Roxana Elena Patru

Verified @infim.ro



           

https://researchid.co/roxulet
18

Scopus Publications

306

Scholar Citations

10

Scholar h-index

11

Scholar i10-index

Scopus Publications


  • High-Entropy Lead-Free Perovskite Bi<inf>0.2</inf>K<inf>0.2</inf>Ba<inf>0.2</inf>Sr<inf>0.2</inf>Ca<inf>0.2</inf>TiO<inf>3</inf> Powders and Related Ceramics: Synthesis, Processing, and Electrical Properties
    Vasile-Adrian Surdu, Mariana-Andreea Marinică, Roxana-Elena Pătru, Ovidiu-Cristian Oprea, Adrian Ionuț Nicoară, Bogdan Ștefan Vasile, Roxana Trușca, and Adelina-Carmen Ianculescu
    MDPI AG
    A novel high-entropy perovskite powder with the composition Bi0.2K0.2Ba0.2Sr0.2Ca0.2TiO3 was successfully synthesized using a modified Pechini method. The precursor powder underwent characterization through Fourier Transform Infrared Spectroscopy and thermal analysis. The resultant Bi0.2K0.2Ba0.2Sr0.2Ca0.2TiO3 powder, obtained post-calcination at 900 °C, was further examined using a variety of techniques including X-ray diffraction, Raman spectroscopy, X-ray fluorescence, scanning electron microscopy, and transmission electron microscopy. Ceramic samples were fabricated by conventional sintering at various temperatures (900, 950, and 1000 °C). The structure, microstructure, and dielectric properties of these ceramics were subsequently analyzed and discussed. The ceramics exhibited a two-phase composition comprising cubic and tetragonal perovskites. The grain size was observed to increase from 35 to 50 nm, contingent on the sintering temperature. All ceramic samples demonstrated relaxor behavior with a dielectric maximum that became more flattened and shifted towards lower temperatures as the grain size decreased.

  • Influence of Grain Size on Dielectric Behavior in Lead-Free 0.5 Ba(Zr<inf>0.2</inf>Ti<inf>0.8</inf>)O<inf>3</inf>–0.5 (Ba<inf>0.7</inf>Ca<inf>0.3</inf>)TiO<inf>3</inf> Ceramics
    Vladimir Lucian Ene, Valentin Razvan Lupu, Claudiu Vasile Condor, Roxana Elena Patru, Luminita Mirela Hrib, Luminita Amarande, Adrian Ionut Nicoara, Lucian Pintilie, and Adelina-Carmen Ianculescu
    MDPI AG
    Fine-tuning of grain sizes can significantly influence the interaction between different dielectric phenomena, allowing the development of materials with tailored dielectric resistivity. By virtue of various synthesis mechanisms, a pathway to manipulate grain sizes and, consequently, tune the material’s dielectric response is revealed. Understanding these intricate relationships between granulation and dielectric properties can pave the way for designing and optimizing materials for specific applications where tailored dielectric responses are sought. The experimental part involved the fabrication of dense BCT-BZT ceramics with different grain sizes by varying the synthesis (conventional solid-state reaction route and sol-gel) and consolidation methods. Both consolidation methods produced well-crystallized specimens, with Ba0.85Ca0.15O3Ti0.9Zr0.1 (BCTZ) perovskite as the major phase. Conventional sintering resulted in microstructured and submicron-structured BCT-BZT ceramics, with average grain sizes of 2.35 μm for the solid-state sample and 0.91 μm for the sol-gel synthesized ceramic. However, spark plasma sintering produced a nanocrystalline specimen with an average grain size of 67.5 nm. As the grain size decreases, there is a noticeable decrease in the maximum permittivity, a significant reduction in dielectric losses, and a shifting of the Curie temperature towards lower values.

