Synthesis of LiCrxMn2-xO4 (x~0.18) by glycine-nitrate method

LiCr0.18Mn1.82O4 spinel has been successfully synthesized by glycine-nitrate method. As a cathode material for lithium batteries it shows initial discharge capacity of 107.1 mAh/g and capacity retention of 93.3% after ten cycles.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

CaCu3Ti4-xRuxO12: Crystal structure, electrical and magnetic properties

The CaCu3 Ti 4 O12 belongs to the large ACu3B4 O12 family of materials. Crystallographic A site is most often occupied by alkaline-earth metals or lanthanides, while B site is occupied by transition metals. The type of cations that build up the structure strongly affects the properties of these. The CaCu 3 Ti 4 O12 has been extensively studied due to its high dielectric permittivity stable over a wide temperature and frequency range (up to 10 5 , for 100-600 K and 10 2 –105 Hz). Because of such characteristics, it has promising application in microelectronics. However, it has been shown that differences in the crystal structure and electrical properties of dielectric ceramics and metallic electrodes, may cause an energy barrier and occurrence of stress on the ceramic-electrode contact which reduces dielectric permittivity. Such stress can be prevented by using dielectric and electrode materials with as much as possible similar crystal structure, especially unit cell parameters. This investigation dealt with detailed structural (XRPD, HRTEM, SAED), dielectric and magnetic study of CaCu 3 Ti 4-xRuxO12 (CCTRO, x = 0, 1 and 4) materials. The results of structural refinement show that in cubic symmetry with space group 3Im , both titanium and ruthenium ions occupied crystallographic B site. Moreover, the variation in stoichiometry slightly affects the value of the unit cell parameters but changes electrical properties of studied material. Thus, substitution of even one atom of Ru in CaCu3 Ti 4-xRuxO12 unit cell is enough to change material properties from dielectric to conductor solving the problem of stress appearance on the contact layer of dielectric/electrode in capacitors.IX Serbian Ceramic Society Conference - Advanced Ceramics and Application : new frontiers in multifunctional material science and processing : program and the book of abstracts; September 20-21, 2021; Belgrad

Influence of dimensionality on phase transition in VO2 nanocrystals

Hydrothermally synthesized one-dimensional and two-dimensional nanocrystals of VO2 undergo phase transition around 65°C, where temperature and mechanism of phase transition are dependent on dimensionality of nanocrystals. Both nanocrystalline samples exhibit depression of phase transition temperature compared to the bulk material, the magnitude of which depends on the dimensionality of the nanocrystal. One-dimensional nanoribbons exhibit lower phase transition temperature and higher values of apparent activation energy than two-dimensional nanosheets. The phase transition exhibits as a complex process with somewhat lower value of enthalpy than the phase transition in the bulk, probably due to higher proportion of surface atoms in the nanocrystals. High values of apparent activation energy indicate that individual steps of the phase transition involve simultaneous movement of large groups of atoms, as expected for single-domain nanocrystalline materials. [Projekat Ministarstva nauke Republike Srbije, br. 142015

Synthesis and cytotoxic activity of a series of bile acid derivatives

The new conjugates of selected bile acids (hyocholic (2), deoxycholic (3), hyodeoxycholic (4) and 12-ketocholic (5) acids) with ethyl 11-aminoundecanoate 7, 8, 11, and 13 were synthesized. The conjugation reaction was carried out in ethyl acetate in the presence of N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) and triethylamine. Under the same experimental conditions, the conjugation reaction involving ethyl 6-aminohexanoate resulted in formation of a conjugate 9 only in the case of deoxycholic acid (3) in addition to the unexpected ethyl ester 10. In the case of the other bile acids (cholic (1), hyodeoxycholic (4) and 12-ketocholic (5) acids) only an unexpected ester formation took place giving esters 6, 12, and 14. Cytotoxic activity against four tumor cell lines (human breast adenocarcinoma ER-, MDA-MB-231; breast adenocarcinoma ER+, MCF-7; cervix epiteloid carcinoma, HeLa S-3; and prostate cancer, PC-3) was evaluated. Conjugate 8 showed strong activity against HeLa S-3 and conjugate 11 for PC-3. Ethyl ester of 12-ketocholic acid 14 showed very strong antiproliferative activity against MCF-7 and HeLa S-3