scholarly journals Outstanding Photoluminescence in Pr3+-Doped Perovskite Ceramics

Micromachines ◽  
2018 ◽  
Vol 9 (9) ◽  
pp. 419
Author(s):  
Jiameng Zhang ◽  
Yanan Hao ◽  
Meihua Bi ◽  
Guoyan Dong ◽  
Xiaoming Liu ◽  
...  
Keyword(s):  
Emission Spectra ◽  
Green Emission ◽  
Emission Peak ◽  
Ferroelectric Ceramics ◽  
X Ray Diffraction ◽  
Green Band ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Application Range ◽  
Pl Emission

Ba (Zr0.2Ti0.8) O3-50% (Ba0.7Ca0.3) TiO3 (BZT-0.5BCT) ceramics with different doping contents of Pr3+ were prepared by the conventional solid-state reaction. The phase structure and crystallinity of the fabricated ceramics were investigated by X-ray diffraction, Raman spectroscopy, and scanning electron microscopy. Photoluminescence (PL) emission spectra were measured to analyze the PL characteristics. The strong intensities of a green band at 489 nm and a red band at 610 nm were observed. The maximum emission intensity of the PL spectrum was achieved in the BZT-0.5BCT ceramic with 0.2% mol of Pr3+ ions. Furthermore, the PL spectra of BZT-0.5BCT ceramics were found to be sensitive to polarization of the ferroelectric ceramics. Compared with the unpoled ceramics, the green emission increased about 42% and a new emission peak at 430 nm appeared for the poled ceramics. With excellent intrinsic ferroelectricity and an enhanced PL property, such material has potential to realize multifunctionality in a wide application range.

scholarly journals Cubic InGaN Grown by MOCVD

1999 ◽  
Vol 4 (S1) ◽  
pp. 239-243
Author(s):  
J.B. Li ◽  
Hui Yang ◽  
L.X. Zheng ◽  
D.P. Xu ◽  
Y.T. Wang
Keyword(s):  
Room Temperature ◽  
Emission Peak ◽  
Buffer Layers ◽  
Cubic Phase ◽  
Yellow Luminescence ◽  
X Ray Diffraction ◽  
High Quality ◽  
X Ray ◽  
Cubic Gan ◽  
Pl Emission

We report on the growth of high-quality cubic phase InGaN on GaAs by MOCVD. The cubic InGaN layers are grown on cubic GaN buffer layers on GaAs (001) substrates. The surface morphology of the films are mirror-like. The cubic nature of the InGaN films is obtained by X-ray diffraction (XRD) measurements. The InGaN layers show strong photoluminescence (PL) at room temperature. Neither emission peak from wurtzite GaN nor yellow luminescence is observed in our films. The highest In content as determined by XRD is about 17% with an PL emission wavelength of 450 nm. The FWHM of the cubic InGaN PL peak are 153 meV and 216 meV for 427 nm and 450 nm emissions, respectively. It is found that the In compositions determined from XRD are not in agreement with those estimated from PL measurements. The reasons for this disagreement are discussed.

scholarly journals Near UV-Blue Excitable Green-Emitting Nanocrystalline Oxide

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
C. E. Rodríguez-García ◽  
N. Perea-López ◽  
G. A. Hirata
Keyword(s):  
Broad Band ◽  
Emission Peak ◽  
Electronic Transitions ◽  
Excitation Band ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Pl Emission ◽  
Intense Broad Band ◽  
Nanocrystalline Oxide

Green-emitting Eu-activated powders were produced by a two-stage method consisting of pressure-assisted combustion synthesis and postannealing in ammonia. The as-synthesized powders exhibited a red photoluminescence (PL) peak located at  nm when excited with  nm UV. This emission peak corresponds to the5D0→7F2transition in Eu3+. After annealing in ammonia, the PL emission changed to an intense broad-band peak centered at  nm, most likely produced by 4f65d1→4f7electronic transitions in Eu2+. This green-emitting phosphor has excitation band in the near UV-blue region (–450 nm). X-ray diffraction analysis reveals mainly the orthorhombic EuAlO3and Al2O3phases. Transmission electron microscopy observations showed that the grains are formed by faceted nanocrystals (~4 nm) of polygonal shape. The excellent excitation and emission properties make these powders very promising to be used as phosphors in UV solid-state diodes coupled to activate white-emitting lamps.

scholarly journals Structural, microstructural and dielectric characterizations of (Bi0.5Na0.5)TiO3based lead-free ferroelectric ceramics

2021 ◽  
pp. 2140006
Author(s):  
B. R. Moya ◽  
A. C. Silva ◽  
A. Peláiz-Barranco ◽  
J. D. S. Guerra
Keyword(s):  
Lead Free ◽  
Ferroelectric Ceramics ◽  
Reaction Sintering ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
Porosity Level ◽  
X Ray ◽  
Ceramic Samples ◽  
Lead Free Ceramics ◽  
Sintering Method

