Engineering Commons^™

Developing A Crystal Viewer Tool For Nanohub, Osiris V. Ntarugera, Gerhard Klimeck

Gerhard Klimeck

Most materials found in nature have their atoms arranged in a regular and repeated pattern known as crystalline structure; this is particularly true for metals. It is very important to understand the crystal structure of materials in order to predict their properties such as the electric conductivity, heat transfer, and more. Particularly, students and scholars in the field of material science need a way to visualize the different crystal structures. Atomic structures of elements are not visible to the naked eye. In that context, a computer based tool can be used to simulate and to visualize the crystal structures of …

Non-Mass Transfer Limited Crystal Growth, Ryan J. Smyth, Caitlin Schram, Stephen P. Beaudoin

The Summer Undergraduate Research Fellowship (SURF) Symposium

There are many different active pharmaceutical ingredients (APIs) that have been discovered in research labs all around the world that can be used to treat and cure patients with a variety of different ailments. The challenge with these APIs in treatments is that they are not soluble in water, thus they low absorption into the blood stream (bio-availability). The key to making these APIs more bio-available is to understand how they grow as crystals and drop out of the aqueous solutions. One of the ways these APIs were made more bio-available is to render them amorphous and suspend them in …

Developing A Crystal Viewer Tool For Nanohub, Osiris V. Ntarugera, Gerhard Klimeck

The Summer Undergraduate Research Fellowship (SURF) Symposium

Most materials found in nature have their atoms arranged in a regular and repeated pattern known as crystalline structure; this is particularly true for metals. It is very important to understand the crystal structure of materials in order to predict their properties such as the electric conductivity, heat transfer, and more. Particularly, students and scholars in the field of material science need a way to visualize the different crystal structures. Atomic structures of elements are not visible to the naked eye. In that context, a computer based tool can be used to simulate and to visualize the crystal structures of …

Thermomechanical Behavior Of Nickel Base Single Crystal Superalloy Towards Understanding Of Weld Hot Cracking, S S. Babu, J M. Vitek, S A. David, M Murugananth

Muruganant Marimuthu

"Thermomechanical responses of three single crystal superalloys were measured in between 600 and 1200 degrees C using a thermomechanical simulator. On-heating results showed no softening while testing below 1000 degrees C. In contrast, extensive softening was observed while testing above 1000 degrees C. This rapid softening is related to dissolution of gamma' precipitates. During on-cooling tests from 1300 degrees C, strength recovery of these samples occurred only below 900 degrees C. The delay in strength recovery is attributed to the extent of undercooling required for rapid decomposition of the gamma phase into mixture of gamma and gamma' phases."

Magnetic Properties In Polycrystalline And Single Crystal Ca-Doped Lacoo3, R Zeng, J C. Debnath, Dapeng Chen, P Shamba, Jianli Wang, S J. Kennedy, S J. Campbell, Tania M. Silver, S. X. Dou

Jianli Wang

Polycrystalline (PC) and single crystalline (SC) Ca-doped LaCoO3 (LCCO) samples with the perovskite structure were synthesized by conventional solid-state reaction and the floating-zone growth method. We present the results of a comprehensive investigation of the magnetic properties of the LCCO system. Systematic measurements have been conducted on dc magnetization, ac susceptibility, exchange-bias, and the magnetocaloric effect. These findings suggest that complex structural phases, ferromagnetic (FM), and spin-glass/cluster-spin-glass (CSG), and their transitions exist in PC samples, while there is a much simpler magnetic phase in SC samples. It was also of interest to discover that the CSG induced a magnetic field …

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

Jianli Wang

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 …

Visualization Of Vortex Motion In Feas-Based Bafe1.9ni0.1as2 Single Crystal By Means Of Magneto-Optical Imaging, Zhi W. Lin, Yong Jian Li, Jian G. Zhu, Xiaolin Wang, S. X. Dou, Youguang Guo, Gang Lei, Yi Wang, Matthew Philips, Michael Cortie, Yan-Cheng Li, Ki-Young Choi, Xun Shi

