The pore size distribution is often an important parameter for transport processes in porous media.Cryoporometry experiments can provide such data in the meso and macropore size up to 1 mm providing the sample tempera...The pore size distribution is often an important parameter for transport processes in porous media.Cryoporometry experiments can provide such data in the meso and macropore size up to 1 mm providing the sample temperature is finely controlled.We use a Peltier based system inserted directly into the NMR probe to control the temperature within 0.05℃and impose temperature ramps down to 0.002℃/min,necessary to characterize the largest pore sizes.The pore size information in the macropore range cannot be obtained from gas adsorption techniques while mercury injection is questionable for the material considered here.For porous materials made of paramagnetic minerals such as lithium-iron phosphate(LiFePO_(4),LFP)or nickel-manganese-cobalt oxides(NMC)and saturated with octamethylcyclotetrasiloxane(OMCTS),the T_(2)relaxation times are very short such as protons from the liquid and frozen phases cannot be separated.Hence the usual cryoporometry experiment cannot be performed.Instead,we propose to use the T_(1)contrast to separate these phases.The method is studied in detail along with some temperature effects linked with the T_(1)variation of the bulk frozen OMCTS.We show an example on two cathode materials part of industrial battery product.展开更多
Due to its high energy efficiency and environmental friendliness,solid-state cooling based on the barocaloric(BC)effect represents a promising alternative to traditional refrigeration technologies relying on greenhous...Due to its high energy efficiency and environmental friendliness,solid-state cooling based on the barocaloric(BC)effect represents a promising alternative to traditional refrigeration technologies relying on greenhouse gases.Plastic crystals displaying orientational order-disorder solid-solid phase transitions have emerged among the most gifted materials on which to realize the full potential of BC solid-state cooling.However,a comprehensive understanding of the atomistic mechanisms on which order-disorder BC effects are sustained is still missing,and rigorous and systematic methods for quantitatively evaluating and anticipating them have not been yet established.展开更多
文摘The pore size distribution is often an important parameter for transport processes in porous media.Cryoporometry experiments can provide such data in the meso and macropore size up to 1 mm providing the sample temperature is finely controlled.We use a Peltier based system inserted directly into the NMR probe to control the temperature within 0.05℃and impose temperature ramps down to 0.002℃/min,necessary to characterize the largest pore sizes.The pore size information in the macropore range cannot be obtained from gas adsorption techniques while mercury injection is questionable for the material considered here.For porous materials made of paramagnetic minerals such as lithium-iron phosphate(LiFePO_(4),LFP)or nickel-manganese-cobalt oxides(NMC)and saturated with octamethylcyclotetrasiloxane(OMCTS),the T_(2)relaxation times are very short such as protons from the liquid and frozen phases cannot be separated.Hence the usual cryoporometry experiment cannot be performed.Instead,we propose to use the T_(1)contrast to separate these phases.The method is studied in detail along with some temperature effects linked with the T_(1)variation of the bulk frozen OMCTS.We show an example on two cathode materials part of industrial battery product.
基金supported by the MINECO Projects PID2020-112975GB-I00 and TED2021-130265B-C22(Spain)by the DGU Project 2021SGR-00343(Catalonia)+2 种基金C.C.acknowledges financial support from the Spanish Ministry of Science,Innovation and Universities under the“Ramón y Cajal”fellowship RYC2018-024947-IC.E.-S.acknowledges financial support from the Spanish Ministry of Science,Innovation and Universities under the“Becas Margarita Salas para la formación de doctores jóvenes”fellowship 2021UPC-MS-67395Additional computational support was provided by the Red Española de Supercomputación(RES)under the grants FI-2022-1-0006,FI-2022-2-0003 and FI-2022-3-0014.
文摘Due to its high energy efficiency and environmental friendliness,solid-state cooling based on the barocaloric(BC)effect represents a promising alternative to traditional refrigeration technologies relying on greenhouse gases.Plastic crystals displaying orientational order-disorder solid-solid phase transitions have emerged among the most gifted materials on which to realize the full potential of BC solid-state cooling.However,a comprehensive understanding of the atomistic mechanisms on which order-disorder BC effects are sustained is still missing,and rigorous and systematic methods for quantitatively evaluating and anticipating them have not been yet established.
