Pure KDP single crystals and KDP crystals doped with TiO 2 nanocrystals were grown by the method of temperature reduction from aqueous solutions. Adsorption of the phosphate-ions on the surface of TiO 2 particles was studied by FTIR spectroscopy. It was shown that the nanoparticles with adsorbed H 2 PO 4 – and (H 2 PO 4 ) 2 2– anions were incorporated predominantly into the positively charged face (1 0 1) of the pyramidal sector of KDP. High-resolution X-ray three-crystal diffractometry (TCD) investigation of the as grown samples of KDP + TiO 2 revealed the presence of the turns of the growth layer “stacks” up to 3 arcsec in the growth sectors {1 0 0} and {1 0 1}. The observed thickness of these “stacks” was of the order of 20–30 μm. For KDP + TiO 2 crystals there was found a relative change of the crystal lattice parameter (Δ d / d ) caused by incorporation of TiO 2 nanoparticles into the boundaries of the growth layers. This gave rise to the formation of a semicoherent binding on the interface between the captured TiO 2 and the matrix. No essential influence of the nanoparticles on the laser damage threshold of KDP with 10 −5 wt.% of TiO 2 was established. PACS 81.10.Dn Keywords A. Optical materials B. Crystal growth D. Adsorption D. Optical properties 1 Introduction Single crystals of potassium dihydrogen phosphate (KDP, KH 2 PO 4 ) possessing a unique set of physical properties have found wide applications in optoelectronics and nonlinear optics [1] . A promising trend in the development of up-to-date functional optical materials based on dielectrics is incorporation of nanoparticles into the crystalline matrixes of traditional nonlinear optical materials, for the improvement of the efficiency of their nonlinear optical response. For instance, it is expedient to use metal oxide nanoparticles, such as TiO 2 nanocrystals, with high concentration of free carriers (conduction electrons) on their surface. Due to their ultrafast nonlinear optical response, these composite materials can serve as advanced nonlinear optical elements which provide efficient conversion of high-power pico- and femtoseconds laser radiation. Thereat, it is necessary to find such a concentration of nanoparticles in the matrix which simultaneously provides high optical characteristics and advanced functional properties of the material. Possible ways for increasing the efficiency of the conversion of laser radiation by structural modification of the known nonlinear optical single crystals (KDP, ADP, LiNbO 3 ) were examined by a number of research groups [2–6] . In particular, an attempt to obtain combined optical media (KDP + SiO 2 ) possessing the properties of both active lasing and nonlinear-optical media was made by Rudneva et al. [7] . In this paper the influence of the size of SiO 2 particles on the probability of their capture was considered, and it was shown that the growing crystal effectively captured 1 × 10 −2 –250 μm SiO 2 particles. In the paper by Elim et al. [8] devoted to the study of the synthesis and physical properties of the nanocomposite polymethyl methacrylate/TiO 2 , the synthesized material was shown to have high values of the cubic nonlinear optical susceptibility (∼10 −9 CGSE units) and ultrafast nonlinear optical response. Such characteristics make it possible to use this nanocomposite as an efficient nonlinear optical switch. Creation of bulk holographic matrixes with high diffraction efficiency on the basis of the combination of a photopolymer matrix and titanium dioxide nanocrystals was reported by Smirnova et al. [9] . The aim of our work was the obtaining of a composite on the base of nonlinear optical KDP matrix with incorporated ТiO 2 nanoparticles. The mechanism of incorporation of titanium dioxide nanoparticles into the prismatic and pyramidal growth sectors of the matrix was considered. The performed detailed analysis of the vibrational and optical spectra of pure KDP and KDP + TiO 2 revealed the changes caused by the incorporation of TiO 2 . The effect of nanoparticles on the structure perfection and laser damage threshold of KDP was studied. 