State of atoms of the transition group elements in dilute solid solutions based on LiMO2 (M = Sc, Ga, Al): IV. Magnetic susceptibility of the LiMxGa1?xO2 solid solutions (M = Cr, Cu)

Magnetic dilution of LiMO₂ complex oxides (M = Cu, Cr) was studied. The results obtained were correlated to the physical and chemical properties of two-dimensional perovskite-like oxides containing copper and lithium. Various valence and spin states of copper and chromium were found, which are associated with essential anisotropy of the local surrounding of a transition element and with the influence of lithium atoms on the electron state of nanoclusters containing these elements. Original Russian Text ? N.P. Bobrysheva, A.A. Selyutin, I.A. Grigorov, 2009, published in Zhurnal Obshchei Khimii, 2009, Vol. 79, No. 4, pp. 538–541. For communication III, see [1].     

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.     

Structure, magnetic, and electric properties of bismuth niobates doped with d-elements: VII. State of copper in the Bi2BaCu x Nb2−x O9−δ solid solutions

Magnetic susceptibility of the Bi₂BaCu _x Nb_2?x O_9?δ solid solutions (0.01 < x < 0.20) with the layered perovskite-like structure was studied. In dilute solid solutions, copper atoms are in the form of Cu(II) monomers. As the concentration increases, the fraction of monomers decreases and the fraction of exchange-bonded aggregates (dimers) of Cu(II) with antiferromagnetic exchange increases. The antiferromagnetic exchange parameter in the copper dimers was estimated at ?300 cm^?1.     

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.     

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.     

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.     

The structures of the solid solutions formed in the system (CrxFe1−x)VO4

Solid solutions (Cr_xFe_1−x)VO₄ can be prepared over a wide composition range and are thermally stable to above 900°C. They are isomorphous with α-MnMoO₄ rather than adopting the CrVO₄ or FeVO₄ structures. At 3000 atm pressure, a reversible transformation to a CrVO₄ type polymorph takes place. substitution of small amounts of phosphate into CrVO₄ also produces an α-MnMoO₄ isomorph.     

Atoms state and interatomic interactions in perovskite-like oxides: XXXII. Formation of paramagnetic clusters in the La1−0.33x Ca0.33x Fe x Al1−x O3 and La1−0.33x Sr0.33x Fe x Al1−x O3 solid solutions

Calcium- and strontium-containing lanthanum orthoferrites have been studied using magnetic dilution method. It has been shown that the iron-atom clusters with competing ferro- and antiferromagnetic exchange interactions can exist. By using Mossbauer spectroscopy, Fe(IV) atoms have been found in the La_1?0.33x Ca_0.33x Fe_xAl_1?x O₃ solid solutions and Fe(III) atoms in two different surroundings have been found in the La_1?0.33x Sr_0.33x Fe _x Al_1?x O₃ solid solutions. The compositions of paramagnetic clusters stable at the infinite dilution have been proposed basing of the magnetic susceptibility and Mossbauer spectroscopy data.     

Defect structures in the brannerite-type vanadates: VIII. Synthesis of the Mg1−yLiyV2−yMoyO6 and Mg1−x−yØxLiyV2−2x−yMo2x+yO6 solid solutions: Effect of strengthening the crystal lattice by substitution of monovalent ion for bivalent ion

It is shown that MgV₂O₆ and LiVMoO₆, both of the brannerite-type structure, exhibit miscibility in the entire composition range resulting in the formation of MgLi = Mg_1−yLi_yV_2−yMo_yO₆ solid solutions. For y > 0.5 significant capacity of the MgLi matrix to the excess Mo⁶⁺ cations compensated by cation vacancies Ø appears and MgLiØ = Mg_1−x−yØ_xLi_yV_2−2x−yMo_2x+yO₆ solutions become stable. Pronounced negative deviations from Vegard's law are simultaneously observed for MgLi solid solutions. An unusual phenomenon is thus observed: monovalent cation (Li⁺) substituted for bivalent cation (Mg²⁺) strengthens the brannerite-type lattice and increases its toleration to cation vacancies. A similar effect has recently been observed for ZnLi and ZnLiØ solid solutions (K. Mocała and J. Ziółkowski, J. Solid State Chem. 71, 426 (1987)); the effect is absent, however, in the case of MnLi and MnLiØ (J. Ziółkowski, K. Krupa, and K. Mocała, J. Solid State Chem. 48, 376 (1983)). Some speculations concerning this effect and some predictions are offered. X-ray data are listed for MgLi solid solutions of various compositions.     

