Journal of the Mineralogical Society of Korea (한국광물학회지)

The Mineralogical Society of Korea (한국광물학회)
권호 표지

Crystal Structure Analysis of $LiN(D_xH_{1-x}){_4}SO_4$ by X-ray and Neutron Diffraction

X-선과 중성자 회절을 이용한 강유전체 단결정 $LiN(D_xH_{1-x}){_4}SO_4$의 결정구조 연구

  • 김신애 (한국원자력연구원 하나로이용기술개발센터) ;
  • 김성훈 (한국원자력연구원 하나로이용기술개발센터) ;
  • 소지용 (한국원자력연구원 하나로이용기술개발센터) ;
  • 이정수 (한국원자력연구원 하나로이용기술개발센터) ;
  • 이창희 (한국원자력연구원 하나로이용기술개발센터)
  • Published : 2007.12.30
Download PDF
⟨ Previous Next ⟩

Abstract

The crystal structure of $Li(ND_4)SO_4$ was analyzed by X-ray and neutron diffraction methods. The crystal is a deuterated $Li(NH_4)SO_4$ and one of the ferroelectric materials with hydrogen atoms. The crystal is orthorhombic at room temperature, $P2_1nb$, with lattice parameters of $a=5.2773(5)\;{\AA},\;b=9.1244(23)\;{\AA},\;c=8.7719(11)\;{\AA}$ and Z=4. Neutron intensity data were collected on the Four-Circle diffractometer (FCD) at HANARO in Korea Atomic Energy Research Institute and X-ray date were given by Prof. Y. Noda of Tohoku University Japan. The structure was refined by full-matrix least-square to final R value of 0.070 for 1450 observed reflections by X-ray diffraction and to final R=0.049 for 745 observed reflections by neutron diffraction. With X-ray data we obtained only one hydrogen atomic position. However, not only all atomic positions of four hydrogen atoms at $NH_4$ but also the occupation factors of D and H were refined with neutron data. From this results we obtained the average chemical structure of this sample, $LiND_{3.05}H_{0.95}SO_4$.

수소원자를 포함한 강유전체 $Li(NH_4)SO_4$의 중수소 치환형인 $Li(ND_4)SO_4$ 단결정에 대해 X-선과 중성자 회절법으로 결정구조를 연구하였다. 이 결정은 상온에서 사방정계이고 공간군은 $P2_1nb$이다. 격자상수는 $a=5.2773(5)\;{\AA},\;b=9.1244(23)\;{\AA},\;c=8.7719(11)\;{\AA}$이며 Z=4이다. 한국원자력연구원의 연구용 원자로인 하나로에 설치된 중성자 4축 단결정 회절장치로 중성자데이터를 수집하였으며, X-선 회절데이터는 일본 동북대학교 물리학과에서 측정하였다. X-선 회절법으로 수집한 1450개의 독립 회절반점에 대하여 최소자승법으로 정밀화하여 최종 신뢰도값 R=0.070을 얻었으며, 중성자 회절법으로는 745개의 회절반점에 대하여 R=0.049을 얻었다. X-선 회절데이터 분석 결과 결정구조 내의 수소원자 중 1개의 위치만을 얻었으나, 중성자 회절법으로는 $NH_4$ 사면체의 수소/중수소원자의 위치는 물론 H를 치환해서 들어간 D의 점유율을 정련하여 측정시료의 평균화학식이 $LiND_{3.05}H_{0.95}SO_4$임을 밝혔다.

Keywords

References

  1. Abrahams, S.C. (1994). Structure relationship to dielectric, elastic and chiral properties. Acta Cryst. A50, 658-685
  2. Diosa, J.E., Aparicio, G.M., Vargas, R.A. and Jurado, J.F. (2000). Phase transitions in $LiNH_{4}SO_{4}$ below and above room temperature. Phys. stat. sol. (b)220, 651-654 https://doi.org/10.1002/1521-3951(200007)220:1<651::AID-PSSB651>3.0.CO;2-T
  3. Dollase, W.A. (1969). $LiNH_{4}SO_{4}$ : A variant of the general tridymite structure. Acta Cryst. B25, 2298-2303
  4. Fischer, P., Sosnowska, I. and Wroblewski, T. (1989). Neutron diffraction refinement and high resolution X-ray study of crystal structure of $LiNH_{4}SO_{4}$. Phys. B.156-157, 118-120
  5. Godfrey, L. and Philip, J. (1996). Phase transition in lithium ammonium sulfate below room temperature: An ultrasonic study. Phys. Rev. B54, 15708-15713
  6. Ichikawa, M. (1995). Geometric and quantum aspects of phase transition and isotope effect in hydrogen- bonded ferroelectrics and related materials. Ferroelectrics 168, 177-192 https://doi.org/10.1080/00150199508007861
  7. Itoh, K., Ishikura, H. and Nakamura, E. (1981). Disordered structure of ferroelectric Ammonium Lithium Sulphate in the high-temperature phase. Acta Cryst., B37, 664-666
  8. Lim, A.R. and Jeong, S.-Y. (1997). Ferroeleastic property of $LiNH_{4}SO_{4}$ single crystals. Phys. stat. sol. (a)164, 673-677 https://doi.org/10.1002/1521-396X(199712)164:2<673::AID-PSSA673>3.0.CO;2-B
  9. Lim, A.R., Han, T.J. and Jeong, S.-Y. (1999). $^{7}Li$ spin-lattice relaxation time in a $LiNH_{4}SO_{4}$ single crystal. Phys. stat. sol. (b)214, 375-379 https://doi.org/10.1002/(SICI)1521-3951(199908)214:2<375::AID-PSSB375>3.0.CO;2-9
  10. Lim, A.R., Park, S.-E. and Jeong, S.-Y. (2000). Phase transition by $^{7}Li$NMR in a $LiNH_{4}SO_{4}$ single crystal. Solid stat. com. 113, 389-394 https://doi.org/10.1016/S0038-1098(99)00503-7
  11. Mashiyama, H. and Kasano, H. (1993). Refined crystal structure of $LiNH_{4}SO_{4}$ including hydrogen atoms in phase II and III. J. Phy. Soc.. Japan 62, 155-162 https://doi.org/10.1143/JPSJ.62.155
  12. Martins, A.R.M., Germano, F.A., Mendes Filho, J., Melo, F.E.A. and Moreira, J.E. (1991). Phase transition in $LiNH_{4}SO_{4}$ below room temperature. Phys. Rew. B. 44, 6723-6727 https://doi.org/10.1103/PhysRevB.44.6723
  13. Solans, X., Mata, J., Calvet, M.T. and Font-Bardia, M. (1999). X-ray structural characterization, Raman and thermal analysis of $LiNH_{4}SO_{4}$ above room temperature. J. Phys.: condens. Matter 11, 8995-9007 https://doi.org/10.1088/0953-8984/11/46/303