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The cathodoluminescence and photoluminescence spectra of cubic boron nitride doped with beryllium under high-pressure and high-temperature conditions are investigated. It is revealed that, upon doping of cubic boron nitride with beryllium, the cathodoluminescence spectra exhibit a broad stable band. An increase in the impurity content leads to a shift in the position of the maximum of this band toward the short-wavelength range from ~315 to ~250 nm and to a change in the crystal color from dark yellow to blue. The structure, the intensity, and the position of the band at the maximum are studied as a function of the temperature of the cathodoluminescence measurement. The nature of the band is tentatively interpreted in the framework of the model of recombination at defects of the donor and acceptor types. It is assumed that several overlapping subbands which are associated with differently charged acceptor levels of beryllium are located in the vicinity of the valence band in the electronic structure of the doped cubic boron nitride. It is found that the photoluminescence spectra of single crystals of the doped cubic boron nitride contain three previously unknown zero-phonon lines at energies of 2.135, 2.270, and 2.600 eV. 相似文献
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E. M. Shishonok 《Journal of Applied Spectroscopy》2004,71(6):880-887
The Raman spectra of single crystals of cubic boron nitride (cBN) doped with beryllium and also synthesized in the absence of dopants are investigated. It is shown that the wide bands at 215 and 535 cm–1 can be registered in the Raman spectra of the (
) faces of undoped cBN crystals and that the Be impurity penetrates into the cBN crystals predominantly in the direction of these faces. In the spectra of the investigated cBN samples doped with Be, the contour of the TO and LO phonon lines does not take the Fano shape, in contrast to diamond, which can point to an insufficient concentration of the dopant for attaining the Fano interference or to the absence of it in cBN. The wide bands have been investigated on the assumption that they are boson-like and result from small-size disorders in both undoped and doped cBN samples with the sp
3 bond deformed by Be.Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 71, No. 6, pp. 803–809, November–December, 2004.This revised version was published online in April 2005 with a corrected cover date. 相似文献
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E. M. Shishonok L. Trinkler S. V. Leonchik B. Berzinya 《Journal of Applied Spectroscopy》2008,75(4):567-575
Under high pressure and temperature conditions, we have obtained samples of thulium-activated cubic boron nitride in the form
of micropowders, ceramics, and polycrystals activated by thulium in the presence of aluminum. We studied the cathodoluminescence
(CL), photoluminescence (PL), and photoluminescence excitation spectra of the samples. In the luminescence spectra we observe
structured bands with maxima at ∼370, ∼475, ∼660, and ∼ 800 nm, assigned to electronic transitions in the triply charged thulium
ions. We have established that the most efficient method for excitation of “blue” luminescence at ∼475 nm for thulium ions
in cBN is excitation by an electron beam. The cBN samples synthesized in the presence of Al have photoluminescence spectra
with a more complex structure compared with samples not containing Al, with the band of dominant intensity at about 660 nm.