  • Grain size-driven effect on the functional properties in Ba<inf>0.6</inf>Sr<inf>0.4</inf>TiO<inf>3</inf> ceramics consolidated by spark plasma sintering
    Roxana-Elena Pătru, Cătălina Andreea Stanciu, Elena Mirabela Soare, Vasile-Adrian Surdu, Roxana Doina Truşcă, Adrian Ionuţ Nicoară, Bogdan Ştefan Vasile, Georgia Boni, Luminiţa Amarande, Nadejda Horchidan,et al.
    Elsevier BV

  • Capacitive and Inductive Effects in Perovskite Solar Cells: The Different Roles of Ionic Current and Ionic Charge Accumulation
    Nicolae Filipoiu, Amanda Teodora Preda, Dragos-Victor Anghel, Roxana Patru, Rachel Elizabeth Brophy, Movaffaq Kateb, Cristina Besleaga, Andrei Gabriel Tomulescu, Ioana Pintilie, Andrei Manolescu,et al.
    American Physical Society (APS)
    ,

  • Negative Capacitance and Switching Dynamics Control Via Non-Ferroelectric Elements
    Andra Georgia Boni, Roxana Patru, Lucian D. Filip, Cristina Chirila, Iuliana Pasuk, Ioana Pintilie, and Lucian Pintilie
    American Chemical Society (ACS)

  • Tetragonal–cubic phase transition and low-field dielectric properties of ch3nh3pbi3 crystals
    Roxana Patru, Hamidreza Khassaf, Iuliana Pasuk, Mihaela Botea, Lucian Trupina, Constantin-Paul Ganea, Lucian Pintilie, and Ioana Pintilie
    MDPI AG
    The frequency and temperature dependence of dielectric properties of CH3NH3PbI3 (MAPI) crystals have been studied and analyzed in connection with temperature-dependent structural studies. The obtained results bring arguments for the existence of ferroelectricity and aim to complete the current knowledge on the thermally activated conduction mechanisms, in dark equilibrium and in the presence of a small external a.c. electric field. The study correlates the frequency-dispersive dielectric spectra with the conduction mechanisms and their relaxation processes, as well as with the different transport regimes indicated by the Nyquist plots. The different energy barriers revealed by the impedance spectroscopy highlight the dominant transport mechanisms in different frequency and temperature ranges, being associated with the bulk of the grains, their boundaries, and/or the electrodes’ interfaces.

  • Enhancing stability of hybrid perovskite solar cells by imidazolium incorporation
    Andrei Gabriel Tomulescu, Lucia Nicoleta Leonat, Florentina Neațu, Viorica Stancu, Vasilica Toma, Sarah Derbali, Ștefan Neațu, Arpad Mihai Rostas, Cristina Beșleagă, Roxana Pătru,et al.
    Elsevier BV

  • Structural, functional properties and enhanced thermal stability of bulk graded (Ba,Sr)TiO<inf>3</inf>structures obtained by spark plasma sintering
    Mihaela Botea, Ioana Pintilie, Vasile-Adrian Surdu, Cătălina-Andreea Stanciu, Roxana-Doina Truşcă, Bogdan Ştefan Vasile, Roxana Patru, Adelina-Carmen Ianculescu, and Lucian Pintilie
    Elsevier BV

  • PVDF–ferrite composites with dual magneto-piezoelectric response for flexible electronics applications: synthesis and functional properties
    Felicia Gheorghiu, Roxana Stanculescu, Lavinia Curecheriu, Elisabetta Brunengo, Paola Stagnaro, Vasile Tiron, Petronel Postolache, Maria Teresa Buscaglia, and Liliana Mitoseriu
    Springer Science and Business Media LLC

  • (Ba,Sr)TiO<inf>3</inf> solid solutions sintered from sol-gel derived powders: An insight into the composition and temperature dependent dielectric behavior
    Roxana Elena Patru, Constantin Paul Ganea, Catalina-Andreea Stanciu, Vasile-Adrian Surdu, Roxana Trusca, Adelina-Carmen Ianculescu, Ioana Pintilie, and Lucian Pintilie
    Elsevier BV

  • Structural and functional properties of BaTiO<inf>3</inf> porous ceramics produced by using pollen as sacrificial template
    Vlad Alexandru Lukacs, Roxana Stanculescu, Lavinia Curecheriu, Cristina Elena Ciomaga, Nadejda Horchidan, Cipriana Cioclea, and Liliana Mitoseriu
    Elsevier BV

