Structure Determination from Powder Diffraction Data for Rechargeable Battery Materials

Recently, research and development into existing compounds that can be made into cathode components in rechargeable post lithium batteries systems is a major priority today. The reciprocal space theory, heavy atom method, direct methods, geometry optimization, and global optimization, all involve chemical and physical knowledge as well. This dissertation discusses such works from the point of a view of structural features for phase changes of battery compounds. The methods and techniques summarize the peculiarities between single X-ray crystal and Powder XRD. ab-initio method for determining the lattice parameters of an unknown structure, Ba(ClO4)2 that was successfully used to characterize crystal systems despite difficulties; Rietveld refinement should be done final step. Magnesium batteries have received attention as a type of post lithium-ion battery because of their potential advantages in cost and capacity. Among the host candidates for magnesium batteries, orthorhombic -V2O5 is one of the most studied materials, and it shows a reversible magnesium intercalation with a high capacity especially in a wet organic electrolyte. Studies by several groups during the last two decades have demonstrated that water plays some important roles in getting higher capacity. Very recently, proton intercalation was evidenced mainly using nuclear resonance spectroscopy. Nonetheless, the chemical species inserted into the host structure during the reduction reaction are still unclear (i.e., Mg(H2O)n2+, Mg(solvent, H2O)n2+, H+, H3O+, H2O or any combination of these). Additionally, the crystal structure of the reduced phase has not been identified. In this work the crystal structure of the magnesium-inserted phase of -V2O5—electrochemically reduced in 0.5 M Mg(ClO4)2 + 2.0 M H2O in acetonitrile—was solved for the first time using a powder synchrotron X-ray structure determination method. An orthorhombic structure (P21212 space group; a = 11.512 Å, b = 10.5483 Å, and c = 4.3681 Å) was identified; the structure was tripled along the b-axis from that of the pristine V2O5 structure. There were three large cavity sites surrounded by oxygen atoms in the structure. Examination of the interatomic distances around the cavity sites suggested that H2O, H3O+, or solvated magnesium ions are too big for the cavities, leading us to conclude that the intercalated species are single Mg2+ ions or protons. The general formula of magnesium-inserted V2O5 is Mg0.17HyV2O5, (0 < y ≤ 1.16). This work provides an explicit answer to the question about Mg intercalation into -V2O5.Li ion batteries (LIBs) are useful energy storage devices for portable electronics applications and electric vehicles. To date, many positive electrode materials for LIBs have been developed with various crystal structures such as layered, spinel, and olivine types. We report a new structure type of material, LiMo4O6, which is