Host‐Sensitized Continuum‐Broad‐Band White‐Light Emitting Yb₂O₃:Er³⁺ Phosphor under CW‐NIR Light Absorption

Abstract

Single cubic phase Yb2O3:Er3+ phosphors have been synthesized via solid state reaction technique and characterized by X‐ray diffraction (XRD) and Field emission scanning electron microscopy (FE‐SEM) analysis. An unusual continuum broad band white colour upconversion (UC) emission has been observed under 980 nm continuous wave (CW) near infrared (NIR) laser diode excitation. Interestingly, the phosphor shows characteristic erbium ion transitions at low pump power, but at high pump power heat associated continuum broad band emission was realized. The continuum broad band emission was explained on the basis of energy level diagram, laser induced pump power dependence and blackbody radiation theory. The heat associated/incandescence‐like light is originated due to heating induced by the nonradiative relaxation followed by sensitization (Yb → Er) and Yb−Yb dimer formation. The synthesized phosphor emits effective broad band white colour emission under high pump power and colour co‐ordinates (white colour: 0.34, 0.32) were located in the chromaticity diagram. Intrinsic optical bistability (IOB) behavior shows the hysteresis‐like loop originated upon variation in the laser pump power. The observed high temperature at point of irradiation of the prepared nanocrystalline phosphor is about ∼ 2442 K at 1430 mW, which is high as compare to tungsten bulb (2400 K for 100 W). The developed phosphors can be useful in white light production, solar cell efficiency enhancement, switchable bistable and as light to heat converter.

A Wide Tunable Nanophosphor NaYO2:Er3+/Yb3+ by Modulating Power Density

“…Hence, it can exceed the nonradiative relaxation rate of the Yb 3+ –Yb 3+ pair to prevent thermal quenching of UC PL. [ 33,34 ]…”

Exploring the intra-4f and the bright white light upconversion emissions of Gd2O3:Yb3+,Er3+-based materials for thermometry

“…5(a) and Table S3 †), which agree with the behaviour of rare-earth oxides. 5,7,12,24,27 The continuous white light emission was analysed for repeated cycles of laser irradiation with both 1 (Fig. 5(b)) and 2 (Fig.…”

“…Over the past decades, an unusual type of anti-Stokes (or upconversion, UC) broadband white light emission under near-infrared (NIR) laser excitation has been reported for organometallic complexes, 1 organic–inorganic hybrid nanostructures, 2 carbon nanotubes, 3 graphene, 4 and oxides, with 5,6 or without 7,8 activator ions (trivalent lanthanides, Ln 3+ , and transition metals). A common and distinguishing feature of this unusual type of UC is the continuous emission from the visible to the IR spectral regions, in contrast to the usual discrete UC emissions observed particularly in Ln 3+ -based materials.…”

Right Against Exploitation under Article 24 of the Indian Constitution

“…The right to life under Article 21 101 has been held to inter alia include substantive rights, such as the right to go abroad, the right to education, right to health and medical aid, the right to shelter, the right against delayed execution, right to livelihood, the right to privacy, the right against custodial death, the right against solitary confinement, assistance from doctors, the right against public hanging and the right against being handcuffed. 102 Even the nonjusticiable Directive Principles of State Policy such as right of every child to a full development 103 , protection of under-trial prisoners 104 , protection of one's cultural heritage 105 , and the right to pollution free water and air 106 have been read into the ambit of Article 21.…”