  • Porous (Ba,Sr)TiO<inf>3</inf> ceramics for tailoring dielectric and tunability properties: Modelling and experiment
    Roxana Stanculescu, Nadejda Horchidan, Carmen Galassi, Mihai Asandulesa, Leontin Padurariu, Cristina Ciomaga, and Liliana Mitoseriu
    National Library of Serbia
    3D Finite Element Method simulations were employed in order to describe tunability properties in anisotropic porous paraelectric structures. The simulations predicted that properties of a ceramic can be tailored by using various levels of porosity. Porous Ba0.6Sr0.4TiO3 (BST) ceramics have been studied in order to investigate the influence of porosity on their functional properties. The BST ceramics with various porosity levels have been obtained by solid-state reaction. Lamellar graphite in different concentration of 10, 20 and 35 vol.%was added as sacrificial pore forming agent. The structural, microstructural, dielectric and tunability properties were investigated. By comparison with dense BST ceramic, porous samples present a fracture mode transformation from intragranular to an intergranular fracture and a decrease of grain size. Lower dielectric constants, low dielectric losses, but higher values of tunability than in the dense material were obtained in the porous BST structures as a result of local field inhomogeneity generated by the presence of air pores-ceramic interfaces.

  • Effect of particle size and volume fraction of BaTiO<inf>3</inf> powders on the functional properties of BaTiO<inf>3</inf>/poly(ε-caprolactone) composites
    M. Airimioaei, R. Stanculescu, V. Preutu, C. Ciomaga, N. Horchidan, S. Tascu, D. Lutic, A. Pui, and L. Mitoseriu
    Elsevier BV

  • The influence of post-sintering re-oxidation treatment on dielectric response of dense and porous Ba<inf>0.70</inf>Sr<inf>0.30</inf>TiO<inf>3</inf> ceramics
    Roxana E. Stanculescu, Cristina E. Ciomaga, Nadejda Horchidan, Carmen Galassi, Florin Mihai Tufescu, and Liliana Mitoseriu
    Elsevier BV

  • Study of the role of porosity on the functional properties of (Ba,Sr)TiO<inf>3</inf> ceramics
    Roxana Stanculescu, Cristina E. Ciomaga, Leontin Padurariu, Pietro Galizia, Nadejda Horchidan, Claudio Capiani, Carmen Galassi, and Liliana Mitoseriu
    Elsevier BV

  • Investigation of low field dielectric properties of anisotropic porous Pb(Zr,Ti)O<inf>3</inf> ceramics: Experiment and modeling
    C. S. Olariu, L. Padurariu, R. Stanculescu, C. Baldisserri, C. Galassi, and L. Mitoseriu
    AIP Publishing
    Anisotropic porous Pb(Zr,Ti)O3 ceramics with various porosity degrees have been studied in order to determine the role of the pore shape and orientation on the low-field dielectric properties. Ceramic samples with formula Pb(Zr0.52Ti0.48)0.976Nb0.024O3 with different porosity degrees (dense, 10%, 20%, 40% vol.) have been prepared by solid state reaction. Taking into consideration the shape and orientation of the pore inclusions, the dielectric properties of porous ceramics have been described by using adapted mixing rules models. Rigorous bounds, derived on the basis on Variational Principle, were used to frame dielectric properties of porous composites. The finite element method (FEM) was additionally used to simulate the dielectric response of the porous composites under various applied fields. Among the few effective medium approximation models adapted for anisotropic oriented inclusions, the best results were obtained in case of needle-like shape inclusions (which do not correspond to the real shape of microstructure inclusions). The general case of Wiener bounds limited well the dielectric properties of anisotropic porous composites in case of parallel orientation. Among the theoretical approaches, FEM technique allowed to simulate the distribution of potential and electric field inside composites and provided a very good agreement between the computed permittivity values and experimental ones.