interesting due to its unique structure. LiMo4O6 consists of infinite anion chains of Mo4O6 where Mo6 clusters are edge-shared and all non-shared edges are capped by oxygen. The infinite chains are aligned parallel to one another and linked by bridging oxygen atoms. Such four parallel Mo4O6 chains create open one-dimensional tunnels to accommodate positive guest ions of Li+. In this study, synthesis of LiMo4O6, and its electrochemical intercalation and structural properties have been characterized with non-aqueous electrolyte system: 1.0M LiPF6 in EC/DMC (1:2). Electrochemical experiments of cyclic voltammetry and galvanostatic charge/discharge have been carried out with a voltage range of 2.0 V ~ 3.2 V vs. Li, a rate of 0.02 mV/s and 1/20C, respectively. A [Co(C6H6N2)2(H2O)2](BF4)2, the CoII atom is located on an inversion centre. The transition metal is in a slightly distorted octahedral coordination environment, defined by the cyano N atoms of four hex-3- enedinitrile ligands in equatorial positions and the O atoms of two water molecules in axial positions. The bridging mode of the hex-3-enedinitrile ligands leads to the formation of cationic chains extending parallel to [110]. The BF4 counter-anion is disordered over two sets of sites [occupancy ratio = 0.512 (19):0.489 (19)]. It is located in the voids between the cationic chains and is connected to the aqua ligands of the latter through O—H F hydrogen bonds. One methylene H atom of the hex-3-enedinitrile ligand forms another and weak C—H O hydrogen bond with a water O atom of a neighbouring chain, thus consolidating the three-dimensional network structure. The previously unknown crystal structure of barium perchlorate anhydrate, determined and refined from laboratory X-ray powder diffraction data, represents a new structure type. The title compound was obtained by heating hydrated barium perchlorate [Ba(ClO4)2 xH2O] at 423 K in vacuo for 6 h. It crystallizes in the orthorhombic space group Fddd. The asymmetric unit contains one Ba (site symmetry 222 on special position 8a), one Cl (site symmetry 2 on special position 16f) and two O sites (on general positions 32h). The structure can be described as a three-dimensional polyhedral network resulting from the corner- and edge-sharing of BaO12 polyhedra and ClO4 tetrahedra. Each BaO12 polyhedron shares corners with eight ClO4 tetrahedra, and edges with two ClO4 tetrahedra. Each ClO4 tetrahedron shares corners with four BaO12 polyhedra, and an edge with the other BaO12 polyhedron. ⓒ 2017 DGISTCHAPTER 1 - INTRODUCTION 1-- CHAPTER 2 - METHODS 3-- 2. 1. Structure Determination from Powder X-ray diffraction data 3-- 2. 2. Bond Valence Sum 4-- 2. 