Shi Xue Dou

Superconductivity has been found in newly discovered iron-based compounds. This paper studies the motion of magnetic vortices in BaFe_1.9Ni_0.1As₂ single crystal by means of the magneto-optical imaging technique. A series of magneto-optical images reflecting magnetic flux distribution at the crystal surface were taken when the crystal was zero-field cooled to 10 K. The behavior of the vortices, including penetration into and expulsion from the single crystal with increasing and decreasing external fields, respectively, is discussed. The motion behavior is similar to that observed in high-T_c superconducting cuprates with strong vortex pinning; however, the …

Anisotropic And Excellent Magnetocaloric Properties Of La 0.7ca0.3mno3 Single Crystal With Anomalous Magnetization, J.C Debnath, Rong Zeng, Jung Ho Kim, Dapeng Chen, S X. Dou

Shi Xue Dou

Magnetic properties and the magnetocaloric effect (MCE) have been investigated in La0.7Ca0.3MnO3 single crystal with applied field along both the ab-plane and the c-direction. Due to the magnetocrystalline anisotropy, the crystal exhibits anisotropy in the MCE. Upon application of a 5 T field, the magnetic entropy changes (SM), reaching values of 7.668 J/(kg K) and 6.412 J/(kg K) for both the ab-plane and the c-direction, respectively. A magnetic entropy change of 3.3 J/(kg K) was achieved for a magnetic field change of 1.5 T at the Curie temperature, TC = 245 K. Due to the absence of grains in the …

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

Shi Xue Dou

Polycrystalline (PC) and single crystalline (SC) samples of La0.7Ca0.3CoO3 (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 (−ΔSM) under zero field cooling (ZFC) and field cooling (FC) to 2.8 K. An interesting result has been obtained, where the −ΔSM–T curves in the low temperature range show totally different features between the ZFC and FC cooling procedures. The −ΔSM shows a large inverse irreversibility value for the ZFC …

Single-Crystal Growth And Anisotropic Magnetic Properties Of Nonstoichiometric Three-Layer Sodium Cobalt Oxides, Dapeng Chen, Xiaolin Wang, C T Lin, S X. Dou

Shi Xue Dou

Large single crystals of α-NaxCoO2 (x=0.91, 0.92, and 0.93) have been successfully fabricated by using the traveling solvent floating zone method. Details on the crystal growth are discussed. The crystal structures were characterized using powder x-ray diffraction and Rietveld refinement. The magnetic susceptibility measurements show that the magnetic properties depend strongly on x. The compound was found to be antiferromagnetic at TN ≈ 20 K for x=0.91 and x=0.92, and paramagnetic for x=0.93. The in-plane and out-of-plane anisotropies were observed for the x=0.91 crystals. In addition, the derived anisotropic g-factor ratios (gab /gc) from the anisotropic susceptibility along H||ab and …

Competition Between The Crystal Field And The Exchange Field In Er3+ Doped Ndmno3, Fang Hong, Zhenxiang Cheng, Xiaolin Wang, S X. Dou

Shi Xue Dou

A careful investigation of specific heat shows that the ground state splitting of Nd3þ has been modified by the Er3þ doping, as it shows a nonlinear dependence on the Er3þ doping rate, due to the competition between the crystal field and the exchange field. This competition could be further confirmed by the anomalies in the magnetic entropy and the ground state splitting found in Nd0.9Er0.1MnO3. On the contrary, the ground state splitting of Er3þ has a linear dependence on the doping rate, indicating its stronger dependence on the crystal field rather than the exchange field.