Glycolate Ti1 − x Fe x (OCH2CH2O)2 − x/2 as a precursor for the preparation of quasi-one-dimensional (1D) solid solutions Ti1 − x Fe x O2 − 2x/2 (0 ≤ x ≤ 0.1)

Quasi-one-dimensional (1D) solid solutions Ti_{1 ? x} Fe _x (OCH₂CH₂O)_{2 ? x/2} (0 < x ≤ 0.1) with the structure of anatase were prepared by heating the glycolate Ti_{1 ? x} Fe _x (OCH₂CH₂O)_{2 ? x/2} in an atmosphere of air at a temperature of >450°C. The conditions of formation and the properties of the new glycolate Ti₃Fe₂(OCH₂CH₂O)₉ were described. It was found that the synthesized Ti_{1 ? x} Fe _x O_{2 ? 2x/2} solid solutions exhibit photocatalytic activity in the reaction of hydroquinone oxidation in an aqueous solution on irradiation with UV light. A correlation between the rate of oxidation of hydroquinone and the concentration of iron in the catalyst was established. A procedure for the preparation of titanium dioxide with the structure of anatase doped with iron and carbon (Ti_{1 ? x} Fe _x O_{(2 ? x/2) ? yCy)} and also composites on its basis, which contain an excess amount of carbon, was proposed.     

Study of series of the M1,M2‖F,Cl,Br quaternary reciprocal systems (M1 and M2 are group 1 s-block elements)

Quaternary reciprocal systems of alkali metal fluorides, chlorides, and bromides were partitioned into simplexes by a geometric method and a graph method. Phase transformations and chemical reactions in the bordering ternary reciprocal systems were described. Conversion lines were experimentally studied, and information on crystallizing phases within the composition prisms of the M₁,M₂‖F,Cl,Br systems (M₁ and M₂ are group 1 s-block elements) was obtained.     

Electric conductivity of solid solutions in Cs2 ? 2x Fe2 ? x A x O4 systems (A = P, V)

Solid solutions based on CsFeO₂ in Cs_{2 ? 2x} Fe_{2 ? x} A _x O₄ systems (A = P, V) were synthesized. Their crystal structure and the temperature and concentration dependences of the total conductivity and its electronic component were studied. The ranges of temperature and composition in which cesium-cation conductivity was dominant were determined. The obtained data were compared with the results of studies of other cesium-conducting solid electrolytes.     

121,123Sb NQR study of solid phases formed in systems (MF)1−x −(M′F) x −SbF3−H2O (M, M′=Na, K, Rb, Cs, and NH4)

Crystalline substances formed in the (MF)_1−x −(M′F) _x −SbF₃−H₂O systems (M, M′=Na, K, Rb, Cs, and NH₄;x=0 to 1) were investigated by^121,123Sb NQR spectroscopy at 77 K. The formation of individual Sb^III complexes NaCs₃Sb₄F₁₆·H₂O and NaKSbF₅·1.5H₂O, and statistically disordered mixed crystals M_1−x −M′ _x −SbF₄ (M, M′=K, Rb, Cs, and NH₄) was established. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 109–112, January, 1999.     

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.     

Vibrational spectroscopic study of the hypophosphite and phosphite anions,H2PO2−2 and HPO2−3, and of their deuteriated analogues in the solid state and in aqueous solution

A full vibrational spectroscopic study of sodium hypophosphite, sodium phosphite and their deuteriated analogues has been made. The vibrations characteristic of the hypophosphite anion have been assigned and the presence of a previously unreported band has been established for the Raman spectrum of the aqueous solution. The first Raman study of deuteriated sodium phosphite has been undertaken and a full vibrational assignment is given.     

Synthesis of a water purification reagent based on the Fe(II), Fe(III), Al(III), Cl−-H2O-OH-system

Formation kinetics of a water purification reagent based on the Fe(II), Fe(III), Al(III), Cl^?-H₂O-OH^? system was studied in relation to the nature and state of the surface of dispersed aluminum, initial concentration of iron(III) ions, and pH value. The chemical composition of heteronuclear coordination compounds of iron and aluminum was determined by potentiometry, nuclear magnetic resonance, and X-ray phase analysis.     

Mössbauer studies of Fe1−xMxBO3 (x = 0, 0.1; M = Al3+, Ga3+, Cr3+) close to the Tc

The results of a Mössbauer study on the effect of substitution of Al³⁺, Ga³⁺, and Cr³⁺ in ferromagnetic FeBO₃ close to the T_c are presented. The Curie temperatures of FeBO₃, Fe_0.9Al_0.1BO₃, Fe_0.9Ga_0.1BO₃, and Fe_0.9Cr_0.1BO₃ have been determined to be 352, 317, 319, and 335 K, respectively. “Anomalous” spectra have been found to appear just 1° below the T_c for FeBO₃, but 15° below the T_c for substituted borates. The inadequacy of static models in explaining these spectra has been pointed out. These spectra have been simulated using relaxation models and estimates of activation energy obtained for spin-flip processes. The results are attributed to dominant superparamagnetic relaxation effects due to the presence of clusters. Mössbauer spectra of FeBO₃ substituted by a magnetic ion, viz., Cr³⁺, are found to differ significantly from those of the above-mentioned samples.