The aim of this work was to synthesize and investigate the roentgenographic and electro-physical properties of new phases, namely double tellurites of neodymium. Oxotellurites of the composition NdMeIITeO4.5(MeII - Ca, Ba) were synthesized by the method of ceramic technology with high-temperature interaction of Nd2O3, TeO2 oxides with carbonates of alkaline earth metals in the interval of 800°С - 1200°С. Roentgenograms of the synthesized compounds were obtained using an Empyrean powder diffractometer by PANalytical and indication was determined using the X’Pert HighScore Plus program. It was found that the synthesized tellurites were crystallized in tetragonal syngony. The unit cell parameters, roentgen and pycnometric densities of the compounds were determined. It was revealed that with increasing ionic radii from Ca to Ba, the lattice parameters and unit cell volumes of synthesized tellurites increase. The assumed structure of the synthesized double tellurites of neodymium is a distorted perovskite structure. A study of the temperature dependence of the dielectric permittivity and electrical resistance of tellurites of neodymium-alkaline earth metals established that they can possess semiconducting properties at 293 K - 483 K. Temperature coefficients of resistance and forbidden zone width of tellurites were calculated.

Gadolinium oxotellurites GdMeTeO4.5 (Me – Mg, Ca) were synthesized using ceramic technology with solidphase interaction of oxides Gd2O3 and TeO2 with carbonates MgCO3 and CaCO3. X-ray characteristics were obtained using an Empyrean powder diffractometer and specialized programs Data Collector version 7.7h and X’Pert HighScore Plus using the Crystallography Open Database and PDF-2. Based on X-ray studies, it was established that the synthesized tellurites crystallize in a tetragonal syngony. The reliability and correctness of the indexing results is confirmed by the satisfactory agreement between the experimental and calculated parameters of the crystal lattice, unit cell volumes, X-ray and pycnometric densities. A study of the temperature dependence of the electrical resistance of gadolinium-magnesium tellurite has established that the compound may have semiconductor properties, with a band gap ∆E = 2.64 ± 0.13 ∙ 10–2 eV. The results can be used for the synthesis and study of new derivatives of tellurium and rare earth elements and are of interest for electronic technology. X-ray characteristics of new tellurites of s-, f-elements are the starting materials for inclusion in fundamental data banks and reference books.

We synthesized samarium oxotellurites SmMTeO4.5 (M — Mg, Ba) by the method of ceramic technology with solid-phase interaction (800–1200 °С) of Sm2O3 and TeO2 oxides with MgCO3 and BaCO3 carbonates. The compounds were characterized by X-ray and electrophysics methods. It has been established that the synthesized compounds crystallize in the tetragonal syngony with the following crystallographic characteristics: SmMgTeO4.5 — a = 12.226; c = 5.783 Å, V0un.cell = 864.38 Å3, Z = 4, ρxray. = 2.876, ρpycn. = (2.874±0.002) g∙cm-3; SmBaTeO4.5 — a = 12.717; с = 6.132Å, V0un.cell = 991.62Å3, Z = 4, ρxray. = 3.264, ρpycn. = (3.260±0.004) g∙cm-3; for both tellurites α = β = γ = 90°. The experimental and calculated values of 2 Th and d-sp, X-ray and pycnometric densities, as well as theoretical and experimental values of unit cell volumes are agreed satisfactorily. Thus, we can confirm correctness and reliability of the results of indexing X-ray patterns of new samarium oxotellurites. We found that increase in the ionic radii from Mg to Ba increases the lattice parameters of the synthesized oxotellurites. Oxotellurites are crystallized in the structural types of distorted perovskite Pm3m. Based on the given study samarium oxotellurites can have semiconductor and ferroelectric properties.

A method for optimizing the settings of a LIBS device aimed at achieving the maximum intensity of analytical lines of the analyte of constant composition is considered using probabilistic-deterministic design of experiments (PDDE). A mixture of Cr, Mn, Fe, Co, and Ni oxides homogenized and diluted by fusion with a lead-phosphate mixture is used as an analyte. It is shown that data of mathematical processing of 25 spectra by the PDDE method can be used to develop mathematical models which relate the line intensity with the energy of the laser pumping lamp, the lag time of the first and second Q-switches, the time delay of the exposure onset, and the total exposure time. The use of the geometric mean and mathematical model in the form of the product of the partial dependences leads to a good correlation between the calculated and experimental values of the intensity for all the considered spectral lines. The simulation results presented for 16 analytical lines of Cr, Mn, Co, and Ni illustrate the applicability of the method under consideration. The experimentally achieved maximum intensities of analytical lines in the matrix of lead-phosphate glass differ from those calculated using the obtained models by 7 – 12 %. There is a linear correlation between the experimental and calculated values of the intensity at R2 = 0.99 and an inclination angle close to 45°. The spectra recorded during the experiment can be used for optimization of other parameters, e.g., the signal-to-noise ratio. The simplicity of calculations and relatively small number of tests in the optimization experiment make the PDDE a promising method for optimizing the LIBS parameters.

