By the method of dynamic calorimetry in the range of 298.15-673 K, the heat capacity of titanium-manganite LaСаTiMnO6, obtained by solid-phase interaction at 800-1200oC from lanthanum, titanium (II), manganese (III) and calcium carbonate oxides was studied. On the dependence curve Ср°~¦(T) in the specified temperature range, a λ-shaped effect was detected at 598 K, probably related to the phase transition of the second kind. A fundamental constant is determined — the standard heat capacity of LaСаTiMnO6, equal to 221±14 J /(mol×K). Its standard entropy, equal to 206±6 J/(mol×K), was estimated by the approximate method of ion increments. Based on experimental data, taking into account the temperature of the phase transition, the equations describing the temperature dependences of Ср°~¦(T) and the thermodynamic functions So (T), Ho (T) — Ho (298.15) and Фхх(Т) of the investigated titanium-manganite lanthanum and calcium are calculated. The standard heat capacity of LaСаTiMnO6 is also calculated using the Debye method, the value of which is in good agreement with experimental data. According to the developed methodology, the standard enthalpy of titanium-manganite formation was calculated, equal to — 3867.5 kJ/mol.

This article discusses possible solutions to one of the problems associated with the low efficiency of existing thermal power plants. These factors are due to both the depreciation of equipment and the lack of any effective technologies for intensifying heat and mass transfer processes. The relevance of research topics is also confirmed by the fact that at the state level it is proposed to legally oblige the subjects of the heat and power industry to carry out preventive measures aimed at optimizing existing enterprises. The description of the reasons for the occurrence of scale deposits that appear in the in-line cavities is given. Due to the fact that the thermal conductivity of solid deposits is much less than the thermal conductivity of the metals from which the heat exchanger tubes are made, they significantly reduce the intensity of the processes and the intensity of heat transfer. Solid deposits lead to a decrease in the coolant flow rate, an increase in fuel consumption and a violation of the technological mode of operation of the entire heat exchange unit. The authors analyzed various technological aspects of various methods for cleaning heat exchanger tubes from solid scale deposits, on the basis of which the advantages of the electrohydraulic treatment method are substantiated. A schematic diagram of the device is given and a brief description of the method of cleaning the pipes of heat exchangers from solid scale deposits is given using electro-hydro-pulse action. The results of the application of this technology for cleaning heat exchange pipes at specific heat and power enterprises are shown, which confirm its advantages over other cleaning methods, both in terms of processing time and energy costs. The influence of the degree of purification of heat exchange pipes from solid deposits on the thermophysical parameters and efficiency of the heat exchanger is considered.

The paper demonstrates the results of the experimental investigation of the thermodynamic and electrophysical properties of the new nanostructured copper-zinc manganite of lanthanum and lithium (LaLi2CuZnMnO6).

The temperature dependences of the electric capacity, dielectric constant and electrical resistance of cobaltecuprate-manganite of lanthanum and sodium of LaNa2CoCuMnO6 and nickelite-cuprate-manganite of lanthanum and sodium of LaNa2NiCuMnO6 were investigated on the LCR-800 serial device (manufactured by Taiwan) at the operating frequencies of 1 kHz, 5 kHz, and 10 kHz in interval of 293–483 K through 10 K continuously in dry air. It was determined that LaNa2CoCuMnO6 in interval of 293–483 K shows the semiconductor conductivity. A band gap (D Е) is 0.54eV. The compound has the high values of the dielectric constant, which are equal 2.17×106 (1 kHz), 2.31×105 (5 kHz), 8.22×104 (10 kHz) at 293 K and 8.49×108 (5 kHz), 7.87×107 (10 kHz) at 483 K. LaNa2NiCuMnO6 in interval of 293–483 K demonstrates the semiconductor conductivity (D Е = 0.48 eV), at 433–443 K — the metallic conductivity and at 453–483 K — the semiconductor conductivity (D Е = 2.33 eV).The values of the dielectric constant are 4.97×103 (1 kHz), 9.2×102 (5 kHz), 5.1×101 (10 kHz) at 293 K and 1.02×106 (1 kHz), 1.98×105 (5 kHz) and 9.76×104 (10 kHz) at 483 K. The compounds can be classified as the narrow-band gap semiconductors and they are of interest for the semiconductor and microcapacitor technologies.

По разработанному методу расчета вычислены стандартные энтальпии образования манганито-ферритов состава LnMIIMnFeO5.5 (Ln – редкоземельный элемент, MII – щелочно-земельный металл). Методом ионных инкрементов рассчитаны их стандартные энтропии и по уравнению Гиббса–Гельмгольца – их стандартные энергии Гиббса образования.

