2 O7 compared to Sn2 Ta2 O7 ; disorder in the BO6 octahedra occurred only in Sn2 Ta2 O7 . This study indicates that an appropriate selection of the B‐site element is vital for suppressing defect and disorder formation in Sn4 O tetrahedra and subsequently improving the hole–carrier–generation efficiency.