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Bridgman Method (bridgman + method)
Kinds of Bridgman Method Selected AbstractsBridgman growth of langasite-type piezoelectric crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2007Anhua Wu Abstract Three langasite family crystals of Sr3Ga2Ge4O14 (SGG), Ca3NbGa3Si2O14 (CNGS), and Sr3NbGa3Si2O14 (SNGS) were successfully grown by the modified Bridgman method. Among them, SGG crystals up to 2 inches were obtained with the multi-crucible industrial Bridgman furnace; SNGS crystal grown in any orientation direction other than along a -axis was realized. Commercially availability SGG boules and the advantage in SNGS crystal indicated that the modified Bridgman technique is a prospective method to realize the mass-production of the langasite-type crystals. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Investigation on growth defects in Pb(Zn1/3Nb2/3)O3 -PbTiO3 crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 11 2006Min Jin Abstract Relaxor ferroelectric crystal (1-x)Pb(Zn1/3Nb2/3)O3 -xPbTiO3 (PZNT) with x=0.07 (PZNT93/7) has been grown by the vertical Bridgman method from the high temperature solution of PZNT-PbO system. The growth defects, such as nucleation core, inclusions, boundaries and particles, were investigated by optical microscope and scanning electron microscope. Sub-structures were found in the flux inclusions and the lack of ZnO component in PZNT crystals was attributed to the existence of ZnO particles in the inclusions. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth and optical characterization of Cd1- xBexSe and Cd1- xMgxSe crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4-5 2005F. Firszt Abstract Cd1- xBexSe and Cd1- xMgxSe solid solutions were grown from the melt by the high pressure Bridgman method. Optical, luminescence and photothermal properties of these materials were investigated. Spectroscopic ellipsometry was applied for determination of the spectral dependence of the complex dielectric function (E) and refractive index n(E) at room temperature in the photon energy range 0.75-6.5 eV for samples with optic axis (c-axis) perpendicular to the air-sample interface. The critical point (CP) parameters for E0 and E1 transitions were determined using a standard excitonic CP function to fit the numerically calculated differential spectra ,2,2/,E2. The dispersion of the refractive index of the alloys was modelled using a Sellmeier-type relation. The values of fundamental and exciton band-gap energies were estimated from the ellipsometric and photoluminescence measurements. The origin of luminescence in Cd1- xBexSe and Cd1- xMgxSe was discussed. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Cr3+ -doped LiNbO3 crystals grown by the Bridgman methodCRYSTAL RESEARCH AND TECHNOLOGY, Issue 3 2005Haiping Xia Abstract The growth of LiNbO3 crystals doped with Cr3+ ions in 0.1, 0.2, and 0.5 mol % concentrations by Bridgman method were reported. The Cr3+ ion concentrations in crystals were measured by inductively coupled plasma spectrometry. Electron paramagnetic resonance had been used to investigate the sites occupied by the Cr3+ ions. Two Cr3+ ion centers located at Li+ and Nb5+ sites (CrLi3+ and CrNb3+ centers, respectively) were observed. Optical absorption and temperature-dependence emission spectra of the Cr3+ ions were reported. The crystal-field parameters and Racah parameters of the Cr3+ ion defect sites were reported and compared with those grown by Czochralski technique. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Purification and crystal growth of TlBr for application as a radiation detectorCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2004I. B. Oliveira Abstract Thallium bromide is a semiconductor compound with high atomic number and density. It has a CsCl-type simple cubic crystal structure and it is non-hygroscopics. The TlBr crystals are relatively soft with a knoop hardness number of 12. In this work, the TlBr commercial powder was purified by zone refining and the purest material section was used for crystal growth by Bridgman method. Efforts have been concentrated on the purification of the TlBr. The purification efficiency has been evaluated (NAA and ICP-MS) by impurities reduction results after zone refining passes. The crystalline quality was evaluated by X-ray diffraction. The characterized TlBr crystal as a detector has shown good response to gamma radiation. