Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Thermal Stability and Effect of Heat Treatment on Manganese Doped Silica Borotellurite Glass  [PDF]
I. Zaitizila, M. K. Halimah, F. D. Muhammad, M. F. Faznny
Journal of Materials Science and Chemical Engineering (MSCE) , 2018, DOI: 10.4236/msce.2018.64004
Glasses with chemical formula of {[(TeO2)0.7(B2O3)0.3]0.8[SiO2]0.2}1-x{MnO2}x where x = 0.00 ≤ x ≤ 0.05 molar fraction were fabricated using melt quenching technique. The temperature used in the heat treatment process of the glass sample is 600?C. Calorimetric measurement had been carried out to study the thermal properties of the fabricated glass. The crystallization kinetics of the glass system we reexamined under non-isothermal conditions via differential scanning calorimetric (DSC). The glass transition (Tg), onset glass transition (To), maximum crystallization temperature (Tc) and melting temperature (Tm) were determined. Results from DSC proved that the studied glasses have good thermal stability (Ts) in which indicates its high resistance to devitrification. Strong indicator for the glass forming ability of a glass material, Hurby parameter (Kgl) was also calculated in this research.
Structural and Optical Properties of Zinc Borotellurite Glass Co-Doped with Lanthanum and Silver Oxide  [PDF]
Faznny Mohd Fudzi, Halimah Mohamed Kamari, Farah Diana Muhammad, Amirah Abd Latif, Zaitizila Ismail
Journal of Materials Science and Chemical Engineering (MSCE) , 2018, DOI: 10.4236/msce.2018.64003
A series of zinc borotellurite glass co-doped with lanthanum and silver oxide with the chemical formula of [{[(TeO2)0.7(B2O3)0.3]0.7(ZnO)0.3}0.96(La2O3)0.04]1-x(Ag2O)x where the molar frac-tion of silver oxide, x = 0.02, 0.04, 0.06, 0.08 and 0.10 had been successfully prepared via the conventional melt-quenching technique. The structural properties of the glasses were unveiled through X-ray Diffraction (XRD) and Fourier Transform Infra-Red (FTIR) spectroscopy while optical properties of the glasses were investigated with Ultra Violet Visible (UV-Vis) spectropho-toscopy. The short range periodic atomic arrangement in the glass matrix that implies the amorphous nature of the glass was confirmed with the presence of a broad hump in the XRD pattern. On the other hand, the three absorption bands observable in the FTIR spectra had proven the existence of BO4, BO3 as well as TeO4 units in the glass network. The absorbance values retrieved from UV-Vis spectroscopy were utilized to calculate the indirect energy band gap and Urbach energy values of the fabricated glass. By employing the equations proposed by Mott and Davis, the obtained indirect energy band gap have val-ues ranging from 2.16 to 4.16 eV.The decreasing trend in indirect energy band gap and increasing Urbach energy values were related to the increasing num-ber of nonbridging oxygen (NBO) in the glass that is created from the breaking of Te-O-Te or B-O-B bonds after lanthanum as well as silver oxide are incor-porated into the zinc borotellurite glass network.