2 Experimental Pure KDP and KDP + TiO 2 crystals were grown from supersaturated aqueous solutions with pH 4.1 in the presence of trace amounts (5 × 10 −5 wt.%) of ions of trivalent transition metals. The acidity of 1 M KH 2 PO 4 solution was controlled by the addition of chemically pure solution of 1 M HCl acid. TiO 2 nanoparticles (15 nm) were synthesized by the sol–gel method: TiCl 4 were precipitated using ammonia, the resulting suspension was washed and subjected to super high frequency heating that led to the formation of pyrotitanic acid H 2 Ti 2 O 5 transformed into TiO 2 after annealing at 600 °С. The size of the nanocrystals was determined by the method of electron microscopy, and quantitative X-ray diffraction phase analysis of the synthesized TiO 2 nanopowder was carried out on a DRON-3М diffractometer in СоK α1 -radiation. It was shown that the experimental values of the interplanar spacing d and the diffraction line intensities completely agreed with the data from the file ASTM No. 04-0477 for the anatase modification of titanium dioxide. To prepare TiO 2 suspension in KDР solution, a weight of TiO 2 (0.08 g) was introduced into 10 ml of 1 M KH 2 PO 4 solution (рН 4.1), and then treated with ultrasound. During 3 h the suspension was agitated at 60 °С by a magnetic stirrer and stored for a day. Afterwards TiO 2 nanoparticles with adsorbed phosphate-ions were subjected to 5-stage rinsing with twice distilled water by centrifugation for the obtaining of (TiO 2 + phosphates) samples. Then the sample was placed in a weighing bottle and dried there at 115 °С. In addition, (TiO 2 + KH 2 PO 4 ) sample was prepared by drying TiO 2 + KH 2 PO 4 suspension (without washing the particles) during 6 h at 115 °С after moisture evaporation. The KH 2 PO 4 + TiO 2 suspension to be used for the growth of the crystals was prepared as follows. A weight of TiO 2 nanoparticles preliminarily dispersed in 10 ml of twice distilled water was added to the solution of 40 g of KDP salt in 100 ml of water at Т = 65 °С. Then the suspension was dispersed again and placed into a glass crystallizer after termination of the process of seed regeneration. Pure KDP and KDP crystals containing TiO 2 nanoparticles (10 −5 –10 −2 wt.%) were grown by the method of temperature reduction in the crystallizer (2000 g of KDP salt were dissolved in 5 L of twice distilled water). The growth solution was stirred at a velocity of 76 rpm. The saturation temperature was 51 ± 0.1 °C ( σ * ∼2/3%), the growth temperature ranged between 51 and 24 °C, and the mother liquor acidity pH 4.1. The final size of the grown crystal was ∼60 mm × 60 mm × 70 mm, the average growth rate ∼3 mm day −1 in both [0 0 1] and [1 0 0] directions. The concentration of TiO 2 was found not to influence the solution pH, saturation temperature and crystal morphology. The Fourier transform infrared spectra of the crystals and of the powders were recorded at room temperature in 400–4000 cm −1 region using Spectrum One PerkinElmer by the KBr pellet technique, the solutions were analyzed in zinc selenide cuvette. The UV–vis–IR absorption spectra for all the samples were registered by a Lambda 35 PerkinElmer spectrophotometer in the direction of the optical axis [0 0 1]. The influence of nanocrystalline anatase particles on the structure perfection of the matrix was investigated on a X-ray three-crystal diffractometer (TCD) [10] . For adequate characterization of the real structure of the crystals [11] the following parameters were chosen: the rocking curve halfwidth β , arcsec; the integral power of X-ray reflection I R and the relative change of the crystal lattice parameter Δ d / d measured by the method [12] . The laser damage threshold of the samples was investigated at the wavelength of the first harmonic of Nd:YAG 3+ laser. During of the measurements the energy of single-mode laser radiation pulse was 2.75 μJ, the frequency of pulse repetition equalled 1 Hz, the pulse duration τ = 10 ns, λ = 1.064 μm. The measurements were carried out on 10 mm × 10 mm × 10 mm samples cut out of the crystal growth sectors {1 0 0} and {1 0 1}. 