The crystal structure data of CoxTiS2 series of compounds in a wide range of Co concentrations (0.00 < x <= 1.00) are summarized. The compounds with high cobalt concentrations (x >= 0.75) have been synthesized for the first time. The P3m1 space group was found to be typical for the compounds with low (x < 0.2) and high (x >= 0.75) Co concentrations, while the compounds with intermediate Co concentrations show different types of ordered structures. The lattice contraction with increasing x up to x = 0.5 is in good agreement with the electromotive force measurements in the Li|Li+|CoxTiS2 electrochemical cell. The magnetic properties of CoxTiS2 strongly depend on the Co content: the spin glass ordering at low (T < 50 K) temperatures, typical for x < 0.25, changes to the ferromagnetic one for 0.75 <= x <= 1.00, which is preserved even at high (T > 900 K) temperatures.

Polycrystalline NixTiS2 (0.10 <= x <= 0.50) compounds have been synthesized for the first time. The crystal structure and electrical properties of these compounds have been studied as a function of Ni concentration using X-ray diffraction and electromotive force (EMF) measurements of Li|Li+|NixTiS2 electrochemical cells. It was found that the P3m1 space group is characteristic for all compounds. The Ni ions occupy only octahedral positions in the interlayer space and are not ordered at any concentration. The Ni concentration does not alter the Fermi level of the compound due to the Ni 3d(z)(2)/Ti 3d(z)(2) and Ni 3d(xz,yz)/S 3p hybridization.

CsAg4Br3–хI2+х solid solutions with x=0.38; 0.50; 0.63 were prepared by solid-phase synthesis; the single-phase of the products was confirmed by X-ray diffraction and differential scanning calorimetry. Studies of the electrical transport characteristics of CsAg4Br3–хI2+х included measurements of the ionic conductivity by the four-probe method in the range of –50…+120°C and an evaluation of the electronic component of the conductivity by the Hebb-Wagner method. It was shown that the ionic conductivity of CsAg4Br3–хI2+х solid solutions in the studied range of compositions is practically independent of x and is very close to that of the well-known superionic conductor RbAg4I5. The activation energy of conduction for all studied compounds is about 10 kJ mol–1. The oxidation potential determined by the stepwise polarization technique for CsAg4Br3–хI2+х solid solutions is noticeably higher than that of RbAg4I5, and is in the range of 0.75–0.78 V (vs. Ag0/Ag+). The high electrochemical characteristics of CsAg4Br3–хI2+х (0.38≤x≤0.63) and the absence of polymorphic transitions in the studied range from –160°C to the melting point (175 – 178°С) make these materials promising for use in electrochemical devices based on solid electrolytes, especially for low temperature applications.

Solid solutions CsAg4Br3 – хI2 + х (x = 0.38; 0.50; 0.68) are prepared by solid-state synthesis; the single phase of the products is confirmed using the methods of X-ray diffraction and differential scanning calorimetry. The studies of electrotransport characteristics of CsAg4Br3 – хI2 + х involve measuring the ionic conductivity by the four-probe method in the temperature interval from –50 to +120°C and estimating its electronic component by the Hebb–Wagner method. It is shown that in the studied interval of compositions, the ionic conductivity of CsAg4Br3 – хI2 + х solid solutions is practically independent of x, approaching the conductivity of the well-known superionic conductor RbAg4I5. The activation energy of conduction is found to be about 10 kJ mol–1 for all compounds studied. The oxidation potential determined by the method of stepwise polarization for CsAg4Br3 – хI2 + х solid solutions is considerably higher as compared with RbAg4I5, being in the range of 0.75–0.78 V (vs. Ag0/Ag+). The high electrochemical characteristics of CsAg4Br3 – хI2 + х (0.38 ≤ x ≤ 0.63) and the absence of polymorphic transitions in the considered interval from –160°С to the melting point (175–178°С) make these materials promising for the use in electrochemical devices, especially in low-temperature applications.

CoxTiS2 (x = 0.20, 0.30, 0.50, 0.75) compounds have a layered crystal structure with Ti atoms surrounded by the S octahedrons in the S-Ti-S layers and Co ions which could be surrounded both by the S octahedrons and tetrahedrons. The features of the crystal structure and magnetic properties of the polycrystalline CoxTiS2 samples were studied as a function of the cobalt concentration using X-ray diffraction and magnetization measurements. The disordered state of the Co atoms (x < 0.20) changes to the ordered one (x ≥ 0.20). The magnetic ordering arises at x = 0.20 with mostly antiferromagnetic interaction. For compound with x = 0.30 and 0.50 there is a weak ferromagnetic ordering. The ferromagnetic ordering is observed in Co0.75TiS2 below Tc = 375 K.

