Powder diffraction data of semimagnetic semiconductors Hg 080 Mn 020 S, •"•90.89' ®o.nS and W. Paszkowicz a) Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland (Received 4 November 1999; accepted 15 February 2000) Powder X-ray diffraction data are reported for semimagnetic semiconductor Hg 089 Fe 011 S and Hg 0 98 Co 0 02 S crystals grown by the Bridgman method and for Hg 0 80 Mn 0 2 oS crystal synthesized by a solid-state reaction method. The crystals have the sphalerite structure of metacinnabar (sphalerite-type high-temperature polymorph of HgS, space group F43m). Phase analysis does not show any trace of other phases. The lattice parameters of the studied samples are a = 5.803 20(5) A, 5.8063(1) A and 5.839 80(6) A, respectively. The calculated density is reported. © 2000 International Centre for Diffraction Data. [S0885-7156(00)00402-4] I. INTRODUCTION Binary chalcogenides of zinc, cadmium and mercury crystallize in tetrahedral structures (sphalerite or wurtzite type). HgS is the only exception from this rule: the form stable at ambient temperature, a-HgS (mineral name: cinna- bar), is a precursor of a nontetrahedral hexagonal cinnabar structure while the sphalerite-type /S-HgS (mineral name: metacinnabar) is stable only at high temperatures. The sta- bility of the mineral metacinnabar is attributed to impurities. A phase transition between a-HgS and /3-HgS for pure mer- cury sulfide occurs on heating at 608 ± 10 K (Curtis, 1962). The transition temperature depends on crystal purity and on deviation from stoichiometry. For natural cinnabar mineral samples the transition is reported to be in the range 673-723 K (Bernard et al, 1992). The high-temperature metacinnabar phase of mercury sulfide can be stabilized when substituting a small fraction of Hg atoms by third- element atoms. If the substituting element is a 3d transition metal (TM=Mn, Fe or Co), the compound remains a semi- conductor but exhibits also some specific magnetic proper- ties. Such compounds belonging to any of semiconductor families with incorporated magnetic atoms are called semi- magnetic semiconductors. The highest reported TM content in yS-Hg^/TMjS is x = 0.375 for TM=Mn (Pajaczkowska and Rabenau, 1977), 0.08 for TM=Fe (Szuszkiewicz et al, 1995, 1998b), 0.04 for TM=Co (Szuszkiewicz et al, 1995, 1998a), and in a-HgS is about 0.10 for TM=Mn (Pajacz- kowska and Rabenau, 1977). In this paper, powder diffraction patterns of /?-Hg,_ x Fe x S, /3-Hg!_ x Co x S and yS-Hg^^n^S solid solu- tions grown by the Bridgman method will be given. II. EXPERIMENTAL Single crystals of/3-Hg]_ x Fe^S and /S-Hg^^Co^S solid solutions were grown by the vertical Bridgman method at a furnace temperature just below 1173 K. Crystal growth using this method requires special care due to a high mercury va- por pressure at elevated temperatures. yS-Hgi^Mn^S com- pound was synthesized by the solid-state reaction [for details see Pajaczkowska and Rabenau (1977)]. Components of 4N purity were used for the crystal growth. For the structure analysis, selected pieces of the crystals were ground in an agate mortar. Powder-diffraction patterns were measured with a Bragg-Brentano diffractometer using step-scanning mode and CuA'a radiation. To reduce the preferred- orientation effect, the finely ground powder was dusted on a specimen holder covered with a thin layer of vaseline. Powder-pattern analysis was performed after stripping off the a 2 component by the Rachinger method. Peak positions and intensities were determined by profile fitting of single peaks. The detailed conditions of diffraction data collection are given in Table I. Chemical analysis and electron micro- probe were applied for the chemical analysis. III. RESULTS x Fe x S and /3-Hg^j.COjS crystals exhibit some concentration gradient with an increased amount of transition metal at the lower part of the crystal. The crystals grown have the sphalerite structure of metacinnabar (high- temperature polymorph of HgS, space group F43m). For Fe « 100 80- 60- 40- 20- 3 100- •fi 80- & eo- I 40- £ 20- .1 0 100- —-JLJl^ 11111. i.. .-"Wr-rTfT^ 60- 40- 20- 0 20 30 40 50 60 70 2e (degrees) ''e-mail address: paszk@ifpan.edu.pl Figure 1. Raw X-ray powder-diffraction pattern of Hgo.89Feo.11S (b) and Hg 098 Co 002 S (c). (a), 116 Powder Diffraction 15 (2), June 2000 0885-7156/2000/15(2)/116/4/$6.00 i 2000 JCPDS-ICDD 116