Marcio Luis Ferreira Nascimento, Vladimir Mikhaĭlovich Fokin
{"title":"硅酸铅过冷液体和玻璃中元素扩散和协同扩散的形成和迁移焓","authors":"Marcio Luis Ferreira Nascimento, Vladimir Mikhaĭlovich Fokin","doi":"10.1007/s13538-024-01503-0","DOIUrl":null,"url":null,"abstract":"<p>Diffusivity, conductivity, and viscosity data of the PbO⋅SiO<sub>2</sub> were collected in the liquid, supercooled liquid, and glassy states. The difference in the dependence of diffusivity, viscous flow, and ionic conductivity on temperature below and above the glass transition temperature (<i>T</i><sub>g</sub>) is interpreted as a discontinuity in the charge carrier’s mobility mechanisms, including new proposals for ionic diffusivity. Charge carrier displacement occurs by an activated mechanism below <i>T</i><sub>g</sub> and through a cooperative mechanism above this temperature. Fitting diffusivity and conductivity data with the proposed model allows one to determine the enthalpies of charge carrier formation and migration separately. In particular, we present experimental results of lead and silicon diffusion species (<i>D</i><sub>Pb</sub> and <i>D</i><sub>Si</sub>) at deep and low undercoolings in PbSiO<sub>3</sub>—considering 16 orders of magnitude and comparing the effective diffusivity for viscous flow, <i>D</i><sub>η</sub>, and its activation energy. A decoupling temperature <i>T</i><sub>d</sub> between the cationic diffusivity and the diffusivity calculated from viscosity, i.e., <i>D</i><sub>η</sub> < (<i>D</i><sub>Si</sub> ≈ <i>D</i><sub>Pb</sub>) was noted. In fact, a noticeable change in the lead self-diffusion coefficients around <i>T</i><sub>d</sub> = 1.19<i>T</i><sub>g</sub> also contributed to this analysis. Thus, above <i>T</i><sub>d</sub>, silicon and lead control the transport mechanism involved in viscous flow, while below this temperature some simpler structures must control the transport process. Such results suggest that viscous flow requires a cooperative motion of some “structural units” rather than just jumps of one or a few isolated atoms, as it occurs in conductivity below <i>T</i><sub>d</sub>. Also, cooperatively rearranging regions or the size of the structural units are quite similar for both processes above <i>T</i><sub>d</sub>.\n</p>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":null,"pages":null},"PeriodicalIF":1.5000,"publicationDate":"2024-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Formation and Migration Enthalpy from Elemental and Cooperative Diffusion in Lead Silicate Supercooled Liquid and Glass\",\"authors\":\"Marcio Luis Ferreira Nascimento, Vladimir Mikhaĭlovich Fokin\",\"doi\":\"10.1007/s13538-024-01503-0\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>Diffusivity, conductivity, and viscosity data of the PbO⋅SiO<sub>2</sub> were collected in the liquid, supercooled liquid, and glassy states. The difference in the dependence of diffusivity, viscous flow, and ionic conductivity on temperature below and above the glass transition temperature (<i>T</i><sub>g</sub>) is interpreted as a discontinuity in the charge carrier’s mobility mechanisms, including new proposals for ionic diffusivity. Charge carrier displacement occurs by an activated mechanism below <i>T</i><sub>g</sub> and through a cooperative mechanism above this temperature. Fitting diffusivity and conductivity data with the proposed model allows one to determine the enthalpies of charge carrier formation and migration separately. In particular, we present experimental results of lead and silicon diffusion species (<i>D</i><sub>Pb</sub> and <i>D</i><sub>Si</sub>) at deep and low undercoolings in PbSiO<sub>3</sub>—considering 16 orders of magnitude and comparing the effective diffusivity for viscous flow, <i>D</i><sub>η</sub>, and its activation energy. A decoupling temperature <i>T</i><sub>d</sub> between the cationic diffusivity and the diffusivity calculated from viscosity, i.e., <i>D</i><sub>η</sub> < (<i>D</i><sub>Si</sub> ≈ <i>D</i><sub>Pb</sub>) was noted. In fact, a noticeable change in the lead self-diffusion coefficients around <i>T</i><sub>d</sub> = 1.19<i>T</i><sub>g</sub> also contributed to this analysis. Thus, above <i>T</i><sub>d</sub>, silicon and lead control the transport mechanism involved in viscous flow, while below this temperature some simpler structures must control the transport process. Such results suggest that viscous flow requires a cooperative motion of some “structural units” rather than just jumps of one or a few isolated atoms, as it occurs in conductivity below <i>T</i><sub>d</sub>. Also, cooperatively rearranging regions or the size of the structural units are quite similar for both processes above <i>T</i><sub>d</sub>.\\n</p>\",\"PeriodicalId\":499,\"journal\":{\"name\":\"Brazilian Journal of Physics\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":1.5000,\"publicationDate\":\"2024-06-18\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Brazilian Journal of Physics\",\"FirstCategoryId\":\"101\",\"ListUrlMain\":\"https://doi.org/10.1007/s13538-024-01503-0\",\"RegionNum\":4,\"RegionCategory\":\"物理与天体物理\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"PHYSICS, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Brazilian Journal of Physics","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.1007/s13538-024-01503-0","RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"PHYSICS, MULTIDISCIPLINARY","Score":null,"Total":0}
Formation and Migration Enthalpy from Elemental and Cooperative Diffusion in Lead Silicate Supercooled Liquid and Glass
Diffusivity, conductivity, and viscosity data of the PbO⋅SiO2 were collected in the liquid, supercooled liquid, and glassy states. The difference in the dependence of diffusivity, viscous flow, and ionic conductivity on temperature below and above the glass transition temperature (Tg) is interpreted as a discontinuity in the charge carrier’s mobility mechanisms, including new proposals for ionic diffusivity. Charge carrier displacement occurs by an activated mechanism below Tg and through a cooperative mechanism above this temperature. Fitting diffusivity and conductivity data with the proposed model allows one to determine the enthalpies of charge carrier formation and migration separately. In particular, we present experimental results of lead and silicon diffusion species (DPb and DSi) at deep and low undercoolings in PbSiO3—considering 16 orders of magnitude and comparing the effective diffusivity for viscous flow, Dη, and its activation energy. A decoupling temperature Td between the cationic diffusivity and the diffusivity calculated from viscosity, i.e., Dη < (DSi ≈ DPb) was noted. In fact, a noticeable change in the lead self-diffusion coefficients around Td = 1.19Tg also contributed to this analysis. Thus, above Td, silicon and lead control the transport mechanism involved in viscous flow, while below this temperature some simpler structures must control the transport process. Such results suggest that viscous flow requires a cooperative motion of some “structural units” rather than just jumps of one or a few isolated atoms, as it occurs in conductivity below Td. Also, cooperatively rearranging regions or the size of the structural units are quite similar for both processes above Td.
期刊介绍:
The Brazilian Journal of Physics is a peer-reviewed international journal published by the Brazilian Physical Society (SBF). The journal publishes new and original research results from all areas of physics, obtained in Brazil and from anywhere else in the world. Contents include theoretical, practical and experimental papers as well as high-quality review papers. Submissions should follow the generally accepted structure for journal articles with basic elements: title, abstract, introduction, results, conclusions, and references.