# Two-Step Solid-State Synthesis of Ternary Nitride Materials

## TL;DR

This paper introduces a two-step solid-state method to synthesize ternary nitride materials without needing high pressure or reactive gases.

## Contribution

A simple two-step synthesis method for ternary nitrides using ion-exchange reactions is proposed.

## Key findings

- The two-step method yields phase-pure MgZrN2, Mg2NbN3, and MgMoN2 with weak paramagnetic properties.
- Low-temperature nucleation followed by high-temperature annealing is critical for successful synthesis.
- Calorimetry shows initial reaction temperatures depend on precursor phase transitions, not direct heating.

## Abstract

Ternary
nitride materials hold promise for many optical, electronic,
and refractory applications; yet, their preparation via solid-state
synthesis remains challenging. Often, high pressures or reactive gases
are used to manipulate the effective chemical potential of nitrogen,
yet these strategies require specialized equipment. Here, we report
on a simple two-step synthesis using ion-exchange reactions that yield
rocksalt-derived MgZrN2 and Mg2NbN3, as well as layered MgMoN2. All three compounds show
almost temperature-independent and weak paramagnetic responses to
an applied magnetic field at cryogenic temperatures, indicating phase-pure
products. The key to synthesizing these ternary materials is an initial
low-temperature step (300–450 °C) to promote Mg-M-N nucleation.
The intermediates then are annealed (800–900 °C) to grow
crystalline domains of the ternary product. Calorimetry experiments
reveal that initial reaction temperatures are determined by phase
transitions of reaction precursors, whereas heating directly to high
temperatures results in decomposition. These two-step reactions provide
a rational guide to material discovery of other bulk ternary nitrides.