Crystal Structures, Phase-Transition, and Photoluminescence of Rare Earth Carbodiimides

Abstract

Rare earth carbodiimides with the general formula RE 2(CN 2) 3 crystallize with two modifications. A monoclinic( C2/m) modification is obtained for RE = Y, Ce-Tm and a rhombohedral ( R3 c) modification for RE = Tm-Lu. The space group R3 c is confirmed by single-crystal structure determination on Lu 2(CN 2) 3 and indexed powder patterns of RE = Tm, Yb and Lu. The use of diverse chemical syntheses conditions for Tm 2(CN 2) 3 revealed the dimorphic character of this compound. In addition, pressure experiments on Tm 2(CN 2) 3 have induced a phase-transition from rhombohedral to monoclinic. This transformation comprises an increase of the coordination number of Tm from 6 to 7, and a unit-cell volume reduction in the order of 20 %. The photoluminescence behavior of lanthanide doped Gd 2(CN 2) 3:Ln samples is presented with different activators (Ln = Ce, Tb) revealing a broad band emission of Gd 2(CN 2) 3:Ce, quite similar to that of the well-known YAG:Ce.

Synthesis of new structurally related cyanamide compounds LiM(CN2)2 where M is Al3+, In3+ or Yb3+

“…The structure of LiIn(CN 2 ) 2 is related to the structure of rhombohedral RE 2 (CN 2 ) 3 compounds, having planar cation and anion layers [10,30,31]. The distances between the adjacent cations in Y 2 (CN 2 ) 3 structure are between 379 and 396 pm, in LiIn(CN 2 ) 2 the In-In distances are shorter, about 333-343 pm.…”

Synthesis, Characterization and Thermal Properties of Iron Material Including Carbodiimide and S-Indacene Structures

“…In the last decade, the chemistry of metallated carbodimiides (MNCN) group has been very developed because of its potential applications in the electronic and magnetic fields [1][2][3][4][5][6][7][8][9][10][11] . In the series of germylcarbodiimides, through the full study of the polycarbodiimidogermylene (Ge II -NCN) n 12 , it has been found that this product shows a conductivity of 10 -2 Scm -1 , and is classified as semiconductor material.…”

“…This result has been explained by the presence of a high electronic delocalization in the polymer chain, due to the alternation of metal atoms and -N=C=N-electron rich spacers group [12][13][14][15] . An important interest has also been observed for the metalcarbodiimide chemistry using rare earth, transition and semi-metals for their potential magnetic, electronic and ceramics properties [1][2][3][4][5][6] . For instances, in the case of magnetic properties, X. Liu 5 and coworkers has described the preparation of MnNCN which has presented antiferromagnet behavior with an ordering temperature below 30 K. An example of properties, in the electronic fields, has been reported for CuNCN 2 which has been considered as a semi-conductor with a resistivity of about 1kΩcm at room temperature.…”

Synthesis of Rare Earth (Oxo)nitridocarbonates by Employment of Supercritical Carbon Dioxide, Single‐source Precursor, Solid‐State, and Ion Exchange Reactions

“…[13,15,16] Due to the high thermal stability of binary rare earth oxides, carbides and nitrides specific synthesis routes are inevitable to expand the field of lanthanide (oxo)nitridocarbonates. Metathesis reactions between lanthanide halides and lithium cyanamide studied by Meyer et al [17] gave access to various rare earth carbodiimide compounds characterized in the last years: La 2 O(CN 2 ) 2 ; [18] Ln 2 (CN 2 ) 3 (Ln = Y, La -Lu); [19] Ce 3 (CN 2 ) 3 N; [20] LiEu 2 (CN 2 )I 3 ; [21] EuCN 2 . [22] Compared to the rapidly growing field of carbodiimide chemistry other rare earth (oxo)nitridocarbonates such as cyanates, dicyanamides or carbamates have been rarely mentioned in the literature.…”