実験報告書様式（一般利用課題・成果公開利用）

MLF Experimental Report

提出日 Date of Report
2014/09/11

課題番号 Project No.

装置責任者 Name of responsible person

2014A0282

石垣 徹

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Crystal structural analyses of Bi-based perovskite ferroelectrics forIBARAKI

establishing their materials design

Diffractometer (iMATERIA) / (BL-20)

実験責任者名 Name of principal investigator

実施日 Date of Experiment

Yuji Noguchi

2014.06.09-11

Materials

Design所属 Affiliation
University of Tokyo
試料、実験方法、利用の結果得られた主なデータ、考察、結論等を、記述して下さい。（適宜、図表添付のこと）
Please report your samples, experimental method and results, discussion and conclusions. Please add figures andtables for better explanation.
1. 試料 Name of sample(s) and chemical formula, or compositions including physical form.
強誘電体粉末(1−x)(Bi0.5Na0.5)TiO3–xBaTiO3x = 0, 0.04, 0.06, 0.08, 0.09, 0.10, 0.12(1−x)(Bi0.5Na0.5)TiO3–x(Bi0.5K0.5)TiO3
x = 0.15, 0.20, 0.23, 0.25, 0.27, 0.30, 0.35(1−x)(Bi0.5Na0.5)TiO3–xBa(Mg1/3Nb2/3)O3x = 0.03, 0.05, 0.07, 0.10(1−x)(Bi0.5Na0.5)TiO3–xBa(Zn1/3Nb2/3)O3
x = 0.03, 0.05, 0.07, 0.10(1−x)BiTiO3–x(Bi0.5Na0.5)TiO3x = 0.01, 0.03, 0.05(1−x)LiNbO3–xBiTiO3x = 0.01, 0.02, 0.03, 0.04, 0.05, 0.07, 0.09, 0.10, 0.15, 0.20(1−x)LiNbO3–xBi(Mn,W)O3x = 0.05, 0.10, 0.20, 0.30(1−x)LiNbO3–xBi(Fe,W)O3x = 0.05, 0.10, 0.20, 0.30

2. 実験方法及び結果 （実験がうまくいかなかった場合、その理由を記述してください。）
Experimental method and results.

If you failed to conduct experiment as planned, please describe reasons.

【Introduction】
Ferroelectric Pb(Zr,Ti)O3 has been widely used for piezoelectric devices such as sensors for mobile phones,actuators for fuel injections in cars, and transducers for medical echography. Recently, the studies on1

2. 実験方法及び結果（つづき） Experimental method and results (continued)
lead-free ferroelectric materials have been intensively conducted from environmental and technological pointsof view. Bismuth sodium titanate [(Bi,Na)TiO3:BNT][1] is considered to be the leading candidate in lead-freematerials. Solid solution (Bi,Na)TiO3–xBaTiO3 [BNT–xBT] has been reported to show enhanced piezoelectric
properties in the form of ceramics with a composition near morphotropic phase boundary (MPB)[2,3]. However,there are some problems to be overcome. One is the problem related to the phase diagram that is still in debate[2-4]: the synthesis of high-purity BNT–BT is quite difficult due to the volatility of Bi [5] giving rise to a deviationof composition and then to a generation of unintentional phase(s).
The objective of this study is to establish a materials design for controlling piezoelectric strain properties in theBNT–BT system. The crystal structures are analyzed by using neutron powder diffraction (NPD) at BL20 in JPARC.
【Experimental】
High purity (1−x)(Bi0.5Na0.5)TiO3–xBaTiO3 (x = 0, 4, 6, 8, 9, 10, 12 %) powders were synthesized by a solidstate reaction adapting a bead-mill processing. Structural characterization was performed by the Rietveld
analyses of NPD data collected at BL20 in J-PARC.
【Results】
In the NPD data, superlattice reflections such as 1⁄2 ̅̅̅̅̅1⁄2 3/2 attributed to monoclinic (M) structure in spacegroup Cc were detected for x ≤ 4 %. Superlattice reflections such as 5⁄2 3/2 0 due to tetragonal (T’) structurein space group P4bm with a small c/a of ~1.00 % were observed for 6 % ≤ x ≤ 7 %. A splitting of the NPD peaks,e.g., of 200 and 002, due to tetragonal (T) P4mm structure with a large c/a of ~1.5 % was observed at x ≥ 8 %.
Figure shows the proposed phase diagram composed of the M(Cc), T’(P4bm), and T(P4mm) phases with twoMPBs in the BNT-BT system obtained by the Rietveld analyses of the NPD data.
[1] G. A. Smolenskii et al., Sov. Phys. Solid State, 2, 2651 (1961). [2] T. Takenaka et al., Jpn. J. Appl. Phys,
30, 2236-2239 (1991). [3] W. Jo et al., J. Appl. Phys, 109 (1), 014110 (2011). [4] C. Ma et al., Adv. Funct. Mater,
23, 5261-5266 (2013). [5] K. Yamamoto et al., Jpn. J. Appl. Phys, 47 (9), 7623-7629 (2008).

Figure. Phase diagram of the BNT–xBT system
obtained by the NPD analysis.

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