# Crystal Structure of Nd10.67Pt4O24, a New Neodymium Platinate

## TL;DR

This paper reports the crystal structure of a new neodymium platinate compound, Nd10.67Pt4O24, and its synthesis and thermal decomposition behavior.

## Contribution

The discovery and structural characterization of a new neodymium platinate compound with a unique crystal structure.

## Key findings

- Nd10.67Pt4O24 has a crystal structure in the I41/a space group, related to double perovskite structures.
- The compound decomposes into Nd2O3 and Pt upon heating, with an intermediate Pt(II) phase observed.
- Two of the four Nd sites are partially occupied to maintain charge neutrality due to Pt(IV) oxidation state.

## Abstract

A new platinate was
recently discovered when Nd2O3 was explored
as a platinum capture material in the Ostwald
process, formed by a direct reaction between gaseous PtO2 and Nd2O3. The crystal structure of this new
platinate and its composition, Nd10.67Pt4O24, are here reported for the first time. The compound is synthesized
either by a direct reaction between PtO2(g) and Nd2O3 or by the citric acid chemical
route. Based on 3-dimensional electron diffraction data and Rietveld
refinement of high-resolution synchrotron and neutron powder diffraction
data, we describe its crystal structure in space group I41/a. The compound is structurally related to the
Ln11–xSrxIr4O24 (Ln = La, Pr, Nd, and Sm) phases
with a double perovskite (A2BB’O6)-like
crystal structure with A-site cation deficiency. Owing to the fixed
oxidation state of Pt(IV), two of the four Nd sites are partly occupied
to provide charge neutrality, with Nd4 taking a split position. On
heating, Nd10.67Pt4O24 decomposes
into Nd2O3 and Pt. A plateau in the thermogravimetric
curves measured in 33 vol % O2 in N2 indicates
the presence of an intermediate Pt(II) phase at around 960 °C,
probably isostructural with La4PtO7.