Magnetic properties of (Cu0.5Ga0.5)1 − x Fe x Cr2S4 solid solutions

Magnetic properties are studied and a magnetic phase diagram is constructed for (Cu_0.5Ga_0.5)_{1 ? x} Fe _x Cr₂S₄ solid solutions formed between chromium chalcogenide spinels (Cu_0.5Ga_0.5)Cr₂S₄ and FeCr₂S₄.     

Synthesis and magnetic properties of Cu0.5Fe0.5 ? x In x Cr2S4 (x = 0?0.4) solid solutions

Multistep synthesis with X-ray diffraction monitoring of the phase composition has been carried out, optimal synthesis parameters have been determined, and the magnetic properties of solid solutions between thiospinels with ordered tetrahedral A lattices (ferrimagnet Cu_0.5Fe_0.5Cr₂S₄ (T _C = 347 K) and anti-ferromagnet Cu_0.5In_0.5Cr₂S₄ (T _N = 35 K) have been studied. Both compounds crystallize in F $\bar 4$ 3m (T _d ² ) structure. Measurements over wide ranges of fields (0.05?C40 kOe) and temperatures (5?C300 K) highlighted the nature of magnetism in the samples; new magnetic species have been discovered.     

Synthesis and magnetic properties of CuCr1.5Sb0.5S4 ? x Se x solid solutions

CuCr_1.5Sb_0.5S_{4 ? x} Se _x (x = 0, 0.5, 3.5, 4) metal chalcogenides with spinel structure have been synthesized for the first time. Unit cell parameters have been calculated and magnetic properties have been measured for the samples prepared. These samples are nonuniform antiferromagnets having Neel temperatures of T _N = 21?C30 K.     

Electrophysical properties of solid solutions of Zn2 − x (Zr a Sn b )1 − x Fe2x O4 compositions

The electrophysical properties of the multicomponent Zn₂ZrO₄ ? Zn₂SnO₄ ? ZnFe₂O₄ system are studied. The electrophysical parameters of solid solutions of Zn_{2 ? x} (Zr _a Sn _b )_{1 ? x} Fe_2x O₄ (x = 0–1.0, Δx = 0.1, a + b = 1) are determined. It is found that the formed solid solutions are semiconductors with electrophysical properties that change in a regular fashion with composition and are distinguished by high values of resistivity (107–1012 Ω cm).     

Magnetic studies on ScyU1−yO2+x solid solutions

Magnetic susceptibilities of Sc_yU_1−yO_2+x solid solutions have been measured from 2.7 K to room temperature. The magnetic moment and Weiss constant have been determined in the temperature range in which the Curie-Weiss law holds. For the solid solutions showing antiferromagnetic transition, the Néel temperature has also been determined. The substitution of Sc³⁺ for U⁴⁺ was found to effect not only magnetic dilution of UO₂, but also oxidation of U⁴⁺ to U⁵⁺. Excess oxygen ions which entered the interstitial sites, weakened the antiferromagnetic interaction between uranium ions and oxidized U⁴⁺ to U⁵⁺. The effect of oxygen vacancies on the antiferromagnetic interaction was small in the concentration range of this experiment (0.8 a/o).     

Electrical properties of Ba2(In1 − x Al x )2O5 solid solutions

The electric conductivity of perovskite-like Ba₂(In_{1 ? x} Al _x )₂O₅ solid solutions (0 < x ≤ 0.20) characterized by structural disordering in the oxygen sublattice was studied as a function of temperature and partial pressure of oxygen in an atmosphere with a low content of water vapors ( $p_{H_2 O}$ = 3 × 10^?5 atm). When In³⁺ was partially replaced by Al³⁺, the oxygen ion conductivity increased because of the disordering of oxygen structural vacancies, leading to a significant increase in the total electric conductivity of the samples.     

