Catalysis and petrochemistry

Growth of monocrystals of double polyphosphate NaMn (PO₃)₃ and its structure

 

---

R.V. Lavrik¹, V.V. Trachevsky², V.A. Diamant³

---

¹National University of Life and Environmental Sciences of Ukraine
²G.M. Kurdyumov Institute for Metal Physics of the NAS of Ukraine
³Vernadsky Institute of General and Inorganic Chemistry of the NAS of Ukraine

---

ABSTRACT

---

Optimum conditions for the growing of single crystals of NaMn(PO₃)₃ compound have been selected. Complete X-ray diffraction analysis has been performed to study synthesized polyphosphate Li₂Mn(PO₃)₄. Structure of the double phosphate belongs to the orthorhombic crystal system, space group Р2₁2₁2₁, lattice parameters: a = 14.446(2), b = 14.463(2), c = 14.522(3) Å, V = 3034 ų, Z = 16, Rho_calc. = 2.757 g/cm³. Structural features of synthesized phosphate have been determined. The compound has been studied using XRD/RSA, DTA and IR spectroscopy techniques along with complete chemical analysis. The crystalline structure of novel double phosphate NaMn(PO₃)₃ has been determined using X-ray diffraction method. X-ray diffraction analysis of white crystals with rhomboidal habit having size of 0.1 × 0.019 × 0.2 mm has been performed using Siemens P3/PC diffractometer under molybdenum radiation with graphite monochromator. As a result of experiment, 3018 reflections (within 0 ≤ h ≤ 11; 0 ≤ k ≤ 11; -12 ≤ l ≤ 0) have been obtained, of which 2133 independent reflections with F > 4δ(І) have been used for calculations. The integrated intensity has been measured using 2 θ : θ method over the range of angles 4.88 ≤ θ ≤ 50.14 at scan rate of 2–28 degrees per minute. Crystalline lattice parameters have been refined according to 36 reflections within the range of angles 16.0 ≤ θ ≤ 32.0. The final value of the divergence factor is Rw = 0.0547. The crystallization range of new double phosphate NaMn(PO₃)₃ has been determined in the melts of Na₂O–P₂O₅–Mn₂O₃ system at a temperature range of 650–900 ⁰С. Furthermore, optimum conditions for the growing of single-crystals of the compound with high yield (over 45 % of weight) have been selected, the series of their physical and chemical properties have been studied and the melting point of the compound has been determined -850 ⁰С. A complete XRD of the synthesized polyphosphate NaMn(PO₃)₃ has been performed and the special features of its structure have been defined: statistically disordered alkali metal atoms with a characteristic coordination number (6); the record period of repetition of tetrahedra [PO₄] in the polyphosphate chains of the structure is 24; the framework of the compound contains “tunnels”, that can be used and modified. These results stimulate further research of the compound and creation of materials on its basis.

---

KEYWORDS

---

double phosphates, IR spectroscopy, PCA, crystallization of single crystals, crystallization from a melt

REFERENCES

---

1. Orlova А.I., Koruttseva A.K., Loginova E.E. The phosphate family of langbaenite structure. Crystal-chemical aspect of immobilization of radioactive waste. Radiochemistry. 2011. 53 (1). 51. [In English] https://doi.org/10.1134/S1066362211010073
2. Urenski P., Rosenman G. Polarization reversal and domain anisotropy in flux-grown KTiOPO₄ and isomorphic crystals. J. Mater. Res. 2001. 16 (5). 1493. [In English].https://doi.org/10.1557/JMR.2001.0208
3. Pet'kov V.I., Asabina E.A., Lukuttsov A.A. Immobilization of cesium into mineral-like matrices of tridymite, konsarite, and langbeinite structure. Radiochemistry. 2015. 57 (6). 632. [In English].https://doi.org/10.1134/S1066362215060119
4. Stus N.V., Nagornyj P.G., Slobodyanik N.S. Ferroelecric properties of crystal of the KTP group. Ukr. Khim. Zh. 2000. 66 (2). 72. [In English].https://doi.org/10.15407/fm24.02.298
5. Zatovsky I.V., Slobodyanik N.S., Uschapivska T.I. et al. Formation of complex phosphates K₂MI^IISn(PO₄)₃ from solutions in melts under crystallization conditions. Funtс. Mater. 2017. 24 (2). 298. [In English].
6. Nagorny P.G., Slobodyanik N.S., Uschapivska T.I. et al. Double phosphates NaMn₆(P₃O₁₀)(P₂O₇)₂ and КMn₆(P₃O₁₀)(P₂O₇)₂ – advanced functional materials. Funtс. Mater. 2018. 25 (4). 1–6. [In English].
7. Kasthuri K.L., Raghavendra P.B., Subramanian C.K. New Titanium-Vanadium Phosphates of Nasicon and Langbeinite Structures, and Differences between the Two Structures toward Deintercalation of Alkali Metal. J. Solid State Chem. 1994. 3 (1). 41. [In English].
8. Zatovsky I.V., Slobodyanik N.S., Ivanenko V.I. et al. Incorporation of hafnium (IV) into KTP framework from phosphate-fluoride fluxes. Cryst. Res. & Tech. 2015. 51 (2). 178. [In English].https://doi.org/10.1002/crat.201500268
9. William T.A., Harrison L.F. and Mark Phillips. Syntheses, Structures, and Properties of RbScFAsO₄ and CsScFAsO₄: Scandium-Containing Analogues of Potassium Titanyl Phosphate (KTiOPO4). Chem. Mater. 1999. 4 (11). 3555. [In English].https://doi.org/10.1021/cm990335j
10. Orlova A.I., Pet'kov V.I., Gul'yanova S.G., Yermilova M.M. Kataliticheskiye svoystva novykh slozhnykh ortofosfatov tsirkoniya i zheleza. Zhurn. fiz. khimii. 2016. 73 (11). 1965–1967. [In Russian].
11. Ogorodnyk I.V., Baumer V.N., Zatovsky I.V. et al. Equilibrium langbeinite-related phosphates Cs_{1 + x}Ln_xZr₂ − _x(PO₄)₃(Ln = Sm–Lu) in the melted systems Cs₂O–P₂O₅–LnF₃–ZrF₄. Acta Cryst. Sec. B. 2007. 63. 819. [In English].https://doi.org/10.1107/S0108768107049385
12. Nagorny P.G., Kornienko Z.I. Effect of sodium fluoride on the interection and crystal formation in the Na₂O–NiO–P₂O₅ system. Ukr. Khim. Zh. 2004. 70 (1). 74. [In English].
13. Chudinova N.N., Murashova Е.V., Zaharova B.S. New complex phosphates of manganese and different metals. J. Inorg. Chem. 1998. 43 (6). 885. [In English].
14. Murashova Е.V., Chudinova N.N. Solid faze synthesis of doubles phosphates Mn (II) and Mn (III). Inorg. Mater. 1998. 10 (34). 1019. [In English].
15. Huang Q., Hwu S.J. Synthesis and characterization of three new layered phosphates, Na₂MnP₂O₇, NaCsP₂O₇ and NaCsMn_0,35Cu_0,65P₂O₇. Inorg. Chem. 1998. 37. 5869. [In English].https://doi.org/10.1021/ic980616d