Low-temperature phase transitions and twin-domain structure of (NH 4)3H(SeO4)2 studied by the electron paramagnetic resonance of Cu2+, VO2+and SeO 3-

Ching Jiun Wu, Jiang-Tsu Yu, Mei Na Tsai, Ssu Hao Lou

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EPR of Cu2+, VO2+, SeO3-, and other paramagnetic impurities and species were used to study the low-temperature phase transitions and twin-domain structure of (NH4) 3H(SeO4)2 crystals. The major findings are; (i) twinning in the monoclinic phases is of the merohedral type (there are three kinds of small domain related by rotations of +or-120 degrees abut the trigonal c axis), (ii) EPR of Cu2+ or SeO3- reveals the coexistence of the high-temperature and the low- temperature phases below the trigonal R3m to monoclinic A2/a phase transition and on further transitions, however, into the two other low-temperature monoclinic phases a single phase was again observed and (iii) impurities and lattice point defects created by ionizing radiations were observed to influence the twinning and crystal structure of the host compound.

Original languageEnglish
Article number012
Pages (from-to)3795-3806
Number of pages12
JournalJournal of Physics: Condensed Matter
Issue number21
Publication statusPublished - 1991 Dec 1


ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics

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