(1–[Formula: see text]Bi[Formula: see text]Na[Formula: see text]TiO3–[Formula: see text]BaTiO3 lead-free ceramics have been obtained from the conventional solid-state reaction sintering method. The structural properties were investigated from X-ray diffraction and Raman spectroscopy techniques. Results revealed well-crystallized ceramic samples with perovskite structure. Microstructural properties, obtained from scanning electron microscopy measurements, have shown high density with very low porosity level. The dielectric response, analyzed as a function of the temperature and several frequencies, showed very broad peaks with a strong frequency dependence of the temperature for the maximum dielectric permittivity for the modified system. Results were analyzed considering the influence of the BaTiO3 content on the studied physical properties.

scholarly journals Preparation and Up-Conversion Luminescence of Yb3+/Er3+/GZO Ceramics

2018 ◽  
Vol 20 (3) ◽  
pp. 15-19
Author(s):  
Guomin Li ◽  
Bing Wang ◽  
Rui Wang ◽  
Huiling Liu
Keyword(s):  
Red Light ◽  
Emission Spectra ◽  
Green Emission ◽  
Power Curve ◽  
X Ray Diffraction ◽  
Solid State Method ◽  
Green Is ◽  
Xrd Pattern ◽  
X Ray ◽  
State Method

Abstract Yb3+/Er3+/GZO ceramics have been synthesized with high temperature solid-state method. The phase and structure of the Yb3+/Er3+/GZO ceramics were characterized by X-ray diffraction (XRD). The XRD pattern that following ions Yb3+, Er3+ and Ga3+ were well doped into the ZnO lattice. Effi cient visible up-conversion (UC) red and green emission were observed under 980 nm excitation. The mechanism of the UC luminescence is investigated on the basis of the UC luminescence emission spectra, the power curve and energy level diagram. The infl uence of doping ions to the intensity ratio of red to green is analyzed and high purity of red light (red/green = 29.9) is fi nally obtained.

Luminescence Properties of Rare Earth Activated Aluminates Based Phosphor

2016 ◽  
Vol 28 ◽  
pp. 115-119
Author(s):  
Anupam Selot ◽  
Kapil Dev ◽  
Mahendra Aynyas ◽  
Sanjay Bhatt
Keyword(s):  
Emission Spectra ◽  
Combustion Method ◽  
Emission Peak ◽  
Prepared Phosphor ◽  
Ultraviolet Region ◽  
X Ray Diffraction ◽  
Quenching Mechanism ◽  
Strong Emission ◽  
X Ray ◽  
Peak Intensity

A blue emitting phosphor BaAl2O4 doped with Gd3+ were prepared by combustion method at 5000C. The prepared phosphor were investigated by X-ray Diffraction to determine the crystalinity. Photoluminescence emission spectra centred at 369 nm under ultraviolet region, which corresponds to 5d-4f transition of Gd3+ ions. The PL spectra showed strong emission peak intensity and extending to 400nm to 453nm.Concentration quenching mechanism were occurred about 1mol% of Gd3+ ion. The results revealed that phosphor prepared by using combustion method can be useful WLED.

Structural and Dielectric Properties of Na0.5Bi0.5TiO3 Ferroelectric Ceramics

2012 ◽  
Vol 585 ◽  
pp. 219-223
Author(s):  
Rekha Kumari ◽  
N. Ahlawat ◽  
Ashish Agarwal ◽  
M. Sindhu ◽  
N.N. Ahlawat
Keyword(s):  
Dielectric Properties ◽  
Solid State Reaction Method ◽  
Wide Frequency Range ◽  
Ferroelectric Ceramics ◽  
Frequency Range ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
Reaction Method ◽  
X Ray ◽  
Different Temperatures

Na0.5Bi0.5TiO3 (NBT) ceramics were synthesized by conventional solid state reaction method. Structural and dielectric properties of these ceramics were investigated. Crystalline phase of sintered ceramics was investigated by X-ray diffraction (XRD). The Rietveld refinement of powder X-ray diffraction revealed that the prepared ceramics exhibit the rhombohedral space group R3c. Dielectric properties of Na0.5Bi0. analyzer.5TiO3 (NBT) ceramics were studied at different temperatures in a wide frequency range using impedance

Preparation of hexagonal cerium oxide nanoflakes by a surfactant-free route and its optical property

2007 ◽  
Vol 22 (11) ◽  
pp. 3006-3013 ◽  
Author(s):  
X. Yu ◽  
P. Ye ◽  
L. Yang ◽  
S. Yang ◽  
P. Zhou ◽  
...  
Keyword(s):  
Cerium Oxide ◽  
Visible Region ◽  
Blue Shift ◽  
Emission Peak ◽  
X Ray Diffraction ◽  
X Ray ◽  
Strong Reflection ◽  
Mean Size ◽  
The Mean ◽  
Pl Emission

Hexagonal cerium oxide nanoflakes have been synthesized by using a surfactant-free route. Transmission electcron microscopy (TEM), x-ray diffraction (XRD), infrared spectroscopy (FTIR), thermogravimetric and differential thermal analysis (TG-DTA), Brunauer–Emmett–Teller adsorption isotherm (BET), photoluminescence (PL), and ultraviolet–visible (UV–VIS) were used to characterize the sample. The mean size of the nanoflakes is about 30 nm and the specific surface is about 70.08 m2·g−1 when annealed at 400 °C. The acidity and superfluous NH4NO3 play a key role on the formation of nanoflakes in which there exists Ce (IV) and very little Ce (III). The nanoflakes exhibit a wide PL emission peak among 350–400 nm, strong absorption ranged from 200–450 nm, and strong reflection in the visible region. As the sizes of as-prepared samples decrease, a clear blue shift in the absorbing edge is observed. The linear relationship between ΔEg and D is shown in a log–log plot. The as-prepared cerium oxide nanoflakes can be widely used as UV absorbent and polishing materials.