3 Results and discussion 3.1 Adsorption of phosphate-ions from aqueous solution by TiO 2 nanoparticles A typical FTIR-spectrum of TiO 2 nanoparticles is presented in Fig. 1 a . The maximum at 650 сm −1 may be connected with the stretching mode vibration of Ti–O–Ti [13] . It is known that the basic vibrations of TiO 2 nanocrystals in the FTIR spectra have the bands caused by the stretching vibrations of Ti–O bonds (550–653 сm −1 ) and the stretching vibrations Ti–O–Ti (436–495 сm −1 ) [14] . The deformation vibrations of the bands (Ti–O–H) on the surface of the nanoparticles give rise to the absorption in 700–1000 сm −1 spectral range. The latter shows vibrations of the surface groups caused by the local defects, the presence of hydroxyls and metal–oxygen bonds on the oxide surface, as well as of different dopants which nature and concentration depend on the technology of TiO 2 synthesis and subsequent treatment. As reported by Bezrodna et al. [14] , the FTIR spectrum of anatase has a three-component band with maxima at 1048, 1137 and 1222 сm −1 corresponding to the spectral range of Ti–O–H deformation vibrations. Subsequent thermal treatment diminishes the intensity of the peak at ν = 1222 сm −1 , caused by the deformation vibrations of ОН-groups, bounded to the surface adsorbed water molecules by weak hydrogen bonds. The band in 3000–3700 сm −1 region with a maximum at 3417 сm −1 ( Fig. 1 a) is characteristic of stretching vibrations of free hydroxyl groups, and may be connected with their presence, as well as with H 2 O molecules which have hydrogen binding with hydroxyl OH − groups on the TiO 2 surface [13–16] . The hydroxyl groups which form weak hydrogen bonds result in the shift of the bands towards longer wavelengths [16] . The absorption at 1640 сm −1 is assumed to be the deformation vibration of the bond Н–О–Н of physically adsorbed water molecules [16] . The presence of СО 2 adsorbed from the atmosphere manifests itself in a very weak maximum of the absorption band at 1395 сm −1 for СО 3 2– ions [16] . Presented in [17] are the absorption maxima in the FTIR spectra of KH 2 PO 4 solution (рН 4.1) connected with H 2 PO 4 – vibrations at 1155, 1070, 945 сm −1 and in the vicinity of 874 сm −1 . These data are close to the ones obtained in the present research: 1158, 1079, 939 and 874 сm −1 . The positions of the maxima for the vibration modes of H 2 PO 4 2– salt and KDР crystals correspond to 1300, 1100, 916–895, 536 сm −1 and 1302, 1100, 905, 536 сm −1 , respectively ( Fig. 1 b). The FTIR spectrum of TiO 2 nanoparticles contains an absorption band with peaks at 1168, 1117 and 1050 сm −1 ( Fig. 1 c). When the phosphate-ions are adsorbed on the particles (even on the ones subjected to multiple washing by twice distilled water) the peak at 1117 сm −1 is shifted to 1106 сm −1 , the peak at 1168 сm −1 disappears, and a sloping region is formed at 1200–1106 сm −1 frequencies. Such a region is typical of KH 2 PO 4 salt ( Fig. 1 b). The peak at 1106 сm −1 is also observed in dried (TiO 2 + KH 2 PO 4 ) samples. The presence of the phosphate-ions on the surface of the nanoparticles TiO 2 shows itself in the absorption band at 536 сm −1 (curve 3, Fig. 1 c). The appearance of such a peak which is also characteristic of KDР salt and KDР crystal results from the deformation vibrations of H 2 PO 4 2– . After the 5-stage rinsing of (TiO 2 + phosphates) samples, the final filtrate does not show the presence of any absorption bands associated with the phosphates-ions ( Fig. 1 b). After the annealing of TiO 2 particles with adsorbed phosphate-ions at 500 °С during 3 h, the peak caused by the presence of these ions disappears ( Fig. 1 d). This is connected with the transformation of KH 2 PO 4 salt into Kurrol's salt after the thermal treatment [18] . Phosphate adsorption on TiO 2 film from Na 2 HPO 4 solutions was reported in [19] . It was shown that the phosphate-ions adsorbed on TiO 2 film only at рН < 11, and predominantly on the positively charged surface. At high рН values there were observed three peaks (1085, 1037 and 980 cm −1 ), which transformed into two peaks at рН 5–6 and at lower рН values (1105 and 1022 сm −1 ). Thus, the surface of TiO 2 nanoparticles can effectively adsorb the phosphate-ions in KH 2 PO 4 solution ( Fig. 2 ). 