• Current Photovoltaic Research
• /
• 제4권1호
• /
• pp.8-11
• /
• 2016

Strong deep ultraviolet emitting aniline and $TiO_2$ composite has been synthesized via hydrolysis and condensation reactions of titaniumisopropoxide ($Ti(OPr)_4$), aniline, and acetic anhydride. Three different weight ratios of aniline and $Ti(OPr)_4$ including 3:1 ($TiO_2An-A$), 2:1 ($TiO_2An-B$), and 1:1 ($TiO_2An-C$) were synthesized and characterized their optical properties. The FTIR spectra of the $TiO_2An-A$, -B, and -C showed the absorption intensities of the benzene ring stretching and bending vibrations, and benzene ring -CH stretching, bending, and deformation vibrations increased with the increase of the amount of aniline. The UV-visible absorption spectra showed that the UV region absorption was slightly increased with the increase of the amount of aniline. The photoluminescence (PL) intensities were exponentially increased with the increase the excitation wavelength from 307 to 317 nm, steadily increased from 300 to 313 nm and slowly increased from 302 to 308 nm for $TiO_2An-A$, -B, and -C, respectively and decreased thereafter. Therefore, the PL intensity is strongly dependent on the weight ratio of $Ti(OPr)_4$ and aniline.

• 대한화학회지
• /
• 제61권4호
• /
• pp.168-178
• /
• 2017

$La/TiO_2$ - graphene composites were synthesized in this study, and applied to the photocatalytic degradation of Rhodamine B (RhB) under UV-visible light irradiation. X-ray diffraction (XRD), surface analysis, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), and Transmission electron microscopy (TEM) analysis demonstrated that $La/TiO_2$ nanoparticles were well distributed on the surface of graphene, and formed the heterostructure of $La/TiO_2$-graphene. Compared to the pure $TiO_2$, $La/TiO_2$-graphene composites displayed much higher photocatalytic activities in RhB degradation under UV-visible light irradiation. The photocatalytic data of $La/TiO_2$-graphene composites exhibit extended light absorption in the visible light region, and possess better charge separation capability than that of pure $TiO_2$. The high photocatalytic activity was attributed to the composite's high adsorptivity, extended light absorption, and increased charge separation efficiency, due to the excellent electrical properties of graphene, and the large surface contact between graphene and $La/TiO_2$ nanoparticles.

• 한국세라믹학회지
• /
• 제34권9호
• /
• pp.993-1001
• /
• 1997

The (0.8PPV+0.2DMPPV) copolymer and silica/borosilicate composites were synthesized by sol-gel process. The organic-inorganic hybrid solution was prepared by using of (0.8PPV+0.2DMPPV) copolymer precursor solution as a raw material for organic components and TEOS and TMB for glass components. Then by drying the solution in vacuum at 5$0^{\circ}C$ for 7days and subsequent heat treatment in vacuum at 15$0^{\circ}C$~30$0^{\circ}C$ for 2h~72h with heating rate of 0.2$^{\circ}C$/min and 1.8$^{\circ}C$/min, the organic-inorganic composites were synthesized. Microstructural evolution of the composites was characterized by DSC, IR spectrocopy, UV/VIS spectroscopy, and TEM. Elimination of the polymer precursor and degradation of the polymer were observed by DSC and Si-O and trans C=C absorption peaks were identified by IR spectra. The polymer was found to be successfully incorporated into the glass matrix and it was confirmed by the absorption peaks from the polymer in the UV/VIS spectra and the TEM results. The absorption peak of the composites was found to shift toward short wavelength side compared to that of the pure polymer and the amount of the blue shift increased with increasing the heat treatment temperature and heat treatment time and with decreasing the heating rate.

• 한국세라믹학회지
• /
• 제47권3호
• /
• pp.249-255
• /
• 2010

To investigate optical properties of (V, Pr)-doped $ZrSiO_4$ green pigments, samples were prepared by the ceramic method using NaF and NaCl as mineralizers. They were characterized by X-ray diffraction, UV-Vis spectroscopy and Raman spectroscopy. The changes of color in the samples during heating and effect of mineralizers were studied in terms of valence of the vanadium and praseodymium in the zircon matrix. (V, Pr)-doped $ZrSiO_4$ pigments give rise to green coloration in $800^{\circ}C$. The oxidation state of V and Pr ions of pigments in the glazed samples were confirmed by UV-Vis absorption spectra. This absorption spectra showed three typical bands of trivalent Pr at the 445, 480~490, 592 nm due to f-f transitions and two broad bands of 302~380, 400~500 nm due to f-d transitions of tetravalent Pr. According to the increasing amounts of $Pr_6O_{11}$, the two broad bands showed decreasing intensity at 290, 640 nm due to d-d transitions of tetravalent V.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2005년도 추계학술발표대회 논문집
• /
• pp.91-94
• /
• 2005

