ÚMVI-odbor keramiky a polymerů

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    Porous silica-doped calcium phosphate scaffolds prepared via in-situ foaming method
    (ELSEVIER SCI LTD, 2024-11-01) Šiška Virágová, Eliška; Novotná, Lenka; Chlup, Zdeněk; Šťastný, Přemysl; Šárfy, Pavlína; Cihlář, Jaroslav; Kučírek, Martin; Benák, Leoš; Streit, Libor; Kocanda, Jan; Sklenský, Jan; Filipovič, Milan; Repko, Martin; Hampl, Aleš; Koutná, Irena; Částková, Klára
    The effect of silica (SiO2) addition (0 wt%-20 wt%) on the microstructural and mechanical properties, as well as the in vitro response of calcium phosphate scaffolds for potential application in bone tissue engineering (BTE) was investigated in this research. Scaffolds characterized by high porosity (77%-88 %) and interconnected spherical pores with a broad range of pore sizes (5-600 mu m) were fabricated using in-situ foaming method. Incorporated silica affected the phase transformation of hydroxyapatite (HA) to beta-tricalcium phosphate (beta-TCP) and led to the development of new crystalline silica-rich phases like silicocarnotite and wollastonite. The reinforcement of silica became apparent during the tests of mechanical properties. Scaffolds with 5 wt% of SiO2 exhibited compressive strength (1.13 MPa) higher than pure HA scaffolds (0.93 MPa). Bone bonding potential of the materials was tested in simulated body fluid (SBF), demonstrating this potential in silica-doped samples. Additionally, degradation experiments showed gradual material degradation, making it suitable for BTE applications. Furthermore, cell culture studies using human mesenchymal stromal cells (MSC) confirmed the scaffold's non- toxicity and provided insights into how the silica content influences cell viability, morphology, and osteogenic potential. The findings of this study offer valuable insights into the design and development of advanced scaffolds with tailored properties for effective BTE applications.
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    Study of the Synthesis of Multi-Cationic Sm-Co-O, Sm-Ni-O, Al-Co-O, Al-Ni-O, and Al-Co-Ni-O Aerogels and Their Catalytic Activity in the Dry Reforming of Methane
    (MDPI, 2024-05-01) Cihlář, Jaroslav; Tkachenko, Serhii; Bednaříková, Vendula; Cihlář, Jaroslav; Částková, Klára; Trunec, Martin; Čelko, Ladislav
    Dense multi-cationic Sm-Co-O, Sm-Ni-O, Al-Co-O, Al-Ni-O, and Al-Ni-Co-O oxide aerogels were prepared by epoxide-driven sol-gel synthesis. Catalysts for dry reformation of methane, Sm2O3/Co, Sm2O3/Ni, Al2O3/Co, Al2O3/Ni, Al2O3/Co, and Ni were prepared by reduction of aerogels with hydrogen and their catalytic activities and C-deposition during dry reformation of methane were tested. Catalytic tests showed high methane conversion (93-98%) and C-deposition (0.01-4.35 mg C/gcat.h). The highest content of C-deposits after catalytic tests was determined for Al2O3/Co and Al2O3/Ni catalysts, which was related to the formation of Al alloys with Co and Ni. A uniform distribution of Co0 and Ni0 nanoparticles (in the form of a CoNi alloy) was found only for the Al2O3/Co and Ni catalysts, which showed the highest activity as well as low C deposition.
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    Optical and electrical performance of translucent BaTiO3-BaSnO3 ceramics
    (ELSEVIER SCI LTD, 2024-08-15) Bijalwan, Vijay; Kaštyl, Jaroslav; Erhart, Jiří; Prajzler, Vladimír; Tofel, Pavel; Sobola, Dinara; Velazquez, Jose J.; Galusek, Dušan; Maca, Karel
    Lead-free piezoceramic with the composition of 0.89BaTiO(3)-0.11BaSnO(3) (BT-11BS) was prepared by solid-state reaction followed by conventional sintering achieving nearly full density. The influence of sintering temperature on electrical properties were thoroughly investigated, implying a significant role in achieving best properties, which were obtained between 1420 and 1440 degrees C. The addition of SnO2 in BaTiO3 solid solution promoted grain growth, eventually resulting in the grain sizes between 145 and 216 mu m. An ultra-high dielectric permittivity >5.0 x 10(4) and related dielectric loss of 3.1 % at similar to 40 degrees C was achieved. A high value of quasi-static piezoelectric constant (d(33)) of 693 pC/N and the converse piezoelectric constant (denoted as d(33)*) reached a value of up to 831 pm/V in the frequency range between 10 and 110 Hz. The transmittance of similar to 25 % in the visible region and similar to 40 % in the infrared region together with good electromechanical properties showcasing a unique combination for this material.
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    Basic microstructural, mechanical, electrical and optical characterisation of BaTiAl6O12 ceramics
    (Elsevier, 2024-06-27) Drdlík, Daniel; Mařák, Vojtěch; Klement, Róbert; Tofel, Pavel; Drdlíková, Katarina; Hadraba, Hynek; Chlup, Zdeněk
    In progressive particle or layered composites based on a combination of BaTiO3 and Al2O3, serving as e.g. ceramic harvesters, new phases are formed during heat treatment. The dominant one is BaTiAl6O12. This study provides information about the microstructural, mechanical and optical properties of the BaTiAl6O12 ceramics. The evolution of the phases during the solid-state reaction synthesis of the BaTiAl6O12 was monitored. The fully dense samples prepared by Spark Plasma Sintering had indentation Vickers hardness and indentation elastic modulus within ranges of 10.1 – 13.7 GPa and 132.0 – 187.0 GPa, depending on loading force. The three-point bending tests of the BaTiAl6O12 samples resulted in flexural strength of 129.9 MPa and fracture toughness of 1.8 MPa.m1/2.The sample showed blue broad-band emission under UV excitation due to the charge-transfer transition of the Ti4+ and defect sites. The BaTiAl6O12 evinced low permittivity (') = 16 and dielectric loss (tan ) < 0.0003 at a frequency 1 kHz.
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    Synthesis and Band Gap Characterization of High-Entropy Ceramic Powders
    (MDPI, 2024-03-22) Dallaev, Rashid; Spusta, Tomáš; Allaham, Mohammad Mahmoud; Spotz, Zdeněk; Sobola, Dinara
    This manuscript presents a comprehensive exploration of the band gap structure in (CoCrFeNiMn)3O4 powders through a series of experimental investigations. The combined use of optical techniques, and X-ray photoelectron spectroscopy in this study offers a comprehensive characterization of the band gap structure in (CoCrFeNiMn)3O4 powders. The findings contribute to the understanding of the material's electronic properties and pave the way for potential applications in electronic and optical devices.