# Effects of Anionic Groups on Structural and Luminescent Properties of ZnO:Sm3+ Phosphors Synthesized via Combustion Method

## TL;DR

This paper studies how different anionic groups affect the structure and light emission of Sm3+-doped ZnO phosphors made through combustion synthesis.

## Contribution

The study demonstrates how anionic groups like BO33− and PO43− influence crystal structure and luminescence in ZnO-based phosphors.

## Key findings

- Borate and phosphate anions induce new crystalline phases with distinct structures and enhanced luminescence.
- Zn4B6O13:Sm3+ shows the most intense photoluminescence and high color purity in the orange region.
- Sulfate anions do not form new phases but leave only minor sulfur traces on ZnO surfaces.

## Abstract

BO33−, PO43−, and SO42− anionic groups were used to study their effects on the structure and luminescence of Sm3+-doped ZnO. ZnO, ZnO:Sm3+, ZnO, Zn4B6O13:Sm3+, and Zn2P2O7:Sm3+ phosphors were successfully synthesized via combustion synthesis. While BO33− and PO43− ions led to the formation of new crystalline phases, the sulfate precursor decomposed during synthesis, yielding ZnO with only minor surface sulfur traces. The XRD results revealed the formation of wurtzite crystal structures in the ZnO, ZnO:Sm3+, and ZnO-SO4:Sm3+ samples, while a complete change of structure was observed after the incorporation of borate (BO33−) and phosphate (PO43−) ions into ZnO:Sm3+ to Zn4B6O13:Sm3+ and Zn2P2O7:Sm3+, respectively. The structures for borate and phosphate ions were confirmed as cubic (Zn4B6O13) and monoclinic (Zn2P2O7) crystal structures, respectively. The morphological studies of ZnO:Sm3+ and ZnO-SO4:Sm3+ were characterized by aggregated particles with different shapes and sizes. Zn4B6O13 and Zn2P2O7 samples were characterized by having cubic and rough surfaces, respectively. The oxidation state of the Sm ions was confirmed by XPS analysis. The photoluminescence studies revealed a broad-band emission for the ZnO:Sm3+ and ZnO-SO4:Sm3+ materials and characteristic Sm3+ emissions (from the 4G5/2 level to lower states 6HJ (J = 5/2, 7/2, 9/2, and 11/2)) for the Zn4B6O13 and Zn2P2O7 samples. Enhanced emissions were observed after the incorporation of anionic group systems. The most intense PL emission was observed from the Zn4B6O13 phosphor material. The CIE calculations revealed that the best color purity results were from Zn4B6O13, which lay in the orange region with 98% color purity.