The borotellurates are heteropoly anion compounds which have tellurate groups attached to boron atoms. The ratio of
tellurate
In chemistry tellurate is a compound containing an oxyanion of tellurium where tellurium has an oxidation number of +6. In the naming of inorganic compounds it is a suffix that indicates a polyatomic anion with a central tellurium atom. to
borate
A borate is any of several boron oxyanions, negative ions consisting of boron and oxygen, such as orthoborate , metaborate , or tetraborate ; or any salt with such anions, such as sodium metaborate, and disodium tetraborate . The name also re ...
reflects the degree of condensation. In
eO4(BO3)2sup>8- the anions are linked into a chain.
[ In eO2(BO3)4sup>10− the structure is zero dimensional with isolated anions. These arrangements of oxygen around boron and tellurium can have forms resembling ]silicates
In chemistry, a silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name i ...
. The first borotellurates to be discovered were the mixed sodium rare earth compounds in 2015.[
The tellurate is of the form TeO6 in an octahedral arrangement. The borate is in the form BO3, with two oxygen atoms shared with two tellurate TeO6 groups.][
Related compounds include boroantimonates, galloborates, borogermanates, ]borophosphates The borophosphates are mixed anion compounds containing borate and phosphate anions, which may be joined together by a common oxygen atom. Compounds that contain water or hydroxy groups can also be included in the class of compounds.
Borophosphates ...
, boroselenates The boroselenates are chemical compounds containing interlinked borate and selenate groups sharing oxygen atoms. Both selenate and borate groups are tetrahedral in shape. They have similar structures to borosulfates and borophosphates The borophosp ...
, boroselenites, and borosulfates The borosulfates are heteropoly anion compounds which have sulfate groups attached to boron atoms. Other possible terms are sulfatoborates or boron-sulfur oxides. The ratio of sulfate to borate reflects the degree of condensation. With (SO4)4sup>5 ...
.
Formation
Borotellurates are formed by heating boric acid
Boric acid, more specifically orthoboric acid, is a compound of boron, oxygen, and hydrogen with formula . It may also be called hydrogen borate or boracic acid. It is usually encountered as colorless crystals or a white powder, that dissolve ...
, and tellurium dioxide
Tellurium dioxide (TeO2) is a solid oxide of tellurium. It is encountered in two different forms, the yellow orthorhombic mineral tellurite, β-TeO2, and the synthetic, colourless tetragonal (paratellurite), α-TeO2. Most of the information regard ...
, with metal carbonates or oxides at over 800 °C.[ Lower temperatures can be used with a flux like ]potassium carbonate
Potassium carbonate is the inorganic compound with the formula K2 CO3. It is a white salt, which is soluble in water. It is deliquescent, often appearing as a damp or wet solid. Potassium carbonate is mainly used in the production of soap and gl ...
.
Reactions
When heated to around 800 °C the borotellurates decompose by emitting TeO3 vapour and form a metal borate[ or metal tellurite.]
List
References
{{Borates
Borates
Tellurates