X-ray Absorption and Emission Spectroscopic Studies of BiMn2-xTixO5 (0 ≤ x ≤ 0:5)

K. H. Chae,P. Thakur,황정남,G. S. Chang,D. K. Shukla,S. Mollah,Ravi Kumar 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.3

The electronic structure of the multiferroic BiMn2-xTixO5(0 ≤ x ≤ 0:5) system was studied by using X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES). The polycrystalline bulk BiMn2-xTixO5 samples were synthesized using a conventional solid-state reaction technique. XAS and XES spectroscopic studies on the O K-, Mn K-, L3;2- and Ti L3;2-edges of the BiMn2-xTixO5 samples and of the reference compounds were performed and the results were compared in order to determine the exact chemical states of functioning ions. The O K-edge XAS and XES results demonstrate a competition between the Mn 3d and the Ti 3d orbitals on hybridizations with the O 2p orbital. The Mn K- and Mn L3;2-edge XAS spectra suggest that the Mn3+ /Mn4+ ratio increases with increasing Ti doping and drives the system towards octahedral symmetry. On the other hand, Ti ions remain at 4+ states for all compositions, as shown by the Ti L-edge XAS. Here, we present and discuss the detailed electronic structures of the BiMn2-xTixO5 samples.

Versatile host-sensitized white light emission in a single-component K₃ZnB₅O₁₀:Dy³⁺ phosphor for ultraviolet converted light-emitting diodes

Dillip, G.R.,Kumar, Grandhe Bhaskar,Bandi, Vengala Rao,Hareesh, M.,Deva Prasad Raju, B.,Joo, S.W.,Bharat, L. Krishna,Yu, Jae Su ELSEVIER SCIENCE 2017 JOURNAL OF ALLOYS AND COMPOUNDS Vol.699 No.-

<P><B>Abstract</B></P> <P>A single-phase white-light-emitting phosphor, K<SUB>3</SUB>ZnB<SUB>5</SUB>O<SUB>10</SUB>:Dy<SUP>3+</SUP>, has been synthesized by a conventional solid-state reaction method. X-ray diffraction (XRD) analysis was used to determine the monoclinic crystal structure of phosphors. The surface states, B 1s, O 1s, K 2p, Zn 2p, and Dy 3d of the phosphor was quantified by X-ray photoelectron spectroscopy (XPS). Diffuse reflectance spectroscopy (DRS) revealed double absorption edges at 3.27 and 5.46 eV for K<SUB>3</SUB>ZnB<SUB>5</SUB>O<SUB>10</SUB> matrix. The formation of defect-levels, zinc interstitials ( Z <SUB> n i </SUB> ) , zinc vacancies ( <SUB> V Z n </SUB> ) , oxygen antisites ( <SUB> O Z n </SUB> ) and oxygen vacancies ( <SUB> V O </SUB> ) in K<SUB>3</SUB>ZnB<SUB>5</SUB>O<SUB>10</SUB>:Dy<SUP>3+</SUP> phosphors were identified by photoluminescent (PL) spectroscopy. The emissions at 405 nm (violet-I), 434 nm (violet-II), and 467 nm (blue) are due to intra-band transitions of ( F X → <SUB> V Z n </SUB> ) , ( Z <SUB> n i </SUB> → <SUB> V Z n </SUB> ) and ( Z <SUB> n i </SUB> → <SUB> O Z n </SUB> ) of the host, respectively. Similarly, the emission at 517 nm (green) corresponds to the transition from free excitons to the oxygen vacancies in the host ( F X → <SUB> V O </SUB> ) . The emissions at 575 and 665 nm are assigned to the <I>f-f</I> transitions of Dy<SUP>3+</SUP> ions within the host matrix. An energy level diagram is proposed to describe the host emission and possible energy transfer from the host to dopant ions in the single-phase phosphor. The phosphor shows good thermal stability with activation energy of 0.52 eV. The combined emissions in the blue, green, yellow, and red regions resulted in white light emission with CIE coordinates of (0.256, 0.258) on the CIE diagram.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Versatile host-sensitized white light emission, K<SUB>3</SUB>ZnB<SUB>5</SUB>O<SUB>10</SUB>:Dy<SUP>3+</SUP> phosphor was synthesized. </LI> <LI> Defect-related surface analysis of phosphor was studied by XPS. </LI> <LI> Energy level diagram was designed to show host to dopant energy transfer process. </LI> <LI> The phosphor has shown good thermal stability with activation energy of 0.52 eV. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Structural Variations of Spontaneously Formed Crystalline Eu(III)-Aliphatic Dicarboxylate Compounds Studied by Powder XRD and Time-resolved luminescence Spectroscopy

Hee-Kyung Kim,Dong Woo Lee,Sojeong Park,Euo Chang Jung,Sang Ho Lim,Wansik Cha,Hye-Ryun Cho 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.1

