Pana (Nita) Cristina
@inflpr.ro
CENTER FOR ADVANCED LASER TECHNOLOGIES
National Institute for Laser, Plasma and Radiation Physics
RESEARCH, TEACHING, or OTHER INTERESTS
Materials Science
Scopus Publications
Scopus Publications
Mihai Sopronyi, Cristina Nita, Jean-Marc Le Meins, Loïc Vidal, Florin Jipa, Emanuel Axente, Camélia Matei Ghimbeu, and Felix Sima
Elsevier BV
Cristina Nita, Biao Zhang, Joseph Dentzer, and Camélia Matei Ghimbeu
Elsevier BV
Anetta Platek-Mielczarek, Cristina Nita, Camélia Matei Ghimbeu, Elzbieta Frackowiak, and Krzysztof Fic
American Chemical Society (ACS)
Various alkali metal (Li+, Na+, K+, Rb+, and Cs+) chlorides with Pluronic F127 were used as a soft-salt template for tuning the textural and structural properties of carbon. Highly conductive metal hydroxide solutions, where the cations are the same as those in the salt template, have been used as electrolytes. By increasing the size of the cation in the template, the textural properties of carbon, such as the specific surface area, micropore volume, and pore size, were remarkably enhanced. It directly translates to an increase in the specific capacitance of the electrode material. For a constant current charge/discharge at 0.1 A g–1, the electrode composed of LiCl-T and operating with 1 mol L–1 LiOH demonstrates the capacitance of 124 F g–1, whereas CsCl-T with the same electrolyte has a capacitance of 216 F g–1. Moreover, the materials show the highest capacitance retention (up to 75%) vs. the current regime applied when the cation used during synthesis matches the cation present in the electrolyte (i.e., LiCl-T with LiOH). Interestingly, capacitance normalized by specific surface area has been found to be the highest when LiOH solution is applied as an electrolyte. Thus, for this metric, the size of ions seems to be a crucial parameter. The importance of mesoporosity is highlighted as well by using materials with a similar fraction of micropores and with or without mesopores. Briefly, the presence of mesopore fraction proved to be essential for improved capacity retention (69% vs. 30%). Besides textural properties, the graphitization degree impacts the electrochemical performance as well. It increases among the samples, in accordance with cation-π binding energy, e.g., LiCl-T is the most “graphitic-like” material and CsCl-T is the most disordered. Thus, the more graphitic-like materials demonstrate higher rate capability and cycle stability.
Anetta Platek, Cristina Nita, Camélia Matei Ghimbeu, Elżbieta Frąckowiak, and Krzysztof Fic
Elsevier BV
Cristina Nita, Julien Fullenwarth, Laure Monconduit, Loïc Vidal, and Camélia Matei Ghimbeu
Elsevier BV
Cristina Nita, Julien Fullenwarth, Laure Monconduit, Jean-Marc Le Meins, Philippe Fioux, Julien Parmentier, and Camélia Matei Ghimbeu
Elsevier BV
Cristina Nita, Julien Fullenwarth, Laure Monconduit, Jean‐Marc Le Meins, Julien Parmentier, Moulay Tahar Sougrati, and Camélia Matei Ghimbeu
Wiley
AbstractHerein, we report a systematic study to understand the influence of the amount of tin metal precursor salt on the formation of carbon/tin hybrid materials and their performances as anodes in Li‐ion batteries. Small Sn metallic particles (ca. 5 nm) covered by a SnO2 layer were uniformly dispersed in a mesoporous carbon for a low loading of tin; whereas, for higher Sn loadings, the formation of Sn‐based particles aggregates (ca. 200 nm) is promoted as well. By increasing the Sn loading from 20 to 80 %, the irreversible capacity was successfully reduced and the reversible capacity improved. This could be related to the decrease of the C/Sn hybrids specific surface area and the increase of the Sn active species. For long‐term cycling, capacity fading was observed, particularly for high Sn loadings assigned to the Sn nanoparticles placed outside the carbon network, which upon lithiation witness large volume expansion, leading to severe particle growth and agglomeration. Therefore, similar reversible capacities at long cycling are reached, no matter the Sn loading. For optimal electrochemical performances, it appears that a balance between the amount of Sn and uniform small Sn‐based particles dispersion within carbon matrix must be assured to design high‐performance anodes for Li‐ion batteries.
