Design of New Functional Materials Based on Complex Oxides with a Tunnel Structure of the Ramsdellite, Hollandite, and Ba2Ti9O20Types

Grigor'eva, L. F.; Петров, С. А.; Sinel’shchikova, O. Yu.; Гусаров, В. В.

doi:10.1023/b:gpac.0000032228.91101.c3

Cited by 3 publications

(6 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The general formula of compounds with a ramsdellite structure can be represented in the form A x B y O 8 (where A = Li; B = Li, Mg, Fe, Ti, Sn, Sb) [3,4]. In the structure of these compounds, oxygen octahedra formed by B cations are joined through common edges into double chains lying along one of the crystallographic axes.…”

Section: Introductionmentioning

confidence: 99%

“…This phase transformation is accompanied by a decrease in the electrical conductivity by several orders of magnitude. In the opinion of a number of authors [2][3][4][5][6], the incorporation of elements in different oxidation states into the octahedral sublattice of ramsdellite-type phases can impart new useful properties to these compounds. In this respect, investigations of complex oxides with a tunnel structure of the ramsdellite type are of particular interest both from the standpoint of the search for new solid electrolytes and for the study of the crystal chemistry of these compounds.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Physicochemical prerequisites of the synthesis of new ionic conductors based on complex oxides with a ramsdellite-type structure

et al. 2008

Self Cite

View full text Add to dashboard Cite

This paper reports on the results of experimental investigations of solid solutions that have a ramsdellite structure and crystallize in the systems. The concentration boundaries of existence of these solid solutions are determined, and their thermal and electrical properties are studied. It is established that the ramsdellite phases crystallizing in the Li 2 O-Fe 2 O 3 -SnO 2 -TiO 2 and Li 2 O-Fe 2 O 3 -TiO 2 systems transform into a metastable hexagonal phase at temperatures of 6 50-700 and 550 ° C, respectively. The results of investigations of this phase transformation by differential thermal analysis, differential scanning calorimetry, and high-temperature X-ray diffraction, as well as measurements of the electrical conductivity of the ramsdellite phases in the Li 2 O-Fe 2 O 3 -SnO 2 -TiO 2 system, indicate that this transition is a first-order phase transition. Solid solutions of ramsdellite phases crystallizing in the Li 2 O-Cr 2 O 3 -TiO 2 system do not undergo the phase transformation under consideration. These solid solutions are stable during multiple dynamic heating to 1000 ° C (under heating-cooling conditions at a rate of 10 − 15 ° C/min). Long-term heat treatments at 1000 ° C (for more than 3 h) lead to their decomposition with the formation of ramsdellite phases of the unknown composition and the Li 2 TiO 3 compound. The electrical conductivities of the solid solutions formed by the ramsdellite phases crystallizing in the Li 2 O-Fe 2 O 3 -TiO 2 and Li 2 O-Cr 2 O 3 -TiO 2 systems at a temperature of 500 ° C are evaluated to be σ ≈ 10 -1.5 S/cm. The transformation of the ramsdellite phases in the Li 2 O-Fe 2 O 3 -TiO 2 system into the metastable hexagonal phases is accompanied by a decrease in the electrical conductivity by several orders of magnitude. The electrical conductivity of Li 1.9 Cr x Ti 3.025 -0.75 x O 7 (0 ≤ x ≤ 0.8) solid solutions remains unchanged upon multiple dynamic heating to 1000 ° C (with subsequent cooling).

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Physicochemical prerequisites of the synthesis of new ionic conductors based on complex oxides with a ramsdellite-type structure

et al. 2008

Self Cite

View full text Add to dashboard Cite

show abstract

Section: Introductionmentioning

confidence: 99%

“…This is responsible for the great variety of their chemical compositions and physical properties [1][2][3]. In particular, hollandites containing alkali cations (K + , Li + + K + ) in tunnels are solid electrolytes in the temperature range 600-900 ° C [1,4]. Hollandites in which potassium (K + ) plays the role of A cations and gallium (Ga 3+ ) or tin (Sn 4+ ) serve as B cations possess properties of medium-temperature catalysts in reactions of the NO x reduction and CO oxidation [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Kinetics and mechanism of the formation of hollandites in the BaO(Cs2O)-Al2O3-TiO2 system from initial mixtures prepared by different methods

et al. 2007

Self Cite

View full text Add to dashboard Cite

The mechanism and kinetics of formation of solid solutions based on hollandite in the BaO(Cs 2 O)-Al 2 O 3 -TiO 2 system are investigated using the initial mixtures prepared by two methods: (i) mechanical grinding and mixing of the initial components and (ii) coprecipitation from aqueous solutions of the salts. It is established that the mechanism of formation of hollandite in the system under investigation depends on the degree of dispersion of the initial mixtures used in the synthesis. When the synthesis is performed with the initial mixture prepared by mechanical grinding and mixing of the initial reactants (the particle size is equal to 50-300 nm), hollandite is formed at temperatures in the range 1100-1250 ° C in the presence of the accompanying phase Cs 2 Al 2 Ti 2 O 8 . When the synthesis is performed with the initial mixture prepared by coprecipitation from aqueous solutions of salts (the particle size is equal to 10-12 nm), hollandite is formed at temperatures in the range 850-1050 ° C. The investigation into the kinetics of formation of the hollandite phase from the above mixtures made it possible to determine the temperature-time conditions for the synthesis of this titanate in the form of a powder with a particle size of approximately 50 nm or in the form of a dense ceramic material with a particle size of ~200 nm.

show abstract

“…In the opinion of a number of authors [2][3][4], variable-valence elements embedded in the octahedral sublattice of ramsdellite-type phases can impart new useful properties to these compounds.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Titanates with a Ramsdellite-Type Tunnel Structure Crystallizing in the Li2O-Fe2O3-TiO2 System in Different Gaseous Media

et al. 2005

Self Cite

View full text Add to dashboard Cite

The ramsdellite-type phases crystallizing in the Li 2 O-Fe 2 O 3 -TiO 2 system in the course of synthesis in gaseous media at different oxygen partial pressures are studied. Solid solutions based on the ramsdellite structure with the composition Li 2 Ti 3x Fe x O 7 -δ (0 ≤ x ≤ 0.7) are prepared in an oxidizing medium ( = 1 atm) for the first time. Analysis of the results obtained by electron paramagnetic resonance and Mössbauer spectroscopy revealed that, in these solid solutions, all iron ions are in the oxidation state Fe +3 .

show abstract

Design of New Functional Materials Based on Complex Oxides with a Tunnel Structure of the Ramsdellite, Hollandite, and Ba₂Ti₉O₂₀Types

Cited by 3 publications

References 36 publications

Physicochemical prerequisites of the synthesis of new ionic conductors based on complex oxides with a ramsdellite-type structure

Physicochemical prerequisites of the synthesis of new ionic conductors based on complex oxides with a ramsdellite-type structure

Kinetics and mechanism of the formation of hollandites in the BaO(Cs2O)-Al2O3-TiO2 system from initial mixtures prepared by different methods

Synthesis of Titanates with a Ramsdellite-Type Tunnel Structure Crystallizing in the Li2O-Fe2O3-TiO2 System in Different Gaseous Media

Contact Info

Product

Resources

About