The Thermal Stability Evaluation of Silver Tellurite Glass for Radioactive Iodine Immobilization

Seong-Sik Shin,Byeong Gwan Lee,Hyeon Jin Eom,Ga Yeong Kim,Hyun Woo Kang,Jung-Hoon Choi,Ki Rak Lee,Hwan-Seo Park 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.1

Uranium-235, used for nuclear power generation, has brought radioactive waste. It could be released into the environment during reprocessing or recycling of the spent nuclear fuel. Among the radioactive waste nuclides, I-129 occurs problems due to its long half-life (1.57×107 y) with high mobility in the environment. Therefore, it should be captured and immobilized into a geological disposal system through a stable waste form. One of the methods to capture iodine in the off-gas treatment process is to use silver loaded zeolite filter. It converts radioactive iodine into AgI, one of the most stable iodine forms in the solid state. However, it is difficult to directly dispose of AgI itself in an underground repository because of its aqueous dissolution under reducing condition with Fe2+. It must be immobilized in the matrix materials to prevent release of iodine as a result of chemical reaction. Among the matrix glasses, silver tellurite glass has been proposed. In this study, additives including Al, Bi, Pb, V, Mo, and W were added into the silver tellurite glass. The thermal properties of each matrix for radioactive iodine immobilization were evaluated. The glasses were prepared by the melt-quenching method at 800°C for 1 h. Differential scanning calorimetry (DSC) was performed to evaluate the thermal properties of the glass samples. From the study, the glass transition temperature (Tg) was increased by adding additives such as V2O5, MoO3, or WO3 in the silver tellurite glass. The relative electro-static field (REF) values of V2O5, MoO3, and WO3 are about three times higher than that of the glass network former, TeO2. It could provide sufficient electro-static field (EF) to the TeO2 interacting with the non-bridging oxygen forming Te-O-M (M = V, Mo, W) links. Therefore, the addition of V2O5, MoO3, or WO3 reinforced the glass network cohesion to increase the Tg of the glass. The addition of MoO3or WO3 in the silver tellurite glass increased Tg and crystallization temperature (Tc) with remaining the glass stability.

Glass-to-cryogenic-liquid transitions in aqueous solutions suggested by crack healing

Kim, Chae Un,Tate, Mark W.,Gruner, Sol M. National Academy of Sciences 2015 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.112 No.38

<P><B>Significance</B></P><P>For decades, physicists, physical chemists, and biologists have been tremendously intrigued by the unusual thermodynamic and kinetic properties of supercooled water. Theories have been proposed to account for the properties but these theories remain contentious for lack of experimental evidence. We investigated phase behavior of water at cryogenic temperatures and showed clear experimental evidence that the two cryogenic glassy states of water (high-density amorphous and low-density amorphous) undergo glass-to-cryogenic-liquid transitions and they are thermodynamically separated by a first-order phase transition. The results provide insight into the physical origin of the anomalous properties of supercooled water.</P><P>Observation of theorized glass-to-liquid transitions between low-density amorphous (LDA) and high-density amorphous (HDA) water states had been stymied by rapid crystallization below the homogeneous water nucleation temperature (∼235 K at 0.1 MPa). We report optical and X-ray observations suggestive of glass-to-liquid transitions in these states. Crack healing, indicative of liquid, occurs when LDA ice transforms to cubic ice at 160 K, and when HDA ice transforms to the LDA state at temperatures as low as 120 K. X-ray diffraction study of the HDA to LDA transition clearly shows the characteristics of a first-order transition. Study of the glass-to-liquid transitions in nanoconfined aqueous solutions shows them to be independent of the solute concentrations, suggesting that they represent an intrinsic property of water. These findings support theories that LDA and HDA ice are thermodynamically distinct and that they are continuously connected to two different liquid states of water.</P>

EAF dust가 함유된 붕규산염계 결정화 유리의 미세구조 분석

안영수,강승구,김유택,이기강,김정환,Ahn, Y.S.,Kang, S.G.,Kim, Y.T.,Lee, G.K.,Kim, J.H. 한국결정성장학회 2006 韓國結晶成長學會誌 Vol.16 No.2

