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Calcium molybdate is considered as a very promising scintillator material for experimental studies of rare processes. This paper reports on the production and characterization of a 40Ca100MoO4 scintillator. Using the Czochralski technique, a crystal of high optical quality with total mass 0.55 kg, 42 mm diameter (minimum) and 53 mm 1ength of the cylindrical section was produced from isotopically enriched raw materials, containing 96.1% of 100Mo and 99.964% of 40Ca. To satisfy the requirement of low intrinsic radioactivity the purity of the materials was monitored at different stages of the production process and it is shown that the concentration of 238U and 232Th in the final crystal does not exceed 0.05 ppb. The scintillation properties of 40Ca100MoO4 were measured over the 8 - 300 K temperature range and it is found that the light yield of the 40Ca100MoO4 crystal is very similar to that of the CaMoO4 reference scintillator. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The prospects for the use of molybdates and tungstates in the opto-electronic devises prompted studies of the structure, as well as luminescence and scintillation properties of MgWO4-MgMoO4 system. The powder samples of (1-x)MgMoO4-xMgWO4 (x = 0; 0.01; 0.05; 0.1; 0.3; 0.5; 0.7; 0.9, and 1.0) were synthesised by the solid state reaction technique at 900?C. The results of the X-ray structure analysis identified three types of crystal structure in the pseudo-binary MgWO4-MgMoO4 system, i. e. -MgMoO4, cuprosheelite -MgMoO4, and wolframite MgWO4. It is shown that a single-phase solid solution MgMo1-xWxO4 with -MgMoO4 structure is formed at x < 0.10, whereas at higher concentration of tungsten the mixture of different phases is created. The phase composition of the sample determines the luminescence spectra; the maximum of the emission band is observed at 520 nm for β-MgMoO4, 590 nm for α-MgMoO4, and 480 nm for MgWO4. A possible correlation between the emission spectra and peculiarities of crystal structure are discussed in terms of the canonical configuration coordinate model. The emission efficiency of magnesium tungstate is found to be highest within the compounds under investigation. The scintillation light yield of MgWO4 at T = 295 K is found to be 0.90±0.15 of that of ZnWO4 and remains high with the decrease of temperature. [ABSTRACT FROM AUTHOR]

Oxide crystal scintillators play a considerable role in fundamental and applied researches. However, working out of new generation of high-sensitivity equipment and new methods of research puts higher requirements. The ZnBO4 (B = W;Mo) crystals were grown from charge in platinum crucibles with high frequency heating, using the Czochralski method. The raw powder with optimum composition was prepared by solid phase high temperature synthesis using ZnO and BO3 (B = W;Mo) with 4-5N purity. Single crystals with sizes up to ⊘50 × 100 mm were grown and scintillation elements of various sizes and shapes (cylinders, rectangular and hexahedron prisms) were produced. High spectrometric characteristics were obtained for ZnWO4:R = 8-10% under excitation by 137Cs (Eγ = 662 keV), low radiation background (less than 0.2 mBq/kg) and low afterglow (0.002%, 20 ms after excitation). The obtained results demonstrate good prospects for ZnWO4 and ZnMoO4 crystal scintillators for application in low-count rate experiments, searching for double beta decay processes, interaction with dark matter particles, and also studies of rare decay processes. The material has also a good potential for application in modern tomography, scintillation bolometers and for other major researches using scintillators. [ABSTRACT FROM AUTHOR]

In this study, we examined the luminescence response of Ti-doped Al2O3 crystals to high-energy vacuum ultraviolet (UV) excitation. In addition to the thoroughly studied emission band of Ti3+ in the near-infrared region and blue emission at 420 nm, we detected a UV emission band at 290 nm. The excitation spectra of all emission bands were measured over the 4–20 eV spectral range. Our results indicate that intrinsic anion defects are involved in the process of the excitation of the 420 nm emission assigned to the charge transfer transitions 2pO2-→3dTi4+. Analysis of the spectral and decay characteristics of the UV emission enables us to suggest that this band is associated with radiative decay of excitons localized at Ti ions. [ABSTRACT FROM AUTHOR]