For the first time, double gadolinium tellurites of the composition GdMIITeO4.5 (MII — Sr, Ba) were synthesized by the solid-phase method. The solid-phase synthesis of samples was carried out from decrepitated gadolinium (III) and tellurium (IV) oxides, strontium, and barium carbonates according to the standard ceramic technology. The synthesis was carried out in the temperature range of 800-1100 °C. The samples obtained were confirmed by X-ray phase analysis. X-ray phase analysis was carried out on an Empyrean instrument in the XRDML Pananalitical format. The intensity of the diffraction maxima was estimated on a 100-point scale. X-ray dif- fraction patterns indexing of the powder of gadolinium tellurites — alkaline earth metals studied were carried out by the homology method. The reliability and correctness of the results of indexing the X-ray diffraction patterns are confirmed by the good agreement between the experimental and calculated values of the interplanar distances (d) and the agreement between the values of the X-ray and pycnometric densities. It was found that compounds GdSrTeO4.5 and GdBaTeO4.5 crystallize in the monoclinic system and have the unit cell parameters, namely GdSrTeO4.5 — a = 12.7610, b = 10.4289, c = 8.6235 Å, V° = 1141.83 Å3, β = 95.77°, Z = 5, ρrent. = 3.22, ρpikn. = (3.10±0.09) g/cm3; GdBaTeO4.5 — a = 15.7272, b = 15.8351, c = 7.1393 Å, V° = 1769.72 Å3, β = 95.53°, Z = 8, ρrent = 3.71, ρpick = (3.61±0.10) g/cm3. Using the Landiya method, the standard heat capacities of the compounds were estimated from the calculated values of the standard entropies, and the temperature dependences of the heat capacities of the gadolinium tellurites synthesized were determined in the temperature range of 298–850 K.

Lanthanum-magnesium-nickel tellurite with composition of La2MgNiTeO7 was synthesized from La2O3, NiO, TeO2 oxides and MgCO3 with the help of the ceramic technology. The temperature dependences of the isobaric heat capacity of tellurite La2MgNiTeO7 were studied on an IT-S-400 calorimeter using an experimental method of dynamic calorimetry in the range of 298.15-673 K. The operation of the calorimeter was checked by measuring the standard heat capacity of alpha-Al2O3. The specific heat capacities were measured, and then the molar heat capacities of the synthesized tellurite were calculated using them. In the study of the dependence of the heat capacity of tellurite La2MgNiTeO7 on temperature at 423 K, a sharp anomalous lambda-shaped jump was found, probably related to a second-order phase transition. This transition can be associated with cationic redistribution, changes in the coefficient of thermal expansion and magnetic moment, as well as changes in dielectric constant and electrical resistivity. The equation of the temperature dependence of the heat capacity of the compound is derived on the basis of the experimental data, taking into account the phase transition temperature of the second kind. The temperature dependences of the heat capacity C-p(0)(T) and thermodynamic functions, namely, the entropy S-0(T), the enthalpy H-0(T) H-0(298.15) and the reduced thermodynamic potential Phi(xx)(T) were calculated based on the experimental data on heat capacities and the calculated standard entropy value S-0(298.15) in the interval 298.15-673 K. For the first time, the temperature dependences of the dielectric constant and electrical resistance of tellurite La2MgNiTeO7 in the temperature range of 293-483 K were studied on the LCR-800 instrument. There are maxima and minima on the curves of lg epsilon similar to f(T) and lgR similar to f(T), which confirm the lambda-shaped effect on the C-p(0)similar to f(T) curve of a successful compound, related to the second-order phase transition. The data obtained show that the tellurite studied has semiconductor properties.

