Photoluminescence of crystalline and disordered BTO : Mn powder: Experimental and theoretical modeling

Disordered and crystalline Mn-doped BaTiO3 (BTO:Mn) powders were synthesized by the polymeric precursor method. After heat treatment, the nature of visible photoluminescence (PL) at room temperature in amorphous BTO:Mn was discussed, considering results of experimental and theoretical studies. X-ray diffraction (XRD), PL, and UV-vis were used to characterize this material. Rietveld refinement of the BTO:Mn from XRD data was used to built two models, which represent the crystalline BTO:Mn (BTO:Mn,) and disordered BTO:Mn (BTO:Mn-d) structures. Theses models were analyzed by the periodic ab initio quantum mechanical calculations using the CRYSTAL98 package within the framework of density functional theory at the B3LYP level. The experimental and theoretical results indicated that PL is related with the degree of disorder in the BTO:Mn powders and also suggests the presence of localized states in the disordered structure. (c) 2006 Elsevier B.V. All rights reserved.

Opusculos del Bto. Nicolas Factor, franciscano observante, entresacados de las vidas impresas y manuscritas, y de los procesos de su beatificacion ...

Mode of access: Internet.

Two-wave mixing in BTO in the presence of detuning

The gain of a weak signal beam is measured in the usual two-wave mixing configuration in a photorefractive BTO crystal by varying a set of parameters, namely the applied electric field, the detuning, the beam ratio and the input intensity of the pump beam. All the experimental results are shown to be in good agreement with a theory based on that of Kukhtarev et al.

Two-wave mixing in BTO in the presence of detuning

The gain of a weak signal beam is measured in the usual two-wave mixing configuration in a photorefractive BTO crystal by varying a set of parameters, namely the applied electric field, the detuning, the beam ratio and the input intensity of the pump beam. All the experimental results are shown to be in good agreement with a theory based on that of Kukhtarev et al.

Denisiuk-type reflection holography display with sillenite crystals for imaging and interferometry of small objects

A novel setup for imaging and interferometry through reflection holography with Bi12TiPO20(BTO) sillenite photorefractive crystals is proposed. A variation of the lensless Denisiuk arrangement was developed resulting in a compact, robust and simple interferometer. A red He-Ne laser was used as light source and the holographic recording occurred by diffusion with the grating vector parallel to the crystal [0 0 1]-axis. In order to enhance the holographic image quality and reduce noise a polarizing beam splitter (PBS) was positioned at the BTO input and the crystal was tilted around the [0 0 1]-axis. This enabled the orthogonally polarized transmission and diffracted beams to be separated by the PBS, providing the holographic image only. The possibility of performing deformation and strain analysis as well as vibration measurement of small objects was demonstrated. (C) 2007 Elsevier B.V. All rights reserved.

Reabilitação energética de um edifício de serviços

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Civil na Área de Especialização de Edificações

Portugal Telecom

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Finance from the NOVA – School of Business and Economics

JIT-tuotannonohjausmenetelmän soveltaminen autoteollisuudessa

Autoteollisuuden kovan kilpailun takia autonvalmistajat ovat etsineet tapoja pienentää kustannuksia, lisätä tuottavuutta ja ylläpitää kannattavuutta, ja ovat ottaneet käyttöön JIT-tuotannonohjausmenetelmän. Autoteollisuus nähdäänkin yleisesti johtavana JIT-menetelmän soveltajana. JIT-menetelmän käytöllä saavutettavat hyödyt ovat hyvin näkyvissä juuri autoteollisuudessa. Tässä työssä käsittelemme, miten JIT-tuotannonohjausmenetelmää sovelletaan autoteollisuudessa. Lisäksi esittelemme käytännön työkaluja, joiden avulla JIT-tuotannonohjaus voidaan toteuttaa autoteollisuudessa.

Hybrid Multiferroic Nanostructure with Magnetic−Dielectric Coupling

The development of methods to economically synthesize single wire structured multiferroic systems with room temperature spin−charge coupling is expected to be important for building next-generation multifunctional devices with ultralow power consumption. We demonstrate the fabrication of a single nanowire multiferroic system, a new geometry, exhibiting room temperature magnetodielectric coupling. A coaxial nanotube/nanowire heterostructure of barium titanate (BaTiO3, BTO) and cobalt (Co) has been synthesized using a template-assisted method. Room temperature ferromagnetism and ferroelectricity were exhibited by this coaxial system, indicating the coexistence of more than one ferroic interaction in this composite system

