Vol.:(0123456789) 1 3 Applied Physics A (2020) 126:294 https://doi.org/10.1007/s00339-020-03472-y Preparation of tetragonal barium titanate nanopowders by microwave solid‑state synthesis Haoyu Qian 1  · Guisheng Zhu 1  · Huarui Xu 1  · Xiuyun Zhang 1  · Yunyun Zhao 1  · Dongliang Yan 1  · Xianyong Hong 1  · Yin Han 1  · Zhenxiao Fu 1  · Shiwo Ta 2  · Aibing Yu 3 Received: 18 December 2019 / Accepted: 16 March 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract Tetragonal-phase BaTiO 3 powders of particle size 370 nm were synthesized by microwave sintering at 850 °C. The raw materials were BaCO 3 , TiO 2 , and alanine. SiC microspheres were used as microwave conductors. The efects of the holding time, sintering aids, and SiC addition on the preparation of BaTiO 3 were investigated. The results indicate that the addition of SiC as a microwave acceptor leads to formation of microwave micro-regions. This enables uniform heating of the raw materials and decreases the calcination temperature needed to obtain BaTiO 3 . Alanine coordinates with Ba, and this loosens the metal–CO 3 bond and promotes separation of CO 2 , decreases the BaCO 3 decomposition temperature, and provides a higher nucleation site density. It gives an idea about the microwave solid-state synthesis of BaTiO 3 powder. Keywords BaTiO 3  · Tetragonal · SiC · Alanine · Microwave micro-region sintering 1 Introduction Perovskite oxide has many properties, e.g., piezoelectric, dielectric, and ferroelectric activities [1,2]. BaTiO 3 is an important perovskite structure material. It is used in mul- tilayer ceramic capacitors (MLCCs), semiconductors, and electroluminescent panels [3,4]. The trend toward minia- turization of components in the electronics industry has increased interest in perovskite oxide nanopowders. For example, the fabrication of high-capacitance, small MLCCs requires the solid-state production of tetragonal-phase BaTiO 3 nanopowders with small highly dispersed parti- cles [5]. The development of methods for decreasing the particle size and improving the uniformity of the BaTiO 3 , while decreasing the synthesis temperature, is therefore a key issue. BaTiO 3 can be synthesized by sol–gel [6,7], solid-state [8,9], hydrothermal [10,11], coprecipitation [12], and micro- wave methods [13]. BaTiO 3 prepared by liquid-phase meth- ods has hydroxyl lattice defects, and this leads to MLCC porosity during sintering [14]. BaTiO 3 has been synthesized by a solid-state method below 1000 °C, with BaCO 3 and TiO 2 as the raw materials [15]. Although solid-state meth- ods are cheap and simple, the products have a large aver- age particle size, high agglomeration, and poor chemical homogeneity, and are not suitable for use in miniaturized electronic devices [16]. However, BaTiO 3 powder synthe- sized by a solid-state method is crystalline and has fewer surface defects than BaTiO 3 prepared by liquid-phase meth- ods. It has good dielectric properties, and its use ensures reliability of MLCCs. Companies such as Taiyo Yuden in Japan are therefore still developing improved solid-state methods for preparing tetragonal BaTiO 3 with small parti- cles. Ando et al. [17] tried to solve the problems associated with solid-state reactions by adding bovine serum albumin to decrease the decomposition temperature of BaCO 3 in the presence of TiO 2 ; this decreases the calcination tempera- ture in BaTiO 3 synthesis. Rui et al. [18] synthesized BaTiO 3 via energy ball milling, which decreased the particle size, * Guisheng Zhu zhuguisheng@guet.edu.cn 1 Guangxi Key Laboratory of Information Materials, Engineering Research Center of Electronic Information Materials and Devices, Ministry of Education, Guilin University of Electronic Science and Technology, Guilin 541004, China 2 State Key Laboratory of Advanced Materials and Electronic Components, Guangdong Fenghua Advanced Technology Holding Co., Ltd, Zhaoqing 526020, China 3 Department of Chemical Engineering, Monash University, Clayton, VIC 3800, Australia