ISSN 0036ꢀ0236, Russian Journal of Inorganic Chemistry, 2010, Vol. 55, No. 12, pp. 1844–1849. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © M.M. Godneva, D.L. Motov, N.N. Boroznovskaya, V.Ya. Kuznetsov, 2010, published in Zhurnal Neorganicheskoi Khimii, 2010, Vol. 55, No. 12, pp. 1957–1962.
SYNTHESIS AND PROPERTIES
OF INORGANIC COMPOUNDS
Synthesis of Rubidium Fluorophosphatozirconates
in the ZrO –H PO –RbF–H O System
2
3
4
2
and Their Luminescent Properties
M. M. Godneva, D. L. Motov, N. N. Boroznovskaya, and V. Ya. Kuznetsov
Tananaev Institute of the Chemistry and Technology of Rare Elements and Mineral Raw Materials, Kola Research Center,
Russian Academy of Sciences, ul. Fersmana 14, Apatity, Murmansk oblast, 184209 Russia
Received May 15, 2009
Abstract—Rubidium fluorophosphatozirconates (RFPZs) were synthesized along sections of the ZrO –
2
3
–
H PO –RbF–H O system where PO4 /Zr = 1–2 (mol/mol) and RbF/Zr = 1–5 (mol/mol) and the initial
3
4
2
solution contains 2–5 wt % ZrO2. The following RFPZs have been isolated for the first time: RbZrF PO4
⋅
2
0
.5H O, Rb H Zr F (PO ) , and RbZr F (PO ) ⋅1.5H O. Their formation fields were determined. The comꢀ
2 3 3 3 3 4 5 3 4 4 3 2
pounds were characterized using powder Xꢀray diffraction, crystalꢀoptical analysis, chemical analysis, elecꢀ
tron probe microanalysis, thermal analysis, and IR spectroscopy. Luminescent properties of the compounds
were measured. All RFPZs are orthophosphates, have high thermal durability, and Xꢀray luminescence
(
XRL). Rb H Zr F (PO ) has the highest XRL intensity.
3 3 3 3 4 5
DOI: 10.1134/S0036023610120053
Alkali and polyvalent metal fluorophosphates are
Phase identification and chemical analysis were
few. Apart from being theoretically important, they are carried out as in [5]. XRL spectra were recorded as
of applied importance on account of their valuable specified in [3].
electrophysical properties [1]. Zirconiumꢀbased phosꢀ
phate ion exchangers are prepared from acid fluoride
solutions [2]. Fluorophosphatozirconates can be
RESULTS AND DISCUSSION
Table 1 displays the compositions of the initial mixꢀ
tures and precipitates. Figure 1 represents a scheme of
phase formation fields. When RbF/Zr (mol/mol) have
high values (greater than 3), phase I is formed; when
these values are low (lower than 3), phase II is formed.
formed in this process. Fluoride compounds of zircoꢀ
nium have Xꢀray luminescence (XRL) [3]. Fluoroꢀ
phosphatozirconates were thought to have a higher
luminescence intensity than compounds containing
only one luminogenous group. For zirconium, we
have isolated one fluorophosphate compound, namely As PO
3
4
−
Zr (mol/mol) changes from 1 to 2, the tranꢀ
shifts up. For 5 wt % ZrO2, phase III
is found within a narrow range of RbF/Zr = 2–
(mol/mol) (Table 2) in a mixture with noncrystalꢀ
lized phase IV
Phase consists mostly of spherulites having the
sition to phase
I
K Zr F (HPO ) (PO ) [4]; most of the RFPZs
3
3
3
4 3
4 2
3
−
obtained with PO Zr of 0.5 (mol/mol) in the initial
4
4
.
solution were basic; and a triple salt ZrF Rb(PO )
⋅
4
4 0.33
.
RbNO3 was prepared [5]. In this work, our efforts were
I
directed to preparing a neutral salt in studying sections
mean refractive index of Nm = 1.535. For phase I,
3
−
chemical analysis is as follows:
of the title system where PO Zr = 1–2 (mol/mol).
4
For RbZrF PO · 0.5H O anal. calcd., wt %:
2
4
2
3
–
+
–
Rb , 26.82; Zr(IV), 28.62; F , 11.92; PO4 , 29.80;
H O, 2.82.
EXPERIMENTAL
2
+
–
Found, wt %: Rb , 26.8; Zr(IV), 30.4; F , 11.8;
3
–
To a continuously stirred ZrO(NO3)2
⋅
2H O initial PO4 , 28.1; H O, 2.8.
2
2
solution, RbF was added at room temperature. Once
the mixture achieved homogeneity, concentrated
H PO was dropped to it. ZrO2 in the solution was calꢀ
In the IR spectrum of phase I (Table 3), there is no
–1
3
4
libration vibrations
(these vibrations are intrinsic to coordinated water),
After the mixture was allowed to stand for 7 to 45 days, but there are bands of water of crystallization at 3500–
ρ
(H O) in the range 700–800 cm
2
culated with account of H PO before RbF was added.
3
4
–1
precipitates were filtered, washed consecutively with 3600 cm [7]. The number of bands of the bending
water and ethanol, and then air dried. vibrations implies that the hydrate contains two types
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