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 …

Crystal Structure And Electronic And Thermal Properties Of Tbfeaso0.85, N Kaurav, Y.T Chung, Y.K Kuo, R S Liu, T S Chan, J.M Chen, J.F Lee, H.S Sheu, Xiaolin Wang, S X. Dou, Sung-Ik Lee, Y.G Shi, A.A Belik, K Yamaura, E Takayama-Muromachi

Shi Xue Dou

The crystal structure and the electronic and thermal properties of a high-quality polycrystalline TbFeAsO0.85 sample made by a high-pressure technique are investigated. The crystal structure, as determined by synchrotron X-ray powder diffraction, possesses a tetragonal unit cell (space group: P4/nmm) with lattice parameters of a=b=3.8851 Å and c =8.3630 Å. In order to elucidate the electronic structure and oxidation states of corresponding elements, X-ray absorption near-edge structure (XANES) spectra are presented. The XANES spectra confirm that the oxidation states of Fe, As, and Tb in the TbFeAsO0.85 sample are ~Fe2+, ~As3−, and ~Tb3+, respectively, which are consistent with the previously …

Angular Dependence Of Pinning Potential, Upper Critical Field, And Irreversibility Field In Underdoped Bafe1.9co0.1as2 Single Crystal, Mahboobeh Shahbazi, Xiaolin Wang, S R. Ghorbani, S. X. Dou, K Y. Choi

Shi Xue Dou

Underdoped BaFe1.9Co0.1As2 single crystal was studied by angular dependence of magneto-transport at fields up to 13 T over a wide range of temperature. Our results show that pinning potential, Uo, decreases slightly for h45 and remains constant for h45, while the upper critical field, Hc2, and the irreversibility field, Hirr, increase with h. According to anisotropic Ginzburg-Landau theory, the anisotropy was determined by scaling the resistivity under different magnetic fields below the superconducting critical temperature, Tc. Anisotropy, C, in the underdoped crystal is found to be temperature dependent and decreases from 2.1 to 1.8 for as T is reduced from …

Dynamics Of Flux-Line Bundles And Voltage-Current Characteristics In A Ba(K)Fe2as2 Single Crystal, K H. Muller, S K. H Lam, Xiaolin Wang, S X. Dou

Shi Xue Dou

Understanding the flux-line dynamics in layered superconductors is of utmost importance for many superconductor applications, yet extracting from measurements the relevant parameters remains a major challenge. Here we report on measurements and theoretical model calculations of voltage-current (V-I) characteristics of a superconducting Ba0.72K0.28Fe2As2 single crystal slightly below its transition temperature in perpendicular magnetic fields between 0.01 and 7 T. We propose a model that describes the flux-line dynamics above, as well as below, the depinning current. The model fits the experimental V-I characteristics remarkably well and is used to extract from the data the field dependence of (a) the depinning …

Thickness-Shear Vibration Of A Rectangular Quartz Plate With Partial Electrodes, Huijing He, Jiashi Yang, John A. Kosinski, Ji Wang

Department of Mechanical and Materials Engineering: Faculty Publications

We study free vibration of a thickness-shear mode crystal resonator of AT-cut quartz. The resonator is a rectangular plate partially and symmetrically electroded at the center with rectangular electrodes. A single-mode, three-dimensional equation governing the thickness-shear displacement is used. A Fourier series solution is obtained. Numerical results calculated from the series show that there exist trapped thickness-shear modes whose vibration is mainly under the electrodes and decays rapidly outside the electrodes. The effects of the electrode size and thickness on the trapped modes are examined.

Thickness-Shear Vibration Of A Rectangular Quartz Plate With Partial Electrodes.Pdf, Huijing He

Huijing He

Ultrasound For Improved Crystallisation In Food Processing, N. Misra, Navneet Deora, Brijesh Tiwari, Patrick Cullen

Articles

Within the food industry, controlling crystallisation is a key factor governing food structure, texture and consumer appeal, with some foods requiring the promotion of crystallisation in a controlled manner (e.g. chocolate) and others a check (e.g. in honey). Sonocrystallisation is the application of ultrasound energy to control the nucleation of a crystallisation process. The use of power ultrasound provides a non-invasive approach to producing crystals with desired properties. Sonocrystallisation facilitates process control, primarily by modulating crystal size distribution and morphology. This paper details the governing mechanisms of sonocrystallisation. Proven and potential applications of the process in foods, including chocolates, honey, …

