Electrical relaxation and the strong-field effect when injection currents are present in metal-oxide-semiconductor systems

The transient currents and stationary current-voltage characteristics of Ta-Ta₂Q₅-MnO₂ systems with negative tantalum polarity are considered. It is shown that in this case space-charge limited currents flow through the system with an exponential distribution of the trap energy when there are deep donor centers. In the intensefield region the Poole-Frenkel effect begins to have an important effect on the injection currents. An appropriate theory is developed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 94–97, May, 1981.     

Electrical strength of oxide films on metals

Electrical breakdown under dc stress is examined for anodic oxide films on tantalum and zirconium of 100–5000 Å thickness. It is found that the strength is greater for the thinner films, which points to an ionization breakdown mechanism. It is considered that allowance must be made for electron traps and formation of a negative space charge in discussing the breakdown of amorphous oxide films.     

Strong field effects in MOS systems containing compensated donors and traps distributed in energy

The current-field temperature relationships of the Ta-Ta₂O₅-MnO₂ system are studied when the tantalum has positive polarity. It is demonstrated that the conductivity of such systems is determined by the Poole-Frenkel effect (PFE) for partially compensated donors. We compare our results with previous results [9]. A theory of the PFE is developed for a model which includes traps with an exponential energy distribution; acceptors, and deep discrete donors.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 3–6, October, 1981.     

Synthesis,spatial structure,and biological activity of 1-AZA-4-oxabicyclo[4.1.0]heptan-5-ones

It has been found that the reaction of - and -amino alcohols with methyl 1,2-dibromopropionate results in the formation of esters of 1-(hydroxyalkyl)aziridine-2-carboxylic acids or 1-aza-4-oxabicyclo[4.1.0]pentan-5-ones, depending on the nature of the original reactants. An x-ray structural analysis of this new bicyclic system has been carried out. The hepatoprotector activity of the new compounds has been studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1349–1354, October, 1984.     

Synthetic,Structural, and Spectroscopic Investigations of K3Nb8O21‐type Complex Oxides K3MTa7O21 (M = Ti,Zr)

Potassium‐containing zirconium(IV)/titanium(IV) tantalum(V) oxides, K₃TiTa₇O₂₁ ( 1 ) and K₃ZrTa₇O₂₁ ( 2 ), of K₃Nb₈O₂₁‐type of compounds are afforded from potassium‐molybdate flux. Both compounds crystallize in the hexagonal space group P6₃/mcm (no. 193) with a = 908.69(2), c = 1202.83(7) pm and c/a = 1.324 (Z = 2) for 1 and a = 913.30(3), c = 1219.21(6) pm and c/a = 1.335 (Z = 2) for 2 , respectively. The Structural motif of [MTa₇O₂₁]^3– (M = Ti⁴⁺ or Zr⁴⁺) consists of edge‐shared (M,Ta)₆O₂₄‐units that are similar to corner‐sharing Ta₆O₂₇ units of synthetic soro‐silicate K₃Ta₃Si₂O₁₃ and double borate K₃Ta₃B₂O₁₂. The solid state bandgap measurements revealed that calculated values (3.26 eV for K₃TiTa₇O₂₁ and 3.14 eV for K₃ZrTa₇O₂₁) are dependent on aperture of Ta–O–Ta bond angle as it was previously shown for perovskite‐type tantalate photocatalysts.