Manganite ferrites NdM 1.5 II MnFeO 6 (M II = Mg, Ca, Sr, Ba) were synthesized from neodymium(III), manganese(III), and iron(III) oxides and alkaline-earth metal carbonates by a ceramic technology. By grinding the obtained compounds in a ball mill, their nanostructured particles were produced, the sizes of which were determined with an electron microscope. X-ray diffraction study established that the nanostructured compounds crystallize in the cubic and tetragonal systems with the following lattice parameters: NdMg 1.5 MnFeO 6 (tetragonal): a = 10.955 Å, c = 17.848 Å, V 0 = 2141.975 Å 3 , Z = 16, V e1.cel1 0 = 133.873 Å 3 , ρ X-ray = 4.80 g/cm 3 , and ρ pycn = 4.76 ± 0.05 g/cm 3 ; NdCa 1.5 MnFeO 6 (cubic): a = 10.809 Å, V 0 = 1262.864 Å 3 , Z = 8, V e1.cel1 0 = 157.858 Å 3 , ρ X-ray = 4.32 g/cm 3 , and ρ pycn = 4.27 ± 0.03 g/cm 3 ; NdSr 1.5 MnFeO 6 (cubic): a = 10.911 Å, V 0 = 1298.953 Å 3 , Z = 8, V e1.cel1 0 = 162.369 Å 3 , ρ X-ray = 4.93 g/cm 3 , and ρ pycn = 4.88 ± 0.05 g/cm 3 ; and NdBa 1.5 MnFeO 6 (tetragonal): a = 11.011 Å, c = 18.001 Å, V 0 = 2182.479 Å 3 , Z = 16, V e1.cel1 0 = 136.405 Å 3 , ρ X-ray = 6.78 g/cm 3 , and ρ pycn = 6.75 ± 0.07 g/cm 3 .

Manganites LaM 3 I M 3 II Mn 4 O 12 (M I = Li, Na, K; M II = Mg, Ca) have been synthesized for the first time by the solid-phase reactions of lanthanum(III) and manganese(II) oxides and lithium, sodium, potassium, magnesium, and calcium carbonates. X-ray diffraction shows that all of them crystallize in the cubic crystal system. Their unit cell parameters are determined.

Manganites NdM I CaMn 2 O 6 (M I = Li, Na, K, Cs) have been synthesized by the solid-phase method from Nd 2 O 3 , Mn 2 O 3 , calcium carbonate, and alkali-metal carbonates. These compounds crystallize in cubic perovskite space group Pm3m. The heat capacities of the manganites have been studied by dynamical calorimetry in the temperature range 298.15-673 K. Abrupt heat capacity anomalies have been revealed. These anomalies are probably associated with second-order phase transitions, which occur at 398 K in NdLiCaMn 2 O 6 , at 373 K in NdNaCaMn 2 O 6 , at 373 and 523 K in NdKCaMn 2 O 6 , and at 473 K in NdCsCaMn 2 O 6 . The equations have been derived to describe the C o p ∼f(n dependences and the temperature dependences of thermodynamic functions.

The heat capacity of the DyLiMgMn2O6 ternary manganite was measured by dynamic calorimetry. The C-p(o) vs. f(T) dependence exhibits a lambda-shaped peak associated with a second-order phase transition at 423 K. Expressions for the temperature dependence of C-p(o) were derived. The Sdegrees(T), Hdegrees(T) - Hdegrees(298.15), and Phi**(T) thermodynamic functions were calculated.

The solid-phase method is used to synthesize ternary manganites of composition DyMIMgMn2O6 (MI − Na, K, Cs); their X-ray investigation is performed to demonstrate that they all crystallize in orthorhombic system. Their heat capacity is determined experimentally in the range from 223 to 673 K, equations are derived which describe the dependences C p o ∼ ƒ(T), and the thermodynamic functions C p o , Ho(T)−Ho(298.15), So(T), and Φ**(T) are calculated. Second-order phase transitions are observed in the process of investigation of heat capacity.

Manganites (NdMCaMn2O6)-Ca-I (M-I = Li, Na, K, Cs) have been synthesized by the solid-phase method from Nd2O3, W2O3, calcium carbonate, and alkali-metal carbonates. These compounds crystallize in cubic perovskite space group Pm3m. The heat capacities of the manganites have been studied by dynamical calorimetry in the temperature range 298.15-673 K. Abrupt heat capacity anomalies have been revealed. These anomalies are probably associated with second-order phase transitions, which occur at 398 K in NdLiCaMn2O6, at 373 K in NdNaCaMn2O6, at 373 and 523 K in NdKCaMn2O6, and at 473 K in NdCsCaMn2O6. The equations have been derived to describe the C-rho(degrees) similar to f(T) dependences and the temperature dependences of thermodynamic functions.