Lead free heterogeneous multilayers with giant magneto electric coupling for microelectronics/microelectromechanical systems applications

Lead free magneto electrics with a strong sub resonant (broad frequency range) magneto electric coupling coefficient (MECC) is the goal of the day which can revolutionise the microelectronics and microelectromechanical systems (MEMS) industry. We report giant resonant MECC in lead free nanograined Barium Titanate–CoFe (Alloy)-Barium Titanate [BTO-CoFe-BTO] sandwiched thin films. The resonant MECC values obtained here are the highest values recorded in thin films/ multilayers. Sub-resonant MECC values are quite comparable to the highest MECC reported in 2-2 layered structures. MECC got enhanced by two orders at a low frequency resonance. The results show the potential of these thin films for transducer, magnetic field assisted energy harvesters, switching devices, and storage applications. Some possible device integration techniques are also discussed

Implementation of global make to inventory strategy at BASF SE

La optimización y armonización son factores clave para tener un buen desempeño en la industria química. BASF ha desarrollado un proyecto llamada acelerador. El objetivo de este proyecto ha sido la armonización y la integración de los procesos de la cadena de suministro a nivel mundial. El proceso básico de manejo de inventarios se quedó fuera del proyecto y debía ser analizado. El departamento de manejo de inventarios en BASF SE ha estado desarrollando su propia estrategia para la definición de procesos globales de manufactura. En este trabajo se presentará un informe de las fases de la formulación de la estrategia y establecer algunas pautas para la fase de implementación que está teniendo lugar en 2012 y 2013.

The effect of bulk light absorption on running photorefractive holograms

The influence of bulk light absorption on running photorefractive holograms is investigated. By solving the coupled wave equations we prove that the beam intensities, but not the beam phases, can be calculated by averaging the coupling constant over the crystal thickness. We show the importance of the effect by calculating the dielectric relaxation time at the crystal front, and from that the quantum efficiency from a feedback-controlled experiment with a 2.05 mm thick BTO crystal.We propose to simulate the effect of bulk light absorption by a rude estimate of the average dielectric relaxation time which is related in a simple way to the dielectric relaxation time at the crystal front, in doing so an error of less than 10% is introduced.

Multi-wavelength holography in Bi12TiO20 crystals: Applications in refractometry

We present a recent development in holography with multimode, large free-spectral range (FSR) diode lasers in photorefractive sillenite crystals. A novel refractometry method based on this type of holographic recording in Bi12TiO20 (BTO) crystals is proposed. The holographic image of a prism-shaped transparent sample appears covered of interference fringes, and as the sample is properly translated, the fringes run along the holographic image. An expression providing the refractive index of the medium as a function of the sample displacement and the correspondent number of running fringes was derived. The refractive indexes of optical (BK7) glass, ethanol, hexan, cumene and aqueous solution of NaCl with different concentrations were measured in order to test the method. The obtained results are in good agreement with the ones reported in literature or measured by us using a commercial Abbe refractometre. (c) 2006 Elsevier B.V. All rights reserved.

Dielectric properties and microstructure of SrTiO3/BaTiO3 multilayer thin films prepared by a chemical route

Multilayer thin films with perovskite structures were produced by the polymeric precursor method. SrTiO3/BaTiO3 (STO/BTO) multilayers were deposited on Pt(111)/Ti/SiO2/Si(100) substrates by the spin-coating technique and heated in air at 700 degreesC. The microstructure and crystalline phase of the multilayered thin films were examined by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), resolution-high transmission electron microscopy (HRTEM), atomic force microscopy (AFM) and X-ray diffraction. The SrTiO3/BaTiO3 multilayer thin films consisted of grainy structures with an approximate grain size of 60 nm. The multilayered thin films showed a very clear interface between the components. The SrTiO3/BaTiO3 multilayer thin films revealed dielectric constants of approximately 527 and loss tangents of 0.03 at 100 kHz. The dielectric constant calculated for this multilayer film system is the value of the sum of each individual component of the film, i.e. The total value of the sum of each SrTiO3 (STO) and BaTiO3 (BTO) layer. The multilayer SrTiO3/BaTiO3 obtained by the polymeric precursor method, also showed a ferroelectric behavior with a remanent polarization of 2.5 muC/cm(2) and a coercive field of 30 kV/cm. The multilayer films displayed good fatigue characteristics under bipolar stressing after application of 10(10) switching cycles. (C) 2001 Published by Elsevier B.V. B.V. All rights reserved.