고온에서 발생한 코크스-미연소탄-소결광의 혼합물 중 미연소탄의 정량화를 위한 분말 X-선 회절법 적용

김재명,정진경,김성만,허완욱,김형순 한국세라믹학회 2003 한국세라믹학회지 Vol.40 No.5

A technique for determination of proportions of char, coal ana coke is needed in order to monitor pulverized coal injection performance in operating blast furnace. Quantitative X-ray powder diffraction analysis can be applied to the problem providing that structural information on carbonaceous materials, coal, char, coke and their mixture are known. Chars were prepared from a coal at different temperatures (1000∼1400$^{\circ}C$) and were characterised by X-Ray powder Diffraction (XRD). The XRD result gave crystallite size (height Lc and diameter, La), aromaticity, number of (002) plane in carbon, and d-spacing. As a result, with increasing heat treat temperature of char, Lc$_{(002)}$, La$_{(10)}$ and number of (002) plane in carbon were increased, and d-spacing and FWHM(Full With Half Maximum) were decreased. Result of prediction of amount of char from the mixtures (char, coke and ore) based on the Lc$_{(002)}$ information of two mixtures (coke and char) showed very close values expected. 고로 연소대의 거동에서 석탄, 미연소탄, 코크스의 함량을 측정할 수 있는 분석기술이 필요하다 탄소질 재료에 분말 X-선 회절 정량법을 적용하여 석탄, 미연소탄, 코크스의 혼합시료에 대하여 탄소의 함량을 정량적으로 파악할 수 있는 방법을 연구하였다. 분석을 위하여 석탄을 1000~140$0^{\circ}C$의 온도에서 시간을 달리하여 미연소탄을 제조하여 XRD를 이용하여 분석하였다. 또한, XRD 분석을 위해 제조된 시료에 대하여 HCI과 HF용액을 이용하여 시료 내에 포함된 광물성분을 제거하였다. XRD측정 결과로부터 결정 층의 두께(L $c_{(002)}$)와 결정 층의 크기(L $a_{(10)}$), 방향족분율, 흑연화도, 면간거리( $d_{0.2}$), 탄소 층의 수( $N_{ι}$)를 측정하였다. 그 결과로 열처리 온도가 증가됨에 따라 L $c_{(002)}$, L $a_{(10)}$, 흑연화도는 증가하였으며, 면간거리와 반가폭은 감소하였다. 따라서 미연소탄-코크스 혼합물에 대한 결정층의 두께자료는 합성시료로부터 미연소탄의 함량을 정량화할 수 있었다.

MLCC용 x(Na0.5K0.5)NbO3-(1-x)BaTiO3 세라믹스의 미세구조 및 구조 분석

하주연 ( Joo Yeon Ha ),김진성 ( Jin Seong Kim ),이희수 ( Hee Soo Lee ),최연규 ( Youn Kyu Choi ),이연숙 ( Yeon Sook Lee ) 대한금속재료학회(구 대한금속학회) 2014 대한금속·재료학회지 Vol.52 No.5

The doping effect of (Na0.5K0.5)NbO3(NKN) on the crystal structure, microstructure and electrical properties of BaTiO3 (BT) ceramics was investigated as alternatives for rare-earth elements. x(Na0.5K0.5) NbO3-(1-x)BaTiO3 ceramics with 0.00 ≤ x ≤ 0.10 were synthesized by a solid-state reaction method. The dielectric constant and the insulation resistance (IR) of the sample with x=0.05 were about 43% and 45% higher, respectively, than those of the undoped one, and the temperature coefficient of capacitance (TCC) met the X7R specification. The sample with x=0.05 had the lowest tetragonality among the four compositionsand had the finest grain size of < 2 um. The sample doped over the solubility limit (x=0.10) showed the lowest dielectric properties by the presence of a secondary phase with a needle shape. Although the addition of NKN decreased the tetragonality, the electrical properties were enhanced by the formation of the defect dipole and conduction electron, which are caused by the compensation of oxygen vacancy and electron. The addition of x=0.05 NKN to BaTiO3 improved the electrical properties due to the substitution behavior that resulted in making the defect dipole and conduction electron.

