John B. Goodenough – författare

Ada® in Practice started lifeas a case studies report, the result of work per­ formed under government contract at SofTech, Inc. as part of an effort to identify and resolve issues related to Ada usage. Although that report has now evolved into a book intended for a more general audience, its objectives are largely unchanged. Asbefore,the primary goal is to promote effective use of Ada, both in general programming and design practice and in embedded computer systems specifically. Many features of Ada will be new to pro­ grammers and designers familiar with other languages; the program examples presented in the case studies are intended to serve as guidelines for proper usage of such features while pointing out common misconceptions and programming errors. In addition, we hope that this book as a whole will highlight the advan­ tages of using Ada at all stages of a program's life cycle, from problem analysis through testing and maintenance. However, it does not purport to hold all the answers to questions ofAda application;areas that would benefit from further investigation or more definitive guidelines are also suggested.

Ada® in Practice started lifeas a case studies report, the result of work per­ formed under government contract at SofTech, Inc. as part of an effort to identify and resolve issues related to Ada usage. Although that report has now evolved into a book intended for a more general audience, its objectives are largely unchanged. Asbefore,the primary goal is to promote effective use of Ada, both in general programming and design practice and in embedded computer systems specifically. Many features of Ada will be new to pro­ grammers and designers familiar with other languages; the program examples presented in the case studies are intended to serve as guidelines for proper usage of such features while pointing out common misconceptions and programming errors. In addition, we hope that this book as a whole will highlight the advan­ tages of using Ada at all stages of a program''s life cycle, from problem analysis through testing and maintenance. However, it does not purport to hold all the answers to questions ofAda application;areas that would benefit from further investigation or more definitive guidelines are also suggested.

Interest in the transition metal oxides with perovskite related structures goes back to the 1950s when the sodium tungsten bronzes NaxWO3 were shown to be metallic [1 ], the system Lal_xSr~MnO3 was found to contain a ferromagnetic conductive phase [2], and La0.sSr0.sCoO3 was reported to be a ferromagnetic metal, but with a peculiar magnetization of 1.5 #a/Co atom [3]. Stoichiometric oxide perovskites have the generic formula AMO3 in which the A site is at the center of a simple cubic array of M sites; the oxide ions form (180 4)) M O M bridges to give an MO3 array of corner shared MO6/2 octahedra and the larger A cations have twelvefold oxygen coordination. Mismatch between the A O and M O equilibrium bond lengths introduces internal stresses. A compressive stress on the MO3 array is accommodated by a lowering of the M O M bond angle from 180 to (180 4)); a tensile stress on the M O M bonds is accommodated by the formation of hexagonal polytypes [4].