붕규산염계 유리 프리트에 중금속이 다량 함유된 전기로 EAF dust(전기로 제강분진, 이하 더스트)를 $10{\sim}80wt%$ 범위로 첨가한 후 용융하여 유리 시편을 얻었다. 제조된 유리의 DTA분석 결과로부터 유리전이온도, $T_g$가 $550^{\circ}C$ 부근임을 확인하였고 이로부터 결정화에 필요한 열처리 조건을 $700^{\circ}C$/10 hr으로 정하였다. 더스트 첨가량이 70wt% 이상인 유리시편은 XRD 분석 결과 spinel 결정 피크만이 나타났으며, 결정화 시편의 경우, 더스트 첨가량이 40wt% 이상부터 spinel 결정이, 80wt% 부터는 spinet과 willemite 피크가 함께 검출되었다. XRD 분석으로는 결정상이 검출되지 않았던 조성의 유리시편에서도 aspect ratio=$0.7{\sim}1.0$인 수십 nm 크기의 결정상 존재가 SEM으로 확인되었고 결정화 시편에서도 더스트 함량이 l0wt%부터 결정상이 관찰되었다. 결정화 시편에서 관찰된 결정상은 그 형태와 분포가 첨가량에 따라 다양하고 비균일 하였으나 더스트 첨가량이 70wt%인 시편에서는 aspect ratio가 1에 가까운 6면체 형상을 나타내었다. Glassy specimen was obtained by melting and quenching a borosilicate glass frit miked with $10{\sim}80wt%$ EAF dust. The glass transition temperature, $T_g$ of glassy specimen was measured around $550^{\circ}C$ from the DTA curve and the eat treatment condition to crystallize a glassy specimen was selected as $700^{\circ}C$/1 hr. The spinel crystal peaks were found in XRD analysis for the glass containing dust > 70 wt%. For the glass-ceramics, however, the spinel peaks in a specimen containing dust > 40 wt%, and the spinel and willemite peaks in dust > 80 wt%. The crystals of several tens of nanometer with aspect ratio of $0.7{\sim}1.0$ were observed at a glassy specimen containing dust > 40 wt% by SEM which was not found by XRD analysis. For the glass-ceramics, the crystals were found in a specimen containing dust of even 10 wt% by SEM. The feature and distribution of crystals observed through the specimen for a glass-ceramics were diverse and not uniform. The crystals found in the glass-ceramics containing 70 wt% dust were hexahedral with an aspect ratio of around unity.

Improving of the luminous efficacy of the YAG:Ce phosphor in glass by doping with the transition metals into the glass frits

Park Young Ji,Kang Tae Wook,Hwang Jonghee,Kim Jin Ho,Kim Sun Woog 한국세라믹학회 2024 한국세라믹학회지 Vol.61 No.1

Phosphor in glass (PiG) has been extensively investigated as color convertor for a white high-power solid lighting system due to their excellent thermal and chemical stabilities and ease of formability. Recently, as the demand on high power LED is increased, color converters are required to improve luminous efficacy. In our previous studies, we have been studied to obtain the PiG materials with high optical efficacy by modifying the chemical composition of glass frits as well as the particle size of the phosphor or glass frits and content of the phosphor in glass. In this study, we modified the chemical composition of glass frits by doping with transition metals such as Ni, Nb, Cu, Ti and Mn to improve the luminous efficacy of the YAG:Ce PiG. The KFP-Nb sample exhibits a higher, the luminous efficacy of the YAG:Ce PiG was successfully enhanced by Nb doping into the glass frits and the luminous efficacy of the PiG sample is estimated to be 86 lm/Wrad.