  • Solvatochromism used in determining some molecular electro-optical parameters
    Luminita Stroia, Roxana-Elena Stanculescu, and Dana Ortansa Dorohoi
    SPIE
    Two spectrally active molecules - carbanion monosubstituted cycloimmonium ylids having as heterocycles benzo-[f]- quinolinium and p-phenyl-pyridazinium - can offer information about the local field of forces in binary solutions. Hyper Chem. 8.0.6 software was used to characterize these molecules from the structural, energetic and electro-optical point of view. The visible band of the cycloimmonium ylids appears by an intramolecular charge transfer (ICT) from the carbanion to the heterocycle. It is very sensitive to the solvent nature. The projection of the excited state dipole moment on the dipole moment in the electronic ground state was obtained for two studied ylids on the basis of the existent theories regarding the intermolecular interactions in liquid phase studied by spectral means.

RECENT SCHOLAR PUBLICATIONS

  • Experimental and theoretical perspective on band gap modulation in Sr2+ modified BaTiO3 capacitors
    Y Zidi, O Khaldi, RE Patru, LN Leonat, M Enculescu, V Toma, ...
    Ceramics International 2025

  • Effect of transition metal ions on the dielectric properties of chromium potassium phosphates
    Z Mighri, RE Patru, LN Leonat, O El Khouja, H Nasri, AM Rostas, ...
    Journal of Alloys and Compounds 1009, 176870 2024

  • Impact of interface defects on the band alignment and performance of TiO/MAPI/CuO perovskite solar cells
    N Filipoiu, M Cuzminschi, CA Pantis-Simut, K Torfason, RE Brophy, ...
    arXiv preprint arXiv:2406.19594 2024

  • DC current-voltage and impedance spectroscopy characterization of nCdS/pZnTe HJ
    I Lungu, RE Patru, AC Galca, L Pintilie, T Potlog
    Scientific reports 14 (1), 12955 2024

  • Downscaling grain size toward the nanometre range–A key-factor for tuning the crystalline structure, phase transitions, dielectric and ferroelectric behaviour in Ba0 8Sr0
    RE Pătru, CA Stanciu, VA Surdu, EM Soare, RD Truşcă, BS Vasile, ...
    Progress in Solid State Chemistry, 100457 2024

  • High-Entropy Lead-Free Perovskite Bi0.2K0.2Ba0.2Sr0.2Ca0.2TiO3 Powders and Related Ceramics: Synthesis, Processing, and Electrical Properties
    VA Surdu, MA Marinică, RE Pătru, OC Oprea, AI Nicoară, BȘ Vasile, ...
    Nanomaterials 13 (22), 2974 2023

  • Influence of Grain Size on Dielectric Behavior in Lead-Free 0.5 Ba(Zr0.2Ti0.8)O3–0.5 (Ba0.7Ca0.3)TiO3 Ceramics
    VL Ene, VR Lupu, CV Condor, RE Patru, LM Hrib, L Amarande, ...
    Nanomaterials 13 (22), 2934 2023

  • Grain size-driven effect on the functional properties in Ba0. 6Sr0. 4TiO3 ceramics consolidated by spark plasma sintering
    RE Pătru, CA Stanciu, EM Soare, VA Surdu, RD Truşcă, AI Nicoară, ...
    Journal of the European Ceramic Society 43 (8), 3250-3265 2023

  • Structural and electrical properties of novel Cr/Fe mixed transition-metal phosphates
    Z Mighri, K Souiwa, AM Rostas, RE Patru, AE Bocirnea, N Iacob, ...
    Inorganic Chemistry 62 (22), 8530-8542 2023

  • DC current-voltage and impedance spectroscopy characterization of CdS/ZnTe heterostructures
    I Lungu, RE Patru, AC Galca, L Pintilie, T Potlog
    Application-oriented material development, 11-11 2023

  • Capacitive and inductive effects in perovskite solar cells: the different roles of ionic current and ionic charge accumulation
    N Filipoiu, AT Preda, DV Anghel, R Patru, RE Brophy, M Kateb, ...
    Physical Review Applied 18 (6), 064087 2022

  • Negative Capacitance and Switching Dynamics Control Via Non-Ferroelectric Elements
    AG Boni, R Patru, LD Filip, C Chirila, I Pasuk, I Pintilie, L Pintilie
    ACS Applied Energy Materials 5 (3), 3307-3318 2022

  • Enhancing stability of hybrid perovskite solar cells by imidazolium incorporation
    AG Tomulescu, LN Leonat, F Neațu, V Stancu, V Toma, S Derbali, ...
    Solar Energy Materials and Solar Cells 227, 111096 2021

