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We propose a method for studying nonlinearity in the cathodoluminescence (CL) characteristics of wide-bandgap materials based on the measurements of the CL energy dependence on the total energy of a pulsed electron beam E b using its bremsstrahlung. It is shown that the x-ray radiant energy produced by a high-power (∼ 10 MW / cm 2) electron beam with particle energies of 50–300 keV is proportional to E b in the case of weak variations in the electron energy distribution of the beam. This direct proportionality between E b and the x-ray radiant energy is experimentally confirmed in the current experiment by measuring the dependence of the molecular nitrogen emission radiant energy at 337 nm excited by a direct electron impact (the 0-0 vibrational transition of the second positive system of the emission bands of N 2 molecule) on the total electron beam energy E b. Using this result, the dependencies of the CL radiant energy on E b are studied for undoped Bi 4 Ge 3 O 12 , PbWO 4 , CeF 3 , and BaF 2 crystals with bright intrinsic luminescence. An interpretation of these dependencies is given using a simple theoretical model and photoluminescence nonlinearity data published in the literature. We estimate the average concentration of the electronic excitations (EE) provided by the electron beam (10 18 – 10 19 e.– h. p. / cm 3) and obtain the approximate dependencies of the CL yield on the EE density for the studied materials. For the CeF 3 crystal, different CL yield dependencies on the EE density are found for the bands at 300 and 350 nm. [ABSTRACT FROM AUTHOR]

Mesoporous crystalline BaF 2 nanopowder with a specific surface area of up to 34.8 m2/g was produced by a pulsed electron beam through the evaporation of targets of micro-sized BaF 2 powder with optical purity (S red = 0.38 m2/g). The texture and thermal features of the BaF 2 nanopowder (before and after annealing in air at a temperature of 200 °C) and some properties of compacts made of the BaF 2 nanopowder by magnetic-pulse compaction and static pressing were studied. Glassy, opaque, and black compacts, which are promising materials for use as scintillators and dosimeters, were produced by magnetic-pulse compaction in a vacuum at a temperature of about 425 °C. It was found that heating up to 425 °C is sufficient for removing defects in nanopowders. The effect of pressing methods on the pulsed cathodoluminescence and photoluminescence spectra of the compacts was studied. Luminescent properties were found to depend on pressing technology. It was also determined that surface color centers, the number of which decreases during heating, are responsible for the pulsed cathodoluminescence band near ∼560 nm. [ABSTRACT FROM AUTHOR]