Semiconducting properties of mixed crystals with perovskite structure

✍ Scribed by G.H. Jonker

• Publisher: Elsevier Science
• Year: 1954
• Weight: 249 KB
• Volume: 20
• Category: Article
• ISSN: 0031-8914
• DOI: 10.1016/s0031-8914(54)80250-3

✦ Synopsis

Many compounds with the general composition ABO3 belong to the class of perovskite structures. The A-ions must be of about the same size as the O-ions and the B-ions must fit between 6 O-ions forming an octahedron. Examples are Na I +Ta s + O3, Ca 2+Ti 4+ O3, La 3 + Fe 3+-O 3. Within this structure different types of ions with different valencies may be combined. We have used this possibility to prepare semiconductors with the elements of the iron transition group. As is known from the theory of V e r w e y and D e B o e r 1) semiconducting properties appear in ionic crystals if one type of metal ions is present in different valency states. Examples are manganites, mixed crystals of Laa+Mn3+O3 and Sr2+Mn4+O3 described by V a n S a n t e n and J o n k e r s). In this system a complication arises as there is a strong ferromagnetic interaction between the Mn 3+ and the Mn4+-ions 8).