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首页> 外文期刊>Polyhedron: The International Journal for Inorganic and Organometallic Chemistry >Pressure effects of a genuine organic crystalline ferromagnet dupeyredioxyl
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Pressure effects of a genuine organic crystalline ferromagnet dupeyredioxyl

机译：真正的有机晶体铁磁体双倍二乙氧基的压力效应

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摘要

We have revealed that the isothermal magnetization M of the genuine organic crystalline dupeyredioxyl (N,N'-dioxy-l,3,5,7-tetramethyl-2,6-diazaadamantane; T-c(0) = 1.48 K) observed below 10 K converges on the S = 1 Brillouin function B-1 ((H + lambdaM)/k(B)T) with lambda = 2.4+/-0.2 or 2zJ/k(B) = 3.6+/-0.3 K, where J and z are, respectively, the averaged exchange interactions and coordination numbers for the S = I spin system. This fact suggests that S = I is constructed within a molecule via a strong ferromagnetic coupling between two S = 1/2 spins on each of the two NO moieties. The modified notation of the Rushbrooke and Wood theory, T-c = 2AzJS(S + 1)/k(B) (A = 0.23+/-0.02 for the three-dimensional Heisenberg systems), is found to quantitatively hold not only for this S = I spin system but also for other S = 1/2 ferromagnets beta-phase p -NPNN (2zJ/k(B) = 3.6 K) and 2,5-DFPNN (2zJ/k(B) = 2.8 K). Pressure effects of this compound have been studied under the hydrostatic pressure (P) up to 15 kbar. T-c(P) is revealed to show a negative pressure effect with the initial gradient a = d(T-c(P))/dP = -0.047 kbar(-1), nearly the same value for other organic ferromagnets as P-phase p-NPNN (-0.048 kbar(-1)) and p-Cl-TEMPO radical (-0.03 kbar(-1)), in contrast to the positive pressure effect for genuine antiferromagnets such as TANOL (a = +0.15 kbar(-1)). Microscopically, different from the above two ferromagnets, the pressure-induced destruction of the orthogonality of molecular orbitals associated with the two NO moieties plays an effective role in reducing the intramolecular ferromagnetic interaction J(0). The possible weaker intermolecular interactions other than J(0) and J are also expected to be more susceptible to the stress of pressure to result in the reduction of their values perhaps even changing their sign, just as in the case of beta-phase NPNN or p-Cl-TEMPO. (C) 2003 Elsevier Science Ltd. All rights reserved. [References: 20]
机译：我们已经揭示了在10 K以下观察到的真正有机晶体二聚二氧基（N，N'-dioxy-1,3,5,7-四甲基-2,6-diazaadamantane; Tc（0）= 1.48 K）的等温磁化强度M收敛于S = 1布里渊函数B-1（（H + lambdaM）/ k（B）T），其中lambda = 2.4 +/- 0.2或2zJ / k（B）= 3.6 +/- 0.3 K，其中J和z分别是S = I自旋系统的平均交换相互作用和配位数。这一事实表明，S = I是通过两个NO部分各自的两个S = 1/2自旋之间的强铁磁耦合在分子内构建的。发现Rushbrooke和Wood理论的修正符号Tc = 2AzJS（S +1）/ k（B）（对于三维Heisenberg系统，A = 0.23 +/- 0.02）不仅在数量上适用于该S = I自旋系统，但对于其他S = 1/2铁磁体β相p -NPNN（2zJ / k（B）= 3.6 K）和2,5-DFPNN（2zJ / k（B）= 2.8 K）。已经在高达15 kbar的静水压力（P）下研究了该化合物的压力效应。发现Tc（P）在初始梯度a = d（Tc（P））/ dP = -0.047 kbar（-1）时显示负压效应，其他有机铁磁体的值几乎与P相p- NPNN（-0.048 kbar（-1））和p-Cl-TEMPO自由基（-0.03 kbar（-1）），与正品反铁磁体（例如TANOL）的正压效应相反（a = +0.15 kbar（-1） ）。在微观上，与上述两个铁磁体不同，与两个NO部分相关的分子轨道正交性的压力诱导破坏在减少分子内铁磁相互作用J（0）中起着有效作用。像J（0）和J之外，可能的较弱的分子间相互作用也更容易受到压力的作用，从而导致其值降低甚至改变其符号，就像在β相NPNN或对氯-TEMPO。 （C）2003 Elsevier ScienceLtd。保留所有权利。 [参考：20]

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