2. Hybrid Cell configuration 5-- CHAPTER 3 – Characterization of Mg-inserted V2O5 in a Wet Organic Electrolyte by Structural-- Determination 7-- INTRODUCTION 7-- EXPERIMENTAL 10-- RESULTS & DISCUSSION 14-- CONCLUSIONS 35-- REFERENCES 36-- CHAPTER 4 – Electrochemical Lithium Intercalation Chemistry of Condensed Molybdenum Metal-- Cluster Oxide: LiMo4O6 41-- INTRODUCTION 41-- EXPERIMENTAL 44-- RESULTS & DISCUSSION 50-- CONCLUSIONS 56-- REFERENCES 57-- CHAPTER 5 - Crystal structure of catena-poly[[[diaquacobalt(II)]-bis(μ-hex- 3-enedinitrile-κ2N:N′)]-- bis(tetrafluoridoborate)] 58-- INTRODUCTION 58-- EXPERIMENTAL 58-- REFINEMENT 60-- RELATED LITERATURE 60-- COMPUTING DETAILS 62-- REFERENCES 68-- CHAPTER 6 - Crystal structure of barium perchlorate anhydrate, Ba(ClO4)2, from laboratory X-ray-- powder data 69-- INTRODUCTION 69-- EXPERIMENTAL 69-- RESULTS & DISCUSSIONS 74-- REFINEMENT DETAILS 77-- REFERENCES 78-- Summary in Korean 80-- Appendix 82X-ray분광학과 핵자기 공명학 (Nuclear Magnetic Resonance Spectroscopy)의 비약적인 발달로 인하여 해마다 수 많은 단백질 구조 및 무기 물질의 3차원 구조가 밝혀 지고 있다. 특히 무기 화합물에서의 성분 분석이나 정량 분석에서는 X-ray 회절을 꼭 사용 해야 한다. X-ray 회절 방법에는 Single Crystal 과 Powder XRD가 있는데, 그 중 Post LIB system에 cathode 전극에 변화를 관측 할 수 있는 도구는 Powder XRD 뿐이다. Powder XRD기술은 Single Crystal과 달리 시료 로부터 얻는 정보가 매우 부족하여 기 알고 있는 무기 구조의 아주 소량의 변화만을 Rietveld refinement로 분석 할 수 있다. 본 연구에서는 마치 Single Crystal 구조를 얻는 것과 같은 분말 구조 규명 및 해석 방법을 구축하여, 산화/환원 하는 무기 물질의 전후 과정 및 완전히 구조가 변형되는 모습을 관측 하였다. 총 4개 연구 테마 중, 5, 6chapters는 무기 구조 결정(Single & Powder)에 방법으로 기술 하였고, 3, 4chapters에서는 이 강력한 기술을 이용하여 미래에 한 층 더 요구 되는 에너지 변환 시스템의 일종으로 활약 할 수 있는 LIB, MIB cathode 후보군인 LiMo4O6, V2O5에 대하여 연구 하였다. 첫 번째와 두 번째 연구는, 위의 무기 구조 결정 방법을 이용하여 LIB, Post LIB system에 대하여 응용한 것이다. 그 첫 번째로 Chevrel like oxide인 InMo4O6를 ionic exchange방법을 이용하여 합성하였고, 이를 LIB system에 적용하여 구조의 변화를 연구 한 것 이다. 합성 확인을 위하여 Rietveld refinement를 이용 하였고, Li ion intercalation 전후에 대한 Lattice parameters 변화를 추정 할 수 있었다. 두 번째 연구는 최근 Post LIB로 각광 받는 Mg ion battery 에 대하여 V2O5를 cathode전극으로 하는 시스템에 대해 살펴본 것이다. 전위 원소인 Vanadium은 산화, 환원 전위가 넓으며, 산소를 갖고 있어 기본적인 OCV높은 몰질 중에 하나 이다. 이런 이유로 많은 연구자들이 이 물질을 기반으로 MIB, NIB, CIB등 여러 연구를 해오고 있다. 본 연구에서 유기 용매를 사용 하였고, 여기에 2M의 물 분자를 더해 Post LIB로서의 가능성 및 intercalation/deintercalation에 대하여 연구 한 것이다. Mg ion intercalation후 space group은 Pmmn에서 P21212로 변형 되었고, b 축으로 3배만큼 증가된 구조를 나타냈다. 세 번째 연구에서는 LiBF4 salt가 코발트 화합물과 이루는 Single crystal 구조에 대해여 Dynamic disorder를 가지고 명확하게 규명하였다. 코발트 원소는 octahedral coordination을 가지고 있으며, inversion center에 위치 하고 있다. 2개의 물 분자는 코발트 중심 원소의 위, 아래도 결합 되어 있으며, cyano 질소 원자는 코발트원자를 중심으로 평면 4고리 모양으로 2차원 결합을 하고 있다. BF4- counter-anion은 두 그룹으로 disorder를 나태 내고 있으며, 그 곳의 occupancy ratio = 0.512(19) : 0.489(19)이다. 2차원 적으로 뻗어 나가는 사슬 사이에 BF4-가 존재 하여 코발트 원자와 결합하는 물분자 H와의 결합도 이끌어 내어 전체적으로 3차원 구조를 이루게 된다. 네 번째 연구는 무수 화합물인 Barium perchorate의 구조를 분말 XRD로 규명한 것이다. TG를 이용하여 물이 증발 되는 온도를 423K 에서 확인하였다. 진공 펌프와 furnace를 이용하여 6시간 동안 무수 화합물을 만들었다. 그 후 air-protect dome을 이용 Ka1 XRD로 data를 얻은 후, Ab intio을 이용하여 Lattice parameters를 결정 하였다. Space group은 Fddd 이며, Asymmetric unit은 각각 1개의 Barium, Chlorine, 2개의 Oxygen으로 이뤄져 있다. Barium의 site symmetry는 222이며 8a special position을 갖는다. Chlorine의 site symmetry는 2이며, 16f special position이다. 2개의 Oxygen은 32f 라는 general position에 위치 한다. GSAG와 Crystals를 이용하여 최종 무수 Barium perchlorate 구조를 확정짓는다. ⓒ 2017 DGISTDoctordCollectio

