The reaction between (ZrO)2P2O7 and NiO at elevated temperatures up to 1340 °C yielded Ni3(PO4)2 and ZrO2 over the whole composition. The reaction between ZrP2O7 and NiO yielded NiO·4ZrO2·3P2O5 and Ni3(PO4)2 in the molar ratios up to equimolarity.

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Glass formation was investigated in the Na2O–TiO2–P2O5, K2O–TiO2–P2O5, BaO–TiO2–P2O5,Na2O–BaO–P2O5, and Na2O–BaO–TiO2–P2O5 systems. In the Na2O–TiO2–P2O5 system, glass containing up to 45.5 mol% TiO2 was found to be formed at the composition of Na2O/P2O5=1, whereas in the K2O–TiO2–P2O5 system the glass formation was observed in a narrow region along the composition of K2O/P2O5=1 in a three-component diagram. In the BaO–TiO2–P2O5 system, only the glass containing about 10 mol% TiO2 as a maximum was obtained. In the Na2O–BaO–TiO2-P2O5 system, the region of glass formation extended with an increase of Na2O up to 30 mol%. These results suggested that a certain amount of Na2O is necessary for the formation of glass containing a large amount of TiO2 in the presence of BaO. The three-component diagrams of the Na2O–TiO2–P2O5 and Na2O–BaO–P2O5 systems indicated that the most favorable amount of Na2O for the glass formation in this four-component system is 27 to 28 mol%.

Mixed solutions of Ca(NO,), and (NH,),HPO, with Ca/P = 1.50 were spray-pyrolyzed at 600°C to produce p-calcium orthophosphate (P-Ca,(PO,),) powder; the spray-pyrolyzed powder was ground and then calcined at 600°C for 1 h. The best crystalline p-Ca,(PO,), powder was obtained from the solution with 1.80 mo1.L-l Ca(NO,),, 1.20 mo1-L-I (NH,),HPO,. The resulting powder was composed of primary particles with sizes of <0.5 pm. Dense P-Ca,(PO,), ceramics with a relative density of 96.1% could be fabricated by firing this compressed powder at 1070°C for 5 h.

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