마게마이트(${\gamma}$-Fe$_2$O$_3$)대한 연구 I -분말 X-선 회절무늬의 Rietveld 분석-

신형섭 한국세라믹학회 1998 한국세라믹학회지 Vol.35 No.10

Crystal structure of needle-shaped maghemite(${\gamma}$-{{{{ { {Fe }_{2 }O }_{3 } }}) has been studied by the Rieveld analysis of powder X-ray diffraction patterns. The tetragonal space group P41,.3212 and cubic space group P41,.32 have been have been used for the refinement of X-ray diffraction patterns. The crystal system of maghemite is closed to tetragonal more than cubic. The tetragonal lattice parameters are a=8.3460$\AA$ and c=25.034$\AA$ The standard X-ray diffraction pattern of the tetragonal maghemite analyzed with space group P41,.3212 is proposed.

Formation of Au Particles in Cu_2-x^ICu₂^IIO_3-δ (x ≈ 0.20; δ ≈ 0.10) Oxide Matrix by Sol-Gel Growth

Das, Bidhu Bhusan,Palanisamy, Kuppan,venugopal, Potu,Sandeep, Eesam,Kumar, Karrothu Varun Korean Chemical Society 2017 대한화학회지 Vol.61 No.1

Formation of Au particles in nonstoichiometric $Cu_{2-x}{^I}Cu{_2}^{II}O_{3-{\delta}}$ ($x{\approx}0.20$; ${\delta}{\approx}0.10$) oxide from aniline + hydrochloric acid mixtures and chloroauric acid in the ratios 30 : 1; 60 : 1; 90 : 1 (S1-S3) by volume and 0.01 mol of copper acetate, $Cu(OCOCH_3)_2.H_2O$, in each case is performed by sol-gel growth. Powder x-ray diffraction (XRD) results show Au particles are dispersed in tetragonal nonstoichiometric dicopper (I) dicopper (II) oxides, $Cu_{2-x}{^I}Cu{_2}^{II}O_{3-{\delta}}$ ($x{\approx}0.20$; ${\delta}{\approx}0.10$). Average crystallite sizes of Au particles determined using Scherrer equation are found to be in the approximate ranges ${\sim}85-140{\AA}$, ${\sim}85-150{\AA}$ and ${\sim}80-150{\AA}$ in S1-S3, respectively which indicate the formation of Au nano-micro size particles in $Cu_{2-x}{^I}Cu{_2}^{II}O_{3-{\delta}}$ ($x{\approx}0.20$; ${\delta}{\approx}0.10$) oxides. Hysteresis behaviour at 300 K having low loop areas and magnetic susceptibility values ${\sim}5.835{\times}10^{-6}-9.889{\times}10^{-6}emu/gG$ in S1-S3 show weakly ferromagnetic nature of the samples. Broad and isotropic electron paramagnetic resonance (EPR) lineshapes of S1-S4 at 300, 77 and 8 K having $g_{iso}$-values ${\sim}2.053{\pm}0.008-2.304{\pm}0.008$ show rapid spin-lattice relaxation process in magnetic $Cu^{2+}$ ($3d^9$) sites as well as delocalized electrons in Au ($6s^1$) nano-micro size particles in the $Cu_{2-x}{^I}Cu{_2}^{II}O_{3-{\delta}}$ ($x{\approx}0.20$; ${\delta}{\approx}0.10$) oxides. Broad and weak UV-Vis diffuse reflectance optical absorption band ~725 nm is assigned to $^2B_{1g}{\rightarrow}^2A_{1g}$ transitions, and the weak band ~470 nm is due to $^2B_{1g}{\rightarrow}^2E_g$ transitions from the ground state $^2B_{1g}$(${\mid}d_{x^2-y^2}$>) of $Cu^{2+}$ ($3d^9$) ions in octahedral coordination having tetragonal distortion.