3.2 Change of the charge state of TiO 2 surface in KH 2 PO 4 solutions The charge of the surface of oxide particles and their electrokinetic potential in water solutions are influenced by dissociation of the surface of МОН-groups (М = metal), adsorption of Н + and ОН – ions and the products of hydrolysis of water-soluble compounds. Under contact with water solutions, the surface of oxide metals (including TiO 2 ) dissociatively adsorbs water molecules, so the surface becomes covered with a layer of hydroxyl groups with a density of 2–10 ОН nm −2 [20] . Water molecules may be adsorbed on the surface defects (oxygen vacancies) due to the interaction with oxygen vacancies and subsequent dissociation [21–23] . Consequently, the proton is transferred to the oxygen atom located on the nanoparticle surface with subsequent formation of two hydroxyl groups [21,22] . The metal and oxygen atoms on the nanoparticle surface show the basic and acid character, respectively. Therefore, the molecules of water may give off the proton to the nearest surface oxygen atom, and this will be followed by the formation of two hydroxyl groups on the metal and oxygen atoms [21] . On the particle surface the hydroxyl groups enter the protolytic reactions with the solution, and the charge distribution becomes equilibrium [20] . The quantity of positively and negatively charged centers on the surface of the particles is the same at the zero charge point (рН zcp ). The surface of TiO 2 particles which are in contact with the solution acquires positive charge when the solution рН < рН zcp and negative charge at рН > рН zcp : Тi–OН + H + → Ti–OH 2 + Тi–OН + ОH → Ti–O – + Н 2 О Adsorption of anions by oxide surface is more probable in the case when the solution pH is less than рН zcp . As reported in [24] , anionic dye is adsorbed on TiO 2 particles predominantly in acid solutions, whereas cationic dye adsorption is observed in alkaline solutions. The value of рН zcp is 6.25 for TiO 2 surface [25] and 6.8 for the mixture of anatase and rutile [24] , depending on the experiment conditions. In the present work all the crystals were grown at рН 4.1, and TiO 2 particles were adsorbed predominantly by the positively charged face (1 0 1) of KDP crystal. This is obviously caused by the change of the particle charge under the influence of the growth solution. As is known, phosphates are adsorbed by the surfaces of iron, titanium, zirconium and aluminum oxides more effectively in comparison with other anions [20] , even in the case when the phosphate concentration is very low (0.001 M) [11,25] . Phosphate-ions are adsorbed on crystalline oxides in a wide range of solution рН, i.e., on the surfaces charged both positively (in this case adsorption is most probable) and negatively [19,20] . The process of adsorption may have either electrostatic or chemical nature [20,26] . Thus, as the surface is being saturated with anions, negative charge accumulates on the outer surface of the Stern layer [20] . At the formation of the internal anion–surface complexes the anion penetrates into the first coordination sphere of the metal ion on the oxide surface through the Stern layer, by substituting the coordinated hydroxyl group. In KН 2 РО 4 solution (рН4.1) the basic ions are H 2 PO 4 – and (H 2 PO 4 ) 2 2– [11] . The incorporation of TiO 2 nanoparticles into the solution leads to the adsorption of the phosphate-ions on the nanoparticle surface ( Fig. 2 ). This is probably due to the electrostatic interaction of the anions with the positively charged centers on the nanoparticle surface. As a result, the internal complexes of anions with the surface (mono-protonated Ti–ОРО 3 Н – and di-protonated Ti–ОРО 3 Н 2 ) are formed. The adsorbed phosphate-ions form hydrogen bonds with the phosphates contained in the solution, thus creating the second layer [27] . A very high concentration of КН 2 РО 4 solution in comparison with that of the nanoparticles, the presence of ions, or ionic pairs separated by the solvent and bound ionic pairs lead to their adsorption on the surface of TiO 2 particles and diminish the surface charge. So, in the process of KDP crystal growth the particles TiO 2 surrounded by the anions are captured by the crystallization front of the positively charged pyramidal face (1 0 1) between the growth layers ( Fig. 3 a ). 