HIGH-PRESSURE SYNTHESIS OF NITRIDE GLASSES

Studies of oxynitride glasses have been encouraged by the interesting changes in physical properties, such as hardness and refractive index, observed when nitrogen is incorporated in glasses. However, despite attempts involving many combinations of different cations, only one of four oxygen atoms has been successfully replaced by nitrogen in phosphate and silicate systems. In the present paper, glass formation in Li3N-Ca3N2-P3N5 is reported. Some attempts to chemically substitute Ca3N2 and Li3N in these glasses are also described. The nitride glasses were obtained by melt quenching in a high-pressure, high-temperature piston cylinder device, The high-pressure experiments oppose thermal decomposition to gaseous nitrogen which previously has limited the nitrogen content in oxynitride glasses. The present examples of this new class of glass have interesting properties, particularly remarkably high refractive index and hardness.