Formation of Au Particles in Cu2−xICu2IIO3−δ (x ≈ 0.20; δ ≈ 0.10) Oxide Matrix by Sol-Gel Growth

Bidhu Bhusan Das,Kuppan Palanisamy,Potu venugopal,Eesam Sandeep,Karrothu Varun Kumar 대한화학회 2017 대한화학회지 Vol.61 No.1

Formation of Au particles in nonstoichiometric Cu2−x ICu2 IIO3−δ (x ≈ 0.20; δ ≈ 0.10) oxide from aniline + hydrochloric acid mixtures and chloroauric acid in the ratios 30 : 1; 60 : 1; 90 : 1 (S1-S3) by volume and 0.01 mol of copper acetate, Cu(OCOCH3)2.H2O, in each case is performed by sol-gel growth. Powder x-ray diffraction (XRD) results show Au particles are dispersed in tetragonal nonstoichiometric dicopper (I) dicopper (II) oxides, Cu2−x ICu2 IIO3−δ (x ≈ 0.20; δ ≈ 0.10). Average crystallite sizes of Au particles determined using Scherrer equation are found to be in the approximate ranges ~85−140 Å, ~85−150 Å and ~80−150 Å in S1-S3, respectively which indicate the formation of Au nano-micro size particles in Cu2−x ICu2 IIO3−δ (x ≈ 0.20; δ ≈ 0.10) oxides. Hysteresis behaviour at 300 K having low loop areas and magnetic susceptibility values ~ 5.835×10−6 −9.889×10−6 emu/gG in S1-S3 show weakly ferromagnetic nature of the samples. Broad and isotropic electron paramagnetic resonance (EPR) lineshapes of S1-S4 at 300, 77 and 8 K having giso-values ~2.053±0.008−2.304±0.008 show rapid spin-lattice relaxation process in magnetic Cu2+ (3d9) sites as well as delocalized electrons in Au (6s1) nano-micro size particles in the Cu2−x ICu2 IIO3−δ (x ≈ 0.20; δ ≈ 0.10) oxides. Broad and weak UV-Vis diffuse reflectance optical absorption band ~725 nm is assigned to 2B1g→ 2A1g transitions, and the weak band ~470 nm is due to 2B1g→ 2Eg transitions from the ground state 2B1g (|dx 2 -y 2>) of Cu2+ (3d9) ions in octahedral coordination having tetragonal distortion.

Sol-Gel Synthesis, Crystal Structure, Magnetic and Optical Properties in ZnCo₂O₃ Oxide

Das, Bidhu Bhusan,Barman, Bittesh Korean Chemical Society 2019 대한화학회지 Vol.63 No.6

Synthesis of ZnCo₂O₃ oxide is performed by sol-gel method via nitrate-citrate route. Powder X-ray diffraction (XRD) study shows monoclinic unit cell having lattice parameters: a = 5.721(1) Å, b = 8.073(2) Å, c = 5.670(1) Å, β = 93.221(8)°, space group P_2/m and Z = 4. Average crystallite sizes determined by Scherrer equation are the range ~14-32 nm, whereas SEM micrographs show nano-micro meter size particles formed in ZnCo₂O₃. Endothermic peak at ~798 K in the Differential scanning calorimetric (DSC) trace without weight loss could be due to structural transformation and the endothermic peak ~1143 K with weight loss is due to reversible loss of O₂ in air atmosphere. Energy Dispersive X-ray (EDX) analysis profile shows the presence of elements Zn, Co and O which indicates the purity of the sample. Magnetic measurements in the range of +12 kOe to -12 kOe at 10 K, 77 K, 120 K and at 300 K by PPMS-II Physical Property Measurement System (PPMS) shows hysteresis loops having very low values of the coercivity and retentivity which indicates the weakly ferromagnetic nature of the oxide. Observed X-band EPR isotropic lineshapes at 300 K and 77 K show positive g-shift at g_iso ~2.230 and g_iso ~2.217, respectively which is in agreement with the presence of paramagnetic site Co²⁺(3d⁷) in the oxide. DC conductivity value of 2.875 ×10^-8 S/cm indicates very weakly semiconducting nature of ZnCo₂O₃ at 300 K. DRS absorption bands ~357 nm, ~572 nm, ~619 nm and ~654 nm are due to the d-d transitions ⁴T_1g(⁴F)→²E_g(²G), ⁴T_1g(⁴F)→⁴T_1g(⁴P), ⁴T_1g(⁴F)→⁴A_2g(⁴F), ⁴T_1g(⁴F)→⁴T_2g(⁴F), respectively in octahedral ligand field around Co²⁺ ions. Direct band gap energy, E_g~ 1.5 eV in the oxide is obtained by extrapolating the linear part of the Tauc plot to the energy axis indicates fairly strong semiconducting nature of ZnCo₂O₃.