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Preparation and investigation of (CuInSe2)x(2ZnSe)1-x and (CuInTe2)x(2ZnTe)1-x solid solution crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2004I. V. Bodnar Abstract The (CuInSe2)x(2ZnSe)1-x and (CuInTe2)x(2ZnTe)1-x solid solution crystals prepared by Bridgman method and chemical vapor transport have been studied. The nature of the crystalline phases, the local structure homogeneity and composition of these materials have been investigated by X-ray diffraction (XRD) and Electron Probe Microanalysis (EPMA) methods. The analysis revealed the presence of chalcopyrite-sphalerite phase transition between 0.6 , X , 0.7. Lattice constants, value of , position parameter and bond length between atoms were also calculated. It was found that the lattice parameters exhibit a linear dependence versus composition. The transmission spectra of solid solution crystals in the region of the main absorption edge were studied. It was established that the optical band gap of these materials changes non-linearly with the X composition. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Spectral properties and thermoluminescence of codoped PbWO4:(Mo,Y) and PbWO4:(F,Y) crystalsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2009Jian-jun Xie Abstract Lead tungstate, PbWO4 single crystals codoped with Mo6+/F, and Y3+ ions were grown using the modified Bridgman method. Optical transmission, X-ray excited luminescence, photoluminescence, ultrashort pulsed X-ray excited fluorescent lifetime and thermoluminescence have been investigated. Compared to pure PbWO4, the codoped PbWO4:(Mo,Y) and PbWO4:(F,Y) crystals exhibit improved transmittance in the short-wavelength region. Luminescence and light-yield measurements demonstrated that Mo6+/F, and Y3+ codoping could enhance the luminescence of PbWO4 and reduce slow decay components. Doped Mo6+ and F, ions in PbWO4 were tentatively considered to occupy W and O sites, while Y3+ ions codoped in PbWO4:Mo/F mostly occupy Pb sublattice sites. The second excitation peak at 335 nm, which is the second effective excitation for the enhanced blue-green emission in as-grown PbWO4:(Mo,Y) and PbWO4:(F,Y) crystals, should be related to MoO42, groups and O vacancies (VO). Thermoluminescence glow curve measurement between RT and 400 °C provides complementary information about trapping states and the effect of Y3+ ion codoping resulting in the reduction of stable and temporary hole centers. Further work is needed to explain the doping and energy-transfer mechanism. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Luminescence properties and growth of pure and anthracene-doped naphthalene crystalsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 10 2007N. Balamurugan Abstract Pure and anthracene-doped naphthalene crystals of high quality with 20 mm diameter and 60 mm length have been grown by the self-seeded vertical Bridgman method. The powder X-ray diffraction studies and the Raman analysis show that the guest molecules appear as defects in the form of irregularly oriented molecules that do not significantly distort the monoclinic structure. The absorbance and fluorescence studies show high Stoke's shift for anthracene-doped naphthalene crystals. From this we deduce that the exciting wavelength of the light (270 nm) is completely absorbed by the naphthalene, so that fluorescence from anthracene takes place as a result of energy transfer from naphthalene. The decay time observed for anthracene-doped naphthalene is 27 ± 2 ns. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Semi-insulating (Cd,Mn)Te:V crystals: Electrical contactsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 5 2007M. Witkowska-Baran Abstract The high-resistivity (Cd,Mn)Te is believed to be suitable to succesfully replace the commonly used (Cd,Zn)Te system as a material for manufacturing large-area X- and ,-ray detectors. The purpose of our study was to elaborate a method of preparing high quality (Cd,Mn)Te crystal plates as well as a technique of producing good electrical contacts to that material. (Cd,Mn)Te was grown using the Bridgman method. The crystals were doped with vanadium to the level of 1016 cm,3. The crystals are twinned in the (111) plane, but by slicing the crystal parallel to the twinning plane we obtained monocrystalline plates of large area (e.g. 30 × 30 mm2), which is essential for application purposes. Proper annealing of those plates in cadmium vapours allowed us to reduce the number of cadmium vacancies forming during the growth process. Due to the vanadium dopant acting as a compensating centre we obtained a semi-insulating material. In order to obtain good contacts to the (Cd,Mn)Te plates we used the method proposed initially for CdTe by Rioux et al. The ZnTe:Sb layers (,1 ,m thick) were grown on the epi-ready (Cd,Mn)Te:V plates by the MBE technique. The grown layers were p-type and formed a good electrical contact to the crystal plates. Finally , a standard technique was used to cover the ZnTe layer by a metal layer. The contacts formed on (111) surfaces of (Cd,Mn)Te were studied. We believe that the contacts to the (111) surface are important for applications. In the paper we describe techniques of preparing electrical contacts and results of their characterization. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effect of variable crucible dropping rate on solid-liquid interface in CdZnTe crystal growthPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2010Chenying Zhou Abstract The Cd0.9Zn0.1Te crystal growth with low pressure and vertical Bridgman method (LPVB) was numerically simulated and analysed by the simulation software of Comsol Multiphysics. In the process of crystal growth, the influence of variable crucible dropping rate on solid-liquid interface was studied in this paper. The variability of crucible dropping rate was achieved by a specifical furnace temperature distribution function, while the selection and analysis of crucible dropping rate was obtained by the combination of orthogonal experimental design method and regression analysis method. In this paper, the value of relative crystal growth rate was defined, and the influence of variable crucible dropping rate on solid-liquid interface was discussed by comparing these values. The simulation results showed that if the crucible dropping rate was 3.5 mm/h (,1) in the first stage and 0.6 mm/h (,2) in the second stage, and the distance (d) between the bottom of crucible and the position of melting point in tempreture field was 0.02 m at the time of dropping rate change, the solid-liquid interface was appreciably convex after 211 hours' growth, and the relative crystal growth rate was 0.45%, which made the solid-liquid interface smooth and kept the crystal grow up spontaneously. [source] Far-infrared spectroscopy of HgMnTe,MnSe mixturePHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2006N. Rom Abstract Far-infrared reflectivity spectrum of Hg0.91Mn0.09Te-MnSe mixture, grown by Bridgman method, was measured in the 80,500 cm,1 range at room temperature. The investigated mixture consists of MnSe clusters randomly distributed in Hg0.91Mn0.09Te matrix. The analysis of the far-infrared spectrum was made by a fitting procedure. The Maxwell-Garnett effective medium theory is used for modeling the effective dielectric function, and by that way calculating both the electron and phonon response. There is a good agreement between the experimental results and the applied model. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Characterisation of Cd1,x,yZnxBeySe crystals by spectroscopic ellipsometry and luminescencePHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2006A. A. Wronkowska Abstract Optical and luminescence properties of Cd1,x,yZnxBeySe solid solutions grown in the composition range 0 < x < 0.15 and 0 < y < 0.30 by the high pressure Bridgman method are reported. Spectroscopic ellipsometry was employed for determination of spectral dependence of the complex dielectric function ,(E), refractive index n(E) and absorption coefficient ,(E) in the photon energy range 0.75,6.0 eV. The dispersion of the refractive index of the alloys was modelled using a Sellmeier-type relation. The excitonic band-gap energies were estimated from the ellipsometric and photoluminescence measurements. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Vertical Bridgman growth and annealing effect of Bi doped ZnSe single crystalPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2004C. B. Oh Abstract In order to prepare p-type ZnSe, bismuth (Bi) as an acceptor dopant was doped into ZnSe single crystal by vertical Bridgman method. Photoluminescence (PL) spectra measured at 4.2 K on as-grown crystal showed the strong shallow donor,acceptor pair (DsAP) emission, deep donor,acceptor pair (DdAP) emission and weak I1Bi emission line. To enhance the activation ratio of Bi in ZnSe single crystals, ZnSe:Bi was annealed in saturated zinc and selenium atmosphere at different temperatures. In the case of annealing in the range of 700,800 °C, DdAP emission disappeared and the intensities of DsAP and I1Bi emission relatively increased. From the dependence of PL spectra on excitation light intensity and the temperature, the acceptor activation energy and deep donor level were estimated about 103 meV and 34 meV, respectively. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||