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Abstract: Strontium silicate Sr2SiO4 undergoes a displacive phase transformation around 85°C. However, the steady state spectra involved in the process lacks investigation. In this paper, two kinds of Sr2SiO4:Eu2+ with and without Ba ions are synthesized. They are tested for XRD patterns and luminescent spectra at varying temperatures. The results show that Ba ions could effectively suppress the phase transition. For sample without Ba, temperature-dependent XRD patterns confirm the occurrence of phase transition and the emission peak positions at varying temperatures demonstrate a hysteresis behavior. The color of sample heated to 100°C under UV illumination is distinguishable from that unheated. This structure-sensitive behavior make Sr2SiO4:Eu2+ as potential thermochromic material. [Copyright &y& Elsevier]

Abstract: A series of phosphors, Eu-doped Ca(Al/Si)2N2(N1−x O x ), derivatives of CaAlSiN3, were synthesized by alloy-nitridation method. We demonstrated that their emission peaks can be tuned from 650nm to 610nm by oxygen preferential substitutions of nitrogen located at one of two crystallographic sites. Two luminescent centers corresponding to two types of Eu2+-coordination modes, i.e. EuNI 2NII 3 and EuNI 2NII 2O, were identified and accounted for the emission band structures, emission band shifts with oxygen/nitrogen substitutions, and the dependence of peak position and integrated emission intensity on temperature. As a typical example, Ca(Al/Si)2N2(N0.80O0.20):0.02Eu showed intense orange–red emission peaking at 622nm and kept the feature of excellent chemical stabilities, which would have potential applications in fabricating the white light-emitting diode. The excellent luminescent properties of these materials, such as wavelength-tunable red emission and excellent chemical stabilities, make them practical for use in typical LED package. [Copyright &y& Elsevier]