  • Tetragonal–Cubic Phase Transition and Low-Field Dielectric Properties of CH3NH3PbI3 Crystals
    RE Patru, H Khassaf, I Pasuk, M Botea, L Trupina, CP Ganea, L Pintilie, ...
    Materials 14 (15), 4215 2021

  • Structural, functional properties and enhanced thermal stability of bulk graded (Ba,Sr)TiO3 structures obtained by spark plasma sintering
    M Botea, I Pintilie, VA Surdu, CA Stanciu, RD Trusca, BS Vasile, R Patru, ...
    Journal of Materials Research and Technology 12, 2085-2103 2021

  • PVDF–ferrite composites with dual magneto-piezoelectric response for flexible electronics applications: synthesis and functional properties
    F Gheorghiu, R Stanculescu, L Curecheriu, E Brunengo, P Stagnaro, ...
    Journal of Materials Science 55 (9), 3926-3939 2020

  • (Ba, Sr) TiO3 solid solutions sintered from sol-gel derived powders: An insight into the composition and temperature dependent dielectric behavior
    RE Patru, CP Ganea, CA Stanciu, VA Surdu, R Trusca, AC Ianculescu, ...
    Ceramics International 46 (4), 4180-4190 2020

  • Structural and functional properties of BaTiO3 porous ceramics produced by using pollen as sacrificial template
    VA Lukacs, R Stanculescu, L Curecheriu, CE Ciomaga, N Horchidan, ...
    doi.org/10.1016/J.CERAMINT.2019.08.292 2020

  • Porous (Ba, Sr) TiO3 ceramics for tailoring dielectric and tunability properties: Modelling and experiment
    RE Stanculescu, N Horchidan, C Galassi, M Asandulesa, L Padurariu, ...
    Processing and Application of Ceramics 11 (4), 235-246 2017

  • The influence of post-sintering re-oxidation treatment on dielectric response of dense and porous Ba0.70Sr0.30TiO3 ceramics
    RE Stanculescu, CE Ciomaga, N Horchidan, C Galassi, FM Tufescu, ...
    Ceramics International 42 (1), 527-536 2016

MOST CITED SCHOLAR PUBLICATIONS

  • Study of the role of porosity on the functional properties of (Ba,Sr)TiO3 ceramics
    R Stanculescu, CE Ciomaga, L Padurariu, P Galizia, N Horchidan, ...
    Journal of Alloys and Compounds 643, 79-87 2015
    Citations: 65

  • PVDF–ferrite composites with dual magneto-piezoelectric response for flexible electronics applications: synthesis and functional properties
    F Gheorghiu, R Stanculescu, L Curecheriu, E Brunengo, P Stagnaro, ...
    Journal of Materials Science 55 (9), 3926-3939 2020
    Citations: 41

  • Structural and functional properties of BaTiO3 porous ceramics produced by using pollen as sacrificial template
    VA Lukacs, R Stanculescu, L Curecheriu, CE Ciomaga, N Horchidan, ...
    doi.org/10.1016/J.CERAMINT.2019.08.292 2020
    Citations: 32

  • Capacitive and inductive effects in perovskite solar cells: the different roles of ionic current and ionic charge accumulation
    N Filipoiu, AT Preda, DV Anghel, R Patru, RE Brophy, M Kateb, ...
    Physical Review Applied 18 (6), 064087 2022
    Citations: 24

  • Investigation of low field dielectric properties of anisotropic porous Pb(Zr,Ti)O3 ceramics: Experiment and modeling
    CS Olariu, L Padurariu, R Stanculescu, C Baldisserri, C Galassi, ...
    Journal of Applied Physics 114, 214101 2013
    Citations: 24

  • Enhancing stability of hybrid perovskite solar cells by imidazolium incorporation
    AG Tomulescu, LN Leonat, F Neațu, V Stancu, V Toma, S Derbali, ...
    Solar Energy Materials and Solar Cells 227, 111096 2021
    Citations: 18