A PCR Analysis of ERα and ERβ mRNA Abundance in Rats and the Effect of Ovariectomy

To study the relative abundance and the changes of both estrogen receptor alpha (ERalpha) and ERbeta mRNA before and after ovariectomy in major organs important to the regulation of calcium homeostasis, we compared the degree of mRNA expression of ERalpha to that of ERbeta in rat tissues by performing competitive reverse transcription polymerase chain reaction (RT-PCR) with internal standards. Both ERalpha and ERbeta were highly expressed in the ovary {ERalpha[(2.2 +/- 0.33) x 10(7) copies/microg of total RNA] > ERbeta[(1.2 +/- 0.33) x 10(5) copies/microg of total RNA]} as we expected. The bone marrow and renal cortex were very important target organs of estrogen because ERalpha was highly expressed approximately 2 x 10(5) copies/microg of total RNA, but marrow cells revealed only a very weak expression of ERbeta [(0.7 +/- 0.21) x 10(2) copies/microg of total RNA]. Both ERalpha and ERbeta were expressed in the trabecular bone [(3.2 +/- 0.56) x 10(3) copy/microg of RNA] and [(2.8 +/- 0.21) x 102 copy/microg of RNA], respectively. However, they were not detected in the cortical bone. In the jejunum, the expression of ERalpha was not detectable, while ERbeta was expressed very weakly [(1.1 +/- 0.24) x 10(2) copies/microg of total RNA]. The thyroid gland expressed low copy numbers of ERbeta [(6.0 +/- 0.23) x 10(2) copies/microg of total RNA], but the parathyroid gland was negative for both ERalpha and ERbeta mRNA. In cultured stromal cells, ERalpha and ERbeta mRNAs were not detected after a 24-h culture; however, the rates of mRNA expression of ERalpha and ERbeta reached approximately 105 copies/microg of total RNA and approximately 10(2) copies/microg of total RNA, respectively, after 9-, 11-, and 13-day cultures. After ovariectomy, the expression of ERalpha mRNA decreased abruptly in the bone marrow and renal cortex, and both ERalpha and ERbeta were barely detected in the trabecular bone. In conclusion, ERalpha might be the main ER in organs important for calcium homeostasis, except in the jejunum. The mRNA expression of ERalpha in the bone marrow and renal cortex decreased abruptly after ovariectomy, which may partially explain why the effect of estrogen deficiency can be amplified and why trabecular bone loss is more predominant than cortical bone loss shortly after surgical or natural menopause.ope

The 750 GeV Diphoton Excess May Not Imply a 750 GeV Resonance

We discuss non-standard interpretations of the 750 GeV diphoton excess recently reported by the ATLAS and CMS Collaborations which do not involve a new, relatively broad, resonance with a mass near 750 GeV. Instead, we consider the sequential cascade decay of a much heavier, possibly quite narrow, resonance into two photons along with one or more invisible particles. The resulting diphoton invariant mass signal is generically rather broad, as suggested by the data. We examine three specific event topologies - the antler, the sandwich, and the 2-step cascade decay, and show that they all can provide a good fit to the observed published data. In each case, we delineate the preferred mass parameter space selected by the best fit. In spite of the presence of invisible particles in the final state, the measured missing transverse energy is moderate, due to its anti- correlation with the diphoton invariant mass. We comment on the future prospects of discriminating with higher statistics between our scenarios, as well as from more conventional interpretations.Comment: Discussion about the ATLAS Moriond EW2016 added. Matched to PRL accepted versio

Optical Spectroscopy of Supernova Remnants in M81 and M82

We present spectroscopy of 28 SNR candidates as well as one H II region in M81, and two SNR candidates in M82. Twenty six out of the M81 candidates turn out to be genuine SNRs, and two in M82 may be shocked condensations in the galactic outflow or SNRs. The distribution of [N II]/H{\alpha} ratios of M81 SNRs is bimodal. M81 SNRs are divided into two groups in the spectral line ratio diagrams: an [O III]-strong group and an [O III]-weak group. The latter have larger sizes, and may have faster shock velocity. [N II]/H{\alpha} ratios of the SNRs show a strong correlation with [S II]/H{\alpha} ratios. They show a clear radial gradient in [N II]/H{\alpha} and [S II]/H{\alpha} ratios: dLog ([N II]/H{\alpha})/dLog R = -0.018 {\pm} 0.008 dex/kpc and dLog ([S II]/H{\alpha})/dLog R = -0.016 {\pm} 0.008 dex/kpc where R is a deprojected galactocentric distance. We estimate the nitrogen and oxygen abundance of the SNRs from the comparison with shock-ionization models. We obtain a value for the nitrogen radial gradient, dLog(N/H)/dLogR = -0.023 {\pm} 0.009 dex/kpc, and little evidence for the gradient in oxygen. This nitrogen abundance shows a few times flatter gradient than those of the planetary nebulae and H II regions. We find that five SNRs are matched with X-ray sources. Their X-ray hardness colors are consistent with thermal SNRs.Comment: 19 pages, 24 figures, 5 tables, ApJ accepte

