Strontium metaphosphate can be prepared by the
solid-state reaction of metaphosphoric acid and the
hydroxide, oxide or carbonate of strontium:
SrCO3 + HPO3 + heat ? Sr(PO3)2 +H2O + CO2
The best temperature to use is about 600°C. Strontium
metaphosphate has the CAS number of 13762-75-
9 and a density of 2.61 g/cm3. It melts at 757°C and
its boiling point is 1384°C. It is somewhat soluble in
water.
The combination of sodium and strontium polyphosphate forms a low-melting glass with a high coefficient of thermal expansion. The melting point of the glass increases with Strontium content. This glass makes seals with low melting metals like aluminium (melting point 650 °C). Normal borosilicate glasses soften above the melting point of aluminium. This mixture is prepared by heating a mixture of diammonium phosphate, sodium carbonate, and Strontium carbonate.
