NIR Luminescence Enhancement of YVO 4 :Nd Phosphor for Biological Application
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ORIGINAL ARTICLE
NIR Luminescence Enhancement of YVO4:Nd Phosphor for Biological Application Júlio Tadashi Tanaka 1 & Susane Bonamin Moscardini 1 & Willian Eurípedes do Nascimento Melo 1 & Helena Brunckova 2 & Eduardo José Nassar 1 & Lucas Alonso Rocha 1 Received: 25 May 2020 / Accepted: 9 November 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract This work reports two systematic studies related to yttrium vanadate (YVO4) phosphors. The first evaluates how the annealing temperature and V5+/Y3+ molar ratio determine the emergence of a single YVO4 tetragonal phase, whereas the second concerns the optimal Nd3+ concentration to improve the infrared emission properties for bio-labelling applications. The YVO4:Nd phosphors were synthesized by adapting the non-hydrolytic sol–gel route. For the first study, samples containing different V5+/Y3+ molar ratios (1.02, 1.48, 1.71, or 3.13) were obtained. For the second study, YVO4:Nd phosphors containing different Nd3+ concentrations (1.0, 3.0, 5.0, or 10.0% in mol) were prepared. X-ray diffractometry and RAMAN spectroscopy results revealed that, regardless of the heat-treatment temperature, the V5+/Y3+ molar ratio of 1.48 was the best composition to avoid undesired phases like Y2O3 and V2O5. Photoluminescence results indicated that the sample containing 3.0% in mol of Nd3+ and annealed at 1000 °C presented the best infrared emission properties. This sample displayed an intense broad band in the ultraviolet region, which was ascribed to the VO43− charge transfer band, as well as several bands in the visible and infrared regions, which were attributed to the Nd3+ intraconfigurational f-f transitions. Regardless of the excitation wavelength (ultraviolet, visible, or nearinfrared), the mean radiative lifetime was about 12.00 µs. The prepared phosphors presented absorption and emission bands in the biological window (BW) regions, which are located between 750 and 900 nm and between 1000 and 1300 nm, so they are candidates for applications in medical imaging and diagnoses. Keywords Infrared emission; photoluminescence; sol–gel . Phosphors . YVO4 . Nd3+
Introduction The YVO4 matrix, which was first introduced by Levine and Palila in 1964 [1], has been extensively studied due to its properties, such as low-energy phonon (around 890 cm− 1) [2]. In addition, its optical, mechanical, and thermal characteristics are fundamental for light emitters [3, 4] and laser hosts [5, 6]. Moreover, when this matrix is doped with lanthanide ions, it presents highly efficient luminescence to excitation by an electron beam, leading to applications in lamps, displays, scintillation detectors, TVs, and cathode ray [7, 8]. Different lanthanide ions have been used to * Lucas Alonso Rocha [email protected] 1
Universidade de Franca, Av. Dr. Armando Salles Oliveira, 201, São Paulo CEP 14404-600 Franca, Brazil
2
Institute of Materials Research, Slovak Academy of Sciences, Watsonova 47, 040 01 Kosice, Slovakia
achieve emission in regions of interest for use in red
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