Abstract

In this work, nickel-doped magnetite nanoparticles (NPs) are synthesized by a modified solution combustion method and subsequently annealed at different temperatures. We report the structural, optical, dielectric, electrical, and magnetic properties of nickel-doped magnetite nanoparticles (NPs) annealed at 800°C, 1000°C, and 1200°C for 180 min. X-ray diffraction is utilized to explore the structural properties of the prepared magnetic nanoparticles. The surface morphology indicates that the particles annealed at 800°C and 1000°C are spherical, while particles annealed at 1200°C are polyhedral in shape and have uniform distribution. Energy-dispersive spectroscopy reveals the presence of the elements Ni, Fe, and O in the synthesized nanoparticles. The optical spectra obtained from UV–visible spectroscopy reveal that heat-treated synthesized samples have allowed a direct energy band gap. Also, the optical band gap shows a decreasing trend from 1.736 eV to 1.679 eV, while Urbach energy shows an increasing trend from 0.279 eV to 0.539 eV, with increasing annealing temperature. Photoluminescence spectra show a small redshift in band-edge emission from 433.77 nm to 440.12 nm with an increase in annealing temperature from 800°C to 1200°C. The dielectric studies are carried out at (1) varying frequency (20 Hz–2 MHz) at room temperature and (2) varying temperature (100–400 K) at constant frequency of 100 kHz. Both temperature- and frequency-dependent dielectric studies show an increase in the dielectric constant and dielectric loss with an increase in annealing temperature. Also, the conductivity increases with increased temperature in all studied samples, indicating semiconducting behavior, and increased conductivity is observed with increased annealing temperature. The conductivity behavior follows Mott's law, confirming the variable-range hopping mechanism in all samples. Magnetic measurements show high coercivity of 199.12 Oe and high remanent magnetization of 27.35 emu/g at lower annealing temperature. Thus, the magnetic properties of the synthesized ferrite nanoparticles can be tuned by adjusting particle size through annealing temperature.

中文翻译：

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掺镍磁铁矿纳米粒子的固溶燃烧合成及退火对其光，电和磁性能的影响

摘要

在这项工作中，掺杂镍的磁铁矿纳米颗粒（NPs）通过改进的溶液燃烧方法合成，然后在不同温度下退火。我们报告了在800°C，1000°C和1200°C退火180分钟的镍掺杂磁铁矿纳米颗粒（NPs）的结构，光学，介电，电和磁性能。X射线衍射被用来探索所制备的磁性纳米颗粒的结构特性。表面形态表明，在800℃和1000℃退火的颗粒是球形的，而在1200℃退火的颗粒是多面体的形状并且具有均匀的分布。能量色散光谱显示合成的纳米粒子中存在元素Ni，Fe和O。从紫外可见光谱获得的光谱表明，经热处理的合成样品具有直接的能带隙。另外，随着退火温度的升高，光学带隙从1.736 eV下降到1.679 eV，而Urbach能量从0.279 eV上升到0.539 eV。光致发光光谱显示，随着退火温度从800°C升高到1200°C，带边发射的红移从433.77 nm减小到440.12 nm。介电研究是在（1）室温下变化的频率（20 Hz–2 MHz）和（2）恒定温度100 kHz的变化温度（100–400 K）下进行的。温度和频率相关的介电研究均表明，介电常数和介电损耗随退火温度的升高而增加。也，在所有研究的样品中，电导率均随温度升高而增加，这表明半导体行为，而随着退火温度的升高，电导率也随之升高。电导率行为遵循莫特定律，确认了所有样品中的变程跳变机理。磁性测量结果表明，在较低的退火温度下，矫顽力为199.12 Oe，并且剩余磁化强度为27.35 emu / g。因此，可以通过在退火温度下调节粒径来调节合成的铁氧体纳米颗粒的磁性。确认所有样本中的变程跳变机制。磁性测量结果表明，在较低的退火温度下，矫顽力为199.12 Oe，并且剩余磁化强度为27.35 emu / g。因此，可以通过在退火温度下调节粒径来调节合成的铁氧体纳米颗粒的磁性。确认所有样本中的变程跳变机制。磁性测量结果显示，在较低的退火温度下，矫顽力为199.12 Oe，并且剩余磁化强度为27.35 emu / g。因此，可以通过在退火温度下调节粒径来调节合成的铁氧体纳米颗粒的磁性。