Mechanism for the stabilization/solidification of arsenic-contaminated soils with Portland cement and cement kiln dust

Yoon, I.H.,Moon, D.H.,Kim, K.W.,Lee, K.Y.,Lee, J.H.,Kim, M.G. Academic Press 2010 Journal of environmental management Vol.91 No.11

In this study, the mechanism for the stabilization/solidification (S/S) of arsenic (As)-contaminated soils with Portland cement (PC), and cement kiln dust (CKD) using 1 N HCl extraction fluid, X-ray powder diffraction (XRPD), X-ray absorption near edge structure (XANES) and Extended X-ray absorption fine structure (EXAFS) spectroscopy was investigated. The degree of As immobilization after stabilization was assessed using a 1 N HCl extraction on the basis of the Korean Standard Test (KST). After 1 day of curing with 30 wt% PC and 7 days of curing with 50 wt% CKD, the concentration of As leached from the amended soils was less than the Korean countermeasure standard (3 mg L<SUP>-1</SUP>). The As concentrations in the leachate treated with PC and CKD were significantly decreased at pH > 3, indicating that pH had a prevailing influence on As mobility. XRPD results indicated that calcium arsenite (Ca-As-O) and sodium calcium arsenate hydrate (NaCaAsO<SUB>4</SUB>.7.5H<SUB>2</SUB>O) were present in the PC- and CKD-treated slurries as the key phases responsible for As(III) and As(V) immobilization, respectively. The XANES spectroscopy confirmed that the As(III) and As(V) oxidation states of the PC and CKD slurry samples were consistent with the speciated forms in the crystals identified by XRPD. EXAFS spectroscopy showed As-Ca bonding in the As(III)-PC and As(III)-CKD slurries. The main mechanism for the immobilization of As-contaminated soils with PC and CKD was strongly associated with the bonding between As(III) or As(V) and Ca.

제올라이트 LSX에서의 CFC-13 분자체 흡착에 관한 결정학적 연구

이용재 ( Yong Jae Lee ),이종원 ( Jong Won Lee ),윤지호 ( Ji Ho Yoon ) 韓國鑛物學會 2008 광물과 암석 (J.Miner.Soc.Korea) Vol.21 No.3

X-ray Powder Diffraction Study of Molybdenum Oxides Formed From the Thermal Reactions of MoS2, MoS2/LiF, and MoS2/Ag in Air

So-Ram Lee,Youhyuk Kim 대한화학회 2020 Bulletin of the Korean Chemical Society Vol.41 No.12

MoS2 can generate useful molybdenum oxides by thermally reacting with LiF or Ag nanoparticles (NPs). MoS2 easily loses sulfide and reacts with oxygen gas upon heating in air to give orthorhombic molybdenum trioxide, α-MoO3. Morphological changes of α-MoO3 from 500 to 900°C were investigated using X-ray powder diffraction and scanning electron microscope. The strong diffraction peaks of the (020), (040), and (060) planes at 800°C revealed highly anisotropic growth of the oxides with a layered crystal structure. In the presence of LiF, MoS2 reacts with oxygen gas to generate Li2MoO4 and MoO2, depending on the LiF concentration. In the presence of Ag NPs, the thermal reactions of MoS2 at 800 and 900°C give silver molybdates Ag2Mo2O7 and Ag2MoO4, respectively. These results demonstrate that MoS2 is an important precursor for generating useful molybdenum oxides on the surface of inert substrates without requiring sophisticated, expensive equipment.

Investigation of the Mineral Components of Porcelain Raw Material and Their Phase Evolution during a Firing Process by Using a Rietveld Quantitative Analysis

Jaegyeom Kim,Eunae Heo,김승주,김종영 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.1

A ceramic raw material for white porcelain and its phase evolution during a firing process were investigated by using Rietveld method based on powder X-ray diffraction data. The raw material was mainly composed of five mineral phases: quartz (SiO2), microcline (KAlSi3O8), albite (NaAlSi3O8), muscovite (KAl2(AlSi3O10)(OH)2), and kaolinite (Al2Si2O5(OH)4). The amount of each mineral phase could be determined by using Rietveld quantitative phase analyses. During the firing process, the microcline, albite, muscovite and kaolinite phases started to react with each other to produce the mullite phase embedded in an amorphous matrix. The amount of quartz remained nearly unchanged until a temperature above 1200 C; then, it converted to an amorphous phase at higher temperatures.