The reaction to synthetize neodymium sulphides from neodymium sulphate octahydrate in a stream of carbon disulphide gas was studied. The dehydration of the octahydrate in vacuum was finished at 300 °C. At 1050-1100 °C in air neodymium oxysulphide, Nd2O2SO4, was formed. Neodymium oxysulphide, Nd2O2S, was formed upon heating with a reducing agent such as annealed carbon. The reaction of neodymium sulphate with carbon disulphide commenced at 500-600 °C, resulting in formation of the disulphide, NdS2. The crystal structure of NdS2 heated at 500 °C was, however, different from that of the sample heated at 600 °C. In the temperature range 800-900 °C α-Nd2S3 was obtained as a single phase after heating for at least 3 h in high flow rates of gas mixtures of nitrogen and high concentrations of carbon disulphide. The sesquisulphide, γ-Nd2S3 (or Nd3S4), was formed at temperatures as high as 1100 °C. The reaction conditions for the compounds mentioned above are discussed together with the analysis of their crystal structures by X-ray powder diffractometry.
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