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RISS 인기검색어
- 검색키워드
- 저자 : Mohapatra Jyoshnarani (검색결과 3 건)
- 무료
- 기관 내 무료
- 유료
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ENHANCEMENT OF FERROMAGNETISM IN NANOCRYSTALLINE Zn_(1-x)Cu_xO (0.03 ≤ x ≤ 0.07)
JYOSHNARANI MOHAPATRA,D. K. MISHRA,P. K. MISHRA,B. P. BAG,S. K. SINGH 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2011 NANO Vol.6 No.4
We report room temperature ferromagnetism (RTFM) in nanocrystalline Zn1-xCuxO (0.03 ≤ x ≤ 0.07) materials synthesized by autocombustion technique. The average particle sizes are in the range of 60 nm. The saturation magnetization and coercivity of 7% Cu-doped ZnO is enhanced significantly in comparison to 3% and 5% Cu-doped ZnO. There is not much variation in the optical band gap due to Cu doping, thus suggesting the uniform distribution of Cu in the ZnO matrix. Micro-Raman and photoluminescence analysis predict the presence of clusters of oxygen vacancies in Cu-doped system which improves with the increase in Cu concentration. This study provides further evidence that oxygen vacancies play an important role in the enhancement of room temperature ferromagnetic property in Cu-doped ZnO.
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Biswal Bijaylaxmi,Mishra Dilip Kumar,Mohapatra Jyoshnarani,Bhuyan Satyanarayan 한국세라믹학회 2022 한국세라믹학회지 Vol.59 No.5
The conventional high-temperature solid-state reaction technique is used to synthesize aluminosilicate ceramics of three different compositions (Al 0.70 Si 0.30 O, Al 0.73 Si 0.27 O, Al 0.75 Si 0.25 O). These aluminosilicate ceramics are systematically investigated by XRD, FTIR, SEM, dielectric, electrical, and UV–visible analysis. The polycrystalline ceramics are well synthesized at a sintering temperature of 1450 °C, confirmed from XRD studies. The IR interferogram reveals the presence of mullite (3Al 2 O 3 2SiO 2 )-type molecules in these aluminosilicate ceramics. The SEM images show the formation of homogeneous microstructures with appreciable density. The room temperature dielectric constant values for Al 0.70 Si 0.30 O, Al 0.73 Si 0.27 O, Al 0.75 Si 0.25 O ceramics are 1.5, 1.8, and 1.7 at 1 MHz frequency with dielectric loss values of 0.02, 0.04, and 0.06 respectively. The ac conductivity spectrum of these samples obeys the Arrhenius equation and the classical correlated barrier hopping model governs the conduction mechanism in these ceramics. Complex impedance analysis confirms the contribution of both grain and grain boundary towards transport processes in these ceramics. The UV–visible spectrum reveals that the synthesized ceramics, Al 0.70 Si 0.30 O, Al 0.73 Si 0.27 O, and Al 0.75 Si 0.25 O have a wide-band-gap of the order of 3.45 eV, 3.42 eV, and 3.39 eV respectively. These ceramics can be preferably used as electronic substrates, packaging material for high-frequency circuits, and infrared transmitting window materials.
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Studies of structural, microstructural, optical and dielectric properties of GdMnO3
Priyadarshinee Supriya,Pati Jayashree,Mahapatra Ranjita,Mohanty Pragyan,Mishra D. K.,Mohapatra Jyoshnarani 한국세라믹학회 2023 한국세라믹학회지 Vol.60 No.1
GdMnO3 has been synthesized by modified solid state reaction route followed by reaction sintering at 950 °C. Characterizations such as XRD, Raman, SEM, EDAX, FTIR, UV–Visible and dielectric have been carried out for the structural, microstructural, optical and dielectric studies. Orthorhombic structure with pbnm space group of GdMnO3 sample has been confirmed from XRD analysis. Uniform distribution with small amount of porosity has been confirmed from SEM analysis. John–Teller mode is observed at 616 cm−1 (B1g) in the Raman spectrum of GdMnO3 sample. The optical band gap value of the synthesized GdMnO3 sample is found to be 3.22 eV which indicates the insulating behavior of the sample. An elevated dielectric constant value with increase in temperature and a very negligible dielectric loss is observed for the synthesized sample which makes its applications in memory storage devices. The room temperature dielectric constant value of GdMnO3 is found to be 649 with dielectric loss factor of 1.73 at 1 kHz frequency which is comparatively higher that of the dielectric constant values already reported. The dielectric constant value at 500 °C is found to be 44,112 with loss factor 1.04 at 1 kHz frequency that it has more significant high temperature applications. Complex impedance and modulus studies confirm the relaxation mechanism as Non-Debye type relaxation.
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