Photoconductivity and photoluminescence in chemically deposited films of CdSSe:CdCl2,Ho

2009 ◽  
Vol 17 (1) ◽  
Author(s):  
S. Bhushan ◽  
A. Oudhia
Keyword(s):  
Optical Absorption ◽  
Emission Spectra ◽  
Shallow Donor ◽  
X Ray Diffraction ◽  
Deep Acceptor ◽  
X Ray ◽  
Impurity Doped ◽  
Layered Growth ◽  
Crystalline Nature ◽  
Pl Emission

AbstractResults of the scanning electron microscopy (SEM), X-ray diffraction (XRD), optical absorption, photoconductivity (PC), and photoluminescence (PL) studies for the CdSSe:CdCl2,Ho films are presented in this paper. The SEM studies of different CdSSe films show a layered growth structure. A crystalline nature of the films is observed in the XRD studies. The regions with stacking fault were also observed in the X-ray diffractograms. The optical absorption spectra of these films show variations corresponding to the band gaps and the grain-sizes obtained under various deposition conditions and also with annealing. The effect of flux, impurities and annealing on the saturated photo to dark current ratio Ipc/Idc is observed in the PC rise and decay studies. The maximum value of Ipc/Idc ∼107 is obtained for the impurity doped annealed films. The PL emission spectra of CdSSe films show two emission peaks associated with the annihilation of free excitons and the transitions between shallow donor and deep acceptor states. In CdSSe:CdCl2,Ho films, two PL emission peaks are observed at 495 nm and 545 nm corresponding to the transitions 5S2→5I8 and 5F3→5I8, respectively, in Ho. The effect of pH on PL and grain size is also included in the present studies.

scholarly journals Ca-Doped ZnO:Al Thin Films: Synthesis and Characterization

Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1023
Author(s):  
Anca-Ionela Istrate ◽  
Iuliana Mihalache ◽  
Cosmin Romanitan ◽  
Oana Tutunaru ◽  
Silviu Vulpe ◽  
...  
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Green Emission ◽  
Rf Magnetron Sputtering ◽  
Emission Peak ◽  
Optical Measurements ◽  
X Ray Diffraction ◽  
Electrical Measurements ◽  
X Ray ◽  
Ca Doping

We unveiled the effect of doping on the morpho-structural and opto/electrical properties of Ca-doped ZnO:Al thin films obtained by RF magnetron sputtering. Scanning electron microscopy (SEM) was performed to reveal the surface morphology, while the composition and crystal structure were investigated by energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The correlation between the microstructure and the electrical conductivity identifies an increase in electrical conductivity up to 145 × 10−3 Ω−1·m−1 at 5 wt.% Ca doping level with the decrease in the grain size. Furthermore, the presence of Ca dopant triggers the occurrence of the emission peak at 430 nm and an increase of the green emission peak in PL spectra. Corroborating the electrical measurements with X-ray diffraction and optical measurements, one can infer that the electrical conductivity is dominated by intrinsic defects developed during deposition and by the existence of dopants.

Cubic InGaN Grown by Mocvd

1998 ◽  
Vol 537 ◽  
Author(s):  
J.B. Li ◽  
Hui Yang ◽  
L.X. Zheng ◽  
D.P. Xu ◽  
Y.T. Wang
Keyword(s):  
Room Temperature ◽  
Emission Peak ◽  
Buffer Layers ◽  
Cubic Phase ◽  
Yellow Luminescence ◽  
X Ray Diffraction ◽  
High Quality ◽  
X Ray ◽  
Cubic Gan ◽  
Pl Emission

AbstractWe report on the growth of high-quality cubic phase InGaN on GaAs by MOCVD. The cubic InGaN layers are grown on cubic GaN buffer layers on GaAs (001) substrates. The surface morphology of the films are mirror-like. The cubic nature of the InGaN films is obtained by X-ray diffraction (XRD) measurements. The InGaN layers show strong photoluminescence (PL) at room temperature. Neither emission peak from wurtzite GaN nor yellow luminescence is observed in our films. The highest In content as determined by XRD is about 17% with an PL emission wavelength of 450 nm. The FWHM of the cubic InGaN PL peak are 153 meV and 216 meV for 427 nm and 450 nm emissions, respectively. It is found that the In compositions determined from XRD are not in agreement with those estimated from PL measurements. The reasons for this disagreement are discussed.

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