Second-harmonic generating properties of polar noncentrosymmetric aluminoborate solid solutions, Al(5-x)Ga(x)BO9 (0.0 ≤ x ≤ 0.5)

A series of solid solutions of polar aluminoborate materials, Al(5-x)Ga(x)BO(9) (0.0 ≤x≤ 0.5) have been synthesized by standard solid-state reactions using Al(2)O(3), Ga(2)O(5), and B(OH)(3) as reagents. The phase purities, crystal structures, and solid solution behavior of the reported materials have been investigated by powder X-ray diffraction. Solid solutions of Al(5-x)Ga(x)BO(9) crystallize in the polar noncentrosymmetric space group, Cmc2(1), with a three-dimensional structure consisting of distorted MO(4), MO(5), MO(6), and BO(3) polyhedra (M = Al or Ga). Powder second-harmonic generating (SHG) measurements on the Al(5)BO(9) using 1064 nm radiation, indicate the material has a SHG efficiency of approximately 2 times that of α-SiO(2) and is not phase-matchable (type 1). Further nonlinear optical (NLO) measurements on the Al(5-x)Ga(x)BO(9) solid solutions indicate a sharp increase in SHG efficiency up to 10 times that of α-SiO(2) for x≥ 0.4. Close structural examination suggests that the alignment of the asymmetric π-delocalization of BO(3) groups is responsible for the abrupt increase of SHG efficiency.     

Magnetic susceptibilities of UO2ThO2ZrO2 solid solutions

Magnetic susceptibilities were measured from 2.2 K to room temperature for solid solutions of UO₂ThO₂ZrO₂ of which the lattice parameters are the same as that of UO₂, i.e., Th_0.7yZr_0.3yU_1−yO₂ solid solutions. The Néel temperature decreases linearly with decreasing uranium concentration, the critical concentration being 69 mole% UO₂. The Néel temperatures of the present solid solutions are nearly in the middle of UO₂ThO₂ solid solutions and UO₂ZrO₂ solid solutions, which indicates that the magnetic dilution effect of ZrO₂ is larger than that of ThO₂. The effective magnetic moment decreases with decreasing uranium concentration, which is due to a decrease in the magnetic interactions with adjacent uranium ions, not due to a change of the strength of crystalline field. The Weiss constant decreases almost linearly with decreasing uranium concentration.     

Thermodynamic properties of solid solutions in the PbSe—AgSbSe2 system

The results of the study of the PbSe—AgSbSe₂ system by measuring the emf of concentration chains with respect to PbSe in a temperature range of 300–450 K are presented. The formation in the system of a wide (37–100 mol.% AgSbSe₂) region of solid solutions based on AgSbSe₂ is shown. The partial thermodynamic functions of PbSe and lead in the alloys are calculated from the equations of the temperature dependences of the emf. The standard thermodynamic functions of formation and standard entropies of solid solutions (2PbSe)_x(AgSbSe₂)_1?x (x = 0.4, 0.6, 0.8, and 0.9) are calculated by the integration of the Gibbs—Duhem equation over the PbSe—AgSbSe₂ section using the literature data on the corresponding thermodynamic data for compounds PbSe and AgSbSe₂.

     

Electrochemical properties of solid solutions in the Li8Zr1 − x Ce x O6 system

Li₈Zr_{1 ? x} Ce _x O₆ solid solutions based on lithium zirconate Li₈ZrO₆ were obtained by solid-state synthesis in an inert atmosphere. Their transport properties (the electron component of the total conductivity, the temperature and concentration dependences of conductivity, and the activation energies) were studied by impedance spectroscopy. The practical stability of the ceramic samples of Li₈Zr_{1 ? x} Ce _x O₆ solid solutions (x = 0–0.07) at 473–573 K against melted lithium was studied.     

