Engineering Commons^™

Magnetocapacitance Effect In Nonmultiferroic Yfe03 Single Crystal, Z X. Cheng, H Shen, J Xu, Peng Liu, S J. Zhang, Jianli Wang, Xiaolin Wang, S X. Dou

Shi Xue Dou

YFeO3 single crystal displays two relaxor-like dielectric relaxations, one at low temperature (170300 K) and one at high temperature (370520 K), which are attributed to the activation of electrons and oxygen vacancies, respectively. Above the temperature at which electrons are activated, the sample displays a large magnetocapacitance effect. Comparison of the impedance Cole-Cole plots measured with and without applied magnetic field reveals that the occurrence of magnetocapacitance effect is accompanied with an increasing in DC conductivity under magnetic field after the activation of electrons, which is explained by the enhancement of electron jumping in Fe2b-O-Fe3b chains by magnetic field. Thus …

Effect Of Polymer Ligand Structures On Fluorescence Of Gold Clusters Prepared By Photoreduction, Luo Li, Zhen Li, Hui Zhang, Shoucun Zhang, Irfan Majeed, Bien Tan

Australian Institute for Innovative Materials - Papers

Blue emission fluorescent Au5 clusters with maximum quantum yield of 20.1% were synthesized by a simple photoreduction method using three specially designed tridentate polymer ligands. The evolution of fluorescent Au nanoclusters (Au NCs) under UV irradiation was studied by fluorescence, UV-Vis and X-ray photoelectron spectroscopic techniques, suggesting that the fluorescence of Au NCs is size-dependent and is associated with the presence of Au(i) ions in the Au NCs. The effect of polymer structure on the fluorescent Au NCs has also been discussed. These highly fluorescent Au NCs have potential applications in the fabrication of optoelectronic devices and light emitting materials.

Correlation Between Structural Parameters And The Magnetocaloric Effect In Epitaxial La0.8ca0.2mno3/Laalo3 Thin Film, J C. Debnath, J H. Kim, Y Heo, A M. Strydom, S X. Dou

Australian Institute for Innovative Materials - Papers

An epitaxial La0.8Ca0.2MnO3/LaAlO 3 (LCMO/LAO) thin film was fabricated using the pulsed laser deposition technique to evaluate the correlation between the crystal structure and the magnetocaloric effect. In our study, the LCMO film was 200 nm in thickness and appeared to have a strong out-of plane texture. We found that each column in the LCMO thin film layer is a domain which has a different ordering direction. These microscopic feature results in anisotropic properties of magnetization, entropy, and relative cooling power. The film exhibited a paramagnetic-to-ferromagnetic second order phase transition at 249 K. The lack of any hysteresis loss also …

Effect Of Sintering Temperature On The Superconducting Properties Of Graphene Doped Mgb2, K S B De Silva, X Xu, Sanjeev Gambhir, D C K Wong, W X Li, Q Y. Hu

Australian Institute for Innovative Materials - Papers

A comprehensive study on the effects of sintering temperature on graphene-doped MgB2 superconductor was conducted. Graphene has emerged as an effective dopant that is capable of improving the critical current density (J-{\rm c}) and flux pinning at a very low doping level, with only a slight reduction of the critical temperature (T-{\rm c}). MgB2 undoped and graphene-doped bulk samples were prepared by the in situ method and sintered within a temperature range from 650 to 950 {\circ}\hbox{C}. It is surprising to note that at the doping level of 1 at.% the sample sintered at 850 {\circ}\hbox{C} shows a J\rm c …

The Effect Of Microscopic Texture On The Direct Plasma Surface Passivation Of Si Solar Cells, S Mehrabian, S Xu, A A. Qaemi, B Shokri, C Chan, K Ostrikov

Australian Institute for Innovative Materials - Papers

Textured silicon surfaces are widely used in manufacturing of solar cells due to increasing the light absorption probability and also the antireflection properties. However, these Si surfaces have a high density of surface defects that need to be passivated. In this study, the effect of the microscopic surface texture on the plasma surface passivation of solar cells is investigated. The movement of 105Hþ ions in the texture-modified plasma sheath is studied by Monte Carlo numerical simulation. The hydrogen ions are driven by the combined electric field of the plasma sheath and the textured surface. The ion dynamics is simulated, and …

Magnetism And The Magnetocaloric Effect In Prmn1. 6fe0. 4ge2, W D. Hutchison, Jianli Wang, S J. Campbell

Australian Institute for Innovative Materials - Papers

The magnetic and magnetocaloric properties of PrMn1.6Fe0.4Ge2around the ferromagnetic transitions T C inter ~ 230 K and T C Pr ~ 30 K have been investigated by magnetisation, 57Fe Mössbauer spectroscopy and electron paramagnetic resonance (EPR) measurements over the temperature range 5–300 K. The broad peaks in magnetic entropy around TC inter (intralayer antiferromagnetism of the Mn sublattice to canted ferromagnetism) and TC Pr (onset of ferromagnetic order of Pr sublattice in addition to ferromagnetically ordered Mn sublattice) are typical of second order transitions with maximum entropy values of -ΔS M ~ 2.0 J/kg K and -ΔS M ~ 2.2 …

Aging Effect Evolution During Ferroelectric-Ferroelectric Phase Transition: A Mechanism Study, Zuyong Feng, Zhenxiang Cheng, Dongqi Shi, S X. Dou

Australian Institute for Innovative Materials - Papers

Aging can significantly modify the dielectric, piezoelectric, and ferroelectric performance of ferroelectrics. However, little attention has been paid to the aging effect during ferroelectric-ferroelectric phase transitions that is essentially correlated with real applications. In this letter, the authors report the aging effect evolution between two ferroelectric phases in an acceptor-doped piezoceramics. The results show that aging-induced double hysteresis loops were exhibited in different ferroelectric phases, but disappeared during ferroelectric-ferroelectric phase transitions, suggesting the mechanism that the intrinsic restoring force for the reversible switching of domains caused by the alignment of defect dipoles was weakened due to ferroelectric dipole reorientation.

