ISSN 0036-0236, Russian Journal of Inorganic Chemistry, 2009, Vol. 54, No. 4, pp. 563–567. © Pleiades Publishing, Inc., 2009.
Original Russian Text © M.M. Godneva, N.N. Boroznovskaya, D.L. Motov, V.M. Klimkin, N.L. Mikhailova, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009,
Vol. 54, No. 4, pp. 617–622.
COORDINATION
COMPOUNDS
Thermal Stability and X-ray-Luminescent Properties
of Fluorozirconates and Fluorosulfatozirconates
M. M. Godnevaa, N. N. Boroznovskayab, D. L. Motova,
V. M. Klimkinc†, and N. L. Mikhailovaa
a Tananaev Institute of the Chemistry and Technology of Rare Elements and Minerals, Kola Research Center,
Russian Academy of Sciences, ul. Fersmana 14, Apatity, Murmansk oblast, 184200 Russia
b Tomsk State University, pr. Lenina 36, Tomsk, 634050 Russia
c Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, Tomsk, Russia
Received December 24, 2007
Abstract—The thermolysis of fluorozirconates (M2ZrF6, M5Zr4F21 · 3H2O, MZrF5 · H2O, Rb2Zr3OF12, and
Cs2Zr3F14 · 1.5H2O) and fluorosulfatozirconates (M2ZrF4SO4, Rb3Zr2F9SO4 · 2H2O, and Cs8Zr4F2(SO4)11
·
16H2O) with M = K, Rb, or Cs in undried air was studied by thermal analysis in tandem with X-ray powder
diffraction. The X-ray luminescence (XRL) intensity was determined for these compounds and their thermol-
ysis products. A mixture of Rb2Zr3OF12 and Rb2ZrF6 luminescent phases was detected in the thermolysis prod-
ucts of Rb5Zr4F21 · 3H2O and RbZrF5 · H2O for the first time. After heat treatment, a considerable quantum yield
was observed for ZnZrF6 · 5H2O, ZnZrF6 · 6H2O, and ZnZr2F10 · 7H2O. The XRL luminescence was affected by
the composition of the phase and the density of excited states (F* and O*).
DOI: 10.1134/S0036023609040123
†
X-ray luminescence (XRL) is an informative tool pounds were not formed [6, 7]; in undried air, where
for studying crystal structures, in particular, for reveal-
ing structural defects. Earlier [1, 2] we studied broad-
band XRL spectra for a number of fluorozirconates and
pyrohydrolysis occurs, oxides can appear.
This work studies the thermal stability of FZs and
fluorosulfatozirconates synthesized in this work. A set FSZs in undried air and the influence of heat treatment
of compounds with intensive luminescence (primarily,
in the UV) was recognized, and they were recom-
mended for use as luminophors (X-ray converters). The
luminescence centres responsible for XRL intensity
were assigned to intrinsic defects (F* and O* excited
states). Heat treatment can either enhance or weaken
XRL intensity [2].
on their X-ray luminescent properties.
EXPERIMENTAL
Synthesis was carried out at room temperature by
adding alkali fluorides to sulfuric acid solutions of zirco-
nium; to prepare zinc compounds, Zn(NO3)2 · 6H2O and
HF were used. The compositions of precursor mixtures
for each compound were determined elsewhere [3].
Thermal analysis in tandem with X-ray powder dif-
fraction was used to study the thermolysis of fluorozir-
conates (FZs) and fluorosulfatozirconates (FSZs) [3].
For some compounds (M2ZrF6, γ-KZrF5, Rb2Zr3OF12,
Cs2ZrF6, Cs5Zr4F21 · 3H2O, Cs2Zr3F14 · 1.5H2O;
Rb3Zr2F9SO4 · 2H2O, Cs8Zr4F2(SO4)11 · 16H2O), thermol-
ysis schemes were presented; for others (Rb5Zr4F21 ·
3H2O, MZrF5 · H2O, and M2ZrF4SO4), provisional
assignment of thermal features was carried out, in some
cases requiring refinement [3–5]. For M5Zr4F21 · 3H2O
and MZrF5 · H2O, endotherms observed below 500°C in
undried air were assigned to polymorphic transitions
and melting (by analogy with hexafluorozirconates) or
to MZrF5 and M2ZrF6 formation [4]. Phase diagrams for
åF–ZrF4 systems are known. When they were studied
in hermetically sealed vessels or in helium, oxide com-
Heating curves were recorded in undried air on an
NTR-70M device with Pt–Pt/Rh thermocouples. Sam-
ple sizes were 0.11–0.27 g; heating rates were 8–
10 K/min. After a number of DTA effects appeared,
heat treatment was stopped; the sample was cooled to
room temperature, and the X-ray diffraction pattern of
the product was recorded on a DRF-2 or DRON-2 dif-
fractometer. X-ray luminescence was excited by X-ray
quanta irradiated by a BSV-2 d c tube (voltage: 25 kV;
current: 10 mA; Mo anticathode). The radiation inten-
sity and spectral composition were recorded in the vis-
ible and UV ranges with reference to the XRL spectrum
of a ZnS standard luminophor.
†
Deceased.
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