Electrochemical studies of LiCr x Fe x Mn2?2x O4 in an aqueous electrolyte

In this paper, LiCr _x Fe _x Mn_2−2x O₄ (x = 0, 0.05, 0.1) electrode materials were prepared by sol–gel technique and characterized by X-ray diffraction (XRD) and transmission electron microscopy or high-resolution transmission electron microscopy techniques. XRD results reveal that the Cr–Fe-co-doped LiCr _x Fe _x Mn_2−2x O₄ materials are phase-pure spinels. The electrochemical properties of the LiMn₂O₄, LiCr_0.05Fe_0.05Mn_1.9O₄, and LiCr_0.1Fe_0.1Mn_1.8O₄ electrodes in 5 M LiNO₃ aqueous electrolyte were investigated using cyclic voltammetry, AC impedance, and galvanostatic charge/discharge methods. In the current range of 0.5–2 A g⁻¹, the specific capacity of the LiCr_0.05Fe_0.05Mn_1.9O₄ electrode is close to that of the LiMn₂O₄ electrode, but the specific capacity of the LiCr_0.1Fe_0.1Mn_1.8O₄ electrode is obviously lower than that of the LiMn₂O₄ electrode. When the electrodes are charge/discharge-cycled at the high current rate of 2 A g⁻¹, the LiCr_0.05Fe_0.05Mn_1.9O₄ electrode exhibits an initial specific capacity close to that of the LiMn₂O₄ electrode, but its cycling stability is obviously prior to that of the LiMn₂O₄ electrode.     

Magnetic properties of TlFe2−xSe2

Mössbauer studies on a mosaic of single crystals of the layered compound TlFe_2−xSe₂ have been carried out at various temperatures between 100 and 460 K. A magnetic transition occurs at ∼450 K. The magnetic ordering within the FeSe layers is antiferromagnetic with the spins oriented along the tetragonal axis. X-Ray diffraction data indicated ordering of the iron vacancies at the chosen composition (x ∼ 0.3) yielding a supercell with a volume five times that of the ThCr₂Si₂ type subcell, the cell parameters being a = 8.6909(5) Å and c = 14.005(1) Å.     

New Fe3+/Cr3+ perovskites with anomalous transport properties: the solid solution La(x)Bi(1-x)Fe(0.5)Cr(0.5)O3 (0.4 ≤ x ≤ 1)

In this work, the sol-gel synthesis, structural characterization, and transport properties of a new solid solution of the general formula La(x)Bi(1-x)Fe(0.5)Cr(0.5)O(3) (0.4 ≤ x ≤ 1) are presented. The solubility limit x has been determined and variation of the lattice parameters measured through profile fitting. The cell parameters, space group, and atomic positions, as obtained by the Rietveld refinement of X-ray diffraction data, are reported. This analysis and electron diffraction studies as well do not reveal any evidence of Fe/Cr ordering. Regarding the transport properties, magnetic and electric characterizations are described. The electrical response with the temperature and frequency has been studied, and a "positive temperature coefficient" for the resistivity has been found for temperatures between 270 and 400 °C. The magnetic behavior is striking because, for all materials studied, zero-field-cooling curves appear above field-cooling ones, an anomalous feature that is interpreted as being due to complex ferromagnetic/antiferromagnetic interactions in the B perovskite sublattice.     

Thermal properties and structure of (As2S3)100−x(Sb4S4)x glassy system

Thermal properties and structure of bulk glasses of (As₂S₃)_1?x(Sb₄S₄)_x system (x varies from 0 to 60 mol%) were studied by differential scanning calorimetry and Raman spectroscopy. It was found that with increasing Sb content the glasses can be sorted out to the three groups. The structure of glasses with x ≤ 10 is build-up mainly from AsS_3/2 pyramidal units and the well-known crystallization resistance of As₂S₃ can explain the reluctance of these undercooled liquids against crystallization. In glasses with a higher content of antimony, i.e., 10 < x ≤ 30 mol%, the vibration characteristics of As₄S₄ clusters appear. Undercooled melts of these glasses crystallize forming both β-As₄S₄ and high-temperature phases of Sb₂S₃. Structure of glasses with the highest antimony content (x > 30 mol%) is based on SbS_3/2 structural units significantly lowering stability of their undercooled melts from which only Sb₂S₃ crystallizes.     

