@article{c39d1bbb8f604af19125221ef29db17f,
title = "Microstructure and ferroelectric properties of MnO 2 -doped bismuth-layer (Ca,Sr) Bi 4Ti 4O 15 ceramics",
abstract = "We have studied the microstructures and ferroelectric properties of Mn O2 -doped bismuth-layered (Ca,Sr) Bi4 Ti4 O15 (CSBTM). The piezoelectric coefficient, dielectric loss, mechanical quality factor, and the P-E hysteresis loop measurements indicate that Mn ions entered both the A and B sites of the pseudoperovskite-layered structure, creating {"}soft{"} and {"}hard{"} doping effects simultaneously. Scanning electron microscopy and energy dispersion spectroscopy showed that the platelike grains in CSBTM ceramics become larger with the increase of Mn O2 additive, and Mn ions are found inside the grains as well as in the grain boundaries. The lattice parameter, room-temperature dielectric constant, and the Curie temperature do not vary with Mn O2 additive. We conclude that the Mn3+ ions play a critical role in the effects of soft and hard behaviors since it can enter both the A and B sites of the perovskite structure.",
author = "Gurong Li and Liaoying Zheng and Qingrui Yin and Bei Jiang and Wenwu Cao",
note = "Funding Information: This work was supported by Chinese National “973” Project No. 2002CB613307, Advanced Technology “863” projects (2001A320504), and NIH under Grant No. RR11795-05. Table I. Ionic radii of Bi, Sr, Ca, Ti, O, and Mn ions, and the electronic characteristic of Mn ions in the lattice. Position Element (ionic radii, {\AA}) Mn 2 + ( 0.91 {\AA} ) Mn 3 + ( 0.70 {\AA} ) Mn 4 + ( 0.52 {\AA} ) Ca 2 + (1.04) No effect Donorlike Donorlike A site Sr 2 + (1.20) No effect Donorlike Donorlike Bi 3 + (1.20) Acceptorlike No effect Donorlike B site T i 4 + (0.64) Acceptorlike Acceptorlike No effect O 2 − (1.36) ⋯ ⋯ ⋯ Table II. Comparison of the properties of piezoelectric ceramics doped by “soft” and “hard” additives. Metal ionssubstitution Dopingeffect ε tan δ e T C E c P r d 33 k p s i j Q m A or B site withhigher valence Soft Increase Increase Decrease Decrease Increase Increase Increase Increase Decrease A or B site withlower valence Hard Decrease Decrease ⋯ Increase Decrease Decrease Decrease Decrease Increase Table III. Thermal chemical data of Mn O 2 ( Mn 4 + ) , Mn 2 O 3 ( Mn 3 + ) , Mn 3 O 4 ( Mn 2 + , Mn 3 + ) , and Mn O ( Mn 2 + ) . Compound H ( kJ mol − 1 ) S ( J K − 1 mol − 1 ) a ( J K − 1 mol − 1 ) b ( 10 − 3 J K − 2 mol − 1 ) c ( 10 5 J K mol − 1 ) Mn O 2 ( s ) − 520.07 53.14 69.454 10.209 − 16.234 Mn 2 O 3 ( s ) − 402.77 59.83 46.484 8.117 − 3.682 Mn 3 O 4 ( s ) − 1386.58 164.01 144.934 45.271 − 9.205 MnO ( s ) − 384.93 59.83 46.484 8.117 − 3.682 FIG. 1. Cross-section SEM micrographs of (a) undoped CSBT and (b) Mn-doped CSBTM ceramics. FIG. 2. The lattice structure of CSBT ceramics. FIG. 3. Temperature dependence of dielectric constant and loss of CSBTM measured at different frequencies: (a) 1, (b) 10, and (c) 100 kHz . FIG. 4. P - E Hysteresis loops of Mn-doped CSBT ceramics. FIG. 5. Property variations with Mn dopant measured at room temperature: (a) dielectric constant and loss; (b) piezoelectric coefficient d 33 and electromechanical coupling constant k p ; and (c) mechanical quality factor Q m and elastic compliance coefficient s E 11 of CSBTM. The data points correspond to y = 0.0 , 1.5, 3.0, 4.5, 6.0 mole % . FIG. 6. Thermal chemical reaction pathways and the reaction temperatures. ",
year = "2005",
month = sep,
day = "15",
doi = "10.1063/1.2058174",
language = "English (US)",
volume = "98",
journal = "Journal of Applied Physics",
issn = "0021-8979",
publisher = "American Institute of Physics Publising LLC",
number = "6",
}