Tim Jurasevich

Purdue University School of Biomedical Engineering

Project Title: Electronic Properties of Ceramic Films
Advisor: Prof. Kvam

Introduction

Strontium Ruthenate (SrRuO3) and Lanthanum Nickelate (LaNiO3) are both perovskites. Perovskites are of the form ABO3 and have a pseudo-cubic structure at room temperature with the A ion at the corners of the cubic unit cell, the B ion in the middle, and the oxygen ions at the face centers.

Conductive metal oxides make good electrodes in ferroelectric memory. Metal electrodes may lead to ferroelectric fatigue because of oxygen deficiency. By using perovskites instead, this problem can be alleviated and perovskites may also have better adhesion to some substrates.

Strontium Ruthenate is orthorhombic (nearly tetragonal) at room temperature. It has a resistivity of approximately 300 m O µΩcm. SrRuO3 sol-gel contains a mixture of ruthenium chloride, ethanol, water, strontium acetate, and hydrogen peroxide and is black in color.

Lanthanum Nickelate is rhombohedral at room temperature. It has a resistivity of approximately 600 m O µΩcm. LaNiO3 sol-gel contains a mixture of lanthanum nitrate, 2-methoxyethanol, monoethanolamine, and nickel acetate and is dark blue in color.

Project Objectives

  • Create SrRuO3 and LaNiO3 thin films by sol-gel processing.
  • Refine sol-gel process.
  • Investigate the properties of the thin films

Approach

  • LaNiO3 and SrRuO3 synthesized by sol-gel processing
  • LaNiO3 and SrRuO3 thin films were spin coated onto glass and silicon substrates, respectively
  • Platinum electrodes were placed on top of the thin films to aid in resistivity measurements
  • Processing methods were altered to observe potential changes in properties
  • X-ray diffraction was used to analyze the orientation of the materials
  • Resistivity was measured using a digital multimeter

Findings

  • SrRuO3 and LaNiO3 can be prepared by sol-gel methods
  • Both thin films exhibit relatively low resistivities
  • Processing changes affect crystallographic texture

Figure 1: XRD – SrRuO3 Sample
Figure 2: Optical Micrograph – SrRuO3 Sample