Manganites NdMMgMn2O6 (M = Li, Na, K, Cs) were prepared by solid-state synthesis from neodymium and manganese oxides, magnesium carbonate, and alkali-metal carbonate. The manganites crystallize in the cubic system with a = 10.98 Angstrom, V = 1323.7 Angstrom(3), V-unit = 13:2.4 Angstrom(3), Z = 10, rho(calcd) = 4.78 g/cm(3), rho(exp) = (4.52 +/- 0.16) g/cm(3) for NdLiMgMn2O6; a = 10.92 Angstrom, V = 1301.8 Angstrom(3), V-unit = 130.2 Angstrom(3), Z = 10, rho(calcd) = 5.07 g/cm(3), rho(exp) = (5.02 +/- 0.05) g/cm(3) for NdNaMgMn2O6; a = 10.96 Angstrom, Vdegrees = 1318.3 Angstrom(3), V-unit = 131.8 Angstrom(3), Z = 10, rho(calcd) = 5.21 g/cm(3), rho(exp) = (5.13 +/- 0.08) g/cm(3) for NdKMaMn(2)O(6); and a = 10.97 Angstrom, V = 1323.4 Angstrom(3), V-unit = 132.3 Angstrom(3), Z = 10, rho(cald) = 6.37 g/cm(3), rho(exp) = (6.02 +/- 0.35) g/cm(3) for NdCsMgMn2O6.

The manganites (MMgDyMn2O6)-Mg-1 (M-I = Li, Na, K, Cs) were synthesized by solid-state annealing from dysprosium oxide, manganese oxide, magnesium carbonate, and alkali metal carbonate. According to X-ray diffraction, these compounds crystallize in the orthorhombic system with the following unit cell parameters : LiMoDyMn2O6, a = 10.54 Angstrom, b = 10.72 Angstrom, c = 17.08 Angstrom, Vdegrees = 1929.9 Angstrom(3), V(cell)degrees =120.6 Angstrom(3), Z = 16, rho(x) = 5.49 g/cm(3), rho(pycn) = (5.30 +/- 0.06) g/cm(3); NaMgDyMn2O6, a = 10.55 Angstrom, b = 10.73 Angstrom, c = 16.92 Angstrom, Vdegrees = 1915.4 Angstrom(3), V(cell)degrees = 119.7 Angstrom(3), Z = 16, rho(x) = 5.76 g/cm(3), rho(pycn) = (5.65+/-0.09) g/cm(3); KMgDyMn2O6, a = 10.60Angstrom, b = 10.75Angstrom, c = 16.83 Angstrom, Vdegrees = 1917.1 Angstrom(3), V(cell)degrees = 119.8 Angstrom(3) Z=16, rho(x) = 5.98 rho(pycn) = (5.90+/-0.05) g/cm(3); CsMgDyMn2O6, a = 10.56 Angstrom, b = 10.74 Angstrom, c = 17.02 Angstrom, Vdegrees = 1930.3 Angstrom(3), Vdegrees(cell) = 120.6 Angstrom(3), Z = 16, rho(x) = 7.23 g/cm(3) rho(pycn) = (7.14 +/- 0.07) g/cm(3).

A mixed manganite of composition LaLiSrMn2O6 , with a cubic structure, is synthesized for the first time by solid-state reactions, using mixtures of appropriate carbonates and oxides, and its heat capacity and electrical resistivity are measured at elevated temperatures.

Manganites LaCsMMn2O6 (M = W Ca, Sr, Ba) have been synthesized by a solid-state technique from oxides and carbonates. Their crystal systems and unit cell parameters have been deten-nined by X-ray powder diffraction. LaCsMgMn2O6 is tetragonal, a = 11.06 Angstrom, c = 22.07 Angstrom, V = 2699.7 Angstrom(3), V-un.cell = 135.0 Angstrom(3), Z = 20, rho(X-ray) = 6.17 g/cm(3), rho(pycn) = 6.14 +/- 0.03 g/cm(3). The LaCsCaMn2O6 is cubic, a = 10.80 Angstrom, V = 1259.7 Angstrom(3), V-un.cell = 125.97 Angstrom(3), Z = 10, rho(X-ray) = 7.35 g/cm(3), rho(pycn) = 7.31 +/- 0.03 g/cm(3). LaCsSrMn2O6 is cubic, a = 10.89 Angstrom, V = 1291.46 Angstrom(3), V-un.cell = 129.146 Angstrom(3), Z = 10, rho(X-ray) = 7.27 g/cm(3), rho(pycn) = 7.25 +/- 0.04 g/cm(3). LaCsBaMn2O6 is tetragonal, a = 11.04 Angstrom, c = 16.98 Angstrom, V = 2069.6 Angstrom(3), V-un.cell = 129.4 Angstrom(3), Z = 16, rho(X-ray) = 7.89 g/cm(3), rho(pycn) = 7.81 +/- 0.07 g/cm(3). The heat capacities of the above phases have been investigated using dynamic calorimetry in a temperature range of 298.15-673 K. Second-order phase transitions have been found in the LaCsMgMn2O6 (448 K) and LaCsSrMn2O6 (498 K). The C(p)degrees similar tof(T) equations and thermodynamic functions C(p)degrees (T), Hdegrees(T) - Hdegrees(298.15), Sdegrees(T), and Phi(T) have been calculated for the range of 298.15-673 K.