Preparation and Electrical Properties of La0.9Sr0.1TiO3+δ.

Wenzhi Li,Fuchi Wang,Zhuang Ma,Lihong Gao

doi:10.3390/ma8031176

Abstract

La1−xSrxTiO3+δ (LST) has been studied in many fields, especially in the field of microelectronics due to its excellent electrical performance. Our previous theoretical simulated work has suggested that LST has good dielectric properties, but there are rare reports about this, especially experimental reports. In this paper, LST was prepared using a solid-state reaction method. The X-rays diffraction (XRD), scanning electron microscope (SEM), broadband dielectric spectroscopy, impedance spectroscopy and photoconductive measurement were used to characterize the sample. The results show that the values of dielectric parameters (the relative dielectric constant εr and dielectric loss tanδ), dependent on temperature, are stable under 350 °C and the value of the relative dielectric constant and dielectric loss are about 52–88 and 6.5 × 10−3, respectively. Its value of conductivity increases with rise in temperature, which suggests its negative temperature coefficient of the resistance. In addition, the band gap of LST is about 3.39 eV, so it belongs to a kind of wide-band-gap semiconductor materials. All these indicate that LST has anti-interference ability and good dielectric properties. It could have potential applications as an electronic material.

Highlights

Ceramic materials have received great attention because of their good stability, heat resistance, component of flexibility and many other excellent physical and chemical properties [1,2]
The LST samples were prepared by high temperature solid state reaction method using high-purity raw materials: La2O3 (99.99%), SrCO3 (AR) and TiO2 (AR)
To study the dielectric properties of LST, both the top and bottom surfaces of the sample were coated with platinum electrodes by vacuum sputtering, and annealed at 150 °C for 20 min to reduce the influence of contact resistance during the electric measurements

Summary

Introduction

Ceramic materials have received great attention because of their good stability, heat resistance, component of flexibility and many other excellent physical and chemical properties [1,2]. In the field of microelectronics, perovskite ceramic materials with a general chemical formula ABO3 have been extensively used in microcircuit, modules and devices [3]. LaTiO3 and SrTiO3 both are ferroelectric ceramic and it has been reported that they have good dielectric properties, such as high dielectric constant, low dielectric loss and good temperature coefficient, etc. In recent years, lanthanum-doped and strontium-doped ceramic composite material as a new kind of perovskite ceramic material has been widely researched and used as solid fuel cell anode material, microwave dielectric material and photo-dew-sensitive material, etc. La1−xSrxTiO3+δ (LST) may have better properties and potential applications. The dielectric and photoelectric properties of bulk LST are currently rarely reported

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