Development of a Patient Dose Verification Method That Uses the Transit Dose Measured with a Glass Dosimeter

정성훈,윤명근,김동욱,정원규,정미주 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.70 No.10

The present study aims to verify patient doses by using a glass dosimeter to measure the radiation penetrating patients during radiation therapy and developing an algorithm based thereon that can simply and accurately calculate the internal doses reserved by the patients. In this study, we developed the algorithm and, as a feasibility study for a clinical test, we verified its accuracy by using a solid water phantom. We developed an algorithm that measured the scatter factor, which represents the correlation between the bottom of the phantoms and the transit-dose measurement unit and calculates the center doses of the phantoms by using the inverse square law and percentage depth dose data. Also, we used a glass dosimeter to measure the transit radiation of 14 patients’ 3D conformal radiation therapy cases and predicted the internal doses of the phantoms by using the results. By comparing these values and those of actual measurements obtained from an ion chamber, we evaluated the accuracy of the developed algorithm. When the developed algorithm was applied for patient dose verification based on the transit doses to 14 patients’ 3D-CRT treatment, as measured using the ion chamber, the average deviation from the measurement values for the phantoms was 0.33% (±0.57%). Based on this result, we confirmed that the algorithm is correct. When the patient doses obtained using a glass dosimeter were verified in the same way, the average deviation was −0.28% (±1.87%). The algorithm for calculating patients’ internal doses based on transit radiation measurements was found to be accurate and is expected to be capable of simply verifying patient doses even when measuring with a glass dosimeter, despite an increased error to a certain degree.

Glass transition, thermal stability and glass-forming tendency of Ge-As-Se-S glassy systems

Alekberov R. I.,Mekhtiyeva S. I.,Mammadov S. M. 한국물리학회 2024 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.84 No.9

Ge 4 As 14 Se 82 , Ge 4 As 14 S 2 Se 80 , Ge 7 As 16 S 5 Se 72 , Ge 10 As 20 S 10 Se 60 , Ge 17.5 As 15 S 15 Se 52.5 , Ge 24 As 19 S 20 Se 37 , Ge 25 As 10 S 25 Se 40 , Ge 26 As 18 S 30 Se 26 , and Ge 33 As 17 S 35 Se 15 chalcogenide glass compositions were synthesized and molar percentage of element have been determined by energy-dispersive X-ray analysis. The parameters study the local structure (d, L), characterizing the chemical regularity (R) and glassy network topology (N co , f), the glass-forming ability (Hr), the thermal stability (Hʹ, S), the glass and crystallization regions (ΔT g-c ) of substances corresponding to diff erent topological glass states (isostatic, rigid, elastic) are determined and physical features of the change of these parameters depending on the composition were studied according to X-ray diff raction, diff erential scanning calorimetry methods and Tanaka's two-dimensional layered structure approach.

Effect of BaO content on the sintering and physical properties of BaO–B₂O₃–SiO₂ glasses

Lim, Eun-Sub,Kim, Byung-Sook,Lee, Joon-Hyung,Kim, Jeong-Joo Elsevier 2006 Journal of non-crystalline solids Vol.352 No.8

<P><B>Abstract</B></P><P>A BaO–B<SUB>2</SUB>O<SUB>3</SUB>–SiO<SUB>2</SUB> glass system was chosen as a candidate composition for the application to Pb-free low temperature sinterable glass. The effect of BaO content on the crystallization, sintering behavior, and properties of the glasses was examined. Both the glass transition temperature and crystallization temperature decreased as the BaO content increased. Crystallization easily occurred during sintering with a BaO content of more than 50mol%, which effectively inhibited the over-firing phenomenon. The dielectric characteristics and thermal expansion coefficient of the glasses were examined and the results were explained on the basis of the crystallization and densification of the specimens.</P>

Optical Properties of B2O3-ZnO-PbO Glasses Doped with Sm3+

이규호,김영석,정영준,김태호,류봉기 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.1

This paper presents results and observations obtained from a study of the eects of zinc oxide on the optical properties of B2O3-ZnO-PbO glass doped with Sm2O3. In this study, we have analyzed the relations of the properties of glass to the local structure and the optical properties of glasses doped with Sm3+. The strong emission bands, 4G5/2-6H5/2 (564 nm) and 4G5/2-6H7/2 (602 nm) of Sm3+, caused by magnetic dipole (MD) transitions increased, but the 4G5/2-6H9/2 (647 nm) emission caused by electrical dipole(ED) transitions decreased as the amount of zinc oxide increases was increased. Keywords: RE doped glass, Sm3+, heavy metal oxide glass, optical transition.

