Electron charge density study of (Na1-xKx)NbO3 in cubic structure

被引：15

作者：

Moriyoshi, Chikako ^{[1
]}

Kato, Jun-ichi ^{[1
]}

Terado, Yoshihiro ^{[1
]}

Wada, Satoshi ^{[2
]}

Takata, Masaki ^{[3
]}

Kuroiwa, Yoshihiro ^{[1
]}

机构：

[1] Hiroshima Univ, Dept Phys Sci, Hiroshima 7398526, Japan

[2] Univ Yamanashi, Dept Appl Chem, Takeda, Kofu 4008510, Japan

[3] RIKEN, Hariman Inst, Sayo, Hyogo 6795148, Japan

来源：

JAPANESE JOURNAL OF APPLIED PHYSICS | 2008年 / 47卷 / 09期

关键词：

NaNbO3; KNbO3; NKN; perovskite; tolerance factor; synchrotron radiation; powder diffraction; maximum entropy method; charge density; thermal motion;

D O I：

10.1143/JJAP.47.7745

中图分类号：

O59 [应用物理学];

学科分类号：

摘要：

The electron charge density study by synchrotron-radiation powder diffraction has been performed for the cubic structure of (Na1-xKx NbO3 (NKN: 0 <= x <= 1) at 1000K to investigate the atomic substitution effect on chemical bonding. Our precise analysis using the maximum entropy method (MEM)/Rietveld method demonstrates that the covalent bonding is formed on the Nb-O bond whereas the Na/K atoms are ionie in the entire composition range. The thermal motion of the Na ion in NaNbO3 is fairly larger than that of the K ion in KNbO3. The charge density distributions around the O atoms in NaNbO3 are extended in the directions perpendicular to the Nb-O bond, which can be related to the rotational mode of the Nb-O-6 octahedron driving the antiferroic phase transition. No such anisotropy is clearly observed in KNbO3 around the O atoms. These behaviors are closely related to the change in the tolerance of the perovskite structure caused by the atomic substitution.

引用

页码：7745 / 7748

页数：4

共 14 条

[1]

ADACHI M, 2001, LANDOLTBORNSTEIN GRO, V3, P311

[2] Direct observation of covalency between O and disordered Pb in cubic PbZrO3 [J].

Aoyagi, S ;

Kuroiwa, Y ;

Sawada, A ;

Tanaka, H ;

Harada, I ;

Nishibori, E ;

Takata, M ;

Sakata, M .

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2002, 71 (10) :2353-2356

[3]

Jaffe B., 1971, PIEZOELECTRIC CERAMI, P135

[4] High-energy SR powder diffraction evidence of multisite disorder of Pb atom in cubic phase of PbZr1-xTixO3 [J].

Kuroiwa, Y ;

Terado, Y ;

Kim, SJ ;

Sawada, A ;

Yamamura, Y ;

Aoyagi, S ;

Nishibori, E ;

Sakata, M ;

Takata, M .

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS, 2005, 44 (9B) :7151-7155

[5] Distinctive charge density distributions of perovskite-type antiferroelectric oxides PbZrO3 and PbHfO3 in cubic phase [J].

Kuroiwa, Y ;

Fujiwara, H ;

Sawada, A ;

Aoyagi, S ;

Nishibori, E ;

Sakata, M ;

Takata, M ;

Kawaji, H ;

Atake, T .

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS, 2004, 43 (9B) :6799-6802

[6] Evidence for Pb-O covalency in tetragonal PbTiO3 -: art. no. 217601 [J].

Kuroiwa, Y ;

Aoyagi, S ;

Sawada, A ;

Harada, J ;

Nishibori, E ;

Takata, M ;

Sakata, M .

PHYSICAL REVIEW LETTERS, 2001, 87 (21) :217601-1

[7] DIELECTRIC PROPERTIES OF SODIUM AND POTASSIUM NIOBATES [J].

MATTHIAS, BT ;

REMEIKA, JP .

PHYSICAL REVIEW, 1951, 82 (05) :727-729

[8] The large Debye-Scherrer camera installed at SPring-8 BL02B2 for charge density studies [J].

Nishibori, E ;

Takata, M ;

Kato, K ;

Sakata, M ;

Kubota, Y ;

Aoyagi, S ;

Kuroiwa, Y ;

Yamakata, M ;

Ikeda, N .

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, 2001, 467 :1045-1048

[9] Lead-free piezoceramics [J].

Saito, Y ;

Takao, H ;

Tani, T ;

Nonoyama, T ;

Takatori, K ;

Homma, T ;

Nagaya, T ;

Nakamura, M .

NATURE, 2004, 432 (7013) :84-87

[10] REVISED EFFECTIVE IONIC-RADII AND SYSTEMATIC STUDIES OF INTERATOMIC DISTANCES IN HALIDES AND CHALCOGENIDES [J].

SHANNON, RD .

ACTA CRYSTALLOGRAPHICA SECTION A, 1976, 32 (SEP1) :751-767

← 1 2 →