Structural, vibrational and optical characterisations of Li₂Ba₃(P₂O₇)₂:Cr³⁺ by solid-state reaction method

ABSTRACT

Cr³⁺ doped Li₂Ba₃(P₂O₇)₂ pyrophosphate nanopowder was successfully synthesised by solid-state reaction technique. The nanopowder was characterised by several techniques. X-ray diffraction analysis reveals orthorhombic crystal structureand average crystallite size values 34.21 and 28.41 nm are determined by Debye Scherrer’s formula and Williamson-Hall (W-H) method. The morphology displayed both SEM and HR-TEM images are irregular stone-like shapes. EDS analysis confirms the constituted elements. The SAED patterns of HR-TEM with well matched with XRD data. FT-IR and Raman spectra analysis confirmed incorporation of Cr³⁺ in the Li₂Ba₃(P₂O₇)₂ pyrophosphate nanopowder. The EPR spectrum exhibited signal at g = 1.968 which is attributed to interaction between Cr³⁺ and Cr³⁺ exchange pair. The site symmetry of Cr³⁺ ions occupy a distorted octahedral. Photoluminescence spectrum exhibited bands correspond to ultraviolet, blue and green regions. The evaluated CCT of 6517 K indicates yellowish-green emission near cold light which reveals that the present prepared sample is useful for LEDs applications.

KEYWORDS:

• Solid state reaction method
• chromium ion doped

Acknowledgments

One of the authors, N.Ch. Anjaneyulu is thankful to CSIR-UGC-NET for providing financial support through NET-JRF scheme (NTA Ref. No. 201610120900 dated 01.04.2021) to carry out the research work.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Authorship contribution statement

N.Ch. Anjaneyulu: Data curation, Writing-original draft, funding acquisition. Y.V.K. Suresh: Writing-review& editing, Methodology. G. Vasu: Formal analysis, investigation, G. Venkata Ramana: visualisation and formal analysis. R.V.S.S.N. Ravikumar: Conception, Writing-Review & Editing and Direction.

Data availability statement

Data will be made available on request.

Prime Novelty statement

Cr³⁺ doped Li₂Ba₃(P₂O₇)₂ pyrophosphate nanopowder was prepared and studied by solid-state reaction technique. The average crystallite size was evaluated from Deby Scherrer’s formula and compared to W-H method. SEM and HR-TEM images at various magnifications show agglomerated stone-like structures. The elemental chemical composition of the sample was determined using EDS analysis and determined compositions of elements Li, O, P, Ba and Cr. The characteristic optical absorption spectra of Cr³⁺ ion and the various optical field parameters were evaluated from the experimental data. The EPR spectrum confirms the octahedral site symmetry of the host lattice ion and the crystal field parameters are calculated. The chromaticity coordinates x = 0.302, y = 0.409 place the colour yellowish-green in the CIE chromaticity diagram. The sample has a CCT value of 6517 K and CRI of 42%, findings suggest that the processed material is suitable for LEDs and lighting applications.

Additional information

Funding

The work was supported by the University Grants Commission - South Eastern Regional Office [NTA Ref. No. 201610120900 dated 01.04.2021].