# Effect of Mn Addition on the Mechanical Properties and Ferroelectric Behavior of Bi0.5Na0.5TiO3 and 94(Bi0.5Na0.5TiO3)–6(BaTiO3) Ceramics

## TL;DR

Adding small amounts of Mn improves the performance of lead-free BNT-BT ceramics, but too much Mn reduces their quality and effectiveness.

## Contribution

The study reveals how Mn doping affects the structure and performance of BNT and BNT-BT ceramics at different concentrations.

## Key findings

- 0.5 mol% Mn increases remanent polarization in BNT-BT to ~33.5 μC/cm².
- High Mn content (5 mol%) causes grain coarsening and reduced densification.
- Mn-doped BNT-BT shows promise for lead-free piezoelectric applications at low Mn levels.

## Abstract

What are the main findings?
Mn doping preserves single-phase perovskite structure in BNT and BNT-BT ceramics.0.5 mol% Mn maximizes remanent polarization in BNT-BT (~33–34 μC/cm2).High Mn content causes grain coarsening and reduced densification.

Mn doping preserves single-phase perovskite structure in BNT and BNT-BT ceramics.

0.5 mol% Mn maximizes remanent polarization in BNT-BT (~33–34 μC/cm2).

High Mn content causes grain coarsening and reduced densification.

What are the implications of the main findings?
Low Mn levels enable tuning of ferroelectric response in lead-free BNT-BT ceramics.Excess Mn degrades electrical performance due to porosity and defect saturation.Mn-doped BNT-BT ceramics are promising for lead-free piezoelectric applications.

Low Mn levels enable tuning of ferroelectric response in lead-free BNT-BT ceramics.

Excess Mn degrades electrical performance due to porosity and defect saturation.

Mn-doped BNT-BT ceramics are promising for lead-free piezoelectric applications.

The effect of Mn addition on the structural, dielectric, ferroelectric, and mechanical properties of Bi0.5Na0.5TiO3 (BNT) and 0.94(Bi0.5Na0.5TiO3)–0.06(BaTiO3) (BNT–BT) ceramics was systematically investigated under identical processing conditions. Powders were calcined at 750 °C for 2 h and 900 °C for 2 h, followed by sintering at 1060 °C for 5 h. Mn contents of 0.5 and 5 mol% were selected to represent low-level substitution and near-saturation regimes. XRD confirmed single-phase perovskite formation within laboratory detection limits, while Raman spectroscopy revealed Mn-induced lattice distortions. Low Mn addition (0.5 mol%) enhanced densification and improved remanent polarization in BNT–BT (Pr = 33.5 μC/cm2). In contrast, 5 mol% Mn promoted grain coarsening, increased porosity, and reduced functional performance. Mechanical properties evaluated using two-parameter Weibull statistics showed composition-dependent variations in characteristic hardness and elastic modulus. The results demonstrate that Mn-doping effects depend strongly on both dopant concentration and host-lattice structural state, distinguishing beneficial substitution from defect-saturation behavior in lead-free BNT-based ceramics.