Gd/Mn Co-Doped CaBi4Ti4O15 Aurivillius-Phase Ceramics: Structures, Electrical Conduction and Dielectric Relaxation Behaviors

Abstract

In this work, Gd/Mn co-doped CaBi4Ti4O15 Aurivillius-type ceramics with the formula of Ca1-xGdxBi4Ti4O15 + xGd/0.2wt%MnCO3 (abbreviated as CBT-xGd/0.2Mn) were prepared by the conventional solid-state reaction route. Firstly, the prepared ceramics were identified as the single CaBi4Ti4O15 phase with orthorhombic symmetry and the change in lattice parameters detected from the Rietveld XRD refinement demonstrated that Gd3+ was successfully substituted for Ca2+ at the A-site. SEM observations further revealed that all samples were composed of the randomly orientated plate-like grains, and the corresponding average grain size gradually decreased with Gd content (x) increasing. For all compositions studied, the frequency independence of conductivity observed above 400 °C showed a nature of ionic conduction behavior, which was predominated by the long-range migration of oxygen vacancies. Based on the correlated barrier hopping (CBH) model, the maximum barrier height WM, the dc conduction activation energy Edc, as well as the hopping conduction activation energy Ep were calculated for the CBT-xGd/0.2Mn ceramics. The composition with x = 0.06 was found to have the highest Edc value of 1.87 eV, as well as the lowest conductivity (1.8 × 10−5 S/m at 600 °C) among these compositions. The electrical modules analysis for this composition further illustrated the degree of interaction between charge carrier β increases, with an increase in temperature from 500 °C to 600 °C, and then a turn to decrease when the temperature exceeded 600 °C. The value of β reached a maximum of 0.967 at 600 °C, indicating that the dielectric relaxation behavior at this temperature was closer to the ideal Debye type.

Sintesis Lapis Empat Fasa Aurivillius Ca1-xBaxBi3,5La0,5Ti4O15 Dengan Metode Lelehan Garam

“…Senyawa Aurivillius CaBi 4 Ti 4 O 15 yang didoping Gd/Mn dengan formula Ca 1-x Gd x Bi 4 Ti 4 O 15 /0,2Mn berfasa tunggal berhasil disintesis. Analisis lanjutan dengan refinement Rietveld menunjukkan bahwa Gd 3+ berhasil menggantikan Ca 2+ di situs A. Peningkatan nilai x menunjuk-kan perilaku relaksor feroelektrik pada material [7]. Peningkatan komposisi dopan pada senyawa Aurivillius lapis empat Ca 1-x Bi 3+x LaTi 4-x Mn x O 15 meningkatkan nilai konstanta dielektrik yang dihasilkan akibat distorsi struktur [8].…”

“…Besarnya ukuran kristal dari senyawa Aurivillius Ca 1-x Ba x Bi 3,5 La 0,5 Ti 4 O 15 ditampilkan pada Tabel 1. Ukuran kristal terlihat menurun dengan kenaikan nilai x. Penurunan ukuran kristal disebabkan oleh beberapa faktor, seperti laju difusi antara ion Ba 2+ dan Ca 2+ mempengaruhi laju pertumbuhan kristal di berbagai arah, yang berkontribusi pada pembentukan kristal dengan ukuran yang lebih kecil [7]. Selain itu, penambahan ion Ba 2+ dengan jari-jari ion yang lebih besar terhadap ion Ca 2+ menghasilkan tegangan dalam kisi kristal, yang menyebabkan pembentukan lebih banyak cacat atau dislokasi dan membatasi pertumbuhan kristal [13].…”

Influence of Mn Ions’ Insertion in Pseudo-Tetragonal Phased CaBi4Ti4O15-Based Ceramics for Highly Efficient Energy Storage Devices and High-Temperature Piezoelectric Applications

“…There exist several research reports where scientists have reported their work on improving the values of remnant polarization ( P r ), d 33 and T C by modifying fabrication techniques or by doping the ions at A and B sites of CBT. Recently, Wu et al reported the fabrication of Gd/Mn co-coped CaBi 4 Ti 4 O 15 ceramics, where a high dc conduction activation energy value of 1.87 eV was reported [ 18 ]. Xi et al fabricated a Ca 0.85 (LiCe) 0.075 Bi 4 Ti 4− x Zn x O 15 ceramic system and reported a high d 33 of 20 pC/N [ 13 ].…”

Microstructural Design and Processing Control of Advanced Ceramics

“…The authors of [20] reported the effects of oxide additives on the phase structures and electrical properties of SrBi 4 Ti 4 O 15 high-temperature piezoelectric ceramics. The authors of [21] revealed the structures, electrical conduction and dielectric relaxation behaviors of the Gd/Mn co-doped CaBi 4 Ti 4 O 15 Aurivillius-phase ceramics. By means of the chemical (substituting ions and oxide additives) modification and microstructural (phase composition and grain size/orientation) design for these three kinds of BLSFs ceramics, the electrical properties of materials were greatly improved.…”