RETRACTED ARTICLE: The effect of deposition pressure on the material properties of pulsed laser deposited BaAl 2 O 4 :Eu
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The effect of deposition pressure on the material properties of pulsed laser deposited BaAl2O4:Eu2+, Dy3+ thin films H. T. Haile1 · F. B. Dejene1 Received: 22 December 2018 / Accepted: 7 May 2019 / Published online: 25 May 2019 © Springer Science+Business Media, LLC, part of Springer Nature 2019
Abstract BaAl2O4:Eu2+, Dy3+ thin films have been successfully deposited by pulsed laser deposition (PLD) method. Formation of crystalline phase was confirmed by X-ray diffraction (XRD) measurement. The average crystallite size calculates using the Scherer’s formula was found to be between 15.2 and 30.5 nm. Scanning electron microscopy (SEM) micrograph revealed that, the films have non uniform morphology with variable grain size for all the deposition conditions. The surface morphology displays some tendency for agglomeration as a function of increasing deposition pressure, which may be due to the sintering or coalesce of small particles into clusters. Atomic force microscopy (AFM) measurements also show an increase in surface roughness as the oxygen deposition pressure is increased. The BaAl2O4:Eu2+, Dy3+ thin-film phosphors exhibit photoluminescence (PL) emission at 495 nm upon 254 nm excitation. This can be attributed to the electronic transition of Eu2+ ions from 4f65d1 to 4f. The present study recommends that this phosphor could be used as luminescent materials for light emitting diode applications.
1 Introduction When a solid material is heated in a temperature range above 600 °C, the infrared emission starts because of the heat applied to the material. This phenomenon is thermal emission, while luminescent/phosphorescent materials converts the incoming radiation into visible light. There are many types of energy forms responsible for luminescence. The form of energy and their corresponding emission of luminescence are given as follow: electromagnetic waves, in particular; UV radiation → photoluminescence, electrical voltage → electroluminescence, mechanical energy → triboluminescence, X-rays → X-ray luminescence, chemical reaction → chemo-luminescence. Keep in mind that thermoluminescence is the stimulation of luminescence, when the material is excited beforehand, which is not related to thermal excitation [1]. Inorganic light-emitting materials activated by rare earth (RE) ions have practical applications in the fields of lighting, display, and communications; such as cathode ray tubes, fiber amplifiers, fluorescent * H. T. Haile hagost1@gmail.com 1
Department of Physics, University of the Free State, QwaQwa Campus, Private Bag X13, Phuthaditjhaba 9866, South Africa
lamps, field emission screens and plasma screens [2]. The luminescence of a phosphor material from a compound matrix and activator is generally correlated to the activator, the host matrix and the atoms around the doped ion [1]. Because of their chemical stability and their powerful photoluminescence (PL) characteristics, the alkaline earth metal oxides doped with E u2+, i.e. M A12O4:Eu2+ (M = Ca, Sr, Ba) have been attracting the attenti