LiNi1 – xCoxPO4 (x = 0.3, 0.5, 0.7) compounds have the olivine structure, space group Pnma, with 3d transition metal ions in the 4c octahedral position. The structural analysis of polycrystalline LiNi1 – xCoxPO4 (x = 0.3, 0.5, 0.7) samples is carried out by elastic neutron scattering, and variants of the mutual distribution of nickel and cobalt ions in the 4c position are studied in detail. For the LiNi0.5Co0.5PO4 compound, six options for the mutual distribution of nickel and cobalt ions are proposed. The best description of the neutron-diffraction patterns for the compounds with x = 0.5 is obtained for two models of the distribution of Ni and Co ions in the sequence: Ni–Co–Ni–Co and Co–Ni–Co–Ni, respectively. Nickel ions form planes in the LiNi0.5Co0.5PO4 sample, parallel to ab and alternating with cobalt planes. To describe the neutron-diffraction patterns of x = 0.3 and x = 0.7 compounds, four variants of models for the mutual distribution of Ni and Co ions in the 4c position are proposed. The four versions of the models considered lead to additional structural reflections that are absent in the experimental neutron-diffraction patterns. The experimental neutron-diffraction patterns of the LiNi0.7Co0.3PO4 and LiNi0.3Co0.7PO4 compounds can best be described using the equiprobable distribution of 3d transition-metal ions.

A new method for the solid-phase synthesis of the superionic conductor CsAg 4 Br 2.5 I 2.5 is proposed, which facilitates the preparation of a single-phase product. The thermal behavior of CsAg 4 Br 2.5 I 2.5 in the temperature range from –160 to +190°С was studied by differential scanning calorimetry, and the absence of polymorphous transitions was confirmed; the only first-order phase transition is observed near 177°C and corresponds to the incongruent melting of the solid electrolyte. It is shown that the dense ceramics can be obtained from CsAg 4 Br 2.5 I 2.5 powder by pressing at room temperature; the optimal value of pressure is determined. Studies of the electrical transport characteristics of CsAg 4 Br 2.5 I 2.5 included measurements of the ionic conductivity by the four-probe method in the range of –60…+120°C and an assessment of the electronic component of the conductivity by the Hebb–Wagner method. The contribution of electron transfer is shown to be negligibly small (~10 –9 S cm –1 ), and the ionic conductivity is close to that of the well-known superionic conductor RbAg 4 I 5 and is characterized by a low activation energy (10.3 kJ mol –1 ). The oxidation potential determined by the stepwise polarization method is 0.78 V, which is noticeably higher than that of RbAg 4 I 5 . The absence of first-order phase transitions at temperatures below the melting point, combined with high ionic conductivity, makes the CsAg 4 Br 2.5 I 2.5 compound more attractive for low-temperature applications, and the increased electrochemical stability makes it more attractive for use in chemical power sources as compared to RbAg 4 I 5 .

A new method for the solid-phase synthesis of the superionic conductor CsAg4Br2.5I2.5 is proposed, which facilitates the preparation of a single-phase product. The thermal behavior of CsAg4Br2.5I2.5 in the temperature range from –160 to +190°С was studied by differential scanning calorimetry, and the absence of polymorphous transitions was confirmed; the only first-order phase transition is observed near 177°C and corresponds to the incongruent melting of the solid electrolyte. It is shown that the dense ceramics can be obtained from CsAg4Br2.5I2.5 powder by pressing at room temperature; the optimal value of pressure is determined. Studies of the electrical transport characteristics of CsAg4Br2.5I2.5 included measurements of the ionic conductivity by the four-probe method in the range of –60…+120°C and an assessment of the electronic component of the conductivity by the Hebb–Wagner method. The contribution of electron transfer is shown to be negligibly small (~10–9 S cm–1), and the ionic conductivity is close to that of the well-known superionic conductor RbAg4I5 and is characterized by a low activation energy (10.3 kJ mol–1). The oxidation potential determined by the stepwise polarization method is 0.78 V, which is noticeably higher than that of RbAg4I5. The absence of first-order phase transitions at temperatures below the melting point, combined with high ionic conductivity, makes the CsAg4Br2.5I2.5 compound more attractive for low-temperature applications, and the increased electrochemical stability makes it more attractive for use in chemical power sources as compared to RbAg4I5.

