Energetics of charge order transition in Bi_1-xSr_xMnO₃

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• 作者：D. Sedmidubský ; A. Strejc ; O. Beneš ; K. Ruž ; ič ; ka ; J. Hejtmá ; nek ; P. Javorský ; M. Nevř ; iva ; C. Martin
• 关键词：Manganites ; Charge order ; Heat capacity
• 刊名：Journal of Solid State Chemistry
• 出版年：2006
• 期刊代码：130_00224596
• 类别：ch
• 出版时间：December 2006
• 卷：179
• 期：12
• 页码：3798-3804
• 文件大小：274 K

摘要

The transition from the high-temperature pseudocubic form of the perovskite manganites <a name="mml95"><a style="text-decoration:none; color:black" href="/science?_ob=MathURL&_method=retrieve&_udi=B6WM2-4KR4C20-1&_mathId=mml95&_user=10&_cdi=6922&_rdoc=29&_acct=C000050221&_version=1&_userid=10&md5=864571ba5b81594b6c8e6902e7e2067e" title="Click to view the MathML source">Bi_1-xSr_xMnO₃, <a name="mml96"><a style="text-decoration:none; color:black" href="/science?_ob=MathURL&_method=retrieve&_udi=B6WM2-4KR4C20-1&_mathId=mml96&_user=10&_cdi=6922&_rdoc=29&_acct=C000050221&_version=1&_userid=10&md5=73d326d93d0ba98938daaf6e627ba49f" title="Click to view the MathML source">x=0.3,0.5,0.8, to their orthorhombically distorted charge-ordered state is examined. As the experimental probe the measuring of the heat capacity by heat flux DSC incremental method above 300 K and by relaxation method below 300 K is used. While a broad symmetrical transition spanning the temperature interval <a name="mml97"> with a maximum at the apparent <a name="mml98"> is observed for <a name="mml99"><a style="text-decoration:none; color:black" href="/science?_ob=MathURL&_method=retrieve&_udi=B6WM2-4KR4C20-1&_mathId=mml99&_user=10&_cdi=6922&_rdoc=29&_acct=C000050221&_version=1&_userid=10&md5=5f43f9dc455e73fa94da4790734248dc" title="Click to view the MathML source">x=0.5, the other two compositions reveal typical <a name="mml100"><a style="text-decoration:none; color:black" href="/science?_ob=MathURL&_method=retrieve&_udi=B6WM2-4KR4C20-1&_mathId=mml100&_user=10&_cdi=6922&_rdoc=29&_acct=C000050221&_version=1&_userid=10&md5=6707fd554898de3b2fe30e3601110f49" title="Click to view the MathML source">λ-shaped peaks often considered as typical for the second order transitions. The total entropy release on heating is interpreted in terms of a simultaneous change of charge, orbital and spin degree of freedom.