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spp1997

新蟲 (初入文壇)

應(yīng)助: 0 (幼兒園)
金幣: 19
帖子: 10
在線: 2.3小時
蟲號: 3713201
注冊: 2015-03-05
性別: GG
專業(yè): 凝聚態(tài)物性 II ：電子結(jié)構(gòu)

[求助] 求翻譯，英譯中

In glass technology crystallization must usually be avoided; however, partially crystallized
glasses or ‘glass-ceramics’, containing fine crystallized particles (nanoparticles), have been
developed for specific applications. These nanoparticles confer particular characteristics to
glasses, such as strength and impact resistance, lower thermal expansion coefficient, partial
or complete opacity, etc [1]. A special type of nanoparticles, ferro- or ferrimagnetically
ordered crystalline nanoparticles imbedded in different diamagnetic matrices such as fluids
or polymers, gives rise to a new kind of magnetism called superparamagnetism and results
in a number of properties which are interesting from a technical viewpoint, for example see
[2].
Partially crystallized glasses containing ferromagnetic nanoparticles constitute a novel
and much more complex class of superparamagnetic materials. Their properties are
mainly determined by morphology (size and shape distributions) and magnetic constants
of such particles. Electron magnetic resonance, sensitive to both the magnetic constants
and the structure of the environment of a magnetic ion, is well adapted to the study
of superparamagnetic nanoparticles [3]. In this case it may be called superparamagnetic
resonance (SPR) to distinguish it from the resonance of individual electron spins usually
referred to as electron paramagnetic resonance (EPR). Up until now, only a few attempts
have been made to carry out quantitative, computer-simulation based analysis of SPR spectra
of magnetic particles dispersed in polycrystalline or glassy systems [3–5].
In a previous work [3] we have dealt with transformations arising in the electron
magnetic resonance spectra of borate glasses containing small amounts of iron oxide
after heat treatment above the glass transition temperature. Namely, the resonance
characteristic of diluted Fe3+ ions in the glass, observed at the effective g-value gef = 4.3
[6], progressively disappears and a new resonance, consisting of superposed broader
and narrower components, grows at gef ≈ 2.0. This compound resonance signal has
been ascribed to a superparamagnetic assembly of crystalline ferromagnetic single-domain
particles arising in the diamagnetic glassy matrix under heat treatment. Good computer fits
to this resonance have been obtained assuming a monodisperse distribution of the particle
sizes.
This paper presents a more detailed analysis of room temperature X-band SPR spectra
obtained after repeated annealing steps of iron-doped borate glass. First, data are reported
on the evolution of the number of spins with annealing, as obtained from resonance intensity
measurements. Then, geometrical characteristics of the magnetic particles obtained from a
series of computer simulations of the spectra are related to the anneal temperature. Finally,
the mechanism of growth of crystallized magnetic particles is discussed.

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1樓 2015-06-16 17:26:25

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jiangguofeng

金蟲 (著名寫手)

翻譯EPI: 248
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專業(yè): 合成藥物化學(xué)

【答案】應(yīng)助回帖

在玻璃工藝當中通常必須避免結(jié)晶；然而,現(xiàn)已為專門的應(yīng)用研制出了含有細小結(jié)晶粒子（納米粒子）的部分結(jié)晶的玻璃或"玻璃陶瓷"。這些納米粒子賦予玻璃一些特殊性能,例如，強度和耐沖擊性,降低熱膨脹系數(shù),部分或全部不透明性,等等[1]。鐵磁或亞鐵磁的有序結(jié)晶納米粒子是一種特殊類型的納米粒子,被包埋在流體或高聚體一類的不同抗磁基質(zhì)中，產(chǎn)生一種稱為超順磁性的新的磁性并帶來了從技術(shù)視角來看值得關(guān)注的多種性質(zhì)，具體詳見[2]。含有鐵磁納米粒子的部分結(jié)晶玻璃構(gòu)成了一種新穎的更加復(fù)雜的超順磁性材料類型。它們性質(zhì)主要是通過此類粒子的形態(tài)（大小與形狀分配）和磁常數(shù)來確定。電子磁共振對磁常數(shù)和磁離子環(huán)境結(jié)構(gòu)都敏感，非常適于超順磁性納米粒子的研究[3]。在這種情況下，為了與通常稱為電子順磁共振(EPR)的單個電子自旋相區(qū)別，這可以被叫做超順磁共振(SPR)。迄今為止，只有少數(shù)嘗試去進行基于分散于多晶或玻璃狀系統(tǒng)中的磁粉的SPR譜圖的定量分析和計算機模擬[3-5]。在以前的研究工作中[3]，我們對經(jīng)高于玻璃態(tài)轉(zhuǎn)化溫度熱處理后的含少量氧化鐵的硼酸鹽玻璃的電子磁共振譜圖中產(chǎn)生的改變進行了處理。也就是,于有效G值gef=4.3觀察到的摻入這種玻璃中的Fe3+離子的共振特性[6]逐漸地消失，于gef≈2.0處逐漸產(chǎn)生一種由重疊的更寬和更窄組分組成的新的共振。這種化合物共振信號已分配給熱處理進行時抗磁玻璃基質(zhì)中產(chǎn)生的結(jié)晶鐵磁單疇顆粒的一種超順磁組裝。已經(jīng)得到針對這種共振的良好計算機配置用以擔任粒子粒徑的單分散分配。本文給出摻鐵硼酸鹽玻璃重復(fù)退火步驟后得到的室溫X波段SPR譜圖更為詳細的分析。首先,報告了由共振強度測定得到的有關(guān)隨著退火自旋數(shù)目演變的情況。然后,由譜圖的一系列計算機模擬得到的磁粉的幾何特性與退火溫度有關(guān)。最后,討論了結(jié)晶磁粉的生長機理。

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2樓2015-06-18 11:56:15

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