Emanuel Axente, Mihai Sopronyi, Camélia Matei Ghimbeu, Cristina Nita, Aissam Airoudj, Gautier Schrodj, and Felix Sima
Elsevier BV
A. Visan, R. Cristescu, N. Stefan, M. Miroiu, C. Nita, M. Socol, C. Florica, O. Rasoga, I. Zgura, L.E. Sima,et al.
Elsevier BV
I. Camps, M. Borlaf, M. T. Colomer, R. Moreno, L. Duta, C. Nita, A. Perez del Pino, C. Logofatu, R. Serna, and E. György
Royal Society of Chemistry (RSC)
Highly photoluminescent Eu doped TiO2 layers prepared by laser-based technique from colloidal sols.
Alicia Martínez de Yuso, Maurizio De Fina, Cristina Nita, Philippe Fioux, Julien Parmentier, and Camelia Matei Ghimbeu
Elsevier BV
Cristina Nita, Mahmoud Bensafia, Cyril Vaulot, Luc Delmotte, and Camelia Matei Ghimbeu
Elsevier BV
Floralice Marimona Miroiu, Nicolaie Stefan, Anita Ioana Visan, Cristina Nita, Catalin Romeo Luculescu, Oana Rasoga, Marcela Socol, Irina Zgura, Rodica Cristescu, Doina Craciun,et al.
Elsevier BV
Andrei Popescu, George Stan, Liviu Duta, Cristina Nita, Camelia Popescu, Vasile-Adrian Surdu, Marius-Adrian Husanu, Bogdan Bita, Rudy Ghisleni, Cameliu Himcinschi,et al.
MDPI AG
Hard carbon thin films were synthesized on Si (100) and quartz substrates by the Pulsed Laser Deposition (PLD) technique in vacuum or methane ambient to study their suitability for applications requiring high mechanical resistance. The deposited films’ surface morphology was investigated by scanning electron microscopy, crystalline status by X-ray diffraction, packing and density by X-ray reflectivity, chemical bonding by Raman and X-ray photoelectron spectroscopy, adherence by “pull-out” measurements and mechanical properties by nanoindentation tests. Films synthesized in vacuum were a-C DLC type, while films synthesized in methane were categorized as a-C:H. The majority of PLD films consisted of two layers: one low density layer towards the surface and a higher density layer in contact with the substrate. The deposition gas pressure played a crucial role on films thickness, component layers thickness ratio, structure and mechanical properties. The films were smooth, amorphous and composed of a mixture of sp3-sp2 carbon, with sp3 content ranging between 50% and 90%. The thickness and density of the two constituent layers of a film directly determined its mechanical properties.
D E Mihaiescu, R Cristescu, G Dorcioman, C E Popescu, C Nita, G Socol, I N Mihailescu, A M Grumezescu, D Tamas, M Enculescu,et al.
IOP Publishing
We report on the fabrication of magnetite/salicylic acid/silica shell/antibiotics (Fe3O4/SA/SiO2/ATB) thin films by matrix-assisted pulsed laser evaporation (MAPLE) to inert substrates. Fe3O4-based powder have been synthesized and investigated by XRD and TEM. All thin films were studied by FTIR, SEM and in vitro biological assays using Staphylococcus aureus and Pseudomonas aeruginosa reference strains, as well as eukaryotic HEp-2 cells. The influence of the obtained nanosystems on the microbial biofilm development as well as their biocompatibility has been assessed. For optimum deposition conditions, we obtained uniform adherent films with the composition identical with the raw materials. Fe3O4/SA/SiO2/ATB thin films had an inhibitory activity on the ability of microbial strains to initiate and develop mature biofilms, in a strain- and antibiotic-dependent manner. These magnetite silica thin films are promising candidates for the development of novel materials designed for the inhibition of medical biofilms formed by different pathogenic agents on common substrates, frequently implicated in the etiology of chronic and hard to treat infections.