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Influence of Fe-doping on the structural and photoluminescence properties and on the band-gap narrowing of SnO2 nanoparticles
Optical Materials ( IF 3.8 ) Pub Date : 2021-08-04 , DOI: 10.1016/j.optmat.2021.111367
P.V. Jithin 1 , K. Sudheendran 2 , K.J. Sankaran 3 , Joji Kurian 1
Affiliation  

In this study the structural and optical properties of Fe-doped SnO2 (Sn1-xFexO2, for x = 0, 0.03, 0.05, 0.07) nanoparticles synthesized by co-precipitation technique and using short durations of sample sintering is reported. The prepared samples are characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Thermogravimetric analysis – differential scanning calorimetry (TG-DSC), UV–Visible spectroscopy (UV-VIS) and Photoluminescence (PL) measurements. The Rietveld refined XRD data shows that all the samples are in tetragonal rutile crystalline phase. Fe doping in the samples hinder grain growth as the average crystallite size (ranging in between 13 and 29 nm) reduces with doping concentration. Information on the phase purity of the samples is obtained via the FTIR and Raman measurements while the Thermogravimetric–Differential Scanning Calorimetric (TG-DSC) studies give an idea on the crystallization process of and the presence of oxygen vacancies in the samples. The finger print wave number region of rutile phase of SnO2 corresponds to the A1g mode, which shows a red shift in the Raman studies undertaken. This is indicative of the effect of the defects arising due to the dopant introduced, which affects the crystallite size and leads to phonon confinement, observed as the red shift of the Raman peaks. The addition of Fe leads to a band-gap narrowing process due to the d – d transition and a feeble absorption occurs in the near infrared region. The Photoluminescence (PL) curve shows a broad and intense emission in the UV region, near ~ 375 nm (3.31 eV), owing to the presence of oxygen vacancies. Apart from this, two additional feeble emission peaks for the 5% and 7% Fe-doped samples also evolve. The substitution of Fe, existing in the Fe2+/Fe3+ state, in place of Sn, existing in the Sn4+ state, gives rise to a charge/oxidation state imbalance. This creates a vacancy in the crystal, which acts as the emission center in the doped semiconductor type SnO2. The PL studies confirm the existence of Fe induced inter bands in the energy band-gap of these samples. The CIE chromaticity diagram shows that the prepared materials are suitable and tunable for blue light LED applications.



中文翻译:

Fe掺杂对SnO2纳米颗粒的结构和光致发光特性以及带隙变窄的影响

在本研究中,Fe 掺杂的 SnO 2 (Sn 1-x Fe x O 2, 对于 x = 0, 0.03, 0.05, 0.07) 报告了通过共沉淀技术和使用短时间样品烧结合成的纳米颗粒。制备的样品通过 X 射线衍射 (XRD)、傅里叶变换红外光谱 (FTIR)、拉曼光谱、热重分析-差示扫描量热法 (TG-DSC)、紫外-可见光谱 (UV-VIS) 和光致发光 (PL ) 测量。Rietveld 精制的 XRD 数据显示所有样品均处于四方金红石晶相。样品中的 Fe 掺杂阻碍了晶粒生长,因为平均微晶尺寸(范围在 13 到 29 nm 之间)随着掺杂浓度而减小。样品的相纯度信息是通过 FTIR 和拉曼测量获得的,而热重-差示扫描量热 (TG-DSC) 研究提供了关于样品中氧空位的结晶过程和存在的想法。SnO 金红石相的指纹波数区图 2对应于 A 1g模式,它显示了所进行的拉曼研究中的红移。这表明由于引入的掺杂剂引起的缺陷的影响,其影响微晶尺寸并导致声子限制,观察为拉曼峰的红移。由于 d - d 跃迁,Fe 的添加导致带隙变窄,并且在近红外区域发生微弱的吸收。由于氧空位的存在,光致发光 (PL) 曲线在接近 ~ 375 nm (3.31 eV) 的紫外区域显示出广泛而强烈的发射。除此之外,5% 和 7% Fe 掺杂样品的两个额外的微弱发射峰也发生了变化。Fe的取代,存在于Fe 2+ /Fe 3+状态,代替 Sn,以 Sn 4+状态存在,导致电荷/氧化状态不平衡。这在晶体中产生了空位,其充当掺杂半导体类型 SnO 2的发射中心。PL 研究证实了这些样品的能带隙中存在 Fe 诱导的间带。CIE 色度图表明所制备的材料适用于蓝光 LED 应用且可调节。

更新日期:2021-08-04
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