Effect Of Frozen Spin On The Magnetocaloric Property Of La0.7ca0.3coo3 Polycrystalline And Single Crystal Samples, J C. Debnath, R Zeng, J H. Kim, P Shamba, Dapeng Chen, S X. Dou

Australian Institute for Innovative Materials - Papers

Polycrystalline (PC) and single crystalline (SC) samples of La_0.7Ca_0.3CoO₃ (LCCO) with the perovskite structure were synthesized by conventional solid-state reaction and the floating-zone growth method. We conducted isothermal magnetization measurements of the PC and SC samples at temperatures from 2.8 K to 140 K, and evaluated the magnetic entropy change (−ΔS_M) under zero field cooling (ZFC) and field cooling (FC) to 2.8 K. An interesting result has been obtained, where the −ΔS_M–T curves in the low temperature range show totally different features between the ZFC and FC cooling procedures. The −ΔS …

Magnetocapacitance Effect In Nonmultiferroic Yfe03 Single Crystal, Z X. Cheng, H Shen, J Xu, Peng Liu, S J. Zhang, Jianli Wang, Xiaolin Wang, S X. Dou

Australian Institute for Innovative Materials - Papers

YFeO3 single crystal displays two relaxor-like dielectric relaxations, one at low temperature (170300 K) and one at high temperature (370520 K), which are attributed to the activation of electrons and oxygen vacancies, respectively. Above the temperature at which electrons are activated, the sample displays a large magnetocapacitance effect. Comparison of the impedance Cole-Cole plots measured with and without applied magnetic field reveals that the occurrence of magnetocapacitance effect is accompanied with an increasing in DC conductivity under magnetic field after the activation of electrons, which is explained by the enhancement of electron jumping in Fe2b-O-Fe3b chains by magnetic field. Thus …

A Sign Of Field-Induced First Order Magnetic State Transition And Giant Reversible Magnetocaloric Effect In Cobalt Hydroxide Nanosheets, Precious Shamba, Rong Zeng, J Q Wang, S X. Dou

Australian Institute for Innovative Materials - Papers

We report the synthesis of β−Co(OH)₂ nanosheets using microwave assisted hydrothermal and conventional chemical reaction methods. A magnetic transition at an onset temperature, T₁ ~ 96 K, and a sign of antiferromagnetic state transition at the Néel temperature, T_N=9~10 K, can be determined from M-T curves and M-H curves magnetic properties investigation. It is found that a sign of field-induced first order transition below 9 K, act as a role of reversing the magnetocaloric effect from negative to positive value. The large reversible magnetic-entropy change (∆S_M) of 17 J/kg K around 11 K for …

The Effect Of Oxidation On The Structure Of Styryl-Substituted Sexithiophenes: A Resonance Raman Spectroscopy And Density Functional Theory Study, Tracy Clarke, Keith Gordon, David L. Officer, Daina K. Grant

Australian Institute for Innovative Materials - Papers

The structures and vibrational properties of a series of styryl-substituted sexithiophenes and their charged species have been examined using resonance Raman spectroscopy in conjunction with density functional theory calculations. The calculated geometries of the radical cations and dications indicate that the quinoidal charged defects are more strongly localized in the center of the thiophene backbone than is observed in other sexithiophenes. This defect confinement, induced by the positions of the styryl substituents, is particularly evident in the dication species. However, the defect confinement weakens when alkoxy groups are added onto the phenyl rings by causing the extension of the charged …

Effect Of Doping On Flux Pinning Of Gdba2cu3o7-Y, L Zhang, X B Xu, S Y Ding, M H Zheng, L Xiao, H T Ren, Y L Jiao, Xiaolin Wang, Zhi W. Lin, Jian G. Zhu

Australian Institute for Innovative Materials - Papers

Cylindrical single grains of GdBa 2Cu3Oy sGd-123d with a diameter of 25 mm were successfully fabricated by melt-texture growth sMTGd process in air to study the influence of different starting powders on flux pinning. Measurements of the magnetic critical current density sJcd showed that it was possible to fabricate large Gd-123 single grain with a high Jc at high temperatures and fields by means of properly controlling the starting powders of Gd 2O3, BaCO3 , and CuO before the process.

The Effect Of Foamy Slag In Electric Arc Furnaces On Electric Energy Consumption, Sima Aminorroaya-Yamini, Hossein Edris

Australian Institute for Innovative Materials - Papers

In electric arc furnace steelmaking units, the essential parameters that considered important are reducing price, increasing production and decreasing environmental pollution. Electric arc furnaces are the largest users of electric energy in industry. The most important techniques that can be used to reduce the electric energy consumption in electric arc furnaces are scrap preheating, stirring, use of burners and hot charge and foamy slag.

Between these methods, use of foamy slag is the most useful and economic factor. Foamy slag can reduce the amount of energy, electrods, refractory consumption, tap to tap time and increases productivity. In this research, method …