Enhancement of green photoluminescence from ZnO:Pr powders

2006 ◽  
Vol 21 (6) ◽  
pp. 1476-1483 ◽  
Author(s):  
Yoshihiro Inoue ◽  
Masaki Okamoto ◽  
Jun Morimoto
Keyword(s):  
Grain Boundaries ◽  
Silica Glass ◽  
Green Emission ◽  
Glass Tube ◽  
Luminescent Properties ◽  
Native Defects ◽  
Zno Varistor ◽  
Doped Zno ◽  
Green Photoluminescence ◽  
Silica Glass Tube

Pr-doped ZnO phosphor powders were prepared by dry reaction within evacuated sealed silica glass tube. Pr2O3 and Pr6O11 were used as additives. Pr concentrations were 0.5, 1, 3, and 5 mol%, and the sintering temperatures were 600, 800, and 1000 °C, respectively. Photoluminescence (PL) and PL excitation (PLE) spectra were measured to study luminescent properties of samples. Some samples showed the enhancement of green emission. This emission is related to native defects in ZnO. Based on the results of PL and PLE, the origin of the enhancement was discussed in view of native defects in ZnO and the defect-related complex in ZnO varistor ceramics. The possible origin is the increase of native defects such as VZn, OZn, and the complex in the vicinity of grain boundaries and ZnO matrix near the surface of grains. The increase of native defects and the complex are probably due to the existence of the Pr3+-ions with binding to native defects, which form the complex by Coulombic potential.

Powder diffraction study of Pd2HgSe3

2017 ◽  
Vol 32 (4) ◽  
pp. 244-248 ◽  
Author(s):  
F. Laufek ◽  
A. Vymazalová ◽  
M. Drábek
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Silica Glass ◽  
Rietveld Method ◽  
Glass Tube ◽  
Layered Crystal ◽  
Unit Cell Parameters ◽  
Cell Parameters ◽  
Layered Crystal Structure ◽  
Silica Glass Tube

The Pd2HgSe3 phase was synthetized from individual elements by the silica glass tube technique and its crystal structure has been refined by the Rietveld method. The Pd2HgSe3 phase crystalizes in P$\bar 3$m1 space group with the unit-cell parameters a = 7.3096(2) Å, c = 5.2829(1) Å, V = 244.45(1) Å3, Dc = 8.84 g/cm3, and Z = 2. In its layered crystal structure, the [PdSe6] octahedra share opposing Se–Se edges with adjacent [PdSe4] squares forming layers parallel with the (001) plane. The layers show AA type stacking along the c-axis. Hg atoms occupy the anti-cubooctahedral voids between two consecutive layers. Pd2HgSe3 is isostructural with Pt2HgSe3 and Pt4Tl2X6 (X = S, Se, or Te) phases. The structure can be viewed as a 2a.2a.c superstructure of PtSe2.

Characterization of Single Grain Boundaries in a Bi-Doped ZnO Varistor Using a Focused Ion Beam System

2000 ◽  
Vol 39 (Part 1, No. 7B) ◽  
pp. 4493-4496 ◽  
Author(s):  
Junji Tanimura ◽  
Osamu Wada ◽  
Hiroshi Kurokawa ◽  
Naomi Furuse ◽  
Masahiro Kobayashi
Keyword(s):  
Grain Boundaries ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Zno Varistor ◽  
Beam System ◽  
Single Grain ◽  
Doped Zno

A re-examination of herzenbergite–teallite solid solution at temperatures between 300 and 700°C

2001 ◽  
Vol 65 (5) ◽  
pp. 645-651 ◽  
Author(s):  
K. Hayashi ◽  
A. Kitakaze ◽  
A. Sugaki
Keyword(s):  
Solid Solution ◽  
Linear Relationship ◽  
Silica Glass ◽  
Glass Tube ◽  
Solid Solution Series ◽  
Solution Series ◽  
Cell Dimensions ◽  
Silica Glass Tube

AbstractIn order to investigate the range of the solid solution series in herzenbergite-teallite minerals, samples of different composition were synthesized. Herzenbergite-teallite minerals were synthesized by an evacuated silica glass tube method at 700°C. A linear relationship between cell dimensions, a, b and c and composition is established. Extension of solid solution to the Pb-rich portion of the system PbS-SnS is limited; the solid solution area is between Pb1.060Sn0.940S2 and SnS at 700°C. Teallite coexisting with galena was also synthesized by hydrothermal recrystallization at 300, 400 and 450°C. The compositions of teallite are Pb1.140Sn0.860S2 at 300°C, Pb1.114Sn0.886S2 at 400°C, and Pb1.124Sn0.876S2 at 450°C, respectively. Their compositions shift towards the PbS end-member from stoichiometric teallite. The cell dimensions of teallite, which was synthesized hydrothermally, follow the linear relationship between cell dimensions and composition established at 700°C.