Analysis Of Electrically-Forced Vibrations Of Piezoelectric Mesa Resonators, Huijing He, Guo-Quan Nie, Jin-Xi Liu, Jiashi Yang

Department of Mechanical and Materials Engineering: Faculty Publications

We study the electrically forced thickness-shear and thickness-twist vibrations of stepped thickness piezoelectric plate mesa resonators made of polarized ceramics or 6-mm class crystals. A theoretical analysis based on the theory of piezoelectricity is performed, and an analytical solution is obtained using the trigonometric series. The electrical admittance, resonant frequencies, and mode shapes are calculated, and strong energy trapping of the modes is observed. Their dependence on the geometric parameters of the resonator is also examined.

Plasmon-Mediated Magneto-Optical Transparency, Vladimir Belotelov, L. E. Kreilkamp, Ilya Akimov, A Kalish, D Bykov, S Kasture, V Yallapragada, A Gopal, A M Grishin, S I Khartsev, Mohammad Nur E Alam, Mikhail Vasiliev, L Doskolovich, D Yakovlev, Kamal Alameh, A K Zvezdin, M Bayer

Research outputs 2013

Magnetic field control of light is among the most intriguing methods for modulation of light intensity and polarization on sub-nanosecond timescales. The implementation in nanostructured hybrid materials provides a remarkable increase of magneto-optical effects. However, so far only the enhancement of already known effects has been demonstrated in such materials. Here we postulate a novel magneto-optical phenomenon that originates solely from suitably designed nanostructured metal-dielectric material, the so-called magneto-plasmonic crystal. In this material, an incident light excites coupled plasmonic oscillations and a waveguide mode. An in-plane magnetic field allows excitation of an orthogonally polarized waveguide mode that modifies optical spectrum …

Anisotropy Of Crystal Growth Mechanisms, Dielectricity, And Magnetism Of Multiferroic Bi2femno6 Thin Films, P Liu, Z X. Cheng, Y Du, L Y. Feng, H Fang, Xiaolin Wang, S X. Dou

Australian Institute for Innovative Materials - Papers

Epitaxial Bi2FeMnO6 (BFMO) thin films deposited on various Nb:SrTiO3 substrates show that the lattice parameters are very sensitive to epitaxial strains. Compressive and tensile strains are induced to the in-plane lattice constants of the (100) and (111) oriented films, respectively, while that of the (110) oriented thin film stay unstrained. The thin films also exhibit a strongly anisotropic growth habit depending on the substrate. Spiral growth, such as in the (100) BFMO film, is unique in samples prepared by pulsed laser deposition. Extrinsic dielectric constants at low frequencies are attributed to oxygen vacancies via the Maxwell-Wagner effect. All the samples …

The Flux Pinning Mechanism, And Electrical And Magnetic Anisotropy In Fe1.04te0.6se0.4 Superconducting Single Crystal, Mahboobeh Shahbazi-Manshadi, Xiaolin Wang, S X. Dou, H Fang, C T. Lin

Australian Institute for Innovative Materials - Papers

The temperature and magnetic field dependences of the magnetization and critical current density of Fe1.04Te0.6Se0.4 single crystals have been investigated, and the flux pinning mechanism has been analysed. The normalized pinning force (fp Fp/F p,max) vs. h(H/Hirr) curves, are scaled using the Dew-Hughes theory, f(h) ≈ hp(1 - h)q with p 1.35 and q 3.06. The angular dependence of the resistivity under different magnetic fields shows a dip-like structure, below the superconducting transition temperature. The anisotropic value of 2 was obtained using Ginzburg-Landau theory.