Hypothetically, this is a consequence of incorporation of thulium ions into the crystalline phases cBN and AlN, which are
equally likely to be formed during synthesis. The observed photoluminescence spectrum of the indicated samples is the superposition
of the photoluminescence spectra of the Tm3+ ions located in the crystal fields of cBN and AlN of different symmetries. The presence in the photoluminescence excitation
spectra (at 450, 490, and 660 nm) of structure, with features at wavelengths shorter than the excited photoluminescence, suggests
a nonresonant mechanism for its excitation. We have established that luminescence of Tm3+ ions is less intense than for other rare earth elements incorporated into cubic boron nitride.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 4, pp. 547–555, July–August, 2008. 相似文献
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Under high pressure conditions, we have obtained samples of samarium-activated cubic boron nitride in the form of micropowders,
ceramic samples, and polycrystals having high-intensity discrete photoluminescence in the red region of the spectrum that
is stable in the temperature range 6 K to 300 K and is assigned to internal f-f electronic transitions in the Sm3+ ions. The materials obtained on the basis of cBN are intended for use as phosphors and light emitters (sources of red light)
having thermal and chemical stability.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 1, pp. 88–93, January–February, 2008. 相似文献
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E. M. Shishonok 《Journal of Applied Spectroscopy》2007,74(2):272-277
Complex and multiband photoluminescence spectra for GB and HBN centers in single crystals of cubic boron nitride (cBN) were
recorded in the wavelength ranges 385–400 nm and 365–395 nm and the nature of these centers was studied. The use of models
involving resonance vibrations and strongly shifted configuration diagrams for the electronic ground state and excited state
made it possible to associate formation of the GB-1 center with the presence of tungsten impurity in cBN. It was established
that the HBN band in the 300–350 nm range of the cathodoluminescence spectra of cBN polycrystals, single crystals, and micropowders
is associated with luminescence centers present in microinclusions of graphite-like boron nitride (hBN). The nature of the
hBN band is tentatively interpreted within the model of recombination of donor and acceptor defects in hBN: respectively nitrogen
vacancies and carbon atoms in positions substituting for nitrogen.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 2, pp. 241–246, March–April, 2007. 相似文献
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Polycrystalline cubic boron nitride prepared with cubic-hexagonal boron nitride under high pressure and high temperature 下载免费PDF全文
Polycrystalline cubic boron nitride(Pc BN) compacts, using the mixture of submicron cubic boron nitride(c BN) powder and hexagonal BN(h BN) powder as starting materials, were sintered at pressures of 6.5–10.0 GPa and temperature of1750℃ without additives. In this paper, the sintering behavior and mechanical properties of samples were investigated.The XRD patterns of samples reveal that single cubic phase was observed when the sintering pressure exceeded 7.5 GPa and h BN contents ranged from 20 vol.% to 24 vol.%, which is ascribed to like-internal pressure generated at grain-to-grain contact under high pressure. Transmission electron microscopy(TEM) analysis shows that after high pressure and high temperature(HPHT) treatments, the submicron c BN grains abounded with high-density nanotwins and stacking faults, and this contributed to the outstanding mechanical properties of Pc BN. The pure bulk Pc BN that was obtained at 7.7 GPa/1750℃ possessed the outstanding properties, including a high Vickers hardness(~ 61.5 GPa), thermal stability(~ 1290℃ in air),and high density(~ 3.46 g/cm~3). 相似文献
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Studying the surface properties of cubic boron nitride (c-BN) thin films is very important to making it clear that its formation mechanism and application. In this paper, c-BN thin films were deposited on Si substrates by radio frequency sputter. The influence of working gas pressure on the formation of cBN thin film was studied. The surface of c-BN films was analyzed by X-ray photoelectron spectroscopy (XPS), and the results showed that the surface of c-BN thin films contained C and O elements besides B and N. Value of N/B of c-BN thin films that contained cubic phase of boron nitride was very close to 1. The calculation based on XPS showed that the thickness of hexagonal boron nitride (h-BN) on the surface of c-BN films is approximately 0.8 nm. 相似文献
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R.M. Chrenko 《Solid State Communications》1974,14(6):511-515
Ultraviolet absorption spectra of cubic boron nitride crystals indicate a minimum value for the band gap of 6.4 ± 0.5 eV. This value is in good agreement with a previously reported maximum value of 6.0 ± 0.5 eV obtained experimentally from soft X-ray spectra. Infrared absorption spectra differ significantly from previously published data. 相似文献
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de Koker N 《J Phys Condens Matter》2012,24(5):055401
