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DOI 10.1007/s10512-015-9944-2
Atomic Energy, Vol. 117, No. 6, April, 2015 (Russian Original Vol. 117, No. 6, December, 2014)
I. Khidirov UDC 539.21;539.27
The study of radiation-stimulated structural changes or phase transformations in inorganic compounds is of fundamental theoretical importance and has great practical value. Even at low temperatures irradiation disrupts the thermodynamic equilibrium of crystals [14]. The aim of the present work is to study the effect of -radiation on the crystal structure of disordered and ordered nonstoichiometric cubic titanium carbohydrides TiC0.47H0.21 and TiC0.50H0.21 by means of powder neutron diffraction analysis.
The neutron diffraction patterns of the samples were obtained with a DN-500 neutron diffractometer, placed on the thermal column of a VVR-SM nuclear reactor at the Institute of Nuclear Physics of the Academy of Sciences of the Republic of Uzbekistan ( = 0.1085 nm). The calculations were performed by means of Rietvelds full-profile analysis [5]. The single-phaseness and uniformity of the samples were evaluated by means of x-ray diffraction patterns obtained with a DRON-3M diffractometer ( = 0.5418 nm). The titanium carbohydride samples TiC0.47H0.21 and TiC0.50H0.21 were prepared by means of self-propagating high-temperature synthesis. Very pure grade soot (carbon powder) and PTM-grade titanium powder, containing 0.35 wt.% hydrogen, were used as the initial charges. For homogenization, after synthesis the samples were annealed in an evacuated and sealed quartz ampoule at 1470 K for 24 h and quenched in water in order to freeze their disordered state. The content of hydrogen and carbon in the samples was determined by chemical analysis to within 0.3%. Irradiation was also conducted in evacuated and sealed quartz ampoules (without heating) in the central vertical channel of a 60Co -source at the
Institute of Nuclear Physics. The average energy of the -rays at the dose rate 2375 rad/sec was e = 1.25 MeV. During irradiation, the temperature of the ampoule together with the sample did not exceed 370 K. At this temperature, no appreciable changes occur in the structure of the titanium carbohydride (onset temperature of structural changes is 720 K) [6]. According to x-ray phase analysis, the samples after homogenizing annealing were uniform and single-phase with NaCl-type structure. No appreciable changes were observed in the concentration of metalloids after irradiation (Table 1). Neutron structural analysis showed that the crystal...