Synthesis and photoluminescence properties of Mn2+ doped Ca1-xSrxCN2 phosphors prepared by a carbon nitride based route

Abstract

Mn 2+ doped Ca1-xSrxCN2 phosphors were synthesized by a solid-state reaction in only 1 h under NH3 atmosphere at 700 °C from doped calcium carbonate and carbon nitride as precursors. The samples were characterized by powder X-ray diffraction, scanning electron microscopy and their diffuse reflectance and luminescence properties were investigated in order to evaluate the potential of such systems as red phosphors. All pure and well-crystallized Mn 2+ doped samples exhibit broad red emission around 680 nm when excited at 270 nm at room temperature corresponding to the 4 T1g( 4 G) → 6 A1g( 6 S) transition. Maximum emission in CaCN2 : Mn is obtained for Mn 2+ content of 4 %mol and is stable up to 343 K and then shows a 20 % decrease at 393 K. Finally, the progressive substitution of Sr 2+ for Ca 2+ evidences a solid solution domain between CaCN2 and β-SrCN2 with continuous increase of the crystal lattice dimensions. However, such substitution has no impact on the wavelength emission but leads to a decrease of the luminescence efficiency of the phosphor.

Tunable Zero Linear Compressibility under a Rational Designed Mechanism of Modular “Dumbbell”: A Density Functional Theory Study

“…To calculate the elastic constants, the lattice geometry was optimized first at ambient pressure. For CaCN 2 , the obtained lattice parameters a = 3.6964 Å and c = 14.8827 Å are deviated by just 0.02% and 0.78% from the initial experiment data ( a = 3.697 Å and c = 14.767 Å), respectively, indicating a high consistency between the experimental and computational data. The calculated matrix of the elastic constants C ij of CaCN 2 is listed as …”

“…To calculate the elastic constants, the lattice geometry was optimized first at ambient pressure. For CaCN 2 , the obtained lattice parameters a = 3.6964 Å and c = 14.8827 Å are deviated by just 0.02% and 0.78% from the initial experiment data (a = 3.697 Å and c = 14.767 Å), 34 respectively, indicating a high consistency between the experimental and computational data. The calculated matrix of the elastic constants C ij of CaCN 2 is listed as i k j j j j j j j j j j j j j j j j j j j j j j j j j j y The calculated material is mechanically stable because the elastic constants meet the elastic stability criteria for Laue class 3̅ m: ELATE 39 was used to analyze the elastic tensor of CaCN 2 and gave the value of 69.32 GPa for bulk modulus.…”

“…To confirm that the “dumbbell” model can indeed result in ZLC, three metal carbodiimides MCN 2 (M = Ca, Fe, or Li 2 ) − with differently shaped “dumbbell” models are carefully selected to investigate their axial compressibilities. In all cases of the three types of MCN 2 , one linear N–C–N pillar paralleled to the c -axis connects with n M atoms ( n = 6 for M = Ca and Fe; n = 8 for M = Li) through the two N ends, forming a “dumbbell”-like unit, as depicted in Figures c–e.…”

Synthesis, crystal structures and semiconducting properties of new hexacyanidometallates

“…The average Ca-N bond length of about 2.5 Å is in good agreement with those reported in literature. 31 The FeC 6 octahedra are slightly distorted from regularity (Fig. 5d).…”

Graphitic Carbon Nitride Emitter: From Structural Modification to Optoelectronics Applications

“…Under specific ratios, g‐C 3 N 4 /copper‐cysteamine composite phosphors can be used for the preparation of WLEDs, and exhibits white light emission with a PLQY of 20% and a high CRI of 94.3. Similar composites, such as g‐C 3 N 4 /K 2 SiF 6 :Mn 4+ composite phosphors, [ 52 ] g‐C 3 N 4 /ZnO/ZnS composite, [ 53 ] Mn 2+ doped Ca 1‐x Sr x /g‐C 3 N 4 composite phosphors [ 54 ] and other g‐C 3 N 4 based composites, have also been studied and reported.…”