  • The influence of post-sintering re-oxidation treatment on dielectric response of dense and porous Ba0.70Sr0.30TiO3 ceramics
    RE Stanculescu, CE Ciomaga, N Horchidan, C Galassi, FM Tufescu, ...
    Ceramics International 42 (1), 527-536 2016
    Citations: 18

  • Effect of particle size and volume fraction of BaTiO3 powders on the functional properties of BaTiO3/poly(epsilon-caprolactone) composites
    M Airimioaei, R Stanculescu, V Preutu, C Ciomaga, N Horchidan, S Tascu, ...
    Materials Chemistry and Physics 182, 246-255 2016
    Citations: 18

  • Porous (Ba, Sr) TiO3 ceramics for tailoring dielectric and tunability properties: Modelling and experiment
    RE Stanculescu, N Horchidan, C Galassi, M Asandulesa, L Padurariu, ...
    Processing and Application of Ceramics 11 (4), 235-246 2017
    Citations: 16

  • Tetragonal–Cubic Phase Transition and Low-Field Dielectric Properties of CH3NH3PbI3 Crystals
    RE Patru, H Khassaf, I Pasuk, M Botea, L Trupina, CP Ganea, L Pintilie, ...
    Materials 14 (15), 4215 2021
    Citations: 10

  • (Ba, Sr) TiO3 solid solutions sintered from sol-gel derived powders: An insight into the composition and temperature dependent dielectric behavior
    RE Patru, CP Ganea, CA Stanciu, VA Surdu, R Trusca, AC Ianculescu, ...
    Ceramics International 46 (4), 4180-4190 2020
    Citations: 10

  • Influence of Grain Size on Dielectric Behavior in Lead-Free 0.5 Ba(Zr0.2Ti0.8)O3–0.5 (Ba0.7Ca0.3)TiO3 Ceramics
    VL Ene, VR Lupu, CV Condor, RE Patru, LM Hrib, L Amarande, ...
    Nanomaterials 13 (22), 2934 2023
    Citations: 7

  • Grain size-driven effect on the functional properties in Ba0. 6Sr0. 4TiO3 ceramics consolidated by spark plasma sintering
    RE Pătru, CA Stanciu, EM Soare, VA Surdu, RD Truşcă, AI Nicoară, ...
    Journal of the European Ceramic Society 43 (8), 3250-3265 2023
    Citations: 7

  • Structural and electrical properties of novel Cr/Fe mixed transition-metal phosphates
    Z Mighri, K Souiwa, AM Rostas, RE Patru, AE Bocirnea, N Iacob, ...
    Inorganic Chemistry 62 (22), 8530-8542 2023
    Citations: 6

  • Structural, functional properties and enhanced thermal stability of bulk graded (Ba,Sr)TiO3 structures obtained by spark plasma sintering
    M Botea, I Pintilie, VA Surdu, CA Stanciu, RD Trusca, BS Vasile, R Patru, ...
    Journal of Materials Research and Technology 12, 2085-2103 2021
    Citations: 5

  • High-Entropy Lead-Free Perovskite Bi0.2K0.2Ba0.2Sr0.2Ca0.2TiO3 Powders and Related Ceramics: Synthesis, Processing, and Electrical Properties
    VA Surdu, MA Marinică, RE Pătru, OC Oprea, AI Nicoară, BȘ Vasile, ...
    Nanomaterials 13 (22), 2974 2023
    Citations: 2

  • DC current-voltage and impedance spectroscopy characterization of nCdS/pZnTe HJ
    I Lungu, RE Patru, AC Galca, L Pintilie, T Potlog
    Scientific reports 14 (1), 12955 2024
    Citations: 1

  • Downscaling grain size toward the nanometre range–A key-factor for tuning the crystalline structure, phase transitions, dielectric and ferroelectric behaviour in Ba0 8Sr0
    RE Pătru, CA Stanciu, VA Surdu, EM Soare, RD Truşcă, BS Vasile, ...
    Progress in Solid State Chemistry, 100457 2024
    Citations: 1

  • Solvatochromism used in determining some molecular electro-optical parameters
    L Stroia, RE Stanculescu, DO Dorohoi
    Proc. SPIE 8001, International Conference on Applications of Optics and 2011
    Citations: 1