New dysprosium-barium double tellurite was synthesized based on ceramic technology. The formation of the equilibrium composition of the compound is controlled by X-ray phase analysis, the results of which revealed that DyBaTeO4.5 dysprosium tellurite was synthesized. For the first time, a calorimetric study of the heat capacity of the new double tellurite DyBaTeO4.5 was carried out in the temperature range of 298.15-673 K. The calibration of the instrument was carried out on the basis of the determination of the heat meter thermal conductivity. The operation of the calorimeter was checked by measuring the alpha-Al2O3 heat capacity. The experimental data of the specific and molar heat capacity were processed by the methods of mathematical statistics. The equation for the dependence C-p(0)similar to f(T) is derived based on the experimental data. The temperature dependences of the thermodynamic functions H degrees(T)-H degrees(298.15), S degrees(T) and, F-xx(T) are determined from C-p(0)similar to f(T) and the calculated value of S degrees(298.15) of tellurite. Anomalous jumps are observed on the dependence C-p(0)similar to f(T), which are probably related to second-order phase transitions. The thermodynamic characteristics of new tellurite can serve as background information for fundamental data banks and reference books, and also used to predict the thermochemical constants of similar compounds.

The isobaric heat capacity of nickelite-tellurite La2SrNiTeO7 was studied by calorimetry at 298.15–673 K. λ-Shaped effects related to the second-order phase transition were revealed for the compound in the given temperature range. The equations of the temperature dependence of the heat capacity were derived taking into account the transition temperatures. The temperature dependences of the heat capacity, entropy, enthalpy, and reduced thermodynamic potential were calculated from the experimental heat capacities and calculated standard entropies of nickelite-tellurite. The temperature dependences of the dielectric constant and electric resistance of nickelite-tellurite at 293–483 K were studied. The curves of the dependences $$\log \varepsilon = f(T)$$ and $$\log R = f(T)$$ have maxima and minima, which confirm the λ-shaped effects related to the second-order phase transition on the curve of $$C_{p}^{ \circ } = f(T)$$ for the compound.

Complex oxide phases, namely new double tellurites of holmium with the composition (HoMeTeO4.5)-Te-II (where Me-II - Sr, Ba) were synthesized with the ceramic technology from Ho(II), Te(IV) oxides and carbonates SrCO3, BaCO3 in the range of 800-1200 degrees C. For the first time the structure of tellurites was investigated by X-ray phase analysis. X-ray phase analysis was performed on the DRON-2.0 device. The intensity of the diffraction peaks was estimated on a stable scale. Radiographs of the synthesized powders were indicated by the homology method. The type of syngony, unit cell parameters, radiographic and pycnometric tellurite densities were determined. HoSrTeO4.5: a = 14.50; b = 14.05; c = 9.04 angstrom; rho(roent.) = 3.73; rho(pycn.) = 3.59 +/- 0.04 g/cm(3); HoBaTeO4.5: a = 12.10; b = 5.49; c = 11.49 angstrom; rho(roent.) = 4.07; rho(pycn.) = 3.93 +/- 0.06 g/cm(3). The correctness of the results of indexing radiographs of tellurites is confirmed by the good agreement between the experimental and calculated values of the reciprocal values of the squares of interplanar distances (10(4)/d(2)) and the consistency of the values of X-ray and pycnometric densities. It has been established that holmium tellurites are synthesized in monoclinic syngony and have a perovskite-like structure. Quantum-chemical calculations of the stable geometry of the synthesized tellurites were carried out using the Gaussian-2009 software package with the help of the UFF molecular method. In this case, equilibrium internuclear distances (long bonds) and bond angles are the parameters. Based on the results of quantum chemical calculations, models of the geometric structure of new holmium tellurites are presented.

The problems of improving the chemometric characteristics of spectral methods of analysis are being intensively studied throughout the world. These problems are especially significant in the field of laser atomic emission spectrometry. In the article, it is proposed to use sample homogenization by fusion with sodium tetraborate. The example of iron in a mixture of oxides consisting of Fe2O3, PbO, CuO, CdO and ZnO has shown that fusion provides advantages over pressing, consisting in increasing the intensity of the spectral lines and increasing the accuracy of the concentration / intensity correlation, as well as an increase in the total number of spectral lines, which can be calibrated satisfactorily. Using the probabilistic-deterministic planning of the experiment and using the composite factor, it is shown that fusion substantially weakens the interrelation of the intensity of the spectral line with the instrument settings, which simplifies the choice of the spectrum registration regime. The observed regularities are explained by the high homogeneity of the vitreous samples, the more complete evaporation of the sample in the laser spark and the absence of interference in the form of a neat atomized sample, an increase in the density (and hence the concentration) of the sample. In the course of the experiments it was additionally established that for melting specimens, it was necessary to use the crucibles from alumina with caution. They dissolve rather quickly in the melt of tetraborate. Nickel crucibles can be used only if nickel is not among the elements that are determined in the sample. Based on the results of the study, there was made a conclusion about the need study of the proposed methodology and its extension to other elements of the periodic system for further.

