Haiduk, Yu. S.

Khort, A. A.

Makhnach, L. V.

Pankov, V. V.

Savitsky, А. А.

Usenka, A. E.

English

Repository of Belarusian National Technical University (BNTU)

Секция 3. Физические, физико-математические, материаловедческие и технологические основы приборостроения 277 личину сенсорного отклика, однако в литературе имеется предположение о более значительной роли дефектности кристаллов и состояния по-верхности (наличие поверхностных ОН-групп) по сравнению с другими факторами.  Литература  1. Гайдук Ю.С. Датчики диоксида азота на основе композиции WO3–In2O3: Материалы 9 МНТК «Приборостроение-2016», Минск, 23–25 ноября 2016 г. Т.1 / Гайдук Ю.С. [и др.] // Белорусский национальный технический университет; под ред. О.К. Гусев [и др.]. – Минск, 2016. – С. 294–296.  2. Гайдук Ю.С. Полупроводниковые газовые дат-чики на основе композиции оксида вольфрама и оксида индия / Гайдук Ю.С. [и др.] // Нано- и микросистемная техника. – 2018. – № 4. – С. 232–242.  3. Haiduk Yu.S. Study of WO3–In2O3 nanocomposites for highly sensitive CO and NO2 gas sensors / Yu.S. Haiduk [at al.] // Journal of Solid State Chemistry. – 2019. – Vol. 273. – P. 25-31.   УДК 667.7 + 681.7  SONOCHEMICAL SYNTHESIS OF (Y,Eu)2O3 PHOSPHORS  Haiduk Yu.S.1, Khort A.A.2, Makhnach L.V.1, Usenka A.E.1, Savitsky А.А.1, Pankov V.V.1  1Belarusian State University Minsk, Republic of Belarus 2A.V. Luikov Heat and Mass Transfer Institute of The National Academy of Sciences of Belarus Minsk, Republic of Belarus  Y2O3:Eu3+ phosphor exhibits red emissions and possesses excellent chemical stability. It is the only existing red phosphor used in three band-fluorescent lamps. Y2O3:Eu3+ has attracted great interest for use as red phosphor in fluorescent lamps, high-resolution projection TVs, protection devices and low voltage displays, being a component of cathode ray tube, plasma display panels and field emission displays [1, 2]. High refractive index (>1.9), large band gap (5.8 eV), physical and chemical stability of pure or doped Y2O3 provide its potential application in optoelectron-ics. The morphology and the particle size affect the emission intensity of phosphor. In general, the luminous efficiency of phosphor reduces with decreasing particle size until the quantum size effect does not occur.  Various synthesis methods of the phosphor are studied in order to obtain nanocrystalline materials. Reducing the particle size of the phosphor will ex-pand fields of its application. For instance, nanocrys-talline phosphors are suitable for high definition tele-vision (HDTV) where conventional bulk phosphor cannot be used [1].  Experimental. In this paper, the structural and morphological properties of samples prepared by the sol-gel and the ultrasonic methods were compared. In the first case, an aqueous solution of ammonia (9.24 M) was added dropwise to an aqueous solution of yt-trium and europium nitrates (0.45 M). The process was carried out under continuously magnetic stirring. The resulting sol was decanted, then dried in air at 150 °C. The xerogel was calcinated for 2 h at various temperatures (400, 600, 800 °C). In case of the ultra-sonic synthesis method, the mixture of reagents was exposed to ultrasound treatment with a frequency of 29 kHz. Thermal behavior of the xerogels was evaluated by simultaneous thermal gravimetric analysis DTA–TG (NETZSCH STA 449 F3 Jupiter) from 20 to 600 °C in nitrogen with heating rate of 10 °C/min. X-ray powder diffraction (XRD) analysis was carried out with DRON-3 X-ray diffractometer with CuKα1 radiation (α = 1.5405 ˚A). The reference data were used from the PDF2 database. The average crystallite size (D) was determined from the diffraction peak broadening using the Scherrer formula D = Kλ/βcosθ, where D is the average particle size in (nm), K is the Scherrer constant (0.89), λ is the wavelength of X-ray source, β is the full width at half-maximum and θ is the Bragg’s angle. The experimental XRD data were processed with HighScorePlus software. Fourier-transform infrared (FTIR) spectra were recorded on Avatar 330 FTIR spectrometer equipped with Smart Diffuse Reflectance system at room temperature us-ing KBr pellet method.  Electron microscopy study was performed by means of the scanning electron microscope Leo-1420 Carl Zeiss.  