Description
Strontium tellurite has the molecular weight of
215.6761 g/mol and the molecular formula of SrTeO3.
It can be formed via the solid-state reaction:
SrO+ TeO2+ heat ? SrTeO3
An inert atmosphere is required. This salt is a metatellurite.
If a solution method is used, a monohydrate
is formed:
SrCl2+ Na2TeO3 ? SrTeO3·H2O+ 2NaCl
Additionally, this compound can be prepared by
reacting tellurium dichloride in a solution of strontium
chloride:
SrCl2+ 2TeCl2+ 3H2O ? Te+ SrTeO3·H2O+ 6HCl
Physical properties
In all cases involving solution chemistry, the product
is a monohydrate. Its CAS number is 13812-57-2 and its
molecular weight is 233.6915 g/mol. Strontium tellurite
(SrTeO3) has been shown by Yamada and Iwasaki
(1972) to possess ferroelectric properties (ferroelectric = a substance exhibiting permanent electric
polarization that varies in strength with the applied
electric field).
The crystal structure of strontium tellurite, SrTeO3, has
been determined at roomtemperature using X-ray diffraction
data obtained from single crystals grown by the Czochralski
method. Selection of a noncentrosymmetric (C2)
structure model was confirmed by the second harmonic
generation (SHG) test. The structure of strontiumtellurite
is built up of three types of distorted [SrO
x] polyhedra
(x=6, 7 and 8) that share their oxygen anions with TeO3
pyramidal units. These main anionic polyhedra are
responsible for establishing two types of tunnels required
for the electron lone pairs of the Te
4+
cation.
In another systematic investigation of strontium tellurite,
SrTeO3, with particular emphasis on crystal chemistry
and phase transitions, the structure of the γ-phase
has been determined at 583 K using a single-crystal analysis.
Both structural and nonlinear optical measurements
indicate a β?γ first-order phase transition
temperature that is close to 563 K. The structure of the
γ-phase is monoclinic (C2) and does not differ essentially
from the a-phase (C2). Comparison of the α and γ structures
shows that the main atomic shifts and tilting are
connected with Te
4, Te
5 and Te
6 pyramids.
Preparation
Aluminate sodalites containing the telluride and tellurite
ions have been synthesized for the first time. The
structures of Sr8[AlO2]12(TeO3)2 and its reduced product
Sr[AlO2]12Te2 have been determined using Rietveld
refinement of powder neutron-diffraction (PND) data.
In Sr8[AlO2]12Te2, the anion occupies a position at the
sodalite cage center, while in Sr8[AlO2]12(TeO3)2 the larger
tellurite ion is displaced to allow reasonable coordination
to the strontium ions.
Sr
1-x PbxTeO3 (0 < x < 0.2) and Sr
1-xLa
2xTe
1+2xO
3+6x
(0 < x < 0.15) solid solutions are synthesized (the latter,
for the first time), and their properties are studied. The results demonstrate that partial substitutions of Pb and
La for Sr extend the temperature stability range of ferroelectric
SrTeO3.
Although a number of research papers have been published,
its usage in industry is miniscule. It is, however,
available commercially by several manufacturers.
