Спектрально-люминесцентные свойства стекол системы (Y-=SUB=-1-x-=/SUB=-Yb-=SUB=-x-=/SUB=-)-=SUB=-2-=/SUB=-О-=SUB=-3-=/SUB=--Al-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=--В-=SUB=-2-=/SUB=-О-=SUB=-3-=/SUB=--SiO-=SUB=-2-=/SUB=- + Cr-=SUB=-2-=/SUB=-О-=SUB=-3-=/SUB=-+Na-=SUB=-2-=/SUB=-О

Fused yttrium-alumoborate glasses doped with ytterbium, silicon, chromium, and sodium were synthesized. The influence of the matrix on the "spectroscopic behavior" of chromium ions and the efficiency of their sensitization of Yb3+ luminescence was established by spectral-luminescence and EPR-studies. It was found that (1) chromium in alkali-free glasses is mainly in the oxidation degree Cr(III) with an appreciable admixture of Cr(IV) and Cr(V), (2) the partial replacement of Al2O3 or B2O3 by SiO2 and Y2O3 by Yb2O3 affects to a different extent the relative concentration of optical centers of chromium ions, (3) the addition of alkali results in the formation of Cr(VI) centers as a result of oxidation of less charged chromium ions and predominantly tetracoordinated Cr4+ and Cr5+, (4) Cr3+ ions make the main contribution to the luminescence sensitization of Yb3+ ions, while Cr4+ ions and to a lesser extent Cr5+ play the role of luminescence quencher and internal filter. Sensitization of Yb3+ luminescence through the charge transfer band in Cr(VI) was found. An alkaline glass doped with Cr and Yb upon excitation through the sensitizer produced a luminescence quantum yield of 32% and the conditions for its enhancement were considered. It is shown that the temperature quenching of luminescence of CrYb-containing glasses is significantly lower than that of Cr-containing glasses.

Comparison of the Hardness-Toughness Relationship of Medium-Mn Steels after Q&T and Q&P Treatments*

In contrast to quenching and tempering (Q&T), with quenching to room temperature, quenching and partitioning (Q&P) usually applies quenching to a temperature between Ms and room temperature. To stabilize a sufficient amount of retained austenite (RA), carbon diffusion from martensite into austenite and a prevention of cementite formation takes place during the successive partitioning step. Larger amount of RA, and its transformation into martensite during plastic deformation, provides Q&P treated steels with an enhanced combination of strength and ductility. In this investigation, the effect of different Q&T and Q&P treatments on the hardness-toughness relationship was determined. These results are compared with the RA contents and mechanical properties provided by tensile testing. The obtained results clearly demonstrate that the optimum parameters for strength and ductility do not match with the best combinations of hardness and toughness. Furthermore, the stability of the RA plays an important role in the understanding of toughness properties of the investigated Q&P steels.

Зависимость характеристик узких линий люминесценции в наноалмазах от параметров возбуждения и температуры

The influence of the excitation parameters and temperature on the spectral characteristics of narrow photoluminescence lines in nanodiamonds obtained by chemical vapor deposition is investigated. It is shown that the ratio of the line intensities in the spectrum depends on the wavelength and power of the excitation radiation. For some lines, with increasing power, a shift in the position of their maximum and broadening is also observed. After irradiation of nanodiamonds with a laser beam with a power density of ~1.2·105 W/cm2, the relative line intensities change. With increasing temperature in the range 79 - 300 K, temperature quenching of their intensity is observed.

Влияние дополнительной имплантации ионов кислорода на дислокационную люминесценцию кремния, содержащего кислородные преципитаты

Dislocation-related photoluminescence is studied in unimplanted and implanted with oxygen ions silicon wafers after multistage heat treatment, used for the formation of internal getter in microelectronics, and final annealing at 1000°С in a chlorine-containing atmosphere. In unimplanted sample, the dislocation-related luminescence line D1 dominates and its intensity is more than one order of magnitude in comparison with another dislocation-related luminescence line D2. With increasing temperature, an intensity of the D1 line increases and then decreases. In implanted sample, the intensities of the D1 and D2 lines increase. For both the lines, temperature quenching of their intensities is observed only. The energies of quenching and increase of the intensities of dislocation-related photoluminescence lines are determined. Possible reasons of observed effects are discussed.