The neutron diffraction, magnetic and heat capacity measurements have been carried out to study the polycrystalline sample LiNi0.5Co0.5PO4 prepared by the glycerol-nitrate synthesis method. Models of Ni- and Co-ion occupation the 4c octahedral position in a crystal structure LiNi0.5Co0.5PO4 are calculated for a paramagnetic state. The best model is the Ni- and Co-ions occupy the 4c site in Pnma patent space-group in sequence Ni–Co–Ni–Co or Co–Ni–Co–Ni. It is shown that nickel ions form ab planes alternating with the planes of cobalt ions in the direction of the c crystallographic axis. At 7 K, an average magnetic moment of 3d-ions is equal to 1.90 (9) μ B. The moments are ordering antiferromagnetically and parallel to the bc plane decreasing to zero at 15 K. In the high-spin state a temperature dependence of the Ni2+/Co2+ ion-magnetic moment is well described within the 2D Ising model with order parameter β = 0.198 and Néel temperature T N = 14.1 (1) K, obtained from heat capacity data. This temperature agrees well with T cr = 14.3 (2) K, determined with magnetic measurement. Maybe the short-range magnetic order exists in LiNi0.5Co0.5PO4 over temperature region (14–16) K, that is confirmed by the maximum on a temperature dependence of the magnetization at 16.1 (5) K.

The LiNiPO 4 , LiNi 0.9 Mn 0.1 PO 4 , and LiNi 0.9 Co 0.1 PO 4 single crystals are studied with heat capacity and neutron diffraction measurements over the temperature interval (10–30) K. Two peaks are observed on the temperature dependence of heat capacity for LiNiPO 4 , and LiNi 0.9 Co 0.1 PO 4 samples. One peak indicates the first order phase transition from an antiferromagnetic commensurate (C) structure to an incommensurate (IC) one upon heating. According to neutron diffraction, in LiNiPO 4 the IC ordering is described by the propagation vector k = 2 π / b (0, 0.080, 0) at the Néel temperature T N = 20.8 K, and k = 2 π / b (0, 0.098, 0) at T N = 20.2(1) K for LiNi 0.9 Co 0.1 PO 4 . A further increase in temperature leads to the second order phase transition to a paramagnetic state at critical temperature T IC = 21.7 K and 21.1 K for LiNiPO 4 and LiNi 0.9 Co 0.1 PO 4 , respectively. The C and IC phases coexist over the temperature interval (20.6–20.8) K and (20.2–21.2) K in LiNiPO 4 and LiNi 0.9 Co 0.1 PO 4 , respectively. In the LiNi 0.9 Mn 0.1 PO 4 the magnetic phase transition occurs at T N = 22.7 K, but a magnetic scattering is observed up to 24.6 K.

Sr2Ni1-xMgxMoO6 double perovskites were synthesized by pyrolysis of glycerol-salt mixtures and their vibrational phonon modes were investigated using optical spectroscopic techniques. X-ray diffraction and Raman spectroscopy were employed to investigate crystal structures of these perovskite materials and purity of the samples. The magnetic ground state of Sr2Ni1-xMgxMoO6 has been characterized using magnetic susceptibility measurements indicating that Sr2Ni0.75Mg0.25MoO6 orders in an antiferromagnetic state at about 56K while Sr2Ni0.5Mg0.5MoO6 and Sr2Ni0.25Mg0.75MoO6 are paramagnetic.

Lithium orthophosphates of the LiMPO4 type (M = Ni, Co, Fe, and Mn) gain intensive development due to the potential applications as electrodes for lithium-ion batteries. The other remarkable property of LiMPO4 is the multiferroicity. We present a study of the crystal structure and magnetic properties, refined anisotropic thermal coefficients and Li-ion migration maps of the LiNi0.9M0.1PO4(M = Co, Mn) single crystals and compared results for the undoped LiNiPO4 and LiMnPO4 ones. All samples have been synthesized by the flux method. In LiNi0.9M0.1PO4(M = Co, Mn), doping increases the lattice constants, unit cell volume, valence bonds, and the anisotropic thermal coefficients. By means of X-ray diffraction and the program package TOPOS, the Li-cation migration maps were obtained. The Li-ions move along the [010] direction which can be clearly visualized in the mixed-metal LiNi0.9 M0.1PO4(M = Co, Mn) single crystals. It was found that the 10% doping of LiNiPO4 by cobalt ions leads to a decrease in the formation temperature and to the suppression of the incommensurate phase. The 10% doping of manganese ions increases the transition temperature, while the temperature range of the incommensurate phase narrows. (C) 2018 Elsevier B.V. All rights reserved.

We present the magnetic properties of LiNi1-xCoxPO4 magnetoelectrics, with x = (0–0.2), and their analysis of concentration dependences. Samples have been synthesized by a glycerol-nitrate method. To refine crystal structure X-ray diffraction measurements were carried out. Magnetic measurements were performed at the external magnetic field of 500 Oe over the temperature range (2–300) K. The neutron powder diffraction patterns of LiNi0.9Co0.1PO4 were recorded over temperature interval from 4.4 K up to 25 K. The partial doping in the LiNi1-xCoxPO4 magnetoelectrics the Ni ions for Co ions leads to a narrowing of the temperature interval where the incommensurate phase is established.

