Nanoindentation study of nickel manganite ceramics obtained by a complex polymerization method

S.M Savić,G Stojanović,D Vasiljević,K Vojisavljević,A Dapčević,A Radojković,S Pršić,G Branković

doi:10.1016/j.ceramint.2016.04.174

S.M Savić, G Stojanović + Show 6 more

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https://doi.org/10.1016/j.ceramint.2016.04.174

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Abstract

The chemical synthesis of nickel manganite powder was performed by a complex polymerization method (CPM). The obtained fine nanoscaled powders were uniaxially pressed and sintered at different temperatures: 1000–1200°C for 2h, and different atmospheres: air and oxygen. The highest density was obtained for the sample sintered at 1200°C in oxygen atmosphere. The energy for direct band gap transition (Eg) calculated from the Tauc plot decreases from 1.51 to 1.40eV with the increase of the sintering temperature. Indentation experiments were carried out using a three-sided pyramidal (Berkovich) diamond tip, and Young's modulus of elasticity and hardness of NTC (negative temperature coefficient) ceramics at various indentation depths were calculated. The highest hardness (0.754GPa) and elastic modulus (16.888GPa) are exhibited by the ceramics sintered at highest temperature in oxygen atmosphere.

Highlights

Negative temperature coefficient (NTC) thermistors, as the main part of many electronical devices, have been in use for long time owing to their excellent semiconductor properties [1]
The XRD pattern of the NMO powder calcined at 800 °C (Fig. 2) shows main reflections that correspond to the cubic spinel phase ( Fd3m space group, ICSD card # 185294)
It can be noticed that the cubic spinel phase formed already at about 800 °C, which is quite lower than in the case of NMO ceramics prepared by the conventional solid state synthesis [32]

Summary

Introduction

Negative temperature coefficient (NTC) thermistors, as the main part of many electronical devices, have been in use for long time owing to their excellent semiconductor properties [1]. Materials for NTC thermistors are usually composed of transition metal spinel and are widely used in different industrial applications today [2,3,4,5]. Nickel manganite (NMO) material has been the subject of considerable practical interest as a potential candidate for NTC applications due to its interesting optical, electron transport, electronic and magnetic properties [6,7,8,9,10]. Nowadays, meeting growing environmental demands, this material has found its great use as a catalyst for volatile organic compounds [11], in electrochemistry as a electrochemical capacitor and in lithium ion battery applications [12,13].

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