유전체 유리 0.8Li2B4O7–0.2Fe2O3 의 비등온 결정화 운동학

백창규,최현우,양용석,임영훈 한국물리학회 2017 New Physics: Sae Mulli Vol.67 No.2

We investigated the non-isothermal crystallization kinetics of 0.8Li$_2$B$_4$O$_7$-0.2Fe$_2$O$_3$ (LBFO) glass. The glass sample was fabricated by using the melt quenching method with precursors of Li$_2$B$_4$O$_7$ and Fe$_2$O$_3$ in a 4:1 molar ratio. Thermal characteristics and structural transformation of the LBFO glass during the phase change from a glass to a crystal were studied by means of differential scanning calorimetry (DSC) and X-ray diffraction (XRD). We found that the crystallization of LBFO glass accompanied a sequential two-step occurrence of hexagonal Fe$_2$O$_3$ and tetragonal Li$_2$B$_4$O$_7$. The non-isothermal crystallization process is described in terms of the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation, and the Avrami exponent $n$ is found to be 2.0 for Fe$_2$O$_3$ and 3.2 for Li$_2$B$_4$O$_7$. The effective activation energy of crystallization is 12.3 eV for Fe$_2$O$_3$ and 14.9 eV for Li$_2$B$_4$O$_7$. The corresponding crystallization mechanism and the activation energy for Fe$_2$O$_3$ and Li$_2$B$_4$O$_7$ are discussed. 0.8Li$_2$B$_4$O$_7$-0.2Fe$_2$O$_3$ (LBFO) 유리를 제조하고 비등온 결정화 과정을 연구하였다. LBFO 유리 시료는 Li$_2$B$_4$O$_7$와 Fe$_2$O$_3$의 몰비가 4:1인 유전체 유리를 녹인 후 급랭하여 제조하였다. LBFO 시료가 유리에서 결정으로 상전이를 할 때 핵생성과 결정성장이 일어나는 과정을 DSC와 XRD를 이용하여 관찰하였다. LBFO의 결정화 봉우리는 육방정계 구조의 Fe$_2$O$_3$와 정방정계 구조의 Li$_2$B$_4$O$_7$로 분리되어 두 개의 봉우리로 나타났다. Fe$_2$O$_3$ 결정화 봉우리 및 Li$_2$B$_4$O$_7$ 결정화 봉우리에 해당하는 비등온 Johnson-Mehl-Avrami- Kolmogorov (JMAK) 식의 Avrami 지수 $n$은 각각 2.0 및 3.2 이며, 유효 활성화 에너지는 12.3 eV와 14.9 eV 이었다. 각 봉우리에 해당되는 결정화 기구와 핵생성 활성화 에너지, 그리고 결정성장 활성화 에너지에 대하여 논의하였다.

Preparation and characterization of glass-ceramics with α-cordierite as the main crystalline phase from bluestone tailings

C.H. Li,W. Zhao,J.L. Zhang,W. Lu,P. Li,B.J. Yan,H.W. Guo 한양대학교 세라믹연구소 2021 Journal of Ceramic Processing Research Vol.22 No.4

The bluestone tailings are quickly expanded in China with the continuous utilization and mining of bluestone resources. Theincremental recycling of bluestone tailings is important to solve the resources waste and environmental pollution. This studyaims to reuse the bluestone tailings as the main material to prepare α-cordierite glass-ceramics based on melting process. Theresults show that the nucleation temperature, crystallization peak temperature and the activation energy for crystallizationdecreased gradually with increasing the percentage of bluestone tailings. The complete preparation parameters of α-cordieriteglass-ceramics include a bluestone tailings percentage of 70%, a heating rate of 5 oC·min^-1, a crystallization duration of 1.5h, a crystallization temperature of 970 oC, a nucleation temperature of 830 oC, and a nucleation duration of 1.0 h. Theperformances analyses reveals that the α-cordierite glass-ceramics based on the optimized parameters exhibits high densityand Vickers hardness, low dielectric loss and water absorption, and strong chemical resistance.