Magnetic Field Induced Discontinuous Spin Reorientation In Erfeo3 Single Crystal, Hui Shen, Zhenxiang Cheng, Fang Hong, Jiayue Xu, Shujuan Yuan, Shixun Cao, Xiaolin Wang

Australian Institute for Innovative Materials - Papers

The spin reorientation of ErFeO3 that spontaneously occurs at low temperature has been previously determined to be a process involving the continuous rotation of Fe3þ spins. In this work, the dynamic process of spin reorientation in ErFeO3 single crystal has been investigated by AC susceptibility measurements at various frequencies and static magnetic fields. Interestingly, two completely discontinuous steps are induced by a relatively large static magnetic field due to the variation in the magnetic anisotropy during this process. It provides deeper insights into the intriguing magnetic exchange interactions which dominate the sophisticated magnetic phase transitions in the orthoferrite systems.

Collective Librations Of Water Molecules In The Crystal Lattice Of Rubidium Bromide: Experiment And Simulation, L M. Lepodise, J Horvat, Roger A. Lewis

Australian Institute for Innovative Materials - Papers

Terahertz spectroscopy of RbBr reveals four prominent absorption lines at room temperature and a further 15 lines at 10 K. Via density-functional-theory (DFT) numerical modelling using the PBE0 hybrid GGA functional, all the absorptions are identified as correlated librations of water molecules in the RbBr lattice. Each libration mode is a combination of rocking, wagging and twisting motions of the water molecules. The number of libration lines and numerical modelling show that the C2v symmetry of water in RbBr is broken. Our modelling shows that the distribution of libration amplitudes and phases for different water molecules in the RbBr unit …

Spin Switching And Magnetization Reversal In Single-Crystal Ndfeo3, S J. Yuan, W Ren, F Hong, Y B. Wang, J C. Zhang, L Bellaiche, S X. Cao, G Cao

Australian Institute for Innovative Materials - Papers

We report an experimental and computational study of single-crystal NdFeO3, which features two inequivalent magnetic sublattices, namely, Fe and Nd sublattices that are coupled in an antiparallel fashion. This paper reveals that a strong interaction between 3d and 4f electrons of the two sublattices along with a spin-lattice coupling drives an extremely interesting magnetic state that is highly sensitive to the orientation and history of weak magnetic field. The following phenomena are particularly remarkable: (1) sharply contrasting magnetization M(T) along the a and c axes; (2) a first-order spin switching along the a axis below 29 K when the system …

Crystal Growth, Structure And Thermal Properties Of Noncentrosymmetric Single Crystals Prca4o(Bo3)3+, Fapeng Yu, Shujun Zhang, Xiufeng Cheng, Xiulan Duan, Tingfeng Ma, Xian Zhao

Australian Institute for Innovative Materials - Papers

Noncentrosymmetric praseodymium calcium oxyborate single crystals, PrCa4O(BO3)3 (PrCOB), were grown by the Czochralski technique. The monoclinic unit cell parameters were found to be a = 8.177 Å, b = 16.157 Å, c = 3.629 Å and Z = 2 with space group Cm. Crystal density was measured using the Archimedes method, being on the order of 3.47 g cm-3. Thermal properties of PrCOB were investigated, where the specific heat was found to be 0.63 J g-1 °C-1 at room temperature, increasing to 0.85 J g-1°C-1 at 700°C. The thermal expansion coefficients were measured to be α11 = 7.99, α22 = …

Optical Vortex Solitary Wave In Bounded Nematic-Liquid-Crystal Cell, Antonmaria A. Minzoni, Luke W. Sciberras, Noel F. Smyth, Annette L. Worthy

Faculty of Engineering and Information Sciences - Papers: Part A

Modulation theory, based on a Lagrangian formulation of the governing equations, is used to investigate the propagation of a nonlinear, nonlocal optical vortex solitary wave in a finite nematic-liquid-crystal cell. The nematic response to the vortex is calculated using the approach of themethod of images (MOI). It is demonstrated that the MOI is a reliable alternative to the usual Fourier series solution as it requires an order of magnitude fewer terms to obtain excellent agreement with numerical solutions. It is found that the cell walls, in addition to repelling the optical vortex solitary wave, as for an optical solitary wave, …

Analysis Of Electrically-Forced Vibrations Of Piezoelectric Mesa Resonators.Pdf, Huijing He, Guoquan Nie, Jinxi Liu, Jiashi Yang

Huijing He