Preparation of red-emitting Eu2+-doped barium calcium silicon oxynitride by solid-state reaction and its luminescence properties

The luminescence properties of Eu2+-doped barium calcium silicon oxynitrides (general formula: Ba4-xCaxSi 6ON10: Eu2+ (x = 1.8 ∼ 2.2)) were examined, together with the preparation conditions for the solid state reaction. Firstly, the stoichiometric amounts of Ba, Ca3N2, SiO2 and Si3N4 were mixed with Eu2O3 (activator; the molar ratios of Eu to (Ca + Ba + Eu) (= m; 0.05 to 1.0)) for the preparation of Ba1.8Ca22Si6ON10: Eu2+, Ba2.0Ca2.0Si6ON10: Eu2+ and Ba2.2Ca1.8Si6ON10: Eu2+, and then the mixtures were heated at a temperature between 1300 and 1550°C for 10 h in N2 atmosphere. The single phase compounds, which were prepared by the heating at and above 1350°C, emitted the red color light whose wavelength could be changed from 638 to 653 nm with increasing m value from 0.05 to 1.00, due to the excitation at the wavelength of 528 nm

Thermal conductivity of M-Si-N (M = Mg, Ca, Sr, Ba) compounds with varying M/Si ratio

The thermal conductivity of M-Si-N (M = Mg, Ca, Sr, Ba) compounds is reviewed. The emphasis is on MgSiN2 (a material which can be derived from AlN by replacing systematically 2Al3+ by Mg2+/Si4+), and Si3N4 (the well known β-modification as well as the recently discovered cubic modification with the spinel structure). In addition the processing, characterisation and thermal conductivity of novel ceramic M-Si-N materials with an M/Si ratio lower than 1 are dealt with. The measured thermal conductivity is compared with estimations of maximum achievable values, and the relation with network connectivity is discussed