Browsing by Author "Ketrush, Petru"

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COORDINATION PECULIARITIES OF THE SALICYLALDEHYDE S-METHYLISOTHIOSEMICARBAZONE IN THE PALLADIUM COMPLEXES
(Academia de Ştiinţe a Moldovei, 2006) Revenco, Mihail; Bourosh, Pavlina; Duca, Gheorghe; Simonov, Yurii; Bulmaga, Petru; Jora, Elena; Gdaniec, Maria; Ketrush, Petru
Two coordination modes of salicylaldehyde S-methylthiosemicarbazone (Me-S-HSATSC-NH2) have been observed in the palladium complexes with this ligand. The interaction between Me-S-HSATSC-NH2 and tetrachloropalladate gives rise to the formation of a compound of the composition Pd(Me-S-SATSC-NH2)Cl which one has a planar structure. The organic ligand behaves as a monodeprotonated acid coordinated by O,N,S donor atoms set. This is the only case when the thioalkylated thiosemicarbazone uses the sulfur atom for coordination. The forth position in the coordination polyhedron of the complex is occupied by the chloride ion.figureMolecular structure of [Pd(Me-S-SATSC-NH2)Cl] and [Pd(Me-S-SATSC-N-NO)NO2]When the solution of K2[Pd(NO2)4] was treated with Me-S-HSATSC-NH2, the organic reagent undergoes a more dramatic chemical transformation carrying out to the formation of a new derivative of thiosemicarbazide – nitrozothioamide Me-S-SATSC-N-NO. The newly synthesized organic reagent is a monodeprotonated acid bound via O,N,N donor set, while the alkylated sulfur atom is uncoordinated. The forth site is occupied by NO2-ion coordinated by nitrogen atom (see fig.). The possible causes, driving the system to the formation of nitrosothioamide, and the impact of the anion on the coordination mode of the organic ligand will be discussed.
ELECTRICAL AND PHOTOELECTRICAL PROPERTIES OF CdS/Cd 1-x Mn x Te HETEROJUNCTIONS
(CEP USM, 2015) Gashin, Petru; Nicorich, Valentin; Cuznetsova, Snejana; Ketrush, Petru; Sumn, Victor
Electrical and photoelectrical properties of CdS/Cd1-xMnxTe heterojunction at different temperatures from 293 K to 393 K were studied. The potential barrier at 293 K makes 0,78 V and is linearly decreasing with temperature increase with a temperature coefficient of 5,5·10-3 V·K-1. From lnIinv= f(1/T) dependence at U=1V the activation energy of 0,61 eV was determined. CdS/Cd0,6Mn0,4Te heterojunction spectral sensitivity at 300 K covers the wavelength region.
INFLUENCE OF DEFECT COMPOSITION ON OPTICAL ACTIVITY OF Mn 2+ IONS IN ZnS CRYSTALS
(2005) Korotkov, Vitalii; Sobolevskaya, Raisa; Bruk, Leonid; Sushkevich, Constantin; Ketrush, Petru; Dubrovin, A.
The Mn Zn2+ ion intracentred luminescence in ZnS crystal (max=590nm, FWHM=160-210meV) and its relation to the native, impurity (the background and aluminum) defects formed at the crystal annealing in the bismuth melt at 950oC during 100hrs was studied. The luminescence of the aluminum doped and undoped ZnS single crystals , before and after annealing, were studied. The aluminum presence on the one hand creates sensitizing centers (the radiation bands close to 400nm and 450nm) and on the other hand makes difficult Mn doping of the crystal. It is supposed that the temperature influence on the Mn Zn2+ ion is determined by the position of the electron and hole Fermi cuazi-levels relative to the deep levels, acting as recombination radiative and noneradiative centers the nature of which is determined by the type of crystal lattice defects. The relation between blue centers of recombinative radiation and Mn bands was shown
STUDIES OF VANADIUM AND VANADIUM OXIDE BASED NANOCOMPOSITE STRUCTURES
(2017) Prilepov, Vladimir; Gashin, Peter A.; Popescu, Mihai; Zalamai, Victor; Spoiala, Dorin; Ketrush, Petru; Nasedchina, Nadejda
The results of the surface morphology studies as well as optical and electrical properties of nano-dimensional vanadium oxide composite structures deposited on various substrates- silica, glass substrates covered by conducting layer of SnO2, pure pyroceramics plates and the same covered by Al2O3, SiO2, Ta2O5 layers are presented. According to Raman spectroscopy results the thin film structure obtained on quartz corresponds to the -V2O5 orthorhombic phase. In contrast with this the Raman spectra of V2O5 films obtained on pyroceramics substrates, passivated by Al2O3, Ta2O5, SiO2 oxides, do not appear clearly marked narrow lines which indicate their amorphous character. The investigation of the optical properties of the fabricated layers in the spectral range of 200-1000 nm had revealed the presence of both allowed direct and indirect electron transitions. In the frequency range of 103-107 Hz the real Z' and imaginary Z'' part of the total impedance of pyroceramics/Al2O3/Al/V2O5/Al structure were studied. The applied direct bias leads to a considerable Z', as well as Z'' decrease. The analysis of the obtained dependencies is carried out by using the method of equivalent circuits.
TECHNOLOGY OF VANADIUM AND ITS OXIDES BASED NANOCOMPOSITE STRUCTURES
(INOE Publishing House, 2014) Prilepov, V.; Gasin, Petru; Chirița, Arcadii; Midoni, V.; Spoiala, Dorin; Ketrush, Petru
The peculiarities of vanadium and its oxides based nanocomposite structures fabrication are brought in this paper. The selected fabrication technological conditions allow creating a V2O5 based dielectric matrix in which conducting clusters are uniformly distributed. Some optical and electrical properties of such structures are presented. It was shown that the obtained layers possess high charge sensitivity.