Effect of Erbium Nanoparticles on Optical Properties of Zinc Borotellurite Glass System  [PDF]
Azlan Muhammad Noorazlan,Halimah Mohamed Kamari,Siti Shafinas Zulkefly,Daud W. Mohamad
Journal of Nanomaterials , 2013, DOI: 10.1155/2013/940917
Abstract: Erbium nanoparticles (NPs) doped zinc borotellurite glasses have been prepared by conventional melt-quenching technique with the chemical composition (where ). The structural properties of the prepared glasses were determined via X-ray diffraction (XRD) analysis and FTIR analysis. It was confirmed that the prepared glasses are amorphous. The bonding parameters of the glasses were analyzed by using FTIR analysis and were confirmed to be ionic in nature. The refractive index increases as the content of erbium NPs increases. The optical absorption spectra revealed that fundamental absorption edge shifts to longer wavelength as the content of erbium NPs increases. The value of band gap had been calculated and shown to be decreased with an increase content of erbium NPs. The Urbach energy was shown to be linearly increased with an increase content of erbium NPs oxides. 1. Introduction Rare-earth doped materials have made the largest interest to develop the photonic system for various applications with regard to their advance optical properties. Erbium oxide is one of the most potential candidates among the lanthanide group in the pursuit of photonic materials research. Erbium consists of trivalent electron which is known to be advantaged to fiber amplifier applications. Nowadays, special attention is paid to explore the optical behavior of the Er3+ ions due to its emission at 1.53?μm, which is ideal for applications in the field of optical data transmission [1]. The choice of a suitable host matrix is important to obtain the excellent optical properties. Tellurite oxide is known to be the best candidate among the heavy metal materials because of its unique optical and electrical properties. The compatibility and solubility of tellurite based glass to the other oxide glasses are the most excellent among the heavy metals. Recently, tellurite based glass has been used in several photonic devices such as precursors for infrared fibers and windows. Formation of pure tellurite oxide glass does not occur without contributions from external element. Borate oxide is known as the best choice to stabilize the glass formation due to its good rare earth ion solubility and hardness. The borate matrix possesses well defined gathering of BO3 triangles and BO4 tetrahedra to form stable borate groups such as diborate, triborate, and tetraborate [2]. Contributions of zinc oxide in the glass formation reduce the melting point and increases the glass forming ability. It has been reported that [3] the effect of zinc oxide decreases the optical energy gap and increase the
Dipole glass and mixed ferroglass phase in SrTiO3 ceramics doped with manganese  [PDF]
M. D. Glinchuk,P. I. Bykov
Physics , 2006,
Abstract: Recently new incipient ferroelectrics with off-center ions SrTiO3 with Mn2+ substituted for Sr2+ was revealed (Tkach et. al PRB 73, 104113 (2006). Experimental investigation of Sr1-xMnxTiO3 properties, namely temperature, frequency and external electric field dependence of dielectric permittivity at different concentrations gave evidence about phase transitions induced by the impurities. However their nature was not found out up to now because of the absence of the theoretical analysis of the results. In this paper we performed such analysis by the theoretical description of the temperature of dielectric permittivity maxima dependence on Mn2+ concentration, the change of residual polarization with temperature, frequency and temperature dependence of the permittivity with Arrhenius and Vogel-Fulcher law at smaller and larger concentration respectively. The obtained results had shown that at x less than 0,03 and x between 0,15 and 0,03 the considered system Sr1-xMnxTiO3 is in dipole glass state and mixed ferroglass phase respectively.
Mechanisms of magnetoelectricity in manganese doped incipient ferroelectrics  [PDF]
R. O. Kuzian,V. V. Laguta,A. -M. Dare,I. V. Kondakova,M. Marysko,L. Raymond,E. P. Garmash,V. N. Pavlikov,A. Tkach,P. M. Vilarinho,R. Hayn
Physics , 2010, DOI: 10.1209/0295-5075/92/17007
Abstract: We report magnetization measurements and magnetic resonance data for SrTiO3 doped by manganese. We show that the recently reported coexistent spin and dipole glass (multiglass) behaviours are strongly affected by the distribution of Mn ions between the Sr and Ti sites. Motivated by this finding we calculate the magnetic interactions between Mn impurities of different kinds. Both LSDA+U and many-body perturbation theory evidence that magnetic and magnetoelectric interactions are mediated by Mn$_B^{4+}$ ions substituting for Ti. We propose two microscopic magnetoelectric coupling mechanisms, which can be involved in all magnetoelectric systems based on incipient ferroelectrics. In the first one, the electric field modifies the spin susceptibility via spin-strain coupling of Mn$_{B}^{4+}$. The second mechanism concerns Mn pairs coupled by the position-dependent exchange interaction.
Enhanced electrochemical properties of manganese dioxde doped with Ag3BiOx
Yang Wenjian, Li Juan, Zhang Xiaogang
International Journal of Electrochemical Science , 2006,
Abstract: In this work, Ag3BiOx was prepared and characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The electrochemical properties of electrolytic manganese dioxide (EMD) cathodes doped with Ag3BiOx were studied by galvanostatic charge/discharge and cyclic voltammetry. The results indicated that the electrochemical performance of EMD electrode was effectively improved by doping of Ag3BiOx. EMD electrode doped with Ag3BiOx possessed remarkably higher discharge voltage, larger capacity and better reversibility than that of pure EMD electrode.
Amplifying characteristics Er-doped chalcogenide glass
Petrovi? Vesna,Stojanovi? Nikola,Slankamenac Milo? P.,Luki? Svetlana R.