Complexation of actinides and lanthanides with carboxylic organic ligands is known to facilitate migration of radionuclides from deep geological disposal systems of spent nuclear fuel. In order to examine the ligand-dependent structures of trivalent actinides and lanthanides, a series of Eu(III)-aliphatic dicarboxylate compounds, Eu2(oxalate)3(H2O)6, Eu2(malonate)3(H2O)6, and Eu2(succinate)3(H2O)2, were synthesized and characterized by using X-ray crystallography and time-resolved laser fluorescence spectroscopy. Powder X-ray diffraction results captured the transition of the coordination modes of aliphatic dicarboxylate ligands from side-on to end-on binding as the carbon chain length increases. This transition is illustrated in malonate bindings involving a combination of side-on and end-on modes. Strongly enhanced luminescence of these solid compounds, especially on the hypersensitive peak, indicates a low site symmetry of these solid compounds. Luminescence lifetimes of the compounds were measured to be increased, which is ascribed to the displacement of water molecules in the innersphere of Eu center upon bindings of the organic ligands. The numbers of remaining bound water molecules estimated from the increased luminescence lifetimes were in good agreement with crystal structures. The excitation-emission matrix spectra of these crystalline polymers suggest that oxalate ligands promote the sensitized luminescence of Eu(III), especially in the UV region. In the case of malonate and succinate ligands, charge transfer occurs in the opposite direction from Eu(III) to the ligands under UV excitation, resulting in weaker luminescence.

INFLUENCE OF Co DOPING ON STRUCTURAL, OPTICAL AND MAGNETIC STUDIES OF Co-DOPED CeO2 NANOPARTICLES

SHALENDRA KUMAR,B. H. KOO,S. K. SHARMA,M. KNOBEL,C. G. LEE 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2010 NANO Vol.5 No.6

We have used the co-precipitation technique to synthesize nanocrystalline Co-doped CeO2 dilute magnetic semiconductors with Co concentrations ranging from 0.0–0.07. X-ray diffraction patterns (XRD) demonstrate that all the samples display single phase cubic structure without any impurity phase. Average particle sizes calculated from XRD and transmission electron microscopy (TEM) studies showed a gradual decrease with increase in Co ions concentration. UV–visible optical spectroscopy measurements reflect an energy band gap, which decreases with the increasing concentration of dopant (x ≤ 0.03). Raman spectra show an intensity loss of classical CeO2 vibration modes, which is an indication of considerable structural modifications and disorder in CeO2 lattice. Magnetic measurements revealed that all the samples exhibit a weak ferromagnetism at room temperature.

$Cl_{2}O_{2}$ 가스에 의한 크롬 박막의 식각 특성 고찰

박희찬,강승열,이상균,최복길,권광호 한국전기전자재료학회 2001 전기전자재료학회논문지 Vol.14 No.8

We investigated the etching characteristics of chromium films by using Cl$_2$/O$_2$ gas mixtures with electron cyclotron resonance plasma. In order to examine the chemical etch characteristics of Cr films by using Cl$_2$/O$_2$ gas plasma, we obtained the etch rate with various gas mixing ratios. By X-ray photoelectron spectroscopy, the surface reaction on the chromium films during the etch was examined. From narrow scan analyses of Cr, Cl, and O, it was confirmed that a chromium oxychlorie (CrCl$_{x}$O$_{y}$) layer was formed on the surface by the etch using Cl$_2$/O$_2$ gas mixtures. We observed a new characteristic emission line during the etch of chromium films using Cl$_2$/O$_2$ gas mixtures by an optical emission spectroscopy. It was found that the peak intensity of this emission line had a tendency compatible with the etch rate. The origin of this emission line was discussed in detail. At the same time, the etched profile was also examined by scanning electron microscope.e.e.

Structural and physical properties of bulk Ni-B alloys processed through powder metallurgy

E. S. Lee,S. K. Park,Y. H. Park 한양대학교 세라믹연구소 2015 Journal of Ceramic Processing Research Vol.16 No.4

Bulk Ni-B alloys with different boron contents of 3, 6, 9 and 12 wt.% were fabricated by a combination of mechanical alloying and hot-pressing of Ni and B powders as starting materials. The various structural phase evolutions depending on the boron contents and processing time were monitored from X-ray diffraction profiles. The core-level and valence-band spectra of the Ni-B alloys based on X-ray photoelectron spectroscopy showed that they were remaining metallic phases within the studied compositions. Furthermore, these materials showed the relatively low electrical resistivities, 1 to 10 (10−3 Ω/m) at a wide range of temperature (25-500 ℃). On the other hand, the thermal diffusivities of these materials were ranged from 2.5 to 7 (10−6 m2 / s), which are markedly lower than that of the conventional metallic materials and similar to those for engineering ceramics. The relatively low thermal conductivities are likely the result of a phonon scattering induced by their fine microstructures.