Tellurite of the composition Li 2 CeTeO 5 is synthesized by solid-phase method from cerium(IV) and tellurium(IV) oxides and lithium carbonate. The type of syngony, the unit cell parameters, and the compound’s X-ray and pycnometry densities are determined via X-ray diffraction analysis. The isobaric heat capacity of lithium–cerium tellurite is studied by means of dynamic calorimetry in the temperature range of 298.15–673 K; the results serve as the basis for deriving C p ° ~ f ( T ) dependency equations and determining the compound’s thermodynamic functions. λ-shaped anomalous effects, due probably to Type II phase transitions, are found on the C p ° ~ f ( T ) dependence.

This paper presents detailed results of new lanthanum tellurite synthesis and its heat capacity calorimetric research. For the first time, a triple lanthanum tellurite was synthesized by the solid-phase method from oxides of lanthanum, nickel (II), tellurium (IV) and calcium carbonate. The generation of the equilibrium composition of the synthesized compound was controlled by the method of X-ray diffraction analysis (XDA) on the diffractometer DRON-2.0. By the results of the XDA it was established that there was synthesized a triple lanthanum tellurite La2CaNiTeO7. Heat capacity at constant pressure of the synthesized tellurite was researched by the method of dynamic calorimetry at the range of 298.15-673 kappa. Based on the experimental data, the equations, describing dependencies of heat capacity of the compound on temperature were calculated. When studying the temperature dependences of the heat capacity of La2CaNiTeO7, abnormally sharp lambda-like peaks probably associated with second-order phase transitions, were observed at 423 K. Temperature dependencies of thermodynamic functions of La2CaNiTeO7 S degrees(T), H degrees(T)-H degrees(298,15), Phi(xx)(Tau) were calculated based on the experimental data C-p degrees(Tau) and the calculated value S degrees(298.15).

The new double holmium-calcium tellurite was synthesized by the ceramic technology. The formation of the equilibrium composition of the compound was monitored by X-ray diffraction. Double tellurite of holmium HoCaTeO4.5 has been synthesized according to the results of X-ray analysis. Calorimetric investigation of the heat capacity of the new double tellurite HoCaTeO4.5 was carried out for the first time in the range of 298.15-673 K. Calibration of the device was carried out on the basis of determining the thermal conductivity of a heat meter. The calorimeter performance was checked by measuring the heat capacity of alpha-Al2O3. The experimental data and the specific molar heat capacities have been processed by methods of mathematical statistics. The dependence equation C-p(0)similar to f(T) has been derived on the basis of experimental data. According C-p(0)similar to(T) and the calculated value of S-0(298.15) of tellurite the temperature dependence of the thermodynamic functions H-0(T)-H-0(298.15), S-0(T) and phi(xx)(T) have been determined. Abnormal jumps have been observed on the dependence C-p(0)similar to(T) associated probably with the phase transitions of the second order. The thermodynamic characteristics of the new tellurite can serve as source materials for inclusion in fundamental data banks and reference books, used to predict the thermochemical constants of similar compounds.

By means of the calorimetric method, we investigate the LaM2NiMnO5 (M—Li, Na, K) nickelitemanganite heat capacities within the range of 298.15–673 K. For the studied compounds, within the stated temperature range, we reveal the λ-like effects respective to the second kind phase transition at 323 and 498 K for compounds containing Li, 323 K and 523 K for compounds containing Na, and 448 K for those containing K. Taking into consideration the phase transition temperatures, we derive the equations of the temperature dependence of the compound heat capacity. On the basis of the experimental values of the heat capacities as well as of the calculation data on the nickelite-manganite standard entropy, we calculate the temperature dependences of the heat capacity, the entropy, the enthalpy, and the reduced thermodynamic potential.

The article shows the possibility of synthesizing new double holmium-calcium tellurite by solid phase method from oxides of holmium (III), tellurium (IV) and calcium carbonate. X-ray analysis shows that tellurite HoCaTeO4.5 crystallizes in the tetragonal structure. The parameters of the tellurite's unit cell, X-ray and pycnometric densities were determined by X-ray analysis as well.

The isobaric heat capacity of double thulium tellurites is studied via dynamic calorimetry in the range of 298.15–673 K. It is used as the basis for deriving the equation C p o ∼ f(T) and determining the thermodynamic functions. Dependences C p o ∼ f(T) are found to have second-order phase λ-transitions.