V. I. Pet’kov

Sintering mechanism for high-density NZP ceramics

We have studied the shrinkage kinetics and mechanism of NaZr2(PO4)3 containing inorganic additives. The sintering of NaZr2(PO4)3 containing ZnO microadditives is shown to follow a liquid-phase mechanism. Effective sintering aids include oxides of metals in the oxidation states 2+ and 3+ that are capable of reacting with sodium zirconium phosphate to form solid solutions. Ceramics having a relative density of 96–99% and isostructural with NaZr2(PO4)3 can be prepared by adding 0.75–2.0 wt % ZnO as a sintering aid capable of influencing the structure of grain boundaries in ceramic materials, pressing green bodies at 200–300 MPa, and sintering them at 1000–1100°C for 7–15 h.

Thermal expansion of NASICON materials

Our and others’ results on the thermal expansion of compounds and the crystal-chemical information about their structure have been used to properly select compositions of new NASICON materials with small thermal expansion and low thermal expansion anisotropy: MxM1−x′Ti2(PO4)3 (M and M′ are alkali metals, 0 ≤ x ≤ 1), M″FeTi(PO4)3 (M″ is an alkaline-earth metal), and Ca0.5(1 + x)FexTi2 − x(PO4)3 (0 ≤ x ≤ 1). Such materials have been synthesized through salt coprecipitation from aqueous solutions and their thermal expansion has been assessed by high-temperature X-ray diffraction. We have determined their unit-cell parameters as functions of temperature and correlated their thermal expansion parameters and composition. The K0.5Rb0.5Ti2(PO4)3 and Rb0.8Cs0.2Ti2(PO4)3 materials obtained combine small volumetric thermal expansion and near-zero thermal expansion anisotropy.

Synthesis, structure, and thermal expansion of sodium zirconium arsenate phosphates

Sodium zirconium arsenate phosphates NaZr2(AsO4)x(PO4)3−x were synthesized by precipitation technique and studied by X-ray diffraction and IR spectroscopy. In the series of NaZr2(AsO4)x(PO4)3−x, continuous substitution solid solutions are formed (0 ≤ x ≤ 3) with the mineral kosnarite structure. The crystal structure of NaZr2(AsO4)1.5(PO4)1.5 was refined by full-profile analysis: space group R

Phase formation, crystal structure, and electrical conductivity of triple phosphates of alkali metals and titanium

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Synthesis and study of the phosphate Cs2Mn0.5Zr1.5(PO4)3

c, a = 8.9600(4)Å, c = 22.9770(9) Å, V = 1597.5(1) Å3, Rwp = 4.55. The thermal expansion of the arsenate-phosphate NaZr2(AsO4)1.5(PO4)1.5 and the arsenate NaZr2(AsO4)3 was studied by thermal X-ray diffraction in the temperature range of 20–800°C. The average linear thermal expansion coefficients (αav = 2.45 × 10−6 and 3.91 × 10−6 K−1, respectively) indicate that these salts are medium expansion compounds.

Synthesis and properties of LiZr2(AsO4)3 and LiZr2(AsO4) x (PO4)3 − x

AbstractFor triple phosphates of composition A′0.5A0.5 Ti2(PO4)3 (A−A′=Li−Na, Na−K, K−Rb), phase formation is studied, the crystal structure is refined, and the electrical conductivity is measured. The compounds are classified with the NaZr2(PO4)3 structure type (NZP, space group R

Synthesis and crystal structure of phosphate Ba1.5Fe2(PO4)3

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Crystal structure of the double magnesium zirconium orthophosphate at temperatures of 298 and 1023 K

c). The phosphate frameworks are built of TiO6 octahedra and PO4 tetrahedra. Extraframework positions M1 are fully occupied by randomly distributed alkali cations. Positions M2 are vacant. Correlations are found between the structural distortion and electrical conductivity of the phosphates, on one hand, and the alkali cation size, on the other.