Sr2Ni1-xMgxMoO6 (x = 0.25 and 0.5) double perovskites were synthesized by pyrolysis of glycerol–salt mixtures and their magnetic properties were investigated. X-ray diffraction was employed to refine crystal structures of these perovskite materials and set sample purity degree. The magnetic ground state of Sr2Ni1-xMgxMoO6 (x = 0.25 and 0.5) has been characterized using magnetic susceptibility measurements. They indicate that Sr2Ni0.75Mg0.25MoO6 is ordered in an antiferromagnetic state below 56 K while Sr2Ni0.5Mg0.5MoO6 is paramagnetic.

Neutron irradiation allows the materials to transform to a state, in which the properties of material become different from an initial state. This paper presents the results of neutron irradiation of several magnetic materials including intermetallic compounds Nd2Fe14B and Er2Fe14B, multiferroics BiFe0.95Mn0.05O3 and Bi(0.85)La(0.1)5FeO(3), oxides LiMn2O4 and Li0.9FePO4. The fast neutrons (E-eff > 0.1 MeV) have been used in a fluence range from 1 x 10(18) n/cm(2) to 2 x 10(20) n/cm(2) at 340 K Er2Fe14B alloy becomes amorphous under irradiation, that results in the reduction of Curie temperature to about 200 K. Irradiation destroys charge ordering in LiMn2O4 leading to the transformation from an incommensurate antiferromagnetic to a commensurate ferrimagnetic structure. Neutron irradiation of BiFe0.95Mn0.05O3 oxide is accompanied by decreasing the amount of impurity phases. On the contrary, in Bi0.85La0.15FeO3 fast neutrons result in the appearance of impurity phases. Neutron irradiation distinctly affects the lattice parameters of Li0.9FePO4 compound even with the relatively low fluence.

We present susceptibility, X-ray and neutron diffraction data on powder orthophosphates LiMnPO4, LiFePO4, LiNi0.9Co0.1PO4, and LiNi0.9Mn0.1PO4. Dependences of structure parameters and magnetic state of these compounds on type of 3d element and content of 3d-electrons have been studied. Magnetic moment of 3d-transition ion is orientated along a-axis in LiMnPO4, along b-axis in LiFePO4, and along c-axis in both LiNi0.9Mn0.1PO4 and LiNi0.9Co0.1PO4. At low temperatures, a magnetic moment magnitude is equal to 4.0(B) in LiMnPO4 and LiFePO4 samples, while it is twice less for LiNi0.9Co0.1PO4.

Measurements of magnetic susceptibility as a function of temperature and soft metal L2,3 and oxygen K X-ray absorption spectra were applied for the characterization of Mn and Co doped LiNiPO4. It was established on the basis of measurements of magnetic susceptibility as a function of temperature that the replacement of 10% of Ni by Mn in LiNiPO4 increases the antiferromagnetic phase transition temperature from 21.3 to 22.8K, while the same amount of cobalt decreases the Neel temperature to 21.0K. The experimental Ni, Mn, and CoL2,3 X-ray absorption spectra compared with the results of crystal field atomic multiplet calculations showed that Ni, Mn, and Co ions are in the 2 + valence states. According to our O K X-ray absorption spectra, there are no doping states in the band gap of Mn and Co doped lithium nickel phosphate.

Magnetic properties of the lithium-transition metal orthophosphates LiNiPO4, LiNi0.9Co0.1PO4, LiNi0.9Mn0.1PO4 and LiMnPO4 single crystals have been studied. Temperature behavior of a susceptibility against a type of 3d-transition ion was analyzed. Anomalous behavior is observed over narrow temperature region near Neel point. This is caused by a commensurate-incommensurate magnetic phase transition in pure LiNiPO4, Co- and Mn-doped samples. Using Curie-Weiss model we calculated magnetic constants.

We studied crystal and magnetic structures of some composite and single-phase multiferroics: (x)MFe2O4 + (1-x)BaTiO3, Ni3-yCoyV2O8, and Bi0.9Ba0.1Fe0.9Ti0.1O3. Composite multiferroics (x)MFe2O4 + (1-x)BaTiO3 with x = (0.2; 0.3; 0.4) and M = (Ni, Co) have ferrimagnetic structure, which is described by the propagation vector k = 0. Oxides Ni3-yCoyV2O8 with y = (0.1; 0.3; 0.5) possess a modulated magnetic structure, described by the vector k = (δ, 0, 0), where δ = 0.283 and 0.348 at 7.4 K for y = 0.1 and 0.5, respectively. In the Bi0.9Ba0.1Fe0.9Ti0.1O3 multiferroic a magnetic order is destroyed at 600 K and the Fe-ion magnetic moment decreases from µ = 3.46(5) μB at 300 K to zero at 600 K.