Surface Structure and Electronic Properties of Lu3Al5O12

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1433
Author(s):  
Weian Guo ◽  
Benxue Jiang ◽  
Jiajie Zhu ◽  
Long Zhang
Keyword(s):  
Single Crystal ◽  
Electronic Properties ◽  
Oxygen Vacancies ◽  
High Efficiency ◽  
Surface Defects ◽  
Light Yield ◽  
Crystal Film ◽  
Structural And Electronic Properties ◽  
High Light Yield ◽  
Formation Energies

Lu3Al5O12 (LuAG) is a famous scintillator that has the advantages of high efficiency, high light yield, and fast decay after being doped with active ions. F centers (oxygen vacancies with two electrons) and antisite defects are the most important defects and can greatly affect the scintillation performance in the bulk materials. However, the surface defects that strongly affect the spectrum of a single crystal (SC) and single crystal film (SCF) and the effect on the electronic properties have not been investigated. In this context, we investigate the surface structural and electronic properties of Lu3Al5O12 using first-principles calculations. The Lu atoms are six-fold and seven-fold coordinated with the O atoms on the S1 and S2 surfaces. The surface oxygen vacancies and antisites have considerably lower formation energies than for the bulk. The oxygen vacancies in the bulk introduce the occupied states in the band gap. The surface electronic states are mainly located on the oxygen atoms and can be eliminated via oxygen vacancies.

Structural and Electronic Properties of Oxygen Vacancies in Monoclinic HfO2

2007 ◽  
Vol 996 ◽  
Author(s):  
Peter Broqvist ◽  
Alfredo Pasquarello
Keyword(s):  
Oxygen Vacancy ◽  
Optical Absorption ◽  
Total Energy ◽  
Band Gap ◽  
Electronic Properties ◽  
Density Functional ◽  
Oxygen Vacancies ◽  
Structural And Electronic Properties ◽  
Defect Levels ◽  
Hybrid Density Functional

AbstractWe study structural and electronic properties of the oxygen vacancy in monoclinic HfO2 for five different charge states. We use a hybrid density functional to accurately reproduce the experimental band gap. To compare with measured defect levels, we determine total-energy differences appropriate to the considered experiments. Our results show that the oxygen vacancy can consistently account for the defect levels observed in optical absorption, direct electron injection, and trap-assisted conduction experiments.

Effect of A Site and Oxygen Vacancies on the Structural and Electronic Properties of Lead-Free KTa0.5Nb0.5O3 Crystal

2016 ◽  
Vol 45 (7) ◽  
pp. 3726-3733 ◽  
Author(s):  
Wenlong Yang ◽  
Li Wang ◽  
Jiaqi Lin ◽  
Xiaokang Li ◽  
Hanjiang Xiu ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Oxygen Vacancies ◽  
Lead Free ◽  
Structural And Electronic Properties ◽  
A Site

Engineering of a new single-crystal multi-ionic fast and high-light-yield scintillation material (Gd0.5–Y0.5)3Al2Ga3O12:Ce,Mg

CrystEngComm ◽  
2020 ◽  
Vol 22 (14) ◽  
pp. 2502-2506 ◽  
Author(s):  
Mikhail Korzhik ◽  
Vladimir Alenkov ◽  
Oleg Buzanov ◽  
Georgy Dosovitskiy ◽  
Andrei Fedorov ◽  
...  
Keyword(s):  
Single Crystal ◽  
Light Yield ◽  
Small Concentration ◽  
High Light ◽  
Czochralski Technique ◽  
High Light Yield ◽  
Crystal Scintillation ◽  
First Time

A single crystal scintillation material (Gd0.5–Y0.5)3Al2Ga3O12 (GYAGG) doped with Ce and codoped with Mg at a small concentration was grown by the Czochralski technique and studied for its scintillation properties for the first time.

scholarly journals Study on Improving the Precise Machinability of Single Crystal SiC by an Ultrasonic-Assisted Hybrid Process

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7320
Author(s):  
Dong Shi ◽  
Tianchen Zhao ◽  
Tengfei Ma ◽  
Jinping Pan
Keyword(s):  
Single Crystal ◽  
High Efficiency ◽  
Surface Defects ◽  
Removal Rate ◽  
Oxide Semiconductor ◽  
Hybrid Process ◽  
Ultrasonic Assisted ◽  
Single Crystal Sic ◽  
Surface Damages ◽  
Sic Wafer

Silicon carbide (SiC) devices have become one of the key research directions in the field of power electronics. However, due to the limitation of the SiC wafer growth process and processing capacity, SiC devices, such as SiC MOSFET (Metal-oxide-semiconductor Field-effect Transistor), are facing the problems of high cost and unsatisfied performance. To improve the precise machinability of single-crystal SiC wafer, this paper proposed a new hybrid process. Firstly, we developed an ultrasonic vibration-assisted device, by which ultrasonic-assisted lapping and ultrasonic-assisted CMP (chemical mechanical polishing) for SiC wafer were fulfilled. Secondly, a novel three-step ultrasonic-assisted precise machining route was proposed. In the first step, ultrasonic lapping using a cast iron disc was conducted, which quickly removed large surface damages with a high MRR (material removal rate) of 10.93 μm/min. In the second step, ultrasonic lapping using a copper disc was conducted, which reduced the residual surface defects with a high MRR of 6.11 μm/min. In the third step, ultrasonic CMP using a polyurethane pad was conducted, which achieved a smooth and less damaged surface with an MRR of 1.44 μm/h. These results suggest that the ultrasonic-assisted hybrid process can improve the precise machinability of SiC, which will hopefully achieve high-efficiency and ultra-precision machining.

FIRST-PRINCIPLES STUDY OF OXYGEN-VACANCY Cu2O (111) SURFACE

2012 ◽  
Vol 11 (06) ◽  
pp. 1261-1280 ◽  
Author(s):  
HUANWEN WU ◽  
NING ZHANG ◽  
HONGMING WANG ◽  
SANGUO HONG
Keyword(s):  
Oxygen Vacancy ◽  
Electronic Properties ◽  
First Principles ◽  
Electronic Structures ◽  
Oxygen Vacancies ◽  
Vacancy Formation ◽  
First Principles Calculations ◽  
First Principles Study ◽  
Formation Energies ◽  
Geometric And Electronic Properties

Geometric and electronic properties and vacancy formation energies for two kinds of oxygen-vacancy Cu 2 O (111) surfaces have been investigated by first-principles calculations. Results show that the relaxation happens mainly on the top three trilayers of surfaces. Two vacancies trap electrons of -0.11e and -0.27e, respectively. The effects of oxygen vacancies on the electronic structures are found rather localized. The electronic structures suggest that the oxygen vacancies enhance the electron donating ability of the surfaces to some extent. The energies of 1.75 and 1.43 eV for the formation of oxygen vacancies are rather low, which indicates the partially reduced surfaces are stable and easy to produce.

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