Metathesis routes to lanthanide pnictides
Abstract
Reaction of Na3As or Na3Sb with anhydrous LnCl3(Ln = Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tb, Yb) at 500–900 °C in sealed Pyrex or quartz ampoules produces crystalline lanthanide arsenides or stibides (LnAs, LnSb, Eu2Sb3, Yb5Sb4), in good yields (70–90%), via, metathesis reactions. Mixed lanthanide arsenides and stibides, Ln0.5Ln′0.5E, (LnLn′= DyEr, NdPr; E = As; LnLn′= LaY, TbHo, TbEr, LaHo and PrHo; E = Sb) are made in a similar fashion by combining mixed lanthanide halide powders with Na3As or Na3Sb and initiating the reaction at 800 °C. Solid solutions of LnAsxPy and LnSbxAsy(Ln = Dy, Sm, Tb; x+y= 1) are made analogously using Na3AsxPy and Na3SbxAsy as starting materials. Lanthanide bismuthides (LnBi), can be made from LnCl3 and Na3Bi; however, decomposition to Ln metal and bismuth occurs on trituration with methanol. The lanthanide arsenides, lanthanide stibides, mixed lanthanide arsenides and mixed lanthanide pnictides were characterised by X-ray powder diffraction (XRD), microanalysis, scanning electron microscopy (SEM), energy dispersive X-rays analysis (EDXA), FTIR and magnetic-moment measurements.