Russian Journal of Applied Chemistry, 2012, Vol. 85, No. 12, pp. 1820−1826.
Pleiades Publishing, Ltd., 2012.
Original Russian Text © V.G. Maiorov, V.Ya. Kuznetsov, A.I. Nikolaev, N.L. Mikhailova, O.A. Zalkind, G.I. Kadyrova, V.K. Kopkov, 2012, published in
Zhurnal Prikladnoi Khimii, 2012, Vol. 85, No. 12, pp. 1931−1937.
AND INDUSTRIAL INORGANIC CHEMISTRY
On Potassium Hexaniobates Released in the Course
of Preparation of Concentrated Niobium(V) Alkaline Solution
V. G. Maiorov, V. Ya. Kuznetsov, A. I. Nikolaev, N. L. Mikhailova,
O. A. Zalkind, G. I. Kadyrova, and V. K. Kopkov
Tananaev Institute of Chemistry and Technology of Rare Elements and Mineral Raw, Kola Scientiﬁ c Center,
Russian Academy of Sciences, Apatity, Russia
Received July 12, 2012
Abstract—Solutions containing 500 g L
were obtained by sintering Nb
with potash followed by
leaching with water. The potassium niobate released from niobium(V) alkaline solutions was examined with an
application of methods of physical and chemical analysis. Hydrates K
О and K
were ﬁ rst obtained.
A large number of niobates of various compositions:
anhydrous and crystalline hydrates, is known. Produc-
ing niobium(V) alkaline solutions carried out usually
by sintering Nb
with oxides, hydroxides, carbonates
of alkali metals followed by treatment of cakes with
water (potassium salts are of a better solubility [1–4]).
In recent years, application and research of niobium(V)
alkaline solutions and niobates are of a growing interest
[5–11]. Concentrated niobium (V) alkaline solutions and
compounds separated from them can be applied to a pro-
duction of welding materials , niobium-containing
catalysts ; niobates are used as precursors for obtain-
ing heteropolyniobates , nanohelices , nanoplates in
semiconductor solar energy converters into electricity ,
molecular sieves  and in other ﬁ elds of contemporary
In the study we continue researches of obtaining a con-
centrated potassium-containing solutions of niobium(V)
and potassium hexaniobates released in the course of it.
(pure reagent grade), K
cally pure grade) were used as major reagents. Sintering
was carried out in a corundum crucibles at 850°C for
10 h, a weight of Nb
on sintering was 10 g, potash
consumption corresponded to the molar ratio of the re-
actant mixture K/Nb = 4.2. Data of [1–4, 11, 14] were
accounted for on selecting the sintering conditions.
cooling to room temperature the cake was treated with
water, the residue after ﬁ ltration was retread with water,
and the content of Nb(V) and K(I) was determined in the
ﬁ ltrate. Mixing time was 2 hours, but on leaching it was
up to 5 hours, since a complete destruction of solid cake
should be reached on it.
For radiographic studies we used a diffractometer
DRON-2 with Cu
-radiation (monochromator graphite).
The accuracy of determination of the distance between
planes was 5 × 10
Å, a lower limit of phases detection
in multiphase and discrete systems was 1%. The database
of  was used on interpreting diffraction patterns.
Thermal analysis was carried out using a synchronous
A 409 PC instrument at a heating rate of
in argon ﬂ ow with weighted samples of about
40 mg in corundum crucibles with lids.
IR spectra were recorded on a Fourier spectrometer
Nicolet 6700 in the frequency range 4000–400 cm
samples were prepared in a matrix of potassium bromide.
Determination of elements were performed by stan-
dard analytical methods: niobium(V), by gravimetric
method, potassium(I), by ﬂ ame photometry [4, 16].
Table 1 shows the results of experiments that char-
acterize the effect of water ﬂ ow on the distribution of