Due to its large pressure range of stability and inert nature, cubic boron nitride has been proposed as a potential pressure standard for high pressure experiments. It is extremely refractive upon compression, although its melting temperature is not known beyond 10 GPa. We apply first-principles molecular dynamics to evaluate the thermodynamics of zincblende structured (cubic) and liquid boron nitride at extreme temperatures and pressures, and compute the melting curve up to 1 TPa by integration of the Clapeyron equation. The resulting equations of state reveal that liquid boron nitride becomes denser than the solid phase at pressures of around 0.5 TPa. This is expressed as a turnover in the melting curve, which reaches a maximum at 510 GPa and 6550 ± 700 K. The origin of this density crossover is explained in terms of the underlying liquid structure, which diverges from that of the zincblende structured solid as the phases are compressed. 相似文献
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We compare the near edge structure (NES) of cubic boron nitride (cBN) measured using both electron energy loss spectroscopy (EELS) and X-ray absorption spectroscopy (XAS) with that calculated using three commonly used theoretical approaches. The boron and nitrogen K-edges collected using EELS and XAS from cBN powder were found to be nearly identical. These experimental edges were compared to calculations obtained using an all-electron density functional theory code (WIEN2k), a pseudopotential density functional theory code (CASTEP) and a multiple scattering code (FEFF). All three codes were found to reproduce the major features in the NES for both ionisation edges when a core-hole was included in the calculations. A partial core hole (1/2 of a 1s electron) was found to be essential for correctly reproducing features near the edge threshold in the nitrogen K-edge and to correctly obtain the positions of all main peaks. CASTEP and WIEN2k were found to give almost identical results. These codes were also found to produce NES which most closely matched experiment based on χ2 calculations used to qualitatively compare theory and experiment. This work demonstrated that a combined experimental and theoretical approach to the study of NES is a powerful way of investigating bonding and electronic structure in boron nitride and related materials. 相似文献
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Current-voltage characteristics (CVC) of synthetic semiconductor diamonds are presented. In certain low-resistance specimens at definite temperature intervals an N-type CVC is found. Investigations performed permit a qualitative explanation of the majority of CVC peculiarities, and determination of the boron acceptor impurity activation energy Ea = 0.36 eV.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 7–12, September, 1978.In conclusion the authors thank Yu. M. Rotner for presenting the synthetic semiconductor diamonds which were studied. 相似文献
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The properties of diamond as a new material for semiconductor electronics have been studied insufficiently at present. One of the most powerful techniques for study of impurity centers is the method of thermostimulated conductivity (TSC).Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 130–132, September, 1978.In conclusion, the authors thank Yu. M. Eotner for providing the synthetic semiconductor diamond specimens for measurement. 相似文献
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The structural characteristics and chemical, morphological, and optical properties of cBN and cBN:Gd micropowders are studied by x-ray diffraction, energy-dispersive electron probe microanalysis (x-ray spectral microanalysis), and photoluminescence techniques. Cubic boron nitride (cBN) micropowders were synthesized at high pressures and temperatures from hexagonal boron nitride (hBN) micropowder and Li3N catalyst. cBN:Gd micropowders were synthesized from mixtures of hBN, Li3N, and GdF3 micropowders. A lattice parameter of a~3.615 ? is calculated for both types of powder (cBN and cBN:Gd). The photoluminescence spectra of the cBN:Gd powder are found to contain emission lines attributable to intracenter optical transitions of Gd3+ ions. 相似文献
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On the basis of the known reflection spectrum, we calculate a complete set of fundamental optical functions for cubic boron
nitride (c-BN) in the region of 2–23 eV. The integral spectrum of dielectric permeability is decomposed into 16 elementary
components. Three main parameters (maximum energy, half-width, and oscillator force) for each of the components are determined.
Using the well-known theoretical calculations for bands of boron nitride as the base we suggest a scheme of the nature of
these dielectric permeability components.
To whom correspondence should be addressed.
Udmurtiya State University, 1, Universitetskaya Str., Izhevsk, 426034, Russia:e-mail: sobolev@matsim.udmurtia.su. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 4, pp. 579–583, July–August, 1999. 相似文献
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Cubic boron nitride (c-BN) films are prepared by the radio frequency magnetron sputtering technique. The stresses and crystallinities of the films are estimated by the Fourier transform infrared spectroscopy of c-BN samples, including the peak shifts and varieties of full widths at half maximum. The effects of the B-C-N interlayer and the two-stage deposition method on the c-BN films are investigated. Then the thick and stable c-BN films are prepared by a combination of the two methods. The properties of the interlayer and film are also characterized. 相似文献
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