ИСТИНА

The paper looks at the method of X-ray diffraction analysis of material structure that was used in our recent research. This method is convenient for studying the structure of substances because it is based on the use of an equipment called a diffractometer that has special counters for recording X-ray diffraction patterns. This device records the intensities and directions of X-ray diffracted on a crystalline sample. It provides high measurement accuracy and reduces the duration of the experiment. The diffractometer makes it possible to measure the intensities of diffracted radiation in a given direction with up to 10 fractions of a percent as well as diffraction angles up to 10 fractions of a minute. In addition, the advantages of this method include non-destructive testing. First this method of X-ray diffraction is based on the phenomenon of X-rays reflection from flat crystal lattices formed by atoms in the material and the Wulff-Bragg's law, which relates the interplanar distance to the X-ray wavelength. Second, the Bragg-Brentano method underlies the most common diffractometers. The Bragg-Brentano method describes the geometry of the inscribed angles for focusing X-rays. It is spoken in detail about the relevant sources of X-ray radiation, in particular, the X-ray tube in which the cathode and anode are located. X-ray wavelength depends on the material of the anode. A tungsten coil heated by electric current usually serves as a cathode and copper as an anode due to the high intensity and wavelength of the radiation, which is comparable with most interplanar spacings of crystalline structures. The goniometer is the main part of the diffractometer along with such details as slits, a sample retainer, and a monochromator. It forms the necessary geometry for obtaining and recording the diffraction pattern. It's function is the simultaneous rotation of the sample by an angle θ and the rotation of the detector by an angle of 2θ, so that the Wulf-Bragg condition is always fulfilled. It should be mentioned that application of this method allowed our study to reveal lattice parameters, the type of crystal structure, and the unit cell volume of certain perovskite samples. These samples were La1-xSrxFeO3 and Ca1-yPryMnO3. After examining the samples, diffractograms were obtained in the form of graphs of the intensity of the X-rays reflected from the sample rotation angle. After processing these graphs we managed to obtain necessary information on the lattice parameters, type of crystal structure, and unit cell volume.