Interplay of ballistic and chemical effects in the formation of structural defects for Sn and Pb implanted silica

Green, R.J.,Hunt, A.,Zatsepin, D.A.,Boukhvalov, D.W.,McLeod, J.A.,Kurmaev, E.Z.,Skorikov, N.A.,Gavrilov, N.V.,Moewes, A. North-Holland 2012 Journal of non-crystalline solids Vol.358 No.23

The electronic structures of Sn and Pb implanted SiO<SUB>2</SUB> are studied using soft X-ray absorption (XAS) and emission (XES) spectroscopy. We show, using reference compounds and ab initio calculations, that the presence of Pb?O and Sn?O interactions can be detected in the pre-edge region of the oxygen K-edge XAS. Via analysis of this interaction-sensitive pre-edge region, we find that Pb implantation results primarily in the clustering of Pb atoms. Conversely, with Sn implantation using identical conditions, strong Sn?O interactions are present, showing that Sn is coordinated with oxygen. The varying results between the two ion types are explained using both ballistic considerations and density functional theory calculations. We find that the substitution of Pb into Si sites in SiO<SUB>2</SUB> requires much more energy than substituting Sn in these same sites, primarily due to the larger size of the Pb ions. From these calculated formation energies it is evident that Pb requires far higher temperatures than Sn to be soluble in SiO<SUB>2</SUB>. These results help explain the complex processes which take place upon implantation and determine the final products.

Cl2/BCl3/Ar 플라즈마에서 반응성 이온들에 의해 식각된 ZnO 박막 표면 연구

우종창,김창일 한국전기전자재료학회 2010 전기전자재료학회논문지 Vol.23 No.10

In the study, the characteristics of the etched Zinc oxide (ZnO) thin films surface, the etch rate of ZnO thin film in Cl2/BCl3/Ar plasma was investigated. The maximum ZnO etch rate of 53 nm/min was obtained for Cl2/BCl3/Ar=3:16:4 sccm gas mixture. According to the x-ray diffraction (XRD) and atomic force microscopy (AFM), the etched ZnO thin film was investigated to the chemical reaction of the ZnO surface in Cl2/BCl3/Ar plasma. The field emission auger electron spectroscopy (FE-AES) analysis showed an elemental analysis from the etched surfaces. According to the etching time, the ZnO thin film of etched was obtained to The AES depth-profile analysis. We used to atomic force microscopy to determine the roughness of the surface. So, the root mean square of ZnO thin film was 17.02 in Cl2/BCl3/Ar plasma. Based on these data, the ion-assisted chemical reaction was proposed as the main etch mechanism for the plasmas.

Cl₂/BCl₃/Ar 플라즈마에서 반응성 이온들에 의해 식각된 ZnO 박막 표면 연구

우종창,김창일,Woo, Jong-Chang,Kim, Chang-Il 한국전기전자재료학회 2010 전기전자재료학회논문지 Vol.23 No.10

In the study, the characteristics of the etched Zinc oxide (ZnO) thin films surface, the etch rate of ZnO thin film in $Cl_2/BCl_3/Ar$ plasma was investigated. The maximum ZnO etch rate of 53 nm/min was obtained for $Cl_2/BCl_3/Ar$=3:16:4 sccm gas mixture. According to the x-ray diffraction (XRD) and atomic force microscopy (AFM), the etched ZnO thin film was investigated to the chemical reaction of the ZnO surface in $Cl_2/BCl_3/Ar$ plasma. The field emission auger electron spectroscopy (FE-AES) analysis showed an elemental analysis from the etched surfaces. According to the etching time, the ZnO thin film of etched was obtained to The AES depth-profile analysis. We used to atomic force microscopy to determine the roughness of the surface. So, the root mean square of ZnO thin film was 17.02 in $Cl_2/BCl_3/Ar$ plasma. Based on these data, the ion-assisted chemical reaction was proposed as the main etch mechanism for the plasmas.

치과용 레진 연마를 위한 바렐 연마재의 성분 분석 및 표면 잔류물 관찰

정안나,박유진,최성민 대한치과기공학회 2021 대한치과기공학회지 Vol.43 No.4

Purpose: This study aimed to produce resin prosthetics using a dental barrel finishing machine. For dental resin grinding, the ingredients of the barrel finishing media were analyzed, and surface residues of the resin were observed. Methods: Two types of barrel finishing media for dental resin grinding were tested. Specimens were made from thermal polymerized, auto polymerized, and photopolymerized resins. Finishing media were analyzed through energy-dispersive X-ray spectroscopy (EDS) component analysis and inductively coupled plasma-optical emission spectrometry (ICPOES) component analysis. Then, the prepared specimen was barrel finished for 25 minutes using two types of barrel finishing media, and scanning electron microscope was photographed to observe the surface residues. Results: As a result of EDS component analysis, both types of finishing media were analyzed for the components of C, O, Zr and Al elements, and industry media (IM) was further analyzed for the components of Si and Mg elements. In the ICP-OES component analysis, Cd and As, which are harmful elements, were detected in IM, and no harmful elements were detected in manufacturing media (MM). Because of observation of surface residues, no residues were observed in the three types of resin specimens that were barrel finished with two types of finishing media. Conclusion: Surface residue wasn’t observed on the specimens polished using two types of finishing media. However, in IM, Cd and As, which are harmful elements, were detected, making it inappropriate for clinical use. In MM, harmful elements were not detected; therefore, clinical use will be possible.