Polypropylene as a matrix has been used for wood polymer composites(WPC). In preparing WPC, the coupling agent, Polypropylene grafted Maleic Anhydride(PP-G-MA) was used in order to obtain a good interfacial bonding force between matrix and fillers and dispersion of wood powders. In this study, the effects of wood powder contents and water absorption on the mechanical properties were experimentally investigated. The tensile strength and flexural strength of composites reached its peak value when the wood powder content was around 60 wt%. However, the peak value of the impact was observed about 30 wt% of wood powder content. The tensile strength and flexural strength increase with increasing the wood power contents. But the impact strength decrease with increasing the wood powder contents. The slight change was observed with the water absorption in the WPC. The optimal condition of the compositions such as Anti-oxidant and UV stabilizers for the outdoor application was suggested in this research.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2006년도 추계학술대회 논문집 광주전남지부
• /
• pp.39-42
• /
• 2006

Titania sols or powders were are very promising materials for environment as photocatalyst. The band gap energy of $TiO_2$ has been known to be 2.8 to 3.2 eV. But the measuring system of its band gap is usually depend on absorption properties. Thus, in this study, absorption properties of $TiO_2$ sols prepared by hydrothermal process were researched with the effect of various particle sizes and concentrations. The mean particle size in $TiO_2$ sols increased as 15 nm to 60 nm, absorption graph measured by UV-Vis spectrometer shows to move red-shift. When dilute solution added with $2^n$ in $TiO_2$, the band gap energy increases as linear function.

• 한국광학회:학술대회논문집
• /
• 한국광학회 1990년도 제5회 파동 및 레이저 학술발표회 5th Conference on Waves and lasers 논문집 - 한국광학회
• /
• pp.172-176
• /
• 1990

A high resolution picosecond absorption kinetic spectrometer utilizing dye emission and a streak camera is presented and compared with other methods of picosecond transient absorption measurements. Typical transient absorption and bleach recovery kinetics measured with this spectrometer are shown. Single wavelength transient absorption or ground state bleach recovery kinetics are determined on the basis of a single laser shot, so that the samples are relatively free frm decomposition by irradiation. Excellent kinetics may be obtained from the near UV to the near IR and are not subject to interference from luminescence of samples. The sensitivity of this spectrometer is very high and it is reasonably easy and convenient to set up and use.

• Journal of the Korean Physical Society
• /
• 제73권11호
• /
• pp.1729-1734
• /
• 2018

Organic-inorganic halide perovskite single crystals undergo phase transition of being cubic, tetragonal, or orthorhombic depending on the temperature. We investigated the $CH_3NH_3PbBr_{3-x}I_x$ single crystals grown by the inverse temperature crystallization method with temperature-dependent UV-Vis absorption and photoluminescence. From the temperature-dependent absorption measurement, the optical band gap is extracted by derivation of absorption spectrum fitting and Tauc plot. In our results, $CH_3NH_3PbBr_{3-x}I_x$ single crystals show that an abrupt change in optical band gap, PL peak position and intensity appears around 120 K - 170 K regions, indicating the phase transition temperature.

• 한국산학기술학회논문지
• /
• 제22권3호
• /
• pp.408-414
• /
• 2021

본 연구의 목적은 수세미오이 추출물을 유산균을 이용한 발효를 통해 항산화 활성과 함께 생체 활성 물질의 생산을 중대하고 자외선 흡수 및 피부 흑색종 세포 성장 억제를 강화하여 피부암 예방 효과를 향상시키는 데 있다. 수세미오이 발효추출물의 총 폴리페놀(TPC)과 항산화 활성도가 30.23 mg GA/g DM와 45.12%로 열수추출물보다 약 1.4배 높은 수준으로 확인되었다. 자외선 흡수율에 있어 발효추출물은 열수추출물보다 1.5배 높은 53.9%의 흡수율을 보였는데 발효를 통해 증가된 TPC에 의해 UV 흡수가 증가했다는 결론을 도출하였다. 항암효과에 있어 발효추출물과 열수추출물에서 각각 1.0 와 2.0 mg/mL에서 피부 흑색종세포에 대한 성장저해 효과가 나타나 추출물 발효에 따른 항암효과가 증가했음을 알 수 있었다. 발효추출물의 자외선 흡수율에 있어 열수출물보다 2.4배 높아 피부암 예방효과가 예상되며, 수세미오이 발효를 통해 항산화, 자외선차단과 피부암 저해 효과를 가지는 화장품, 식품 및 의약품 소재 개발 가능할 것으로 사료된다.

• 천문학회보
• /
• 제34권1호
• /
• pp.65.2-65.2
• /
• 2009