3.3 Matrix structure perfection, linear transmission spectra and laser-induced damage threshold of KDP + TiO 2 crystals The grown KDP + TiO 2 crystals have the so-called growth bands in the prismatic growth sectors in the crystallographic direction [1 0 0] and in the pyramidal growth sector [0 1 1] ( Fig. 3 a and b). The crystal grown from the solution with 10 −5 –10 −4 wt.% of the nanoparticles is transparent, whereas at 10 −3 wt.% of TiO 2 the growth bands become noticeable. The rocking curves show the turns of the growth layer stacks up to 3 arcsec ( Fig. 4 ) in the prismatic and pyramidal sectors. For pure KDP crystals such a behavior of rocking curves was not observed. The thickness of the growth layer stack (20–30 μm) was determined from the shape of the rocking curves. So, at the growth of KDP crystals with TiO 2 nanoparticles the latter are rejected by the crystallization front and then “captured” by the boundaries of the growth layer stacks, that obviously results in angular turns of the growth layer stacks. TiO 2 nanoparticles (15 nm) can be “captured” by the growing crystal with subsequent formation of a semicoherent boundary between the growth layer stacks, and the appearance of two-dimensional ordered distribution of the nanoparticles in the crystal. The presence of such semicoherent boundaries has no essential influence on the rocking curve halfwidth β , the integral reflection power I R and the crystal lattice parameter in the bulk of the growth layer stack ( Table 1 ). At the same time, for the KDP + TiO 2 samples there is established relative increase of the crystal lattice parameters Δ d / d along the growth layer stacks. This is caused by incorporation of anatase nanoparticles in the boundaries of layer-by-layer growth followed by the formation of semicoherent bonding with the crystal. The increase of the crystal lattice parameters revealed in the samples containing nanocrystalline anatase particles points to a change of the binding force in the crystal lattice of KDP + TiO 2 . The linear transmission spectra were measured on 0.8 mm thick plates of pure KDP and KDP + TiO 2 with polished (0 0 1) faces. The main optical loss in the visible and near IR regions is caused by the reflection of light from the input and output faces of the crystal. As seen from Fig. 5 , the samples cut out of the pyramidal sector {1 0 1} are characterized by high transmission, and have no peculiarities in the spectra (∼82% in the UV and ∼90% in the near infrared regions, respectively). For the growth sectors {1 0 0} of pure KDP, a characteristic decrease of the transition which makes ∼70% at 270 nm wavelength is observed in the UV region [28] . The rise of the absorption in the UV region [29,28] is defined by incorporation of the impurities contained in the initial salt into different growth sectors. In the visible and UV regions the transition spectra of the growth sectors {100} and {101} of the samples grown from the solutions containing 10 −5 wt.% of TiO 2 are similar to the spectra of pure KDP. With the rise of the nanoparticle concentration in the solution up to 10 −4 wt.% the transmission of the samples in vis–NIR spectral range increases. This is especially noticeable in the UV region for the growth sectors {1 0 0}, and seems to be connected with the resonance interaction of the inherent crystal defects and anatase nanocrystals. The crystals grown from the solutions with TiO 2 concentration of about 10 −3 wt.