Uterine Artery Doppler Velocimetry During Mid-second Trimester to Predict Complications of Pregnancy Based on Unilateral or Bilateral Abnormalities

We performed this study to evaluate uterine artery Doppler velocimetry (UADV) measurement of unilateral or bilateral abnormalities as a predictor of complications in pregnancy during the mid-second trimester (20-24 weeks). We enrolled 1,090 pregnant women who had undergone UADV twice: once between the 20th and 24th week (1st stage) and again between the 28th and 32nd week (2nd stage) of pregnancy, and then delivered at Yonsei Medical Center. UADV was performed bilaterally. Follow-up UADV was performed between the 28th and 32nd week, and the frequencies of pregnancy-induced hypertension (PIH), fetal growth restriction (FGR), and preterm delivery (before 34 weeks of gestation) were determined. Chi-squared and t-tests were used where appropriate, with p < .05 considered significant. According to the results of UADV performed between 20-24 weeks of gestation, 825 women (75.7%) were included in the normal group, 196 (18.0%) in the unilateral abnormality group, and 69 (6.3%) in the bilateral abnormality group. The incidences of FGR were 8.0%, 10.2%, and 26.1%, and the incidences of PIH were 0.1%, 3.6%, and 14.5%, respectively. The incidence of PIH was significantly lower in the normal group. The incidences of preterm delivery were 2.2%, 5.6%, and 8.7%, respectively. PIH developed in 46.7% of patients with bilateral abnormal findings in both the 1st and 2nd stage tests, and developed in none of the patients with normal findings in both tests. Abnormal results found by UADV performed between the 20-24th weeks of pregnancy, such as high S/D ratios regardless of placental location and the presence of an early diastolic notch, were associated with significant increases in the incidences of intrauterine growth restriction (IUGR) and PIH. This was true for both bilateral and unilateral abnormalities. Abnormal findings in bilateral UADV during the second trimester especially warrant close follow up for the detection of subsequent development of pregnancy complications

Satellite Laser Ranging System at Geochang Sta

Korea Astronomy and Space Science Institute (KASI) has been developing the space optical and laser tracking (SOLT) system for space geodesy, space situational awareness, and Korean space missions. The SOLT system comprises satellite laser ranging (SLR), adaptive optics (AO), and debris laser tracking (DLT) systems, which share numerous subsystems, such as an optical telescope and tracking mount. It is designed to be capable of laser ranging up to geosynchronous Earth orbit satellites with a laser retro-reflector array, space objects imaging brighter than magnitude 10, and laser tracking low Earth orbit space debris of uncooperative targets. For the realization of multiple functions in a novel configuration, the SOLT system employs a switching mirror that is installed inside the telescope pedestal and feeds the beam path to each system. The SLR and AO systems have already been established at the Geochang station, whereas the DLT system is currently under development and the AO system is being prepared for testing. In this study, the design and development of the SOLT system are addressed and the SLR data quality is evaluated compared to the International Laser Ranging Service (ILRS) tracking stations in terms of single-shot ranging precision. The analysis results indicate that the SLR system has a good ranging performance, to a few millimeters precision. Therefore, it is expected that the SLR system will not only play an important role as a member of the ILRS tracking network, but also contribute to future Korean space missions