Pyrochlore solid solutions (LaxY1−x)2Mo2O7, x = 0.0 to 0.5. Spin-glass-like behavior

The (La_xY_1−x)₂Mo₂O₇ system was investigated in the range x = 0.0 to x = 0.5. Single-phase materials exist up to x = 0.4; the x = 0.5 composition has a small impurity contamination. The lattice constants are linear with x and range from 10.224 Å (x = 0.0) to 10.461 Å (x = 0.5). These lattice constants span the same range as the R₂Mo₂O₇ series from R = Y to R = Nd. In this series, there is a discontinuous change from ferromagnetic long-range order to short-range spin-glass-like order between R = Gd and R = Tb. Yet, the solid solutions all show spin-glass-like properties with maxima in the susceptibility in the 20–25 K range and sample-history-dependent effects at lower temperatures. Deviations from the Curie-Weiss Law occur well above the susceptibility maxima. The Weiss constants change from −61 to +41 K for x = 0.0 and x = 0.5, respectively, indicating a competition between antiferromagnetic and ferromagnetic exchange interactions. This competition, coupled with the inherent frustration of the Mo⁴⁺ lattice in space group Fd3m is a possible origin of the spin-glass properties.     

Thermodynamic properties of solid solutions of silica in forsterite (Mg2Si1+γO4+2γ)

From solid state electrochemical measurements on Mg₂SiO₄SiO₂ solid solutions in air at 1300 K ≤ T ≤ 1780 K the thermodynamic (excess) functions are calculated. A pronounced nonideality is found.     

Electric properties of oxyfluorides Ba2In2O5−0.5x F x with brownmillerite structure

Synthesis of fluoro-substituted substances based on brownmillerite Ba₂In₂O₅ is carried out. The width of the homogeneity region of the Ba₂In₂O_5?0.5x F _x (0 < x ≤ 0.25) solid solution was established using X-ray analysis. Measurement of temperature dependences of conductivity in atmospheres with different partial pressure of water vapor (pH₂O = 3.3 and 2 × 10³ Pa) showed an increase in conductivity at T ≤ 550°C in a humid atmosphere, which is due to appearance of proton transport. The dependence of conductivity on partial oxygen pressure (pO₂ = 0.21 × 10⁵ to 10^?15 Pa) is studied in the temperature range of 500–1000°C; ion transport numbers are calculated. The method of polarization measurements was used to determine transport numbers of fluoride. Total conductivity is divided into ion (proton, oxygen, and fluoride ion) and electron components. Analysis of concentration dependences of conductivities showed that low concentrations of fluoride allow increasing both the total and partial conductivities (oxygen-ion and proton) and, besides, allow shifting the “order-disorder” phase transition by 100°C to the low temperature range.     

Rubidium-cationic conductivity of Rb2−2x Ga2−x A x O4 (A = P, V, Nb, Ta) solid electrolytes

Solid solutions based on rubidium monogallate RbGaO₂ with a general formula Rb_2?2x Ga_2?x A _x O₄ (A = P, V, Nb, and Ta) are synthesized. Their crystal structure and temperature and concentration dependences of conductivity are studied. The highest rubidium-cationic conductivity is (1.8–3.9) × 10^?3 S cm^?1 at 400°C and (1.4–2.1) × 10^?2 S cm^?1 at 700°C. These results are compared with the data for rubidium monogallate doped with four-charged cations and solid solutions based on RbAlO₂.     

Magnetic susceptibility of La1–уCе y AlO3 solid solutions

Russian Journal of General Chemistry - Magnetic properties of the La1–уCе y AlO3 solid solutions (y = 0.02–0.20) were studied by the magnetic dilution method....     

Synthesis and study of the properties of the solid solutions K2Y1−x Tb(Tm) x (MoO4)(PO4) and K2Y1−x Tm x (MoO4)(PO4)0.95(VO4)0.05

The solid solutions K₂Y_1?x Tb(Tm) _x (MoO₄)(PO₄) and K₂Y_1?x Tm _x (MoO₄)(PO₄)_0.95(VO₄)_0.05 were synthesized, which are isostructural and crystallize in the orthorhombic crystal system (space group Ibca). The luminescence intensity of the terbium-containing samples increases with increase in the terbium content. The thulium-containing samples are characterized by intense luminescence in the blue spectral region and concentration quenching of luminescence. The introduction of the vanadate anion adversely affects the luminescence intensity.