% have a large number of inclusions, predominantly in the pyramidal sector. This leads to the diminution of the total transmission value down to 50% due to effective scattering on optical inhomogeneities. The formation of cracks in the bulk of KDP-type crystals under laser irradiation is considered in [30] . The length of the formed cracks and, consequently, the size of the zone of destruction around the damage center depend on the mechanical strength of the crystals along certain crystallographic directions [30] . TiO 2 nanoparticles with a concentration of 10 −5 wt.% are found to have no essential influence on the laser damage threshold of KDP crystals. The rise of TiO 2 concentration up to 10 −4 –10 −3 wt.% decrease the laser-induced damage threshold by a factor of 3–3.5 in comparison with pure KDP both in the direction [0 0 1] and [1 0 0] ( Fig. 6 ). Thus, the probability of laser-induced damage rapidly increases with the rise of the fluence. It is obvious that TiO 2 nanoparticles are the centers responsible for the absorption which decreases the laser damage threshold. 4 Conclusions The method of FTIR-spectroscopy is used to study the adsorption of phosphate-ions on the surface of TiO 2 nanoparticles in supersaturated KH 2 PO 4 solution. It is established that the nanoparticles with adsorbed phosphate-ions are incorporated predominantly into the pyramidal growth sector of KDP crystals. Thus, TiO 2 nanoparticles are captured by the crystallization front and embedded between the growth layers. It is shown that the nanoparticles have no essential influence on the laser damage threshold of KDP with 10 −5 wt.% of TiO 2 . References [1] D. Eimerl Ferroelectrics 72 1987 397 [2] B. Kahr S.-H. Jang J. Anand Subromony M.P. Kelly L. Bastin Adv. Mater. 8 1996 941 [3] I. Pritula V. Gayvoronsky Yu. Gromov M. Kopylovsky M. Kolybayeva V. Puzikov A. Kosinova Yu. Savvin Yu. Velikhov A. Levchenko Opt. Commun. 282 2009 1141 [4] P. Kumaresan B.S. Moorthy P.M. Anbarasan J. Cryst. Growth 310 2008 1999 [5] G. Bhagavannarayana S. Parthiban S. Meenakshisundaram Cryst. Growth Des. 8 2008 446 [6] R.K. Choubey R. Trivedi M. Das P.K. Sen P. Sen S. Kar K.S. Bartwal R.A. Ganeev J. Cryst. Growth 311 2009 2597 [7] E.B. Rudneva V.L. Manomenova A.É. Voloshin A.A. Kaminskiǐ A.B. Vasil’ev B.V. Mchedlishvili Crystallogr. Rep. 51 2006 142 [8] H.I. Elim W. Ji A.H. Yuwono J.M. Xue J. Wang Appl. Phys. Lett. 82 2003 2691 [9] T.N. Smirnova O.V. Sakhno V.I. Bezrodnyj J. Stumpe Appl. Phys. B 80 2005 947 [10] V.F. Tkachenko M.A. Rom A.A. Babichenko V.P. Kuznetsov Instrum. Exp. Technol. 2 1992 277 [11] R.P. Pantaler O.M. Smirnova A.B. Blank Funct. Mater. 11 2004 784 787 [12] Patent А.С. SU 1702265 А1. [13] L. Zhao J. Yu J. Colloid Interface Sci. 304 2006 84 [14] T. Bezrodna G. Puchkovska V. Shymanovska J. Baran H. Ratajczak J. Mol. 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Potassium dihydrophosphate single crystals were grown from aqueous solutions onto a point seed using temperature reduction method by doping with different molar values of urea. The characterization of the grown crystals was made by visible and Fourier transform infrared spectroscopy, Vicker's hardness studies, X-ray powder diffraction, non-linear optical and laser damage threshold measurements. By comparing these crystals with the ones grown from the pure solution, it is shown that 0.2–2.0M of the urea additive enhances the laser damage threshold and the second harmonic efficiency more than by 25 and 20%, respectively. By means of the Bond method using a multipurpose three-crystal X-ray diffractometer it is shown that the presence of urea additive increases the crystal lattice parameter c of the grown crystals, whereas the lattice parameter a is by an order less sensitive to the changing urea concentration in the solution. The Vicker's hardness studies at room temperature carried out on (100) and (001) crystallographic planes show an increased hardness of the doped crystals (grown in the presence of urea additive) on the plane (001) in comparison with that of pure potassium dihydrophosphate crystal.