Results and discussion. Intensive luminescence in the red region of the spectrum under UV excitation (270 nm) was acquired after xerogel calcination at ~550 °C (2  h) and higher.     Fig. 1 – XRD spectrum of the sample (powder) of the composition Y2O3–Eu2O3 (4 % wt. Eu2O3, annealing 600 ˚C, 2 h). prepared by the sonochemical method  12-я Международная научно-техническая конференция «Приборостроение – 2019» 278 XRD analysis established the formation of a solid solution (Eu,Y)2O3 based on the cubic structure of Y2O3. Figure 1 shows XRD spectrum of the sample prepared by the ultrasonic method (sol-gel synthesis in an ultrasonic field).  The sizes of crystallites for powder samples, syn-thesized under ultrasound and annealed at 400, 600 and 800  C, were 7, 10 and 13 nm, respectively. In the absence of an ultrasonic field, the indicated values were 8, 12 and 16 nm. In the process of synthesis, the same phase composition was formed over the temper-ature range of 400 ÷ 800 °C, i. e. cubic modification of yttrium oxide Y2O3 (Card № 43-1036).  According to TGA data (Fig. 2) complete decom-position of Y(OH)3 and Eu(OH)3 took place at calci-nation temperature 600 °C in air. Weight loss of sam-ple after six steps of physical and chemical dehydra-tion was 83.51 %.      Fig. 2 – DTA–TG spectrum of the sample of the composi-tion Y2O3–Eu2O3 (4 % wt. Eu2O3, annealing  600 ˚C, 2 h) prepared by the sonochemical method     Fig. 3 – FTIR spectra of the samples of the composition Y2O3–Eu2O3 (4 %wt. Eu2O3, annealing 600 ˚C, 2 h) syn-thesized by sol gel technique: 1 - in an ultrasonic field of 29 kHz; 2 - without ultrasonic treatment   The sonochemically derived as-prepared Y(OH)3:Eu (4 %wt) show OH bands at 3615 cm–1 along with bands near 475 ÷ 720 cm-1 of Y–O, Eu–O that are in agreement with literature data. After calci-nation at 800 °C, the FTIR spectra containY–O and Eu–O adsorption bands at 410,2 ÷ 602,8 cm-1. An in-sufficient difference in the absorption intensity of the denoted areas was observed for the samples, prepared with the application of ultrasonic field and without it, that could be induced only by difference in particle size and morphology of the powders (Fig. 3).  The broad absorption band with a maximum at 3650 cm-1 is probably associated with fluctuations of physically and chemically bound water, the intensity of this band decreases with an increase of calcination temperature.  According to SEM data, Y(OH)3:Eu powder (4 %wt) (Figure 4) is a mixture of nanoscale particles of irregular shape with the size of 50÷ 150 nm. The powder consists of fairly homogeneous particles, par-tially agglomerated. The proportion of particles with the size less than 250 nm is 708.2 (per 1000 particles), their density is ≈ 5.58 μm–1. Within the 0-250 nm par-ticle fraction, irregularly shaped particles from 50 nm in diameter are distinguishable. Separate large parti-cles up to 2.0 microns are agglomerates of flattened particles.     Fig. 4 – SEM imageof the Y2O3–Eu2O3 (4 % wt. Eu2O3, annealing 600 °C, 2 h)   Conclusion. The use of the ultrasonic technique provided a significant decrease in the size of crystal-lites (areas of coherent scattering) and the size of sep-arate particles.  In comparison to the Pechini method, which al-lows to obtain particles with crystalline size 21 nm [3] after annealing at 600 °C, the sol-gel method with ul-trasonic treatment is notable for its simplicity and en-vironmental friendliness (there is no emission of gases during the degradation of the organo-containing gel, duration of the synthesis process is much shorter).   References  1. Jayaramaiah J.R. Luminescence studies of europium doped yttrium oxide nanophosphor / J.R. Jayaramaiah, B.N. Lakshminarasappa, B.M. Nagabhushana // Sens. and Actu-atorsB. Chem. – 2012. – Vol. 173. – P. 234– 238.  2. Mariscal-Becerra, L. Luminescent characteristics of layered yttrium oxide nano-phosphors doped with euro-pium / L. Mariscal-Becerra [at al.] // Journal of Applied Physics. – 2017. – Vol. 121. – Issue 12 – P. 125111 https://doi.org/10.1063/1.4979209 3. Mikhailov M.D Synthesis and study of the structure of nanoparticles of oxides Y2O3:Eu / M.D. Mikhailov [et al.] // Modern problems of science and education. – 2012. – № 2 (In Russiаn).  

Sonochemical synthesis of (Y,Eu)2O3 phosphors

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Sonochemical synthesis of (Y,Eu)2O3 phosphors

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