Hemijska Industrija , 2010, DOI: 10.2298/hemind091221033p
Abstract: The paper presents the measurement results of optical amplifying characteristics of Er-doped As-S-Ge chalcogenide glasses. The measurements included the amplification of useful laser source power during propagation along two axes of samples. A fluorescence maximum at the wavelengths between 1500 nm and 1540 nm was identified, which corresponds to the transition of electrons from the 4I13/2 level to the 4I15/2 level within the 4f shell of Erbium ions (Er3+). Measuring the signal strength showed that the passage through the erbium doped chalcogenid glass amplification of the useful signal occurs and this increase is proportional to the length of propagation through the doped glass.
Coordination-driven magnetic-to-nonmagnetic transition in manganese doped silicon clusters  [PDF]
V. Zamudio-Bayer,L. Leppert,K. Hirsch,A. Langenberg,J. Rittmann,M. Kossick,M. Vogel,R. Richter,A. Terasaki,T. M?ller,B. v. Issendorff,S. Kümmel,J. T. Lau
Physics , 2013, DOI: 10.1103/PhysRevB.88.115425
Abstract: The interaction of a single manganese impurity with silicon is analyzed in a combined experimental and theoretical study of the electronic, magnetic, and structural properties of manganese-doped silicon clusters. The structural transition from exohedral to endohedral doping coincides with a quenching of high-spin states. For all geometric structures investigated, we find a similar dependence of the magnetic moment on the manganese coordination number and nearest neighbor distance. This observation can be generalized to manganese point defects in bulk silicon, whose magnetic moments fall within the observed magnetic-to-nonmagnetic transition, and which therefore react very sensitively to changes in the local geometry. The results indicate that high spin states in manganese-doped silicon could be stabilized by an appropriate lattice expansion.
Bose glass and Mott glass of quasiparticles in a doped quantum magnet  [PDF]
Rong Yu,Liang Yin,Neil S. Sullivan,J. S. Xia,Chao Huan,Armando Paduan-Filho,Nei F. Oliveira Jr.,Stephan Haas,Alexander Steppke,Corneliu F. Miclea,Franziska Weickert,Roman Movshovich,Eun-Deok Mun,Vivien S. Zapf,Tommaso Roscilde
Physics , 2011, DOI: 10.1038/nature11406
Abstract: The low-temperature states of bosonic fluids exhibit fundamental quantum effects at the macroscopic scale: the best-known examples are Bose-Einstein condensation (BEC) and superfluidity, which have been tested experimentally in a variety of different systems. When bosons are interacting, disorder can destroy condensation leading to a so-called Bose glass. This phase has been very elusive to experiments due to the absence of any broken symmetry and of a finite energy gap in the spectrum. Here we report the observation of a Bose glass of field-induced magnetic quasiparticles in a doped quantum magnet (Br-doped dichloro-tetrakis-thiourea-Nickel, DTN). The physics of DTN in a magnetic field is equivalent to that of a lattice gas of bosons in the grand-canonical ensemble; Br-doping introduces disorder in the hoppings and interaction strengths, leading to localization of the bosons into a Bose glass down to zero field, where it acquires the nature of an incompressible Mott glass. The transition from the Bose glass (corresponding to a gapless spin liquid) to the BEC (corresponding to a magnetically ordered phase) is marked by a novel, universal exponent governing the scaling on the critical temperature with the applied field, in excellent agreement with theoretical predictions. Our study represents the first, quantitative account of the universal features of disordered bosons in the grand-canonical ensemble.
Is manganese-doped diamond a ferromagnetic semiconductor?  [PDF]
Steven C. Erwin,C. Stephen Hellberg
Physics , 2003, DOI: 10.1103/PhysRevB.68.245206
Abstract: We use density-functional theoretical methods to examine the recent prediction, based on a mean-field solution of the Zener model, that diamond doped by Mn (with spin S=5/2) would be a dilute magnetic semiconductor that remains ferromagnetic well above room temperature. Our findings suggest this to be unlikely, for four reasons: (1) substitutional Mn in diamond has a low-spin S=1/2 ground state; (2) the substitutional site is energetically unfavorable relative to the much larger "divacancy" site; 3) Mn in the divacancy site is an acceptor, but with only hyperdeep levels, and hence the holes are likely to remain localized; (4) the calculated Heisenberg couplings between Mn in nearby divacancy sites are two orders of magnitude smaller than for substitutional Mn in germanium.
Page 1 /100
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.