For the first time, the method of temperature lowering was used to grow KDP single crystals from aqueous solutions containing TiO2 (anatase) nanocrystals. The concentration of TiO2 in the initial solution varied from 10(-3) to 10(-5) M/l. Using the method of three-crystal X-ray diffractometry, the presence of turns of the growth layer packets similar to 3 arcsec was revealed in KDP:TiO2 crystals for the sectors {100} and {101}. The observed thickness of the growth packets was on the order of 20-30 mu m. There was found the sixfold rise of the crystal lattice parameters Delta d/d in the doped crystal relatively to the pure one caused by incorporation of the nanoparticles into the boundaries of layer-by-layer growth and a formation of semicoherent bond with the crystal. It was found the effect of giant nonlinear optical response of anatase nanoparticles manifestation in KDP crystalline matrix.

In the report the review of existing methods of sterilization of medical products is submitted. The advantages of industrial accelerators in radiation technologies of sterilization are given. BINP works and results of researches on sterilization and producing of medical goods at accelerators ILU series are described. Most of investigations were spent in collaboration with various organizations.

Potassium dihydrophosphate single crystals were grown from aqueous solutions onto a point seed using temperature reduction method by doping with different molar values of Urea. The characterization of the grown crystals was made by visible and fourier transform infrared spectroscopy, Vicker's hardness studies, X-ray powder diffraction, nonlinear optical and laser damage threshold measurements. By comparing these crystals with the ones grown from the pure solution, it is shown that 0.2 divided by 2.0 M of the Urea additive enhances the laser damage threshold and the second harmonic efficiency more than by 25 and 20 %, respectively. The Vicker's hardness studies carried out on (100) and (001) crystallographic planes show an increased hardness of the doped crystals (grown in the presence of Urea additive) on the plane (001) in comparison with that of pure potassium dihydrophosphate crystal.

The report describes electron beam electromagnetic forming system, which is destined for irradiation of cylindrical long goods, specifically for PE tubes 160mm diameter. System consists of electromagnet, power supply units, beam distributions control units, etc. for use at an electron accelerator at 5MeV and 50kW. The particular geometry of the magnet poles and their mutual arrangement are creating an irradiation field that allows the electrons to irradiate the surface of the product close to 90°.

The converters were designed for generation of intensive bremsstrahlung radiation. The powerful electron beam (5MeV, 50kW) was generated by ILU-10 accelerator. The converters differ in technology of manufacturing and material of target, tungsten carbide or tantalum. The aluminum board with the channels for cooling water is used as the base of the converter and filter for low energy part of bremsstrahlung spectrum. The converters can be installed in vacuum or outside the accelerator in air under the beam window. The results of testing of different converters are given.

This paper presents the description of high power linear accelerators for industrial applications. 5 MeV accelerator having 50 kW beam power has been developed and is serially manufactured now. This accelerator can be used in two modes: electron and X-ray generation (using special target). The accelerator with X-ray target can be widely used for food product treatment. Two of such accelerators have been already supplied to USA. New more powerful accelerator is in the process of designing now. The accelerator has a modular structure and consists of the chain of accelerating cavities, connected by the on-axis located coupling cavities with coupling slots in the walls. Main parameters of the accelerator are: operating frequency of 176 MHz, energy of electrons of 5-10 MeV depending on the number of accelerating cavities, average beam power up to 300 kW at duty factor of 15%. The necessary RF pulse power can be obtained, for example, from TH628 diacrode.

During last years the demand for pasteurization and desinsection of various food products (meat, chicken, sea products, vegetables, fruits, etc.) had increased. The treatment of these products in industrial scale requires the usage of powerful electron accelerators with energy 5-10 MeV and beam power at least 50 kW or more. The report describes the ILU accelerators with energy range up to 10 MeV and beam power up to 150 kW. The different irradiation schemes in electron beam and X-ray modes for various products are described. The design of the X-ray converter and 90degrees beam bending system are also given. (C) 2002 Elsevier Science Ltd. All rights reserved.