Structural changes of various types of silica glass tube upon blowing with hydrogen–oxygen flame

2004 ◽  
Vol 349 ◽  
pp. 38-45 ◽  
Author(s):  
Yosuke Kokubo ◽  
Nobu Kuzuu ◽  
Izumi Serizawa ◽  
Ling-Hai Zeng ◽  
Kenji Fujii
Keyword(s):  
Silica Glass ◽  
Structural Changes ◽  
Glass Tube ◽  
Oxygen Flame ◽  
Silica Glass Tube

scholarly journals Fabrication of a Porous TiO2-Coated Silica Glass Tube and Its Application for a Handy Water Purification Unit

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Tsuyoshi Ochiai ◽  
Shoko Tago ◽  
Hiromasa Tawarayama ◽  
Toshifumi Hosoya ◽  
Hitoshi Ishiguro ◽  
...  
Keyword(s):  
Water Purification ◽  
Silica Glass ◽  
Aqueous Suspension ◽  
Glass Tube ◽  
E Coli ◽  
Purification Unit ◽  
Silica Layers ◽  
Virus Size ◽  
Uv C ◽  
Silica Glass Tube

A simple, handy, reusable, and inexpensive water purification unit including a one-end sealed porous amorphous-silica (a-silica) tube coated with 2 μm of porous TiO2photocatalyst layers has been developed. Both TiO2and a-silica layers were formed through outside vapor deposition (OVD). Raman spectrum of the porous TiO2-coated a-silica glass tube indicated that the anatase content of the TiO2layers of the tube was estimated to be approximately 60 wt%. Developed porous TiO2-coated a-silica glass tube has been assayed for the tube filtering feature againstEscherichia coli(E. coli) solution used as one of the typical bacteria size species or Qβphage also used as typical virus size species and compared with the feature of porous a-silica tubes alone. The tubes removedE. colicompletely from the aqueous suspension which contained 106 CFU/mL ofE. coliwithout UV irradiation. The porous TiO2-coated a-silica glass tube with UV-C lamps successfully reduced the Qβphage amount in the suspension from 109to 103 PFU/mL.

Darstellung und Kristallstruktur von Hexacaesium-hexatelluridodigermanat( III) (Cs6Ge2Te6)

1999 ◽  
Vol 54 (8) ◽  
pp. 1095-1098 ◽  
Author(s):  
Bernd Friede ◽  
Martin Jansen
Keyword(s):  
Alkali Metal ◽  
Title Compound ◽  
Silica Glass ◽  
Glass Tube ◽  
Stoichiometric Ratio ◽  
Bond Lengths ◽  
Counter Ions ◽  
Silica Glass Tube

The new compound hexacaesium hexatellurido digermanate(III), Cs6Ge2Te6, has been prepared by reacting the elements in a stoichiometric ratio at 923 K in an evacuated silica glass tube. The title compound crystallizes as black columns and is isostructural to K6G e2Te6 (C2/c, a = 17.027(2), b = 14.237(1), c = 10.104(1) Å, β = 96.701(8)°, Z = 4 (5130 reflections, R1 (I > 2 σ (I)) = 0.042). The structure ist composed of isolated distorted Te6 octahedra, with Ge-Ge dumbbells at the centres. The caesium cations are arranged between the isolated Ge2Te6 octahedra. The Ge-Ge bond lengths in A6Ge2Te6 (A = alkali metal) increase significantly as the counter ions are varied from sodium to caesium.

scholarly journals Fabrication of TiO2-coated Porous Silica Glass Tube and Evaluation as Environmental Purification Unit

2019 ◽  
Vol 87 (1) ◽  
pp. 1-7
Author(s):  
Mio HAYASHI ◽  
Tsuyoshi OCHIAI ◽  
Shoko TAGO ◽  
Hiromasa TAWARAYAMA ◽  
Toshifumi HOSOYA ◽  
...  
Keyword(s):  
Silica Glass ◽  
Porous Silica ◽  
Glass Tube ◽  
Purification Unit ◽  
Porous Silica Glass ◽  
Silica Glass Tube

Microchemistry of ZnO Varistors

1992 ◽  
Vol 50 (2) ◽  
pp. 1694-1695
Author(s):  
K. K. Soni ◽  
J. Hwang ◽  
V. P. Dravid ◽  
T. O. Mason ◽  
R. Levi-Setti
Keyword(s):  
Grain Boundaries ◽  
Multiple Roles ◽  
Grain Boundary Engineering ◽  
Ion Microprobe ◽  
Dopant Distribution ◽  
Important Ingredient ◽  
Zno Varistor ◽  
Zno Varistors ◽  
Zno Powder ◽  
The University

ZnO varistors are made by mixing semiconducting ZnO powder with powders of other metal oxides e.g. Bi2O3, Sb2O3, CoO, MnO2, NiO, Cr2O3, SiO2 etc., followed by conventional pressing and sintering. The non-linear I-V characteristics of ZnO varistors result from the unique properties that the grain boundaries acquire as a result of dopant distribution. Each dopant plays important and sometimes multiple roles in improving the properties. However, the chemical nature of interfaces in this material is formidable mainly because often trace amounts of dopants are involved. A knowledge of the interface microchemistry is an essential component in the ‘grain boundary engineering’ of materials. The most important ingredient in this varistor is Bi2O3 which envelopes the ZnO grains and imparts high resistance to the grain boundaries. The solubility of Bi in ZnO is very small but has not been experimentally determined as a function of temperature.In this study, the dopant distribution in a commercial ZnO varistor was characterized by a scanning ion microprobe (SIM) developed at The University of Chicago (UC) which offers adequate sensitivity and spatial resolution.

Synthesis and crystal structure of (Ag,Pd)22Se6

2013 ◽  
Vol 28 (1) ◽  
pp. 13-17 ◽  
Author(s):  
F. Laufek ◽  
A. Vymazalová ◽  
D.A. Chareev ◽  
A.V. Kristavchuk ◽  
J. Drahokoupil ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
Glass Tube ◽  
Structure Type ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Cell Parameters ◽  
Silica Glass Tube

The (Ag,Pd)22Se6 phase was synthesized from individual elements by silica glass tube technique and structurally characterized from powder X-ray diffraction data. The (Ag,Pd)22Se6 phase crystallizes in Fm$\overline3$m symmetry, unit-cell parameters: a = 12.3169(2) Å, V = 1862.55(5) Å3, Z = 4, and Dc = 10.01 g/cm3. The crystal structure of the (Ag,Pd)22Se6 phase represents a stuffed 3a.3a.3a superstructure of the Pd structure (fcc), where only 4 from 108 available octahedral holes are occupied. Its crystal structure is related to the Cr23C6 structure type.

Study on Low Temperature Conduction Mechanism of Al Doped ZnO/SiO2/ P-Si Heterojunction

2021 ◽  
Vol 904 ◽  
pp. 363-368
Author(s):  
Xiao Yan Zhou ◽  
Bang Sheng Yin
Keyword(s):  
Activation Energy ◽  
Impedance Spectroscopy ◽  
Low Temperature ◽  
Grain Boundaries ◽  
Ac Conductivity ◽  
Spray Pyrolysis Method ◽  
Temperature Conductivity ◽  
Calculated Activation Energy ◽  
Doped Zno ◽  
Temperature Conduction

The 3 at% Al doped ZnO thin films were deposited on p-Si substrate with a native SiO2 layer by spray pyrolysis method. Low temperature conduction behaviors were studied by analysis of impedance spectroscopy and low temperature ac conductivity. The results of impedance spectroscopy showed that the grain boundaries contributed to the resistivity of Al doped ZnO/SiO2/p-Si heterojunction. The calculated activation energy was 0.073 eV for grain boundaries. The equivalent circuit to demonstrate the electrical properties of Al doped ZnO/SiO2/p-Si heterojunction was a series connection of two parallel combination circuits of a resistor and a universal capacitor. Low temperature ac conductivity measurements indicated that the conductivity increased with temperature. Low